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First Nobel Prizes awarded.

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Edward VII becomes King of United Kingdom

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Second Boer War ends

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Cuba gains independence from the United States

Cuba gained formal independence from the U.S. on May 20, 1902, as the Republic of Cuba. Under Cuba's new constitution, the U.S. retained the right to intervene in Cuban affairs and to supervise its finances and foreign relations. Under the Platt Amendment, the U.S. leased the Guantánamo Bay naval base from Cuba.

https://en.wikipedia.org/wiki/Republic_of_Cuba_(1902%E2%80%931959)
Saravia Melina Belen

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First controlled heavier-than-air flight of the Wright Brothers

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Russo-Japanese War starts

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Albert Einstein's formulation of relativity.

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World War I begins

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Russian Revolution (1905)

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The U.S. Declares War

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WESTERN and ITALIAN FRONTS, 1917

Strategies for 1917

In planning their effort on the Western Front in 1917, Britain and France put hope in a French general, Robert Nivelle. Nivelle was an artillery officer who had become a hero at Verdun and famous for his declaration, referring to the Germans, that "they will not pass." He believed he had invented the formula for a successful offensive against the Germans: a massive, denser, creeping bombardment that would breakdown the German defenses, followed closely by a massive assault of troops. He declared that if he did not produce a breakthrough within the first 48 hours of battle he would stop the offensive rather than shed more blood.

The Germans, meanwhile, were planning to cripple Britain with their submarine offensive. They planned to remain on the defensive on the Western Front in 1917, and in places on that front their military secretly withdrew to what was known as the Hindenburg Line - the Germans making their front line straighter, twenty-five miles shorter, and stronger.

On April 5, the French began the shelling as the first step in Nivelle's offensive, shelling that continued to April 15. Meanwhile, on the 9th, a British offensive began that was designed to pull Germans away from the impending French offensive, and it was costly in British lives. Nivelle began his assault with troops on the 16th, and his forces in the center and right flanks advanced a mile and a half or two miles, but his left flank, supported by the first few tanks in warfare, failed. German machine guns continued killing numerous attackers. Nivelle's hoped for breakthrough did not happen. But admitting defeat was too much for General Nivelle. Rather than call off his offensive as he had promised, he pushed on, and the slaughter continued. Weary French soldiers, fed up with the prospect of death and what they believed were government lies about the war, mutinied, led by older veterans of the war. Soldiers being transported to the front ganged up on their officers, against military policemen and against railway men taking them to the front. An entire division that had fought at Verdun refused to go into battle. And the revolt spread to half the French army.

Stretches along the French front were undefended, but the Germans, remaining on the defensive, were not aggressively appraising the enemy lines and failed to notice.

French civilians joined the unrest. People demonstrated in the streets. Labor went out on strike. The French high command managed to keep the rebellion a secret from the outside world. Nivelle was replaced by a general who had long believed in a defensive strategy: Henri Pétain. Pétain doubled soldier leave-times, and he improved their food. He had ringleaders of the mutiny shot or sent to Devil's Island. In some rebellious units, every tenth man was shot as a demonstration that authority had to be obeyed. French troops were told there would be no more offensives. Moved by Germany's renewed submarine warfare, the US had declared war on Germany in April, and by mid-June the crisis in France had passed, with soldiers defending France's entire line and France waiting for the arrival of troops from the United States.

The Germans remained focused on their submarine offensive, which had begun in February and was sinking ships at a rate that posed a great danger to Britain. Lloyd-George urged a new convoy system - convoys of warships to accompany freighters. Most of Britain's admirals resisted the idea, complaining, among other things, that it would put "too many eggs in one basket" and present too big of a target for the Germans. The commander in chief of Britain's navy, Admiral David Beatty, supported Lloyd-George. Admiral William Sims of the United States Navy also supported the convoy system, and the first convoy began at the end of May.

A British offensive in Flanders began on June 7, the primary goal of which was to clear the Belgian coast of Germany's submarine bases. This offensive was preceded by a British artillery bombardment announcing its coming, a bombardment that could be heard in London. Around the Belgian town of Ypres, the British advanced only a couple of miles - another failure. But plans were made for another assault. A preparatory air offensive began on July 11, with 500 British and 200 French aircraft. Artillery bombardment began on July 18. The assault on the ground began on July 31, and it brought no appreciable gains. Bombardments had destroyed water drainage in the area, and with the heavy rains the battlefields had become soft mud and contiguous pools of water-filled shell holes. Men easily sank up to their waists. Movement was most difficult, but the British commander, Douglas Haig, ordered the advance to continue anyway, and by November the British had lost another 300,000 as dead or wounded.

The British and the French had been improving their ability to calibrate artillery barrages, keeping artillery rounds "just over the shoulders" of their advancing troops while keeping the Germans pinned down. And the British had been developing their new tanks - a step up from armored cars and from tractors that had been used to pull artillery. The British had used eleven tanks without success in an attack at the Somme in 1916. On November 20, 1917, the British used a large number of tanks - 381 - for the first time in an offensive near Cambrai, about 40 miles south of Ypres. The tanks ran in front of and with their troops in a surprise attack - an attack without preparatory artillery shelling. A breakthrough was made along a six-mile stretch of front. The British took 7,500 German prisoners and captured 120 guns, with few casualties. They had made a bulge forward in their line against the Germans, but with their previous losses in 1917 they lacked the reserves needed to keep going. Then the Germans counterattacked in a flanking maneuver, and the British fell back.

The Italian Front

An Italian offensive that had been planned to help the French and British had begun in May, with 38 Italian divisions massed along its mountainous front against 14 Austrian divisions. The Italians gained little ground, and they lost 157,000 in dead and wounded and the Austrians 75,000, approximately the number of Union and Confederate dead in the entire US Civil War.

In August, Italy launched its second offensive for the year, while enjoying a two to one advantage in men over the Austrians. The Austrians fell back. German troops again went to the rescue of the Austrians. The Germans wished to see Italy knocked out of the war in 1917, to join Serbia (knocked out in 1915) and Romania (knocked out in 1916). But facing a British offensive the Germans were able to spare only six divisions from its Russian front. A combined German and Austrian counter-offensive against Italy began along the lower elevations on the eastern half of the Austrian-Italian front. And in late October they broke through the Italian line, with a great battle being fought at the little town of Caporetto. The Italians fell back in a rout - more the fault of Italy's military leaders than its rank and file. Some Italian units fought with bravery and determination, but the breakdown of their front against Austria broke their morale.

The unexpected collapse of the Italian front was more than the Germans had been prepared for. The Germans and Austrians were unable to exploit it. Six French and five British divisions arrived in Italy and shored up the Italian defense line along the Piave River, and the war had become more popular with the Italian public as they sought revenge against their nation's humiliation.

Sources

The First World War: A Complete History, by Martin Gilbert, 1996

Copyright © 1998-2014 by Frank E. Smitha. All rights reserved.

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WESTERN and ITALIAN FRONTS, 1917 In planning their effort on the Western Front in 1917, Britain and France put hope in a French general, Robert Nivelle. Nivelle was an artillery officer who had become a hero at Verdun and famous for his declaration, referring to the Germans, that "they will not pass."

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the UNITED STATES DECLARES WAR (1 of 2)

The US against German strategy | the United States prepares for War: 1917

The US against German strategy

In his 1916 campaign for re-election Wilson complained to advisors about his campaign slogan "he kept us out of war." Mindful of the emotionalism in 1915 with the sinking of the Lusitania, he spoke of his being powerless before any tide of opinion that might sweep the nation as the result of some "damned" German submarine captain's "calculated outrage." But, during the remainder of his 1916 electioneering, Wilson went along with the campaign slogan, while his campaign continued with other slogans such as peace with honor, prosperity, preparedness, and the eight-hour day. Wilson's Republican opponent, Charles Evan Hughes, attacked Wilson for not being tough enough on the Entente powers, meaning the British - a position that appealed to the Irish. Theodore Roosevelt sided with the Republicans and attacked Wilson for using "high sounding words" and, referring to Wilson's failures in Mexico, giving the nation "shabby deeds."

President Woodrow Wilson, 1917

In November, Wilson won 49 percent of the vote to 46 percent for Hughes. Wilson then turned his attention to urging Europe's warring nations to negotiate a compromise settlement - a peace without victory for either side. He was opposed to the kind of alliances that had accompanied Europe's going to war, and he proposed a peace in which all the warring parties and neutrals would join a League of Nations, a league that would guarantee to all nations "fundamental rights, equal sovereignty, freedom from aggression, freedom of the seas, and eventual disarmament." The League of Nations, he announced, would "ensure peace and justice throughout the world."

Wilson's call for a negotiated end to the war created a stir in Europe. Britain's response was that Germany should withdraw from the territories it occupied and pay the Entente powers for damages it had caused, and the French continued to insist that Germany withdraw from their territory. In Germany, the Social Democratic Party announced that it favored a compromise peace, a peace without annexations of territory - a reestablishment of the borders of 1914. In the United States, hostility toward Britain was at a high point because of Britain's handling of the Irish rebellion, and Wilson was fed up with Britain for its indifference to his peace proposals, its continuing violation of the rights of US and other neutral shipping on the high seas, its censoring American mail, and its blacklisting US companies that traded with Germany and Austria-Hungary.

Germany's hawkish newspapers and others continued to oppose any compromise. For them there was no substitute for military victory. Some Germans believed that the United States was already in effect in the war on the side of Britain. Germany's Supreme Command assured King William that if submarine warfare brought the United States into the war, Britain would be forced to sue for peace before US troops could arrive in significant numbers. Many were inclined to accept the judgment of their nation's leading military men on military matters. And so too was Kaiser Wilhelm, who accepted their analysis.

Kaiser Wilhelm. After 1916 Germany was largely in the hands of his military.

Eugene Debs (1912). In 1917 he had simplified the war to a squabble over profits.

Wilhelm was nervous and wanted peace. He was alarmed about the suffering of his subjects and disgusted by Britain's naval blockade. And he also wished for a military victory. He was determined to carry out his role as Germany's God-appointed ruler. His government notified Washington of its intentions to resume unrestricted submarine warfare. It offered American ships passage to one British port a week, at Falmouth - a ship that, to avoid being torpedoed, had to be marked by flags, painted with certain signs, and had to follow a described sea lane across the Atlantic. The Wilson administration rejected all this, and on January 31, 1917, the Germans began their new program of submarine warfare.

Wilson, under attack in the United States for being too soft, responded with a call for "armed neutrality," which meant the arming of US merchant ships to defend themselves against submarines. The British moved to influence opinion in the United States, and on February 28 it made public a telegram that Germany's new Secretary of State, Arthur Zimmermann, had sent in mid-January to the German minister in Mexico. The telegram advised the minister in Mexico that war between the United States and Germany might come with Germany's new submarine offensive. He said that Germany would offer Mexico an alliance with Germany and promised Mexico the return of Arizona, New Mexico and Texas. Britain's release of the telegram had an impact. A wave of indignation swept across the US, the indignation that Wilson had feared.

During the month of March, Americans debated whether to go to war. Pacifists in the United States had some stature, with roots going back to the 19th century in the abolitionist, woman's suffrage and labor movements. The socialist leader, Eugene Debs, came out of retirement and described the war as a squabble over profits for businessmen and munitions makers. Socialists accused big business of fomenting war in order to profit from arms sales, and they complained that the United States was going to war for the capitalist class at the expense of the working class. Anarchists, leftist labor leaders, pacifist Christian ministers, various editors and a few politicians held firm against the war. But millions favored war, believing that the US should stand up and fight for its rights. Theodore Roosevelt was with those favoring war. He still believed that fighting wars was spiritually uplifting. Russia had overthrown Tsar Nicholas in February, and it was argued that the US would be fighting a war against autocracy.

A majority in Congress favored war, and Wilson found his advisors unanimously in favor of war. Wilson feared that war might bring a spirit of brutality to the US and jeopardize reforms. He agonized. No evidence exists that he was influenced by a desire to serve armament manufacturers or to save the investments of those who had been lending money to the Entente powers - largely men who had opposed him in his run for office in 1916 and to whom Wilson owed nothing.

Wilson came down on the side of his advisors, and he created a rationale for his decision. He went before a joint session of Congress and announced that the United States would not choose "the path of submission." The world, he told Congress and the nation, must be "made safe for democracy." He called for a new balance of power. At the end of his speech, when he asked for a declaration of war, Congress exploded in applause.

On April 6 the House of Representatives voted 373 to 50 in favor of declaring war, and the Senate voted in favor 82 to 6. Rather than having been made somber by the weight of their decision, congressmen greeted the results of their votes by standing on their chairs, waving their American flag lapel pins and cheering.

The evangelist Billy Sunday was cheered by the decision, and his view was echoed by the Los Angeles Times, which joined Billy Sunday in claiming that the United States was on its way to fighting "Christ's war." There were religious leaders who protested that the war was a violation of Christianity. A few Americans were embittered, and some joined those who Wilson as acting on behalf of big business. But many who had opposed going to war or had harbored doubts about it now believed that it was their duty to support the war effort. War meant that young American men would die, and the patriotic thing to do was to lend a hand in the coming struggle.

Copyright © 2000-2014 by Frank E. Smitha. All rights reserved.

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the UNITED STATES DECLARES WAR (1 of 2) The US against German strategy | the United States prepares for War: 1917 In his 1916 campaign for re-election Wilson complained to advisors about his campaign slogan "he kept us out of war."

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SPENGLER, DURKHEIM and WEBER (1 of 2)

Oswald Spengler, Spirit and Decline | The Sociologists Durkheim and Weber

Oswald Spengler, Spirit and Decline

Another German describing the world and what should be done about it was Oswald Spengler. He had studied math, science, history and philosophy, and he wrote The Decline of the West, first published in 1918. It was popular in Germany. There, in the wake of defeat in the Great War, people thought the world was going to hell.

Spengler did some old-fashioned idea spinning. He called it "penetrating recognition." He complained that history written by others was just facts. His approach was old-fashioned too in his adherence to the concept of "essence." He tried employing his penetrating recognition to grasp the essence of civilizations other than his own. He came up with the grand conclusion that each civilization was an isolated entity animated by a dominant idea or world view ( weltanschauung). Each civilization, he claimed, had its "soul," or "spirit," a style of art and thought that grows and decays.

He wrote: "Every Culture [is] ... unmistakable in its tendency." He included in this tendency "dark metaphysical relations" and a "soul-myth called Will, Force and Deed." He wrote vaguely of a culture having "ripened to its limit," of "life symbols," and a "high plane of contemplation." He wrote that "great events of history were not really achieved by peoples; they [the events] themselves created the peoples."

Spengler noted that the way history was being written by others was a revealing sign "that our path is downward" - in other words in a phase of cultural decline.

In addition to other historians as villains, he added urban growth. He wrote:

Long ago the country bore the country-town and nourished it with her best blood. Now the giant city sucks the country dry, insatiably and incessantly demanding and devouring fresh streams of men, till it wearies and dies in the midst of an almost uninhabited waste of country.

... In place of a type-true people, born of and grown on the soil, there is a new sort of nomad, cohering unstably in fluid masses, the parasitical city dweller, traditionless, utterly matter-of-fact, religionless, clever, unfruitful, deeply contemptuous of the countryman and especially that highest form of countryman, the country gentleman.

It is the Late city that first defies the land, contradicts Nature in the lines of its silhouette, denies all Nature. It wants to be something different from and higher than Nature.

As a man of culture, Spengler included in his writings sprinklings of Hegel, Goethe, Nietzsche, and others, building, he suggested, on what passed as wisdom from the old greats. Hegel's belief that history was a journey of spirit was compatible with Spengler's view of history.

Spengler entertained a great man theory of history. He saw great men as embodying a spirit quality that elevated a civilization. Mustering his power at penetrating recognition and understanding great men, Spengler voted for Hitler in 1932.

Spengler saw democracy as "decadent, and with his "penetrating recognition" he looked with approval upon the spirit of "Prussianism" - a militaristic authoritarianism. He praised the "kind of commanding that makes obedience a proud, free and noble habit."

But Spengler became disappointed with Hitler. He met Hitler after Hitler became chancellor, and he found him insufficiently cultured and therefore inadequate as a Great Man. Also he thought that Hitler was not mobilizing Germany's strength adequately enough to meet the challenges of Germany's enemies.

Spengler died in 1936, not long after writing that Man is,

... too shallow and cowardly to endure the fact of the mortality of everything living. He wraps it up in rose-colored progress-optimism, he heaps upon it the flowers of literature, he crawls behind the shelter of ideals so as not to see anything.

Copyright © 1998-2018 by Frank E. Smitha. All rights reserved.

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SPENGLER, DURKHEIM and WEBER (1 of 2) Oswald Spengler, Spirit and Decline | The Sociologists Durkheim and Weber Another German describing the world and what should be done about it was Oswald Spengler. He had studied math, science, history and philosophy, and he wrote The Decline of the West, first published in 1918.

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Civil War in Russia and the Rise of Lenin

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MUSSOLINI and FASCISM in ITALY (1 of 5)

Romantic Heroism in War | Frustration for Mussolini in 1919 | 1920: a Failed Revolution and a Good Year for Mussolini | Road to Power in 1921-22 | Prime Minister Mussolini Increases His Power

Heroism in War

World War I - or the Great War as it was also called - elevated some of Italy's young men who were proud to be combatants for their nation. For many Italians the war elevated their pride for their nation, and there was the sense that Italy had a common cause and should not be divided by class antagonisms. One such Italian, who was proud to have fought in the war, was Benito Mussolini.

Mussolini was the son of an impoverished worker-intellectual, a blacksmith, who named his son after the 19th century Mexican revolutionary, Benito Juarez. Benito Mussolini was a bright boy and a voracious reader in his youth. He hated the rich. More accurately, he envied the rich. He became a school teacher, and he became editor of the Socialist Party newspaper.

In 1915, as Italy pondered whether to go to war, Mussolini broke with the pacifism of the socialists. He editorialized for Italy's involvement in the war on the side of the Allies, claiming that France's defeat would end liberty in Europe. He argued that Italy's involvement in the war would hasten the socialist revolution. He did not want Italy to miss involvement in what he would call a grand drama. The Socialist Party responded by expelling him. So Mussolini started his own newspaper, The People of Italy, receiving funds from the French.

Prime Minister Mussolini

Mussolini was so excited about the war that when Italy declared war he joined Italy's prestigious Bersaglieri regiment as a private. He liked the trotting and getting into shape - stomach in and chest out. He was sent to the front, and in February 1917, after six months, he was wounded during hand grenade practice. He was hospitalized for months, and during convalescence he took up the cause of praising his nation's soldiers and veterans. By October 1917 he was back at his newspaper in Milan, and later that year he was blaming "defeatists" and "the politicians" for failure at the front - the great rout after the battle at Caporetto.

Mussolini advanced himself by publishing his Diary of the War. His view of international events was Darwinist. The masthead of his paper glorified armed struggle. It read: "He who has steel has bread." His paper attacked those, including the Socialist Party, who called for peace.

The war did not go as well as for Italy as Mussolini had hoped, and the nation was suffering economically. People were casting about for targets of blame, and in February 1918, Mussolini joined those who spoke with disgust about parliamentary squabbling. Mussolini described parliamentary democracy as "effete." By now he had forgotten about the liberty he had claimed might be lost with France's defeat. Italy, he said, should set things right by making a clean sweep. Italy, he announced, needed a dictator. And advocating patriotism, he attacked what he called the "sickly internationalism" of Lenin and Wilson.

Copyright © 1998-2018 by Frank E. Smitha. All rights reserved.

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MUSSOLINI and FASCISM in ITALY (1 of 5) Romantic Heroism in War | Frustration for Mussolini in 1919 | 1920: a Failed Revolution and a Good Year for Mussolini | Road to Power in 1921-22 | Prime Minister Mussolini Increases His Power World War I - or the Great War as it was also called - elevated some of Italy's young men who were proud to be combatants for their nation.

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The treaty of Versailles held Germany responsible for the war and imposed harsh penalties to them.

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Prohibition in the United States

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home | 1901-WW2 Index

ECONOMICS: the AUSTRIAN SCHOOL and KEYNES (1 of 2)

Austrian School of Economics | John Maynard Keynes

Austrian School of Economics

Carl Menger (1840-1921) addressed the "diamond-water paradox" that had been puzzling classical economists: the fact that humanity finds diamonds more valuable than water although water is far more important. Like the philosopher Schopenhauer, Menger concluded that people followed impulses more than reason. Menger focused on the uncertainties in human behavior. He asserted that complete knowledge of what is going to happen economically does not exist and that decisions based on expectations of what will happen involve risk. Producers take a risk because they cannot predict with certainty that what they receive in sales will be greater than their production costs. As obvious as this is to people today, it was not the economic model that was standard before Menger. With these observations Menger began what became known as the Austrian School of Economics. Menger believed that it was for entrepreneurs to collect and evaluate information as best they could and to take calculated risks - a view that more than a century later would appear as platitude.

Carl Menger. He introduced into pricing theory the public acting other than with logic.

A fellow Austrian, Eugen von Böhm-Bawerk (1851-1914), read Carl Menger's "Principles of Economics," became an adherent of his theories and wrote criticisms of Marx's economics, describing capitalists as helping rather than exploiting their employees. Böhm-Bawerk taught courses at the University of Vienna, and among his students were those who would become well-known as associates of the Austrian School of Economics: Joseph Schumpeter, Ludwig von Mises and Henryk Grossman.

Schumpeter taught at Harvard beginning in 1932 and was most influential. He described capitalism as in a failure-success continuum rather than just headed for failure as Marx had described. Schumpeter claimed that socialistic creations would hamper the beneficence of the individualist entrepreneur hero. Among his students was Alan Greenspan, chairman of the US Board of Governors of the Federal Reserve, 1987-2006, who shared with Ayn Rand a belief in the individualist enterpreneur hero.

Ludwig von Mises and Friedrich von Hayek were also from Europe. They ran from Hitler, von Mises to New York and Hayek to London. Hayek was responding to European fascism and to economic policies in the Soviet Union. He claimed that government guided by majority opinion made sense only if that opinion was independent of government. Hayek believed it best to leave a free play of ideas among the masses in economic matters. He and von Mises believed that people following their own innovations and doing what they see as in their interest is better than a few bureaucrats trying to constrict economic development into a plan of their making - no matter how bright the planners. Hayek won the Nobel Memorial Prize in Economic Sciences in 1974.

Copyright © 1998-2018 by Frank E. Smitha. All rights reserved.

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Economics: the Austrian School and Keynes

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home | 1901-WW2 Index ECONOMICS: the AUSTRIAN SCHOOL and KEYNES (1 of 2) Austrian School of Economics | John Maynard Keynes Carl Menger (1840-1921) addressed the "diamond-water paradox" that had been puzzling classical economists: the fact that humanity finds diamonds more valuable than water although water is far more important.

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In 1928 Alexander Fleming discovered penicillin .

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Stock markets crashed and the U.S slumped into the Great Depression

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First FIFA World Cup

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Ernst Mach was an Austrian physicist, 62 at the turn of the century. He criticized the concepts of space and time that were a part of Newtonian physics, and as such he preceded Albert Einstein. In 1930 Einstein would say that, "It is justified to consider Mach as the precursor of the General Theory of Relativity."

Albert Einstein, 1921

Mach was to have his name attached to speed delineations: mach 1, mach 2, et cetera. He described bullets traveling faster than the speed of sound compressing air and creating shock waves.

Philosophically, Mach went from scientific methodology to a philosophy of science - the two not always understood as different. Scientific methodology was a tool that said nothing about how one should think about anything outside the aspect of nature being studied. Many who used the tool of scientific methodology believed in the supernatural. Mach addressed the question of one's ability to know and preferred to draw a line, claiming that we cannot know more than what scientific methodology can tell us. He argued that all knowledge was based on sensation, perception and what can be measured.

Mach did not accept atomic theory because atoms could not be observed or measured. Then Einstein came along and pushed beyond Mach's conclusions that the speed of light is constant and that energy (as in explosions) is mass multiplied by the speed of light, squared. This Einstein did trying to understand gravitation and his Theory of Special Relativity.

A part of the new physics was quantum mechanics worked on by Einstein and others. Differences of opinion developed. Quantum mechanics was about causation with wave-like motion at the atomic and subatomic levels. Like all science it was about measurement. In Quantum mechanics what appeared to be the randomness of particles made measurement difficult or impossible. What could be measured were effects. The random aspect in Quantum mechanics was not about whether the universe moved in a determined fashion. But some lost sight of it as a measurement problem and turned it into a metaphysical question: determinism versus indeterminism.

After Mach's death, scientists confirmed Einstein's physics in a combination of empirical observation and mathematics. Mach's philosophy of science holding to observation and measurement remained.

Mach's philosophy was rejected, however, by Lenin in his book on epistemology titled Materialism and Empiriocriticism, published in 1909. It was to have little impact outside the Soviet Union. Lenin's book was a reaction to a three volume work Empiriomonism by Alexander Bogdanov, a fellow Russian Social Democrat. Bogdanov was trying to merge Marxism with the philosophy of Ernst Mach, Lenin stood firm in declaring that there was a reality outside of heads. We all know, he complained, that nature came before humans. Mach had not been denying that this was so. Wanting to avoid metaphysics, Mach merely left that question as outside the realm of science. But Lenin didn't like leaving an individual thinker chained to his subjectivity and he put Mach in league with the famous philosopher of solipsism, Bishop Berkeley.

The philosophy of science withstood Lenin's challenge. Soviet physics would be identical with physics in the West despite Lenin's dialectical materialism. Scientists would not find dialectal materialism useful in solving problems in physics, biology or other disciplines.

Einstein also dabbled in philosophy and his physics and philosophy were not entirely separable. Einstein has been described as "the architect of grand unification in physics." In his book, Conciliance (page 6), Edward O. Wilson writes of Einstein expressing pleasure at "his successful alignment of the microscopic physics of capillaries with the macroscopic, universe-wide physics of gravity."

Einstein believed in questioning his assumptions as he went along, and it was this questioning that took him along the great mental distance that he traveled. He pursued the philosophical consequences of his discoveries. He warned that concepts should be subject to revisions. Regarding time and space he had stretched the mind and moved from what had been Newtonian presuppositions. For Einstein, space could not be perceived as an absolute. Instead it was relative to a point of reference. And time was also not an absolute; it was relative to the movement of an object. This boggled the mind of those who wanted to go beyond their own subjectivity, perceptions and point of reference.

Einstein was bothered by the subjectivity, and he worked at establishing a-priori principles (knowledge independent of experience) upon which to rest theories in the physical sciences. In this he was trying to go beyond Mach's philosophy of sticking to observation and measurement.

Copyright © 1998-2018 by Frank E. Smitha. All rights reserved.

xxx

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Ernst Mach was an Austrian physicist, 62 at the turn of the century. He criticized the concepts of space and time that were a part of Newtonian physics, and as such he preceded Albert Einstein. In 1930 Einstein would say that, "It is justified to consider Mach as the precursor of the General Theory of Relativity."

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Hitler in Germany

Between 1933 and 1945 the Nazi totalitarian regime ruled Germany.

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1936
King Edward VIII's abdication
After ruling for less than one year, Edward VIII becomes the first English monarch to voluntarily abdicate the throne. He chose to abdicate after the British government, public, and the Church of England condemned his decision to marry the American divorcée Wallis Warfield Simpson.
On December 12, his younger brother, the duke of York, was proclaimed King George VI.

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Spain and Civil War

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The second World War (1939-1945)

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Pearl Harbor and War in Southeast Asia

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The man without qualities, by Robert Musil

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Ficciones, by Jorge Luis borges

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A continuación se muestra la composición de cada una de las versiones, tanto de los libros prístinos como de la posterior edición doble, Ficciones.

El jardín de senderos que se bifurcan Editar

Fue publicado en 1941 por Editorial Sur.​ Incluye un prólogo escrito por el autor y los siguientes cuentos: Tlön, Uqbar, Orbis Tertius, El acercamiento a Almotásim, Pierre Menard, autor del Quijote, Las ruinas circulares, La lotería en Babilonia, Examen de la obra de Herbert Quain, La biblioteca de Babel y El jardín de senderos que se bifurcan.

Fechas de publicaciones Editar

Se brindan aquí las fechas de la primera aparición de cada uno de los cuentos agrupadas según el medio en el que fueron publicadas y en orden cronológico.

La biblioteca de Babel: una versión anterior de esta obra fue publicada en el número 59 (en agosto de 1939), con el título La biblioteca total.​ A su vez, esa narración precursora está basada en una pieza de Kurd Laßwitz titulada Die Universalbibliothek.​

Tema del traidor y del héroe: este cuento se publicó en el año 1944.​ En septiembre de 2013 investigadores del Programa de investigación y búsqueda de fondos borgeanos de la Biblioteca Nacional de Argentina encontraron un manuscrito inédito con el párrafo final de la versión del cuento publicada en Ficciones, no incluido en la versión publicada en la revista Sur, entre las páginas del número 112 de dicha revista, el mismo donde originalmente se publicó el relato.​

Diario La Nación Editar

La forma de la espada: se publicó en julio de 1942.​

El fin: se publicó en 1953.​

El Sur: fue publicado por primera vez en 1953.​ El manuscrito original, datado en el mismo año, es uno de los pocos cuentos que Jorge Luis Borges escribió a mano. En junio de 2002 la casa Christie's lo remató a un precio de € 193.750.​

En otros medios Editar

El acercamiento a Almotásim: este es uno de los pocos relatos de Borges que se encuentran publicados en dos libros (otro caso importante es el del relato La intrusa, publicado originalmente en El Aleph y luego republicado en El informe de Brodie, en 1970).[cita requerida] Fue escrito en el año 1935.​

El jardín de senderos que se bifurcan: este cuento fue escrito en el año 1941, y publicado posteriormente en 1944 en la primera edición del libro que trata este artículo.​​

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A continuación se muestra la composición de cada una de las versiones, tanto de los libros prístinos como de la posterior edición doble, Ficciones.

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DEWEY, RUSSELL and WHITEHEAD (1 of 2)

John Dewey and Bertrand Russell | Alfred Whitehead

John Dewey and Bertrand Russell

John Dewey (1859-1952), according to Bertrand Russell, was "the leading living philosopher in America." Russell described Dewey as having "had a profound influence, not only among philosophers, but on students of education, aesthetics, and political theory."

Dewey believed in democracy, and he focused on the connection between democracy and people learning to think for themselves. He was against the old belief that common people were too dumb to know what was good for themselves and should remain dependent on authority in questions as to what was to be done. Dewey viewed schools, particularly elementary and secondary schools, as often repressive and often failing to promote exploration and growth. He advocated reforms designed to develop students' abilities at problem solving. He rejected the old method that limited children to learning by rote memory - which was to continue to exist in the authoritarian Islamic Madrasah schools in the late 20th and early 21st centuries.

Dewey wrote of education as something apart from propaganda:

Apart from the thought of participation in social life the school has no end nor aim. As long as we confine ourselves to the school as an isolated institution we have no final directing ethical principles, because we have no object or ideal. (Morris & Shapiro, 1993, p. 97)

Dewey's ideas on education were put into practice in 1896 at the University of Chicago Laboratory School, working on education theory for nursery schools through the 12th grade. It was labeled progressive education. It was described as learning by doing and involved becoming aware of a problem, defining the problem, proposing an hypothesis to solve it and evaluating the consequences of the hypotheses.

Dewey's move away from authoritarians included a belief that there should be at least a little student participation in decisions that affect their learning. He also had concern for the rights and academic autonomy of teachers. He was a member of the first teacher's union in New York City, and he was a founder of the American Association of University Professors.

Dewey was influenced by the publication of William James' Principles of Psychology, published in 1890. James was trained as a medical doctor and developed a philosophy of psychology that connected mental life and behavior with adaptation to one's environment, and James favored the development of psychological theories not readily testable by controlled experiments. Dewey participated in the study of psychology connected to his interest in theory of education.

In epistemology, Dewey was a pragmatist, like James. What Dewey called "instrumentalism" held that the truth or falsity of an idea was to be evaluated by how effectively it explains and predicts as opposed to how accurately it describes reality outside of our heads. This was more of the subjectivity detested by Lenin. And Bertrand Russell also objected. Russell wrote that he agreed with Dewey on many matters but that he regretted that he was "compelled to dissent" regarding Dewey's theory of knowledge.

Russell believed that people should consider their ability to ascertain truth with a degree of modesty. The perfect model of truth, wrote Russell, is the multiplication table, "which is precise and certain and free from all temporal dross." Russell was concerned with maintaining an awareness of "truth" as something independent of human control. This, he believed, would help limit an "intoxication of power" that had invaded philosophy and was "the greatest danger of our time."

Indeed, Mussolini considered himself a philosophical pragmatist. And in the 1920s some liberals in the United States praised him with enthusiasm for his having made capitalism work, including making trains run on time. And, still on the subject of pragmatism, there was praise in the US for Mussolini having turned back the tide of materialism and anti-clericalism and for having stimulated the virtue of patriotism. Before Mussolini was appointed prime minister, his Fascist squads had learned that violence applied against their opponents - socialists and liberals - worked. It was a truth about violence limited to circumstances in Italy at the time. But Russell was interested in truth beyond some immediate pragmatism.

Dewey and the World Wars

In his book, Icarius Syndrome, Peter Beinart describes Dewey and his colleague, Charles Beard, as two of the "loudest academic cheerleaders" for US entry into World War I. Beinart writes that Dewey predicted that wartime mobilization "would shift power from private to public hands, from selfish tribes to unbiased experts." (p. 40) The war turned Dewey and Beard into opponents of involvement in another war. In the early 1920s Dewey urged the US Congress to draft legislation to abolish war. (p. 59.)

According to Beinart, "in their opposition to American entry into World War II... Dewey and Beard were moral perfectionists, men who would allow the greatest of evils to triumph for fear of implicating themselves in the lesser evil of war." (p. 82)

Copyright © 2007-2015 by Frank E. Smitha. All rights reserved.

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DEWEY, RUSSELL and WHITEHEAD (1 of 2) John Dewey and Bertrand Russell | Alfred Whitehead John Dewey (1859-1952), according to Bertrand Russell, was "the leading living philosopher in America." Russell described Dewey as having "had a profound influence, not only among philosophers, but on students of education, aesthetics, and political theory."

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End of World War II
2nd September 1945

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The Holocaust ends after ~12 million deaths, including 6 million Jews.

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August 6th and 9th, 1945
Unite States ordered this bombing to Japanese Impire

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1946
First government of
Juan Domingo Perón

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Starts The Cold War.
A period of geopolitical tension between the Sovietic Union and the United States and their respective allies.

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Queen Elizabeth II becomes Monarch of the Commonwealth realms.

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The assassination of J. F. Kennedy

President John F. Kennedy was assassinated on November 22, 1963 at 12:30 p.m. while riding in a motorcade in Dallas during a campaign visit. Kennedy’s motorcade was turning past the Texas School Book Depository at Dealey Plaza with crowds lining the streets—when shots rang out. The driver of the president’s Lincoln limousine, with its top off, raced to nearby Parkland Memorial Hospital, but after being shot in the neck and head, Kennedy was pronounced dead at 1 p.m. He was 46 years old. A generation of Americans would forever remember where they were when they heard about the president’s assassination, as it would have a profound political and cultural impact on the nation.

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Dr. René Favaloro created the cardiac bypass

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The first manned mission to the Moon

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Starts civic-military dictatorship of Argentina.

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Introduction of the first mass-produced personal computers.

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Murder of John Lennon
On the evening of 8 December 1980, English musician John Lennon, formerly of the Beatles, was fatally shot in the archway of the Dakota, his residence in New York City. The perpetrator was Mark David Chapman, an American Beatles fan who had travelled from Hawaii.

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End of dictatorship in Argentina.

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1985 The Live Aid concert is held in order to fund relief efforts for the famine in Ethiopia during the time Mengistu Haile Mariam ruled the country;

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First use of DNA fingerprinting.

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Fall of the Berlin Wall; Revolutions of 1989 and collapse of the Soviet Bloc in Europe.

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SPENGLER, DURKHEIM and WEBER (1 of 2)

Oswald Spengler, Spirit and Decline | The Sociologists Durkheim and Weber

Oswald Spengler, Spirit and Decline

Another German describing the world and what should be done about it was Oswald Spengler. He had studied math, science, history and philosophy, and he wrote The Decline of the West, first published in 1918. It was popular in Germany. There, in the wake of defeat in the Great War, people thought the world was going to hell.

Spengler did some old-fashioned idea spinning. He called it "penetrating recognition." He complained that history written by others was just facts. His approach was old-fashioned too in his adherence to the concept of "essence." He tried employing his penetrating recognition to grasp the essence of civilizations other than his own. He came up with the grand conclusion that each civilization was an isolated entity animated by a dominant idea or world view ( weltanschauung). Each civilization, he claimed, had its "soul," or "spirit," a style of art and thought that grows and decays.

He wrote: "Every Culture [is] ... unmistakable in its tendency." He included in this tendency "dark metaphysical relations" and a "soul-myth called Will, Force and Deed." He wrote vaguely of a culture having "ripened to its limit," of "life symbols," and a "high plane of contemplation." He wrote that "great events of history were not really achieved by peoples; they [the events] themselves created the peoples."

Spengler noted that the way history was being written by others was a revealing sign "that our path is downward" - in other words in a phase of cultural decline.

In addition to other historians as villains, he added urban growth. He wrote:

Long ago the country bore the country-town and nourished it with her best blood. Now the giant city sucks the country dry, insatiably and incessantly demanding and devouring fresh streams of men, till it wearies and dies in the midst of an almost uninhabited waste of country.

... In place of a type-true people, born of and grown on the soil, there is a new sort of nomad, cohering unstably in fluid masses, the parasitical city dweller, traditionless, utterly matter-of-fact, religionless, clever, unfruitful, deeply contemptuous of the countryman and especially that highest form of countryman, the country gentleman.

It is the Late city that first defies the land, contradicts Nature in the lines of its silhouette, denies all Nature. It wants to be something different from and higher than Nature.

As a man of culture, Spengler included in his writings sprinklings of Hegel, Goethe, Nietzsche, and others, building, he suggested, on what passed as wisdom from the old greats. Hegel's belief that history was a journey of spirit was compatible with Spengler's view of history.

Spengler entertained a great man theory of history. He saw great men as embodying a spirit quality that elevated a civilization. Mustering his power at penetrating recognition and understanding great men, Spengler voted for Hitler in 1932.

Spengler saw democracy as "decadent, and with his "penetrating recognition" he looked with approval upon the spirit of "Prussianism" - a militaristic authoritarianism. He praised the "kind of commanding that makes obedience a proud, free and noble habit."

But Spengler became disappointed with Hitler. He met Hitler after Hitler became chancellor, and he found him insufficiently cultured and therefore inadequate as a Great Man. Also he thought that Hitler was not mobilizing Germany's strength adequately enough to meet the challenges of Germany's enemies.

Spengler died in 1936, not long after writing that Man is,

... too shallow and cowardly to endure the fact of the mortality of everything living. He wraps it up in rose-colored progress-optimism, he heaps upon it the flowers of literature, he crawls behind the shelter of ideals so as not to see anything.

Copyright © 1998-2018 by Frank E. Smitha. All rights reserved.

xxx

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SPENGLER, DURKHEIM and WEBER (1 of 2) Oswald Spengler, Spirit and Decline | The Sociologists Durkheim and Weber Another German describing the world and what should be done about it was Oswald Spengler. He had studied math, science, history and philosophy, and he wrote The Decline of the West, first published in 1918.

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1930's The Great Depression
Investors – also known as risk-takers – were pulling their money out of the economy, away from risk. Unemployment was rising, and consumers had less money to spend, adding to the downward spiral. Bankruptcies were more numerous. Bank loans were not being repaid. There was no federally guaranteed depositors insurance to inspire depositor confidence.

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Nazi invasion of Poland triggers the beginning of World War II in Europe.

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She died from typhus
https://es.wikipedia.org/wiki/Ana_Frank

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The Cold War didn't have direct combat between the U.S and the Soviet Union but it implied political manuvering and espionage.

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Containment

By the time World War II ended, most American officials agreed that the best defense against the Soviet threat was a strategy called "containment." In his famous "Long Telegram," the diplomat George Kennan (1904-2005) explained the policy: The Soviet Union, he wrote, was "a political force committed fanatically to the belief that with the U.S. there can be no permanent modus vivendi [agreement between parties that disagree]." As a result, America's only choice was the "long-term, patient but firm and vigilant containment of Russian expansive tendencies."

"It must be the policy of the United States," he declared before Congress in 1947, "to support free peoples who are resisting attempted subjugation...by outside pressures." This way of thinking would shape American foreign policy for the next four decades.

Did you know? The term 'cold war' first appeared in a 1945 essay by the English writer George Orwell called 'You and the Atomic Bomb.'

The Cold War: The Atomic Age

The containment strategy also provided the rationale for an unprecedented arms buildup in the United States. In 1950, a National Security Council Report known as NSC-68 had echoed Truman's recommendation that the country use military force to contain communist expansionism anywhere it seemed to be occurring. To that end, the report called for a four-fold increase in defense spending.

In particular, American officials encouraged the development of atomic weapons like the ones that had ended World War II. Thus began a deadly " arms race." In 1949, the Soviets tested an atom bomb of their own. In response, President Truman announced that the United States would build an even more destructive atomic weapon: the hydrogen bomb, or "superbomb." Stalin followed suit.

As a result, the stakes of the Cold War were perilously high. The first H-bomb test, in the Eniwetok atoll in the Marshall Islands, showed just how fearsome the nuclear age could be. It created a 25-square-mile fireball that vaporized an island, blew a huge hole in the ocean floor and had the power to destroy half of Manhattan. Subsequent American and Soviet tests spewed radioactive waste into the atmosphere.

The ever-present threat of nuclear annihilation had a great impact on American domestic life as well. People built bomb shelters in their backyards. They practiced attack drills in schools and other public places. The 1950s and 1960s saw an epidemic of popular films that horrified moviegoers with depictions of nuclear devastation and mutant creatures. In these and other ways, the Cold War was a constant presence in Americans' everyday lives.

The Cold War and the Space Race

Space exploration served as another dramatic arena for Cold War competition. On October 4, 1957, a Soviet R-7 intercontinental ballistic missile launched Sputnik (Russian for "traveling companion"), the world's first artificial satellite and the first man-made object to be placed into the Earth's orbit. Sputnik's launch came as a surprise, and not a pleasant one, to most Americans.

In the United States, space was seen as the next frontier, a logical extension of the grand American tradition of exploration, and it was crucial not to lose too much ground to the Soviets. In addition, this demonstration of the overwhelming power of the R-7 missile-seemingly capable of delivering a nuclear warhead into U.S. air space-made gathering intelligence about Soviet military activities particularly urgent.

In 1958, the U.S. launched its own satellite, Explorer I, designed by the U.S. Army under the direction of rocket scientist Wernher von Braun, and what came to be known as the Space Race was underway. That same year, President Dwight Eisenhower signed a public order creating the National Aeronautics and Space Administration (NASA), a federal agency dedicated to space exploration, as well as several programs seeking to exploit the military potential of space. Still, the Soviets were one step ahead, launching the first man into space in April 1961.

That May, after Alan Shepard become the first American man in space, President John F. Kennedy (1917-1963) made the bold public claim that the U.S. would land a man on the moon by the end of the decade. His prediction came true on July 20, 1969, when Neil Armstrong of NASA's Apollo 11 mission, became the first man to set foot on the moon, effectively winning the Space Race for the Americans.

U.S. astronauts came to be seen as the ultimate American heroes. Soviets, in turn, were pictured as the ultimate villains, with their massive, relentless efforts to surpass America and prove the power of the communist system.

The Cold War and the Red Scare

Meanwhile, beginning in 1947, the House Un-American Activities Committee ( HUAC) brought the Cold War home in another way. The committee began a series of hearings designed to show that communist subversion in the United States was alive and well.

In Hollywood, HUAC forced hundreds of people who worked in the movie industry to renounce left-wing political beliefs and testify against one another. More than 500 people lost their jobs. Many of these "blacklisted" writers, directors, actors and others were unable to work again for more than a decade. HUAC also accused State Department workers of engaging in subversive activities. Soon, other anticommunist politicians, most notably Senator Joseph McCarthy (1908-1957), expanded this probe to include anyone who worked in the federal government.

Thousands of federal employees were investigated, fired and even prosecuted. As this anticommunist hysteria spread throughout the 1950s, liberal college professors lost their jobs, people were asked to testify against colleagues and "loyalty oaths" became commonplace.

The Cold War Abroad

The fight against subversion at home mirrored a growing concern with the Soviet threat abroad. In June 1950, the first military action of the Cold War began when the Soviet-backed North Korean People's Army invaded its pro-Western neighbor to the south. Many American officials feared this was the first step in a communist campaign to take over the world and deemed that nonintervention was not an option. Truman sent the American military into Korea, but the Korean War dragged to a stalemate and ended in 1953.

In 1955, the United States and other members of the North Atlantic Treaty Organization (NATO) made West Germany a member of NATO and permitted it to remilitarize. The Soviets responded with the Warsaw Pact, a mutual defense organization between the Soviet Union, Albania, Poland, Romania, Hungary, East Germany, Czechoslovakia and Bulgaria that set up a unified military command under Marshal Ivan S. Konev of the Soviet Union.

Other international disputes followed. In the early 1960s, President Kennedy faced a number of troubling situations in his own hemisphere. The Bay of Pigs invasion in 1961 and the Cuban missile crisis the following year seemed to prove that the real communist threat now lay in the unstable, postcolonial "Third World."

Nowhere was this more apparent than in Vietnam, where the collapse of the French colonial regime had led to a struggle between the American-backed nationalist Ngo Dinh Diem in the south and the communist nationalist Ho Chi Minh in the north. Since the 1950s, the United States had been committed to the survival of an anticommunist government in the region, and by the early 1960s it seemed clear to American leaders that if they were to successfully "contain" communist expansionism there, they would have to intervene more actively on Diem's behalf. However, what was intended to be a brief military action spiraled into a 10-year conflict.

The End of the Cold War and Effects

Almost as soon as he took office, President Richard Nixon (1913-1994) began to implement a new approach to international relations. Instead of viewing the world as a hostile, "bi-polar" place, he suggested, why not use diplomacy instead of military action to create more poles? To that end, he encouraged the United Nations to recognize the communist Chinese government and, after a trip there in 1972, began to establish diplomatic relations with Beijing.

At the same time, he adopted a policy of "détente"-"relaxation"-toward the Soviet Union. In 1972, he and Soviet premier Leonid Brezhnev (1906-1982) signed the Strategic Arms Limitation Treaty (SALT I), which prohibited the manufacture of nuclear missiles by both sides and took a step toward reducing the decades-old threat of nuclear war.

Despite Nixon's efforts, the Cold War heated up again under President Ronald Reagan (1911-2004). Like many leaders of his generation, Reagan believed that the spread of communism anywhere threatened freedom everywhere. As a result, he worked to provide financial and military aid to anticommunist governments and insurgencies around the world. This policy, particularly as it was applied in the developing world in places like Grenada and El Salvador, was known as the Reagan Doctrine.

Even as Reagan fought communism in Central America, however, the Soviet Union was disintegrating. In response to severe economic problems and growing political ferment in the USSR, Premier Mikhail Gorbachev (1931-2022) took office in 1985 and introduced two policies that redefined Russia's relationship to the rest of the world: "glasnost," or political openness, and " perestroika," or economic reform.

Soviet influence in Eastern Europe waned. In 1989, every other communist state in the region replaced its government with a noncommunist one. In November of that year, the Berlin Wall-the most visible symbol of the decades-long Cold War-was finally destroyed, just over two years after Reagan had challenged the Soviet premier in a speech at Brandenburg Gate in Berlin: "Mr. Gorbachev, tear down this wall." By 1991, the Soviet Union itself had fallen apart. The Cold War was over.

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Cold War: Summary, Combatants, Start & End

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The Cold War rivalry between the United States and the Soviet Union lasted for decades and resulted in anti-communist suspicions and international incidents that led the two superpowers to the brink of nuclear disaster.

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The fall of the  Berlín wall

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Fotos: El 30º aniversario de la caída del muro de Berlín, en imágenes

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Los presidentes de Alemania, Polonia, la República Checa, Eslovaquia y Hungria han participado en los actos del momento que propició la reunificación alemana

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Nazi invasion of Poland triggers the beginning of World War II in Europe.

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Financial crisis often know as 'The lost decade'.

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Argentina and the United Kingdom and North Ireland fought to conquer the Malvinas Islands, Sandwich Island and South Georgia Island.

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The Chernobyl disaster was caused by a nuclear accident that occurred on Saturday 26 April 1986

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The Chernobyl disaster began on 26 April 1986 with the explosion of the No. 4 reactor of the Chernobyl Nuclear Power Plant, near the city of Pripyat in the north of the Ukrainian SSR, close to the border with the Byelorussian SSR, in the Soviet Union. It is one of only two nuclear energy accidents rated at seven-the maximum severity-on the International Nuclear Event Scale, the other being the 2011 Fukushima nuclear accident in Japan. The initial emergency response and subsequent mitigation efforts involved more than 500,000 personnel and cost an estimated 18billion roubles -roughly US$68billion in 2019, adjusted for inflation. It is considered the worst nuclear disaster in history.

The accident occurred during a test of the steam turbine's ability to power the emergency feedwater pumps in the event of a simultaneous loss of external power and coolant pipe rupture. Following an accidental drop in reactor power to near-zero, the operators restarted the reactor in preparation for the turbine test with a prohibited control rod configuration. Upon successful completion of the test, the reactor was then shut down for maintenance. Due to a variety of factors, this action resulted in a power surge at the base of the reactor which brought about the rupture of reactor components and the loss of coolant. This process led to steam explosions and a meltdown, which destroyed the containment building. This was followed by a reactor core fire which lasted until 4 May 1986, during which airborne radioactive contaminants were spread throughout the USSR and Europe. In response to the initial accident, a 10-kilometre (6.2 mi) radius exclusion zone was created 36 hours after the accident, from which approximately 49,000 people were evacuated, primarily from Pripyat. The exclusion zone was later increased to a radius of 30 kilometres (19 mi), from which an additional ~68,000 people were evacuated.

Following the reactor explosion, which killed two engineers and severely burned two more, an emergency operation to put out the fires and stabilize the surviving reactor began, during which 237 workers were hospitalized, of which 134 exhibited symptoms of acute radiation syndrome (ARS). Among those hospitalized, 28 died within the following three months. In the following 10 years, 14 more workers (9 of whom had been hospitalized with ARS) died of various causes mostly unrelated to radiation exposure. 15 childhood thyroid cancer deaths were attributed to the disaster as of 2011. A United Nations committee found that to date fewer than 100 deaths have resulted from the fallout. Model predictions of the eventual total death toll in the coming decades vary. The most widely cited study conducted by the World Health Organization in 2006 predicted 9,000 cancer-related fatalities in Ukraine, Belarus and Russia.

Background

Reactor cooling after shutdown

Reactor decay heat shown as % of thermal power from time of sustained fission shutdown using two different correlations. Due to decay heat, solid fuel power reactors need high flows of coolant after a fission shutdown for a considerable time to prevent fuel cladding damage, or in the worst case, a full core meltdown.

In power-generating operation, most of the heat generated in a nuclear reactor by its fuel rods is derived from nuclear fission, but a significant fraction (over 6%) is derived from the radioactive decay of the accumulated fission products, a process known as decay heat. This decay heat continues for some time after the fission chain reaction has been stopped, such as following a reactor shutdown, either emergency or planned, and continued pumped circulation of coolant is essential to prevent core overheating, or in the worst case, core meltdown. RBMK reactors, like those at Chernobyl, use water as a coolant, circulated by electrically driven pumps. The coolant flow rate is considerable - Reactor No. 4 had 1661 individual fuel channels, each requiring a coolant flow of 28 m ³/h (990 cu ft/h) at full reactor power, for a total of over 45 million litres per hour (12 million gallons per hour) for the entire reactor.

In case of a total power loss at the station, each of Chernobyl's reactors had three backup diesel generators, but they took 60-75 seconds to attain full load and generate the 5.5‑ megawatt output required to run one main pump. In the interim, special counterweights on each pump would enable them to provide coolant via inertia, thereby bridging the gap to generator startup. However, a potential safety risk existed in the event that a station blackout occurred simultaneously with the rupture of a 600-millimetre (24 in) coolant pipe (the so-called Design Basis Accident). In this scenario the emergency core cooling system (ECCS) needed to pump additional water into the core, replacing coolant lost to evaporation.

It had been theorized that the rotational momentum of the reactor's steam turbine could be used to generate the required electrical power to operate the ECCS via the feedwater pumps. The turbine's speed would run down as energy was taken from it, but analysis indicated that there might be sufficient energy to provide electrical power to run the coolant pumps for 45 seconds. This would not quite bridge the gap between an external power failure and the full availability of the emergency generators, but would alleviate the situation.

Safety test

The turbine run-down energy capability still needed to be confirmed experimentally, and previous tests had ended unsuccessfully. An initial test carried out in 1982 indicated that the excitation voltage of the turbine-generator was insufficient; it did not maintain the desired magnetic field after the turbine trip. The electrical system was modified, and the test was repeated in 1984 but again proved unsuccessful. In 1985, the test was conducted a third time but also yielded no results due to a problem with the recording equipment. The test procedure was to be run again in 1986 and was scheduled to take place during a controlled power-down of reactor No. 4, which was preparatory to a planned maintenance outage.

A test procedure had been written, but the authors were not aware of the unusual RBMK-1000 reactor behaviour under the planned operating conditions. It was regarded as purely an electrical test of the generator, not a complex unit test, even though it involved critical unit systems. According to the regulations in place at the time, such a test did not require approval by either the chief design authority for the reactor (NIKIET) or the Soviet nuclear safety regulator. The test program called for disabling the emergency core cooling system, a passive/active system of core cooling intended to provide water to the core in a loss-of-coolant accident, and approval from the Chernobyl site chief engineer had been obtained according to regulations.

The test procedure was intended to run as follows:

Test preparation

1. The test would take place prior to a scheduled reactor shutdown

2. The reactor thermal power was to be reduced to between 700 MW and 1,000 MW (to allow for adequate cooling, as the turbine would be spun at operating speed whilst disconnected from the power grid)

3. The steam-turbine generator was to be run at normal operating speed

4. Four out of eight main circulating pumps were to be supplied with off-site power, while the other four would be powered by the turbine

Electrical test

1. When the correct conditions were achieved, the steam supply to the turbine generator would be closed off, and the reactor would be shut down

2. The voltage provided by the coasting turbine would be measured, along with the voltage and RPMs of the four main circulating pumps being powered by the turbine

3. When the emergency generators supplied full electrical power, the turbine generator would be allowed to continue free-wheeling down

Test delay and shift change

The test was to be conducted during the day-shift of 25 April 1986 as part of a scheduled reactor shut down. The day shift crew had been instructed in advance on the reactor operating conditions to run the test, and, in addition, a special team of electrical engineers was present to conduct the one-minute test of the new voltage regulating system once the correct conditions had been reached. As planned, a gradual reduction in the output of the power unit began at 01:06 on 25 April, and the power level had reached 50% of its nominal 3,200 MW thermal level by the beginning of the day shift.

The day shift performed many unrelated maintenance tasks, and was scheduled to perform the test at 14:15. Preparations for the test were carried out, including the disabling of the emergency core cooling system. Meanwhile, another regional power station unexpectedly went offline. At 14:00, the Kiev electrical grid controller requested that the further reduction of Chernobyl's output be postponed, as power was needed to satisfy the peak evening demand, so the test was postponed.

Soon, the day shift was replaced by the evening shift. Despite the delay, the emergency core cooling system was left disabled. This system had to be disconnected via a manual isolating slide valve, which in practice meant that two or three people spent the whole shift manually turning sailboat-helm-sized valve wheels. The system would have no influence on the events that unfolded next, but allowing the reactor to run for 11 hours outside of the test without emergency protection was indicative of a general lack of safety culture.

The night shift had very limited time to prepare for and carry out the experiment. Anatoly Dyatlov, deputy chief-engineer of the Chernobyl Nuclear Power Plant, was present to supervise and direct the test. He was one of the test's chief authors and he was the highest-ranking individual present. Unit Shift Supervisor Aleksandr Akimov was in charge of the Unit 4 night shift, and Leonid Toptunov was the Senior Reactor Control Engineer responsible for the reactor's operational regimen, including the movement of the control rods. 25-year-old Toptunov had worked independently as a senior engineer for approximately three months.

Unexpected drop of the reactor power

The test plan called for a gradual decrease in reactor power to a thermal level of 700-1000 MW, and an output of 720 MW was reached at 00:05 on 26 April. However, due to the reactor's production of a fission byproduct, xenon-135, which is a reaction-inhibiting neutron absorber, power continued to decrease in the absence of further operator action, a process known as reactor poisoning. In steady-state operation, this is avoided because xenon-135 is "burned off" as quickly as it is created from decaying iodine-135 by the absorption of neutrons from the ongoing chain reaction, becoming highly stable xenon-136. With the reactor power reduced, high quantities of previously produced iodine-135 were decaying into the neutron-absorbing xenon-135 faster than the reduced neutron flux could "burn it off". Xenon poisoning in this context made reactor control more difficult, but was a predictable and well-understood phenomenon during such a power reduction.

When the reactor power had decreased to approximately 500 MW, the reactor power control was switched from LAR (Local Automatic Regulator) to the Automatic Regulators, in order to manually maintain the required power level. AR-1 then activated, removing all four of AR-1's control rods automatically, but AR-2 failed to activate due to an imbalance in its ionization chambers. In response, Toptunov reduced power to stabilize the Automatic Regulators' ionization sensors. The result was a sudden power drop to an unintended near- shutdown state, with a power output of 30 MW thermal or less. The exact circumstances that caused the power drop are unknown. Most reports attribute the power drop to Toptunov's error, but Dyatlov reported that it was due to a fault in the AR-2 system.

The reactor was now producing only 5% of the minimum initial power level prescribed for the test. This low reactivity inhibited the burn-off of xenon-135 within the reactor core and hindered the rise of reactor power. To increase power, control-room personnel removed numerous control rods from the reactor. Several minutes elapsed before the reactor was restored to 160 MW at 00:39, at which point most control rods were at their upper limits, but the rod configuration was still within its normal operating limit, with Operational Reactivity Margin (ORM) equivalent to having more than 15 rods inserted. Over the next twenty minutes, reactor power would be increased further to 200 MW.

The operation of the reactor at the low power level (and high poisoning level) was accompanied by unstable core temperatures and coolant flow, and, possibly, by instability of neutron flux. The control room received repeated emergency signals regarding the low levels in one half of the steam/water separator drums, with accompanying drum separator pressure warnings. In response, personnel triggered several rapid influxes of feedwater. Relief valves opened to relieve excess steam into a turbine condenser.

Reactor conditions priming the accident

The combined effect of these various actions was an extremely unstable reactor configuration. Nearly all of the 211 control rods had been extracted manually, and excessively high coolant flow rates through the core meant that the coolant was entering the reactor very close to the boiling point. Unlike other light-water reactor designs, the RBMK design at that time had a positive void coefficient of reactivity at low power levels. This meant that the formation of steam bubbles (voids) from boiling cooling water intensified the nuclear chain reaction owing to voids having lower neutron absorption than water. Unbeknownst to the operators, the void coefficient was not counterbalanced by other reactivity effects in the given operating regime, meaning that any increase in boiling would produce more steam voids which further intensified the chain reaction, leading to a positive feedback loop. Given this characteristic, reactor No. 4 was now at risk of a runaway increase in its core power with nothing to restrain it. The reactor was now very sensitive to the regenerative effect of steam voids on reactor power.

Test execution

Plan view of reactor No. 4 core. The number on each control rod indicates the insertion depth in centimeters one minute prior to the disaster.
neutron detectors (12)
control rods (167)
short control rods from below reactor (32)
automatic control rods (12)
pressure tubes with fuel rods (1661)

At 01:23:04, the test began. Four of the eight main circulating pumps (MCP) were to be powered by voltage from the coasting turbine, while the remaining four pumps received electrical power from the grid as normal. The steam to the turbines was shut off, beginning a run-down of the turbine generator. The diesel generators started and sequentially picked up loads; the generators were to have completely picked up the MCPs' power needs by 01:23:43. As the momentum of the turbine generator decreased, so did the power it produced for the pumps. The water flow rate decreased, leading to increased formation of steam voids in the coolant flowing up through the fuel pressure tubes.

Reactor shutdown and power excursion

At 01:23:40, as recorded by the SKALA centralized control system, a scram (emergency shutdown) of the reactor was initiated as the experiment was wrapping up. The scram was started when the AZ-5 button (also known as the EPS-5 button) of the reactor emergency protection system was pressed: this engaged the drive mechanism on all control rods to fully insert them, including the manual control rods that had been withdrawn earlier.

The personnel had already intended to shut down using the AZ-5 button in preparation for scheduled maintenance and the scram likely preceded the sharp increase in power. However, the precise reason why the button was pressed when it was is not certain, as only the deceased Akimov and Toptunov partook in that decision, though the atmosphere in the control room was calm at that moment. Meanwhile, the RBMK designers claim that the button had to have been pressed only after the reactor already began to self-destruct.

Steam plumes continued to be generated days after the initial explosion[37]

Consequently, injecting a control rod downward into the reactor in a scram initially displaced neutron-absorbing water in the lower portion of the reactor with neutron-moderating graphite. Thus, an emergency scram could initially increase the reaction rate in the lower part of the core. This behaviour was discovered when the initial insertion of control rods in another RBMK reactor at Ignalina Nuclear Power Plant in 1983 induced a power spike. Procedural countermeasures were not implemented in response to Ignalina. The IAEA investigative report INSAG-7 later stated, "Apparently, there was a widespread view that the conditions under which the positive scram effect would be important would never occur. However, they did appear in almost every detail in the course of the actions leading to the Chernobyl accident."

A few seconds into the scram, a power spike did occur, and the core overheated, causing some of the fuel rods to fracture. Some have speculated that this also blocked the control rod columns, jamming them at one-third insertion. Within three seconds the reactor output rose above 530 MW.

Instruments did not register the subsequent course of events; it was reconstructed through mathematical simulation. Per the simulation, the power spike would have caused an increase in fuel temperature and steam buildup, leading to a rapid increase in steam pressure. This caused the fuel cladding to fail, releasing the fuel elements into the coolant and rupturing the channels in which these elements were located.

Steam explosions

The reactor lid (upper biological shield)[39] nicknamed "Elena"[40] with torn off fuel channel piping is shown lying on its side where it came to rest in the explosion crater. The view transitions to showing the relative position of the paired steam tanks, reactor hall floor and roof trusses overlaid on the explosion crater. Source animation

As the scram continued, the reactor output jumped to around 30,000 MW thermal, 10 times its normal operational output, the indicated last reading on the power meter on the control panel. Some estimate the power spike may have gone 10 times higher than that. It was not possible to reconstruct the precise sequence of the processes that led to the destruction of the reactor and the power unit building, but a steam explosion-like the explosion of a steam boiler from excess vapour pressure-appears to have been the next event. There is a general understanding that it was explosive steam pressure from the damaged fuel channels escaping into the reactor's exterior cooling structure that caused the explosion that destroyed the reactor casing, tearing off and blasting the upper plate called the upper biological shield, to which the entire reactor assembly is fastened, through the roof of the reactor building. This is believed to be the first explosion that many heard.

This explosion ruptured further fuel channels, as well as severing most of the coolant lines feeding the reactor chamber, and as a result, the remaining coolant flashed to steam and escaped the reactor core. The total water loss combined with a high positive void coefficient further increased the reactor's thermal power.

A second, more powerful explosion occurred about two or three seconds after the first; this explosion dispersed the damaged core and effectively terminated the nuclear chain reaction. This explosion also compromised more of the reactor containment vessel and ejected hot lumps of graphite moderator. The ejected graphite and the demolished channels still in the remains of the reactor vessel caught fire on exposure to air, significantly contributing to the spread of radioactive fallout and the contamination of outlying areas. The explosion is estimated to have had the power equivalent of 225 tons of TNT.

After the larger explosion, several employees at the power station went outside to get a clearer view of the extent of the damage. One such survivor, Alexander Yuvchenko, recounts that once he stepped out and looked up towards the reactor hall, he saw a "very beautiful" laser-like beam of blue light caused by the ionized-air glow that appeared to be "flooding up into infinity".

Crisis management

Fire containment

Contrary to safety regulations, bitumen, a combustible material, had been used in the construction of the roof of the reactor building and the turbine hall. Ejected material ignited at least five fires on the roof of the adjacent reactor No. 3, which was still operating. It was imperative to put those fires out and protect the cooling systems of reactor No. 3. Inside reactor No. 3, the chief of the night shift, Yuri Bagdasarov, wanted to shut down the reactor immediately, but chief engineer Nikolai Fomin would not allow this. The operators were given respirators and potassium iodide tablets and told to continue working. At 05:00, Bagdasarov made his own decision to shut down the reactor, which was confirmed in writing by Dyatlov and Station Shift Supervisor Rogozhkin.

Shortly after the accident, firefighters arrived to try to extinguish the fires. First on the scene was a Chernobyl Power Station firefighter brigade under the command of Lieutenant Volodymyr Pravyk, who died on 11 May 1986 of acute radiation sickness. They were not told how dangerously radioactive the smoke and the debris were, and may not even have known that the accident was anything more than a regular electrical fire: "We didn't know it was the reactor. No one had told us." Grigorii Khmel, the driver of one of the fire engines, later described what happened:

We arrived there at 10 or 15 minutes to two in the morning ... We saw graphite scattered about. Misha asked: "Is that graphite?" I kicked it away. But one of the fighters on the other truck picked it up. "It's hot," he said. The pieces of graphite were of different sizes, some big, some small enough to pick them up [...] We didn't know much about radiation. Even those who worked there had no idea. There was no water left in the trucks. Misha filled a cistern and we aimed the water at the top. Then those boys who died went up to the roof-Vashchik, Kolya and others, and Volodya Pravik ... They went up the ladder ... and I never saw them again.

Anatoli Zakharov, a fireman stationed in Chernobyl since 1980, offered a different description in 2008: "I remember joking to the others, 'There must be an incredible amount of radiation here. We'll be lucky if we're all still alive in the morning.'" He also stated, "Of course we knew! If we'd followed regulations, we would never have gone near the reactor. But it was a moral obligation-our duty. We were like kamikaze."

It was thought by some that the core fire was extinguished by a combined effort of helicopters dropping more than 5,000 tonnes (11 million pounds) of sand, lead, clay, and neutron-absorbing boron onto the burning reactor. It is now known that virtually none of these materials reached the core. Historians estimate that about 600 Soviet pilots risked dangerous levels of radiation to fly the thousands of flights needed to cover reactor No. 4 in this attempt to seal off radiation.

From eyewitness accounts of the firefighters involved before they died (as reported on the CBC television series ), one described his experience of the radiation as "tasting like metal", and feeling a sensation similar to that of pins and needles all over his face. This is consistent with the description given by Louis Slotin, a Manhattan Project physicist who died days after a fatal radiation overdose from a criticality accident.

The explosion and fire threw hot particles of the nuclear fuel and also far more dangerous fission products (radioactive isotopes such as caesium-137, iodine-131, strontium-90, and other radionuclides) into the air. The residents of the surrounding area observed the radioactive cloud on the night of the explosion.

Radiation levels

The ionizing radiation levels in the worst-hit areas of the reactor building have been estimated to be 5.6 roentgens per second (R/s), equivalent to more than 20,000 roentgens per hour. A lethal dose is around 500 roentgens (~5 Gray (Gy) in modern radiation units) over five hours, so in some areas, unprotected workers received fatal doses in less than a minute. Unfortunately, a dosimeter capable of measuring up to 1,000 R/s was buried in the rubble of a collapsed part of the building, and another one failed when turned on. Most remaining dosimeters had limits of 0.001 R/s and therefore read "off scale". Thus, the reactor crew could ascertain only that the radiation levels were somewhere above 0.001 R/s (3.6 R/h), while the true levels were much higher in some areas.

Because of the inaccurate low readings, the reactor crew chief Aleksandr Akimov assumed that the reactor was intact. The evidence of pieces of graphite and reactor fuel lying around the building was ignored, and the readings of another dosimeter brought in by 04:30 were dismissed under the assumption that the new dosimeter must have been defective. Akimov stayed with his crew in the reactor building until morning, sending members of his crew to try to pump water into the reactor. None of them wore any protective gear. Most, including Akimov, died from radiation exposure within three weeks.

Evacuation

The nearby city of Pripyat was not immediately evacuated. The townspeople, in the early hours of the morning, at 01:23 local time, went about their usual business, completely oblivious to what had just happened. However, within a few hours of the explosion, dozens of people fell ill. Later, they reported severe headaches and metallic tastes in their mouths, along with uncontrollable fits of coughing and vomiting. As the plant was run by authorities in Moscow, the government of Ukraine did not receive prompt information on the accident.

Shevchenko then spoke over the phone to Volodymyr Shcherbytsky, general secretary of the Communist Party of Ukraine and de facto head of state, who said he anticipated a delegation of the state commission headed by Boris Shcherbina, the deputy chairman of the Council of Ministers of the USSR.

A commission was established later in the day to investigate the accident. It was headed by Valery Legasov, First Deputy Director of the Kurchatov Institute of Atomic Energy, and included leading nuclear specialist Evgeny Velikhov, hydro-meteorologist Yuri Izrael, radiologist Leonid Ilyin, and others. They flew to Boryspil International Airport and arrived at the power plant in the evening of 26 April. By that time two people had already died and 52 were hospitalized. The delegation soon had ample evidence that the reactor was destroyed and extremely high levels of radiation had caused a number of cases of radiation exposure. In the early daylight hours of 27 April, approximately 36 hours after the initial blast, they ordered the evacuation of Pripyat. Initially it was decided to evacuate the population for three days; later this was made permanent.

By 11:00 on 27 April, buses had arrived in Pripyat to start the evacuation. The evacuation began at 14:00. A translated excerpt of the evacuation announcement follows:

For the attention of the residents of Pripyat! The City Council informs you that due to the accident at Chernobyl Power Station in the city of Pripyat the radioactive conditions in the vicinity are deteriorating. The Communist Party, its officials and the armed forces are taking necessary steps to combat this. Nevertheless, with the view to keep people as safe and healthy as possible, the children being top priority, we need to temporarily evacuate the citizens in the nearest towns of Kiev region. For these reasons, starting from 27 April 1986, 14:00 each apartment block will be able to have a bus at its disposal, supervised by the police and the city officials. It is highly advisable to take your documents, some vital personal belongings and a certain amount of food, just in case, with you. The senior executives of public and industrial facilities of the city has decided on the list of employees needed to stay in Pripyat to maintain these facilities in a good working order. All the houses will be guarded by the police during the evacuation period. Comrades, leaving your residences temporarily please make sure you have turned off the lights, electrical equipment and water and shut the windows. Please keep calm and orderly in the process of this short-term evacuation.

To expedite the evacuation, residents were told to bring only what was necessary, and that they would remain evacuated for approximately three days. As a result, most personal belongings were left behind, and residents were only allowed to recover certain items after months had passed. By 15:00, 53,000 people were evacuated to various villages of the Kiev region. The next day, talks began for evacuating people from the 10-kilometre (6.2 mi) zone. Ten days after the accident, the evacuation area was expanded to 30 kilometres (19 mi).: 115, 120-121  The Chernobyl Nuclear Power Plant Exclusion Zone has remained ever since, although its shape has changed and its size has been expanded.

Official announcement

Evacuation began one and a half days before the accident was publicly acknowledged by the Soviet Union. In the morning of 28 April, radiation levels set off alarms at the Forsmark Nuclear Power Plant in Sweden, over 1,000 kilometres (620 mi) from the Chernobyl Plant. Workers at Forsmark reported the case to the Swedish Radiation Safety Authority, which determined that the radiation had originated elsewhere. That day, the Swedish government contacted the Soviet government to inquire about whether there had been a nuclear accident in the Soviet Union. The Soviets initially denied it, and it was only after the Swedish government suggested they were about to file an official alert with the International Atomic Energy Agency, that the Soviet government admitted that an accident had taken place at Chernobyl.

At first, the Soviets only conceded that a minor accident had occurred, but once they began evacuating more than 100,000 people, the full scale of the situation was realized by the global community. At 21:02 the evening of 28 April, a 20-second announcement was read in the TV news programme : "There has been an accident at the Chernobyl Nuclear Power Plant. One of the nuclear reactors was damaged. The effects of the accident are being remedied. Assistance has been provided for any affected people. An investigative commission has been set up."

This was the entire announcement, and the first time the Soviet Union officially announced a nuclear accident. The Telegraph Agency of the Soviet Union (TASS) then discussed the Three Mile Island accident and other American nuclear accidents, which Serge Schmemann of The New York Times wrote was an example of the common Soviet tactic of whataboutism. The mention of a commission also indicated to observers the seriousness of the incident, and subsequent state radio broadcasts were replaced with classical music, which was a common method of preparing the public for an announcement of a tragedy in the USSR.

Around the same time, ABC News released its report about the disaster. Shevchenko was the first of the Ukrainian state top officials to arrive at the disaster site early on 28 April. There she spoke with members of medical staff and people, who were calm and hopeful that they could soon return to their homes. Shevchenko returned home near midnight, stopping at a radiological checkpoint in Vilcha, one of the first that were set up soon after the accident.

There was a notification from Moscow that there was no reason to postpone the 1 May International Workers' Day celebrations in Kiev (including the annual parade), but on 30 April a meeting of the Political bureau of the Central Committee of the CPSU took place to discuss the plan for the upcoming celebration. Scientists were reporting that the radiological background level in Kiev was normal. At the meeting, which was finished at 18:00, it was decided to shorten celebrations from the regular three and a half to four hours to under two hours.

Several buildings in Pripyat were officially kept open after the disaster to be used by workers still involved with the plant. These included the Jupiter factory (which closed in 1996) and the Azure Swimming Pool, used by the Chernobyl liquidators for recreation during the clean-up (which closed in 1998).

Core meltdown risk mitigation

Chernobyl lava-like corium, formed by fuel-containing mass, flowed into the basement of the plant.[69]

Bubbler pools

Two floors of bubbler pools beneath the reactor served as a large water reservoir for the emergency cooling pumps and as a pressure suppression system capable of condensing steam in case of a small broken steam pipe; the third floor above them, below the reactor, served as a steam tunnel. The steam released by a broken pipe was supposed to enter the steam tunnel and be led into the pools to bubble through a layer of water. After the disaster, the pools and the basement were flooded because of ruptured cooling water pipes and accumulated firefighting water.

The smoldering graphite, fuel and other material above, at more than 1,200 °C (2,190 °F), started to burn through the reactor floor and mixed with molten concrete from the reactor lining, creating corium, a radioactive semi-liquid material comparable to lava. It was feared that if this mixture melted through the floor into the pool of water, the resulting steam production would further contaminate the area or even cause a steam explosion, ejecting more radioactive material from the reactor. It became necessary to drain the pool. These fears ultimately proved unfounded, since corium began dripping harmlessly into the flooded bubbler pools before the water could be removed. The molten fuel hit the water and cooled into a light-brown ceramic pumice, whose low density allowed the substance to float on the water's surface.

Unaware of this fact, the government commission directed that the bubbler pools be drained by opening its sluice gates. The valves controlling it, however, were located in a flooded corridor in a subterranean annex adjacent to the reactor building. Volunteers in diving suits and respirators (for protection against radioactive aerosols), and equipped with dosimeters, entered the knee-deep radioactive water and managed to open the valves. These were the engineers Alexei Ananenko and Valeri Bezpalov (who knew where the valves were), accompanied by the shift supervisor Boris Baranov. All three men were awarded the Order For Courage by Ukrainian President Petro Poroshenko in May 2018.

Foundation protection measures

The government commission was concerned that the molten core would burn into the earth and contaminate groundwater below the reactor. To reduce the likelihood of this, it was decided to freeze the earth beneath the reactor, which would also stabilize the foundations. Using oil well drilling equipment, the injection of liquid nitrogen began on 4 May. It was estimated that 25 tonnes (55 thousand pounds) of liquid nitrogen per day would be required to keep the soil frozen at −100 °C (−148 °F). This idea was quickly scrapped.

Bolshov's graphite cooling plate, alongside the prior nitrogen injection proposal, were not used following the drop in aerial temperatures and indicative reports that the fuel melt had stopped. It was later determined that the fuel had flowed three floors, with a few cubic meters coming to rest at ground level. The precautionary underground channel with its active cooling was therefore deemed redundant, as the fuel was self-cooling. The excavation was then simply filled with concrete to strengthen the foundation below the reactor.

Immediate site and area remediation

Debris removal

In the months after the explosion, attention turned to removing the radioactive debris from the roof. While the worst of the radioactive debris had remained inside what was left of the reactor, it was estimated that there was approximately 100 tons of debris on that roof which had to be removed to enable the safe construction of the "sarcophagus"-a concrete structure that would entomb the reactor and reduce radioactive dust being released into the atmosphere. The initial plan was to use robots to clear the debris off the roof. The Soviets used approximately 60 remote-controlled robots, most of them built in the Soviet Union itself. Many failed due to the difficult terrain, combined with the effect of high radiation fields on their batteries and electronic controls. In 1987, Valery Legasov, first deputy director of the Kurchatov Institute of Atomic Energy in Moscow, said: "We learned that robots are not the great remedy for everything. Where there was very high radiation, the robot ceased to be a robot-the electronics quit working."

Consequently, the most highly radioactive materials were shoveled by Chernobyl liquidators from the military wearing heavy protective gear (dubbed "bio-robots"). These soldiers could only spend a maximum of 40-90 seconds working on the rooftops of the surrounding buildings because of the extremely high doses of radiation given off by the blocks of graphite and other debris. Though the soldiers were only supposed to perform the role of the "bio-robot" a maximum of once, some soldiers reported having done this task five or six times. Only 10% of the debris cleared from the roof was performed by robots; the other 90% was removed by 3,828 men who absorbed, on average, an estimated dose of 25 rem (250 mSv) of radiation each.

Construction of the sarcophagus

With the extinguishing of the open air reactor fire, the next step was to prevent the spread of contamination. This could be due to wind action which could carry away loose contamination, and by birds which could land within the wreckage and then carry contamination elsewhere. In addition, rainwater could wash contamination away from the reactor area and into the sub-surface water table, where it could migrate outside the site area. Rainwater falling on the wreckage could also weaken the remaining reactor structure by accelerating corrosion of steelwork. A further challenge was to reduce the large amount of emitted gamma radiation, which was a hazard to the workforce operating the adjacent reactor No. 3.

The solution chosen was to enclose the wrecked reactor by the construction of a huge composite steel and concrete shelter, which became known as the "Sarcophagus". It had to be erected quickly and within the constraints of high levels of ambient gamma radiation. The design started on 20 May 1986, 24 days after the disaster, and construction was from June to late November. This major construction project was carried out under the very difficult circumstances of high levels of radiation both from the core remnants and the deposited radioactive contamination around it.

The construction workers had to be protected from radiation, and techniques such as crane drivers working from lead-lined control cabins were employed. The construction work included erecting walls around the perimeter, clearing and surface concreting the surrounding ground to remove sources of radiation and to allow access for large construction machinery, constructing a thick radiation shielding wall to protect the workers in reactor No. 3, fabricating a high-rise buttress to strengthen weak parts of the old structure, constructing an overall roof, and provisioning a ventilation extract system to capture any airborne contamination arising within the shelter.

Investigations of the reactor condition

During the construction of the sarcophagus, a scientific team, as part of an investigation dubbed "Complex Expedition", re-entered the reactor to locate and contain nuclear fuel to prevent another explosion. These scientists manually collected cold fuel rods, but great heat was still emanating from the core. Rates of radiation in different parts of the building were monitored by drilling holes into the reactor and inserting long metal detector tubes. The scientists were exposed to high levels of radiation and radioactive dust.

Area cleanup

The official contaminated zones saw a massive clean-up effort lasting seven months. The official reason for such early (and dangerous) decontamination efforts, rather than allowing time for natural decay, was that the land must be repopulated and brought back into cultivation. Within fifteen months 75% of the land was under cultivation, even though only a third of the evacuated villages were resettled. Defence forces must have done much of the work. Yet this land was of marginal agricultural value. According to historian David Marples, the administration had a psychological purpose for the clean-up: they wished to forestall panic regarding nuclear energy, and even to restart the Chernobyl power station.: 78-79, 87, 192-193

Although a number of radioactive emergency vehicles were buried in trenches, many of the vehicles used by the liquidators, including the helicopters, still remained, as of 2018, parked in a field in the Chernobyl area. Scavengers have since removed many functioning, but highly radioactive, parts. Liquidators worked under deplorable conditions, poorly informed and with poor protection. Many, if not most of them, exceeded radiation safety limits.

The urban decontamination liquidators first washed buildings and roads with "Barda", a sticky polymerizing fluid, designed to entrap radioactive dust.[dubious ]

A unique "clean up" medal was given to the clean-up workers, known as "liquidators".

Investigations and the evolution of identified causes

To investigate the causes of the accident the IAEA used the International Nuclear Safety Advisory Group (INSAG), which had been created by the IAEA in 1985. It produced two significant reports on Chernobyl; INSAG-1 in 1986, and a revised report, INSAG-7 in 1992. In summary, according to INSAG-1, the main cause of the accident was the operators' actions, but according to INSAG-7, the main cause was the reactor's design. Both IAEA reports identified an inadequate "safety culture" (INSAG-1 coined the term) at all managerial and operational levels as a major underlying factor of different aspects of the accident. This was stated to be inherent not only in operations but also during design, engineering, construction, manufacture and regulation.

The INSAG-7 conclusion of major factors contributory to the accident was:

"The Accident is now seen to have been the result of concurrence of the following major factors: specific physical characteristics of the reactor; specific design features of the reactor control elements; and the fact that the reactor was brought to a state not specified by procedures or investigated by an independent safety body. Most importantly, the physical characteristics of the reactor made possible its unstable behaviour."

INSAG-1 report (1986)

The first official Soviet explanation of the accident was given by Soviet scientists and engineers to representatives of IAEA member states and other international organisations at the first Post-Accident Review Meeting, held at the IAEA in Vienna 25-29 August 1986. This explanation effectively placed the blame on the power plant operators. The IAEA INSAG-1 report followed shortly afterwards in September 1986, and on the whole also supported this view, based also on the information provided in discussions with the Soviet experts at the Vienna review meeting. In this view, the catastrophic accident was caused by gross violations of operating rules and regulations. For instance; "During preparation and testing of the turbine generator under run-down conditions using the auxiliary load, personnel disconnected a series of technical protection systems and breached the most important operational safety provisions for conducting a technical exercise."

It was stated that at the time of the accident the reactor was being operated with many key safety systems turned off, most notably the emergency core cooling system (ECCS), LAR (Local Automatic control system), and AZ (emergency power reduction system). Personnel had an insufficient understanding of technical procedures involved with the nuclear reactor, and knowingly ignored regulations to expedite the electrical test completion. Several procedural irregularities also helped to make the accident possible, one of which was insufficient communication between the safety officers and the operators in charge of the test.

Soviet criminal trial (1987)

The trial took place from 7 to 30 July 1987 in a temporary courtroom set up in the House of Culture in the city of Chernobyl, Ukraine. Five plant employees ( Anatoly S. Dyatlov, the former deputy chief engineer; Viktor P. Bryukhanov, the former plant director; Nikolai M. Fomin, the former chief engineer; Boris V. Rogozhin, the shift director of Reactor 4; and Aleksandr P. Kovalenko, the chief of Reactor 4); and Yuri A. Laushkin (Gosatomenergonadzor [USSR State Committee on Supervision of Safe Conduct of Work in Atomic Energy] inspector) were sentenced to ten, ten, ten, five, three, and two years respectively in labor camps. The families of Aleksandr Akimov, Leonid Toptunov and Valery Perevozchenko had received official letters, but prosecution against the employees had been terminated at their deaths.

Anatoly Dyatlov was found guilty "of criminal mismanagement of potentially explosive enterprises" and sentenced to ten years imprisonment-of which he would serve three-for the role that his oversight of the experiment played in the ensuing accident.

INSAG-7 report (1992)

A simplified diagram comparing the Chernobyl RBMK and the most common nuclear reactor design, the Light water reactor. RBMK issues: 1. Using a graphite moderator in a water-cooled reactor, permitting criticality in a total loss of coolant accident. 2. A positive steam void coefficient that made the destructive power excursion possible. 3. Control rods design; taking 18-20 seconds to be fully inserted, and with graphite tips that increased reactivity initially. 4. No reinforced containment building.[21][28][101]

In the INSAG-7 report, most of the earlier accusations against staff for breach of regulations were acknowledged to be either erroneous, being based on incorrect information obtained in August 1986, or were judged less relevant. The INSAG-7 report also reflected the view of the 1991 USSR State Commission account which held that the operators' actions in turning off the emergency core cooling system, interfering with the settings on the protection equipment, and blocking the level and pressure in the separator drum did not contribute to the original cause of the accident and its magnitude, although they may have been a breach of regulations. In fact, turning off the emergency system designed to prevent the two turbine generators from stopping was not a violation of regulations. Soviet authorities had identified a multitude of operator actions as regulation violations in the original 1986 report while no such regulations were in fact in place.

The primary design cause of the accident, as determined by INSAG-7, was a major deficiency in safety features, in particular the "positive scram" effect due to the control rods' graphite tips that actually initially increased reactivity when control rods entered the core to reduce reactivity. There was also an overly positive void coefficient of the reactor, whereby steam-generated voids in the fuel cooling channels would increase reactivity because neutron absorption was reduced, resulting in more steam generation, and thereby more voids; a regenerative process.

To avoid such conditions, it was necessary for the operators to track the value of the reactor operational reactivity margin (ORM) but this value was not readily available to the operators and they were not aware of the safety significance of ORM on void and power coefficients. However, regulations did forbid operating the reactor with a small margin of reactivity. Yet "post-accident studies have shown that the way in which the real role of the ORM is reflected in the Operating Procedures and design documentation for the RBMK-1000 is extremely contradictory", and furthermore, "ORM was not treated as an operational safety limit, violation of which could lead to an accident".

Even in this revised analysis, the human factor remained identified as a major factor in causing the accident; particularly the operating crew's deviation from the test programme. "Most reprehensibly, unapproved changes in the test procedure were deliberately made on the spot, although the plant was known to be in a very different condition from that intended for the test." This included operating the reactor at a lower power level than the prescribed 700 MW before starting the electrical test. The 1986 assertions of Soviet experts notwithstanding, regulations did not prohibit operating the reactor at this low power level.

Positive void coefficient

Control rod design

There was a significant flaw in the design of the control rods. The reactor core was 7 metres (23 feet) high. The upper half of the rod 7 metres (23 feet) was boron carbide, which absorbs neutrons and thereby slows the reaction. The bottom section of each control rod was a 4.5 meter graphite displacer, which prevented the channels from filling with water when rods were withdrawn. The flaw lay in the 1.25-metre (4.1-foot) gap between the bottom of the graphite displacer and the bottom of the reactor, meaning that the lowest portion of control rod channel was filled with water and not graphite. See page 123. Fig 11-10. With this design, when the rods were inserted from the fully retracted position to stop the reaction on the AZ-5 signal, the graphite displaced neutron-absorbing water, causing fewer neutrons to be absorbed and increasing reactivity. For the first 11 to 14 seconds of rod deployment until the boron was in position, reactor power across the floor of the reactor could increase, rather than decrease. This feature of control rod operation was counter-intuitive and not known to the reactor operators.

Management and operational deficiencies

Other deficiencies were noted in the RBMK-1000 reactor design, as were its non-compliance with accepted standards and with the requirements of nuclear reactor safety. While INSAG-1 and INSAG-7 reports both identified operator error as an issue of concern, the INSAG-7 identified that there were numerous other issues that were contributing factors that led to the incident. These contributing factors include:

1. The plant was not designed to safety standards in effect and incorporated unsafe features

2. "Inadequate safety analysis" was performed

3. There was "insufficient attention to independent safety review"

4. "Operating procedures not founded satisfactorily in safety analysis"

5. Safety information not adequately and effectively communicated between operators, and between operators and designers

6. The operators did not adequately understand safety aspects of the plant

7. Operators did not sufficiently respect formal requirements of operational and test procedures

8. The regulatory regime was insufficient to effectively counter pressures for production

9. There was a "general lack of safety culture in nuclear matters at the national level as well as locally"

Fizzled nuclear explosion hypothesis

Their evidence came from Cherepovets, a city 1,000 kilometres (620 mi) northeast of Chernobyl, where physicists from the V.G. Khlopin Radium Institute measured anomalous high levels of xenon-135 -a short half-life isotope-four days after the explosion. This meant that a nuclear event in the reactor may have ejected xenon to higher altitudes in the atmosphere than the later fire did, allowing widespread movement of xenon to remote locations. This was an alternative to the more accepted explanation of a positive-feedback power excursion where the reactor disassembled itself by steam explosion.

Pakhomov and Dubasov's nuclear fizzle hypothesis was examined in 2017 by Lars-Erik De Geer, Christer Persson and Henning Rodhe, who put the hypothesized fizzle event as the more probable cause of the first explosion. Both analyses argue that the nuclear fizzle event, whether producing the second or first explosion, consisted of a prompt chain reaction that was limited to a small portion of the reactor core, since self-disassembly occurs rapidly in fizzle events.

De Geer, Persson and Rodhe commented:

"We believe that thermal neutron mediated nuclear explosions at the bottom of a number of fuel channels in the reactor caused a jet of debris to shoot upwards through the refuelling tubes. This jet then rammed the tubes' 350kg plugs, continued through the roof and travelled into the atmosphere to altitudes of 2.5-3km where the weather conditions provided a route to Cherepovets. The steam explosion which ruptured the reactor vessel occurred some 2.7 seconds later."

This second explosion was estimated by the authors to have had the power equivalent of 225 tons of TNT.

Release and spread of radioactive materials

At Chernobyl, approximately 100,000 square kilometres (39,000 sq mi) of land was significantly contaminated with fallout, with the worst hit regions being in Belarus, Ukraine and Russia. Lower levels of contamination were detected over all of Europe except for the Iberian Peninsula. Most of the fallout with radioactive dust particles was released during the first ten days after the accident. By around May 2, a radioactive cloud had reached the Netherlands and Belgium.

It was Sweden's elevated radioactivity level, detected at noon on 28 April that, having been determined as not caused by a leak at the Swedish plant, first suggested a serious nuclear problem originating from the western Soviet Union. The evacuation of Pripyat on 27 April had been silently completed without the disaster being declared outside the Soviet Union. A rise in radiation levels in the subsequent days had also been measured in Finland, but a civil service strike delayed the response and publication.

Contamination from the Chernobyl accident was scattered irregularly depending on weather conditions, much of it deposited on mountainous regions such as the Alps, the Welsh mountains and the Scottish Highlands, where adiabatic cooling caused radioactive rainfall. The resulting patches of contamination were often highly localized, and localized water-flows contributed to large variations in radioactivity over small areas. Sweden and Norway also received heavy fallout when the contaminated air collided with a cold front, bringing rain. There was also groundwater contamination.

Rain was deliberately seeded over 10,000 square kilometres (3,900 sq mi) Belarus by the Soviet Air Force to remove radioactive particles from clouds heading toward highly populated areas. Heavy, black-coloured rain fell on the city of Gomel. Reports from Soviet and Western scientists indicate that the Belarusian SSR received about 60% of the contamination that fell on the former Soviet Union. However, the 2006 TORCH report stated that up to half of the volatile particles had actually landed outside the former USSR area currently making up of Ukraine, Belarus, and Russia. An unconnected large area in Russian SFSR south of Bryansk was also contaminated, as were parts of northwestern Ukrainian SSR. Studies in surrounding countries indicate that more than one million people could have been affected by radiation.

2016 data from a long-term monitoring program (The Korma Report II) shows a decrease in internal radiation exposure of the inhabitants of a region in Belarus close to Gomel. Resettlement may even be possible in prohibited areas provided that people comply with appropriate dietary rules.

In Western Europe, precautionary measures taken in response to the radiation included banning the importation of certain foods. A 2006 study by the French society for nuclear energy found that contamination was "relatively limited, diminishing from west to east", such that a hunter consuming 40 kilograms of contaminated wild boar in 1997 would be exposed to about one millisievert.

Relative isotopic abundances

At different times after the accident, different isotopes were responsible for the majority of the external dose. The remaining quantity of any radioisotope, and therefore the activity of that isotope, after 7 decay half-lives have passed, is less than 1% of its initial magnitude, and it continues to reduce beyond 0.78% after 7 half-lives to 0.10% remaining after 10 half-lives have passed and so on. Some radionuclides have decay products that are likewise radioactive, which is not accounted for here. The release of radioisotopes from the nuclear fuel was largely controlled by their boiling points, and the majority of the radioactivity present in the core was retained in the reactor.

All of the noble gases, including krypton and xenon, contained within the reactor were released immediately into the atmosphere by the first steam explosion. The atmospheric release of xenon-133, with a half-life of 5 days, is estimated at 5200 PBq.

50 to 60% of all core 1760×10radioiodine in the reactor, about 1760 PBq (¹⁵ becquerels), or about 0.4 kilograms (0.88 lb), was released, as a mixture of sublimed vapour, solid particles, and organic iodine compounds. Iodine-131 has a half-life of 8 days.

20 to 40% of all core caesium-137 was released, 85 PBq in all. Caesium was released in aerosol form; caesium-137, along with isotopes of strontium, are the two primary elements preventing the Chernobyl exclusion zone being re-inhabited. equals 24 kilograms of caesium-137. Cs-137 has a half-life of 30 years.

Tellurium-132, half-life 78 hours, an estimated 1150 PBq was released.

An early estimate for total nuclear fuel material released to the environment was %; this was later revised to %. This corresponds to the atmospheric emission of 6 tonnes (5.9 long tons; 6.6 short tons) of fragmented fuel.

Two sizes of particles were released: small particles of 0.3 to 1.5 micrometres, each an individually unrecognizable small dust or smog sized particulate matter and larger settling dust sized particles that therefore were quicker to fall-out of the air, of 10 micrometres in diameter. These larger particles contained about 80% to 90% of the released high boiling point or non-volatile radioisotopes; zirconium-95, niobium-95, lanthanum-140, cerium-144 and the transuranic elements, including neptunium, plutonium and the minor actinides, embedded in a uranium oxide matrix.

Environmental impact

Water bodies

The Chernobyl nuclear power plant is located next to the Pripyat River, which feeds into the Dnieper reservoir system, one of the largest surface water systems in Europe, which at the time supplied water to Kiev's 2.4 million residents, and was still in spring flood when the accident occurred. The radioactive contamination of aquatic systems therefore became a major problem in the immediate aftermath of the accident.

In the most affected areas of Ukraine, levels of radioactivity (particularly from radionuclides ¹³¹I, ¹³⁷Cs and ⁹⁰Sr) in drinking water caused concern during the weeks and months after the accident. Guidelines for levels of radioiodine in drinking water were temporarily raised to 3,700 Bq/L, allowing most water to be reported as safe. Officially it was stated that all contaminants had settled to the bottom "in an insoluble phase" and would not dissolve for 800-1000 years. A year after the accident it was announced that even the water of the Chernobyl plant's cooling pond was within acceptable norms. Despite this, two months after the disaster the Kiev water supply was switched from the Dnieper to the Desna River. Meanwhile, massive silt traps were constructed, along with an enormous 30-metre (98 ft) deep underground barrier to prevent groundwater from the destroyed reactor entering the Pripyat River.

Groundwater was not badly affected by the Chernobyl accident since radionuclides with short half-lives decayed away long before they could affect groundwater supplies, and longer-lived radionuclides such as radiocaesium and radiostrontium were adsorbed to surface soils before they could transfer to groundwater. However, significant transfers of radionuclides to groundwater have occurred from waste disposal sites in the 30 km (19 mi) exclusion zone around Chernobyl. Although there is a potential for transfer of radionuclides from these disposal sites off-site (i.e. out of the 30 km (19 mi) exclusion zone), the IAEA Chernobyl Report argues that this is not significant in comparison to current levels of washout of surface-deposited radioactivity.

Bio-accumulation of radioactivity in fish resulted in concentrations (both in western Europe and in the former Soviet Union) that in many cases were significantly above guideline maximum levels for consumption. Guideline maximum levels for radiocaesium in fish vary from country to country but are approximately 1000 Bq/kg in the European Union. In the Kiev Reservoir in Ukraine, concentrations in fish were in the range of 3000 Bq/kg during the first few years after the accident.

Chernobyl's radiocaesium deposits were used to calibrate sedimentation samples from Lake Qattinah in Syria. The provides a sharp, maximal, data point in radioactivity of the core sample at the 1986 depth, and acts as a date check on the depth of the in the core sample.

Flora, fauna, and funga

After the disaster, four square kilometres (1.5 sq mi) of pine forest directly downwind of the reactor turned reddish-brown and died, earning the name of the " Red Forest". Some animals in the worst-hit areas also died or stopped reproducing. Most domestic animals were removed from the exclusion zone, but horses left on an island in the Pripyat River 6 km (4 mi) from the power plant died when their thyroid glands were destroyed by radiation doses of 150-200 Sv. Some cattle on the same island died and those that survived were stunted because of thyroid damage. The next generation appeared to be normal. The mutation rates for plants and animals have increased by a factor of 20 because of the release of radionuclides from Chernobyl. There is evidence for elevated mortality rates and increased rates of reproductive failure in contaminated areas, consistent with the expected frequency of deaths due to mutations.

On farms in Narodychi Raion of Ukraine it is claimed that from 1986 to 1990 nearly 350 animals were born with gross deformities such as missing or extra limbs, missing eyes, heads or ribs, or deformed skulls; in comparison, only three abnormal births had been registered in the five years prior.

Subsequent research on microorganisms, while limited, suggests that in the aftermath of the disaster, bacterial and viral specimens exposed to the radiation (including Mycobacterium tuberculosis, herpesvirus, cytomegalovirus, hepatitis-causing viruses, and tobacco mosaic virus) underwent rapid changes. Activations of soil micromycetes have been reported. It is currently unclear how these changes in species with rapid reproductive turnover (which were not destroyed by the radiation but instead survived) will manifest in terms of virulence, drug resistance, immune evasion, and so on; a paper in 1998 reported the discovery of an Escherichia coli mutant that was hyper-resistant to a variety of DNA-damaging elements, including x-ray radiation, UV-C, and 4-nitroquinoline 1-oxide (4NQO). Cladosporium sphaerospermum, a species of fungus that has thrived in the Chernobyl contaminated area, has been investigated for the purpose of using the fungus' particular melanin to protect against high-radiation environments, such as space travel. The disaster has been described by lawyers, academics and journalists as an example of ecocide.

Human food chain

With radiocaesium binding less with humic acid, peaty soils than the known binding "fixation" that occurs on kaolinite rich clay soils, many marshy areas of Ukraine had the highest soil to dairy-milk transfer coefficients, of soil activity in ~ 200 kBq/m ² to dairy milk activity in Bq/L, that had ever been reported, with the transfer, from initial land activity into milk activity, ranging from 0.3 −2 to 20 −2 times that which was on the soil, a variance depending on the natural acidity-conditioning of the pasture.

In 1987, Soviet medical teams conducted some 16,000 whole-body count examinations on inhabitants in otherwise comparatively lightly contaminated regions with good prospects for recovery. This was to determine the effect of banning local food and using only food imports on the internal body burden of radionuclides in inhabitants. Concurrent agricultural countermeasures were used when cultivation did occur, to further reduce the soil to human transfer as much as possible. The expected highest body activity was in the first few years, where the unabated ingestion of local food, primarily milk consumption, resulted in the transfer of activity from soil to body; after the dissolution of the USSR, the now-reduced scale initiative to monitor the human body activity in these regions of Ukraine, recorded a small and gradual half-decadal-long rise, in internal committed dose, before returning to the previous trend of observing ever lower body counts each year.

This momentary rise is hypothesized to be due to the cessation of the Soviet food imports together with many villagers returning to older dairy food cultivation practices and large increases in wild berry and mushroom foraging, the latter of which have similar peaty soil to fruiting body, radiocaesium transfer coefficients.

After the disaster, four square kilometres (1.5 sq mi) of pine forest directly downwind of the reactor turned reddish-brown and died, earning the name of the "Red Forest", though it soon recovered.[135] This photograph was taken years later, in March 2009,[146] after the forest began to grow again, with the lack of foliage at the time of the photograph merely due to the local winter at the time.[147]

Of the 440,350 wild boar killed in the 2010 hunting season in Germany, approximately one thousand were contaminated with levels of radiation above the permitted limit of 600 becquerels of caesium per kilogram, of dry weight, due to residual radioactivity from Chernobyl. While all animal meat contains a natural level of potassium-40 at a similar level of activity, with both wild and farm animals in Italy containing "415 ± 56 becquerels kg−1 dw" of that naturally occurring gamma emitter.

Because Elaphomyces fungal species bioaccumulate radiocaesium, boars of the Bavarian Forest that consume these "deer truffles" are contaminated at higher levels than their environment's soil. Given that nuclear weapons release a higher ¹³⁵C/ ¹³⁷C ratio than nuclear reactors, the high ¹³⁵ C content in these boars suggests that their radiological contamination can be largely attributed to the Soviet Union's nuclear weapons testing in Ukraine, which peaked during the late 1950s and early 1960s.

In 2015, long-term empirical data showed no evidence of a negative influence of radiation on mammal abundance.

Precipitation on distant high ground

On high ground, such as mountain ranges, there is increased precipitation due to adiabatic cooling. This resulted in localized concentrations of contaminants on distant areas; higher in Bq/m ² values to many lowland areas much closer to the source of the plume. This effect occurred on high ground in Norway and the UK.

The Norwegian Agricultural Authority reported that in 2009 a total of 18,000 livestock in Norway required uncontaminated feed for a period before slaughter, to ensure that their meat had an activity below the government permitted value of caesium per kilogram deemed suitable for human consumption. This contamination was due to residual radioactivity from Chernobyl in the mountain plants they graze on in the wild during the summer. 1,914 sheep required uncontaminated feed for a time before slaughter during 2012, with these sheep located in only 18 of Norway's municipalities, a decrease from the 35 municipalities in 2011 and the 117 municipalities affected during 1986. The after-effects of Chernobyl on the mountain lamb industry in Norway were expected to be seen for a further 100 years, although the severity of the effects would decline over that period. Scientists report this is due to radioactive caesium-137 isotopes being taken up by fungi such as Cortinarius caperatus which is in turn eaten by sheep while grazing.

United Kingdom

The United Kingdom restricted the movement of sheep from upland areas when radioactive caesium-137 fell across parts of Northern Ireland, Wales, Scotland, and northern England. In the immediate aftermath of the disaster in 1986, the movement of a total of 4,225,000 sheep was restricted across a total of 9,700 farms, to prevent contaminated meat entering the human food chain. The number of sheep and the number of farms affected has decreased since 1986. Northern Ireland was released from all restrictions in 2000, and by 2009, 369 farms containing around 190,000 sheep remained under the restrictions in Wales, Cumbria, and northern Scotland. The restrictions applying in Scotland were lifted in 2010, while those applying to Wales and Cumbria were lifted during 2012, meaning no farms in the UK remain restricted because of Chernobyl fallout.

The legislation used to control sheep movement and compensate farmers (farmers were latterly compensated per animal to cover additional costs in holding animals prior to radiation monitoring) was revoked during October and November 2012, by the relevant authorities in the UK. Had restrictions in the UK not occurred, a heavy consumer of lamb meat would likely have received a dose of 4.1 mSv over a lifetime.

Human impact

Acute radiation effects and immediate aftermath

The only known, causal deaths from the accident involved workers in the plant and firefighters. The reactor explosion killed two engineers and severely burned two others who were among the 237 workers hospitalized in the immediate aftermath. Of the hospitalized workers, 134 exhibited symptoms of acute radiation syndrome, including one disputed case. 28 of the hospitalized workers died within the following three months, all of whom were hospitalized for ARS and 26 were among the 56 patients hospitalized for burns. Among the fatalities in the acute phase (approximately three months), all but one patient (with grade 2 ARS) were hospitalized for grade 3 or 4 ARS. Fifteen out of 22 patients with grade 3 ARS survived. Only one patient out of 21 with grade 4 ARS survived.

There were a number of fishermen on the reservoir a half-kilometer from the reactor to the east. Of these, two shore fishermen, Protosov and Pustavoit, are said to have sustained doses estimated at 400 roentgens and vomited, but survived. The vast majority of Pripyat residents slept through the distant sound of the explosion, including station engineer Breus, who only became aware at 6am, the beginning of his next work shift. He was later taken to hospital and, while there, made the acquaintance of one teen who had ventured out alone by bicycle to watch the roof fires during the night, stopping for a time and viewing the scene at the "Bridge of Death" . Contrary to this sensationalist label, the youthful night biker was treated and released from hospital, remaining in touch with Breus as of 2019.

Most serious cases of ARS were treated with the assistance of American specialist Robert Peter Gale, who documented a first of its kind treatment and supervized a number of bone marrow transplant procedures which were not successful. In 2019, Gale wrote a letter to correct the popularized, though egregious, portrayal of his patients as dangerous to visitors. All those who died were station operators and firefighters, over half of which from the continued wearing of dusty soaked uniforms, causing beta burns to cover large areas of skin. In the first few minutes to days, (largely due to Np-239, a 2.4-day half-life) the beta-to-gamma energy ratio is some 30:1. Owing to the large area of burned skin and sensitivity of the GI tract, bacterial infection was and remains the overarching concern to those affected with ARS, as a leading cause of death, quarantine from the outside environment is a part of the normal treatment protocol. Many of the surviving firefighters, continue to have skin that is atrophied, spider veined with underlying fibrosis due to experiencing extensive beta burns.

Long-term impact

In the 10 years following the accident, 14 more people who had been initially hospitalized (9 who had been hospitalized with ARS) died of various causes mostly unrelated to radiation exposure. Only two of these deaths were the result of myelodysplastic syndrome. Scientific consensus, in the form of the Chernobyl Forum, suggests that, although unexpected, there has been no statistically significant increase in the incidence rate of solid cancers among rescue workers. Follow-up studies have also found this to be the case, with apparent increases in thyroid cancer simply attributed to more meticulous cancer screening for rescue workers.

Childhood thyroid cancer is an exception, with approximately 4,000 new incidents in the general population by 2002 within contaminated regions of Belarus, Russia, and Ukraine, most of which are attributed to high environmental levels of radioactive iodine shortly after the accident. The recovery rate is ~99%, with only 15 terminal cases (9 deaths) at the time of the report. There has been no increase in mutation rate among the children of the liquidators or general population living in the contaminated areas.

From this same report is also a commonly cited estimate for potential future cancer fatalities in the form of an increase in cancer mortality (i.e. lethality) which speculated that, at worst, ~4,000 additional cancer-related fatalities were to be expected. Although it is reasonable and forward-thinking to assume that an increase in mortality has occurred among the affected population, studies have yet to confirm such an increase with meaningful statistical certainty.

Whether the area was publicly announced as a contaminated area is a better predictor of general health than the contamination itself. "Resettlement status" is an even stronger predictor: the residents of contaminated regions who were evacuated and resettled into uncontaminated regions can be compared with the residents who remained in the contaminated regions. Resettled citizens erroneously believed they had an illness related to radiation exposure more often than citizens who remained in the contaminated regions. This brings into question the effectiveness of resettlement.

By 2000, the number of Ukrainians claiming to be radiation "sufferers" ( poterpili) and receiving state benefits had jumped to 3.5 million, or 5% of the population. Many of these are populations resettled from contaminated zones or former or current Chernobyl plant workers. There was and remains a motivated "push" to achieve "sufferer" status as it gives access to state benefits and medical services that would otherwise not be made available. The apparent increases of ill health in this large group result partly from increased medical vigilance following the accident; many benign cases that would previously have gone unnoticed and untreated (especially of cancer) are now being registered.

In September 1987, the IAEA held an Advisory Group Meeting at the Curie Institute in Paris on the medical handling of the skin lesions relating to the acute deaths.

Effects of main harmful radionuclides

The four most harmful radionuclides spread from Chernobyl were iodine-131, caesium-134, caesium-137 and strontium-90, with half-lives of 8.02 days, 2.07 years, 30.2 years and 28.8 years respectively. The iodine was initially viewed with less alarm than the other isotopes, because of its short half-life, but it is highly volatile and now appears to have travelled furthest and caused the most severe health problems. Strontium is the least volatile of the four and is of main concern in the areas near Chernobyl itself.

Long term hazards such as caesium tends to accumulate in vital organs such as the heart, while strontium accumulates in bones and may thus be a risk to bone-marrow and lymphocytes. Radiation is most damaging to cells that are actively dividing. In adult mammals cell division is slow, except in hair follicles, skin, bone marrow and the gastrointestinal tract, which is why vomiting and hair loss are common symptoms of acute radiation sickness.

Disputed investigation

The two primary individuals involved with the attempt to suggest that the mutation rate among animals was, and continues to be, higher in the Chernobyl zone, are the Anders Moller and Timothy Mousseau group. Apart from continuing to publish experimentally unrepeatable and discredited papers, Mousseau routinely gives talks at the Helen Caldicott organized symposiums for " Physicians for Social Responsibility", an anti-nuclear advocacy group devoted to bring about a "nuclear free planet". In years past, Moller was previously caught and reprimanded for publishing papers that crossed the scientific "misconduct"/"fraud" line. The duo have more recently attempted to publish meta-analyses, in which the primary references they weigh-up, analyse and draw their conclusions from is their own prior papers along with the discredited book Chernobyl: Consequences of the Catastrophe for People and the Environment.

Withdrawn investigation

In 1996, geneticist colleagues Ronald Chesser and Robert Baker published a paper on the thriving vole population within the exclusion zone, in which the central conclusion of their work was essentially that "The mutation rate in these animals is hundreds and probably thousands of times greater than normal". This claim occurred after they had done a comparison of the mitochondrial DNA of the "Chernobyl voles" with that of a control group of voles from outside the region. The paper appeared on the front cover of the journal Nature. Not long after publication, the authors discovered they had incorrectly classified the species of vole and therefore were genetically comparing two entirely different vole species. They issued a retraction in 1997.

Following the accident, journalists mistrusted many medical professionals (such as the spokesman from the UK National Radiological Protection Board), and in turn encouraged the public to mistrust them. Throughout the European continent, due to this media-driven framing of the contamination, many requests for induced abortions of otherwise normal pregnancies were obtained out of fears of radiation from Chernobyl.

Worldwide, an estimated excess of about 150,000 elective abortions may have been performed on otherwise healthy pregnancies out of fears of radiation from Chernobyl, according to Robert Baker and ultimately a 1987 article published by Linda E. Ketchum in the Journal of Nuclear Medicine which mentions but does not reference an IAEA source on the matter.

The available statistical data excludes the Soviet-Ukraine-Belarus abortion rates, as they are presently unavailable. From the available data, an increase in the number of abortions in what were healthy developing human offspring in Denmark occurred in the months following the accident, at a rate of about 400 cases. In Italy, a "slightly" above the expected number of induced abortions occurred, approximately 100. In Greece, following the accident, many obstetricians were unable to resist requests from worried pregnant mothers over fears of radiation. Although it was determined that the effective dose to Greeks would not exceed one mSv (100 mrem), a dose much lower than that which it was determined would induce embryonic abnormalities or other non- stochastic effects, there was an observed 2,500 increase of otherwise wanted pregnancies being terminated.

No evidence of changes in the prevalence of human deformities/birth congenital anomalies that might be associated with the accident are apparent in Belarus or Ukraine, the two republics that had the highest exposure to fallout. In Sweden and in Finland where no increase in abortion rates occurred, it was likewise determined that "no association between the temporal and spatial variations in radioactivity and variable incidence of congenital malformations [was found]." A similar null increase in the abortion rate and a healthy baseline situation of no increase in birth defects was determined by assessing the Hungarian Congenital Abnormality Registry. Findings were also mirrored in Austria.

In very high doses, it was known at the time that radiation could cause a physiological increase in the rate of pregnancy anomalies, but unlike the dominant linear no-threshold model of radiation and cancer rate increases, it was known, by researchers familiar with both the prior human exposure data and animal testing, that the "Malformation of organs appears to be a deterministic effect with a threshold dose" below which, no rate increase is observed. This teratology (birth defects) issue was discussed by Frank Castronovo of the Harvard Medical School in 1999, publishing a detailed review of dose reconstructions and the available pregnancy data following the Chernobyl accident, inclusive of data from Kiev's two largest obstetrics hospitals.

The Chernobyl liquidators, essentially an all-male civil defense emergency workforce, would go on to father normal children, without an increase in developmental anomalies or a statistically significant increase in the frequencies of germline mutations in their progeny. This normality is similarly seen in the children of the survivors of the Goiânia accident.

A 2021 study based on whole-genome sequencing of children of parents employed as liquidators indicated no trans-generational genetic effects of exposure of parents to ionizing radiation.

Cancer assessments

A report by the International Atomic Energy Agency examines the environmental consequences of the accident. The United Nations Scientific Committee on the Effects of Atomic Radiation has estimated a global collective dose of radiation exposure from the accident "equivalent on average to 21 additional days of world exposure to natural background radiation"; individual doses were far higher than the global mean among those most exposed, including 530,000 primarily male recovery workers (the Chernobyl liquidators) who averaged an effective dose equivalent to an extra 50 years of typical natural background radiation exposure each.

Estimates of the number of deaths that will eventually result from the accident vary enormously; disparities reflect both the lack of solid scientific data and the different methodologies used to quantify mortality-whether the discussion is confined to specific geographical areas or extends worldwide, and whether the deaths are immediate, short term, or long term. In 1994, thirty-one deaths were directly attributed to the accident, all among the reactor staff and emergency workers.

In a peer-reviewed paper in the International Journal of Cancer in 2006, the authors expanded the discussion on those exposed to all of Europe (but following a different conclusion methodology to the Chernobyl Forum study, which arrived at the total predicted death toll of 4,000 after cancer survival rates were factored in) they stated, without entering into a discussion on deaths, that in terms of total excess cancers attributed to the accident:

The risk projections suggest that by now [2006] Chernobyl may have caused about 1000 cases of thyroid cancer and 4000 cases of other cancers in Europe, representing about 0.01% of all incident cancers since the accident. Models predict that by 2065 about 16,000 cases of thyroid cancer and 25,000 cases of other cancers may be expected due to radiation from the accident, whereas several hundred million cancer cases are expected from other causes.

Two anti-nuclear advocacy groups have publicized non-peer-reviewed estimates that include mortality estimates for those who were exposed to even smaller amounts of radiation. The Union of Concerned Scientists (UCS) calculated that, among the hundreds of millions of people exposed worldwide, there will be an eventual 50,000 excess cancer cases, resulting in 25,000 excess cancer deaths, excluding thyroid cancer. However, these calculations are based on a simple linear no-threshold model multiplication and the misapplication of the collective dose, which the International Commission on Radiological Protection (ICRP) states "should not be done" as using the collective dose is "inappropriate to use in risk projections".

Thyroid cancer incidence in children and adolescents in Belarus

Adolescents, ages 15 to 18

While widely regarded as having a cause and effect relationship, the causality of Chernobyl with the increases in recorded rates of thyroid cancer is disputed,[221] as in both the US and South Korea, upon the advent of ultrasonography and widespread medical screening, the latter recorded an almost identical epidemic in thyroid cancer rates, with South Korea reporting a 15 fold increase upon the switch of diagnostic tool, the highest thyroid cancer rate in the world.[222]

Yet the death rate from thyroid cancer has remained the same as prior to the technology. For these and other reasons, it is suggested that no reliable increase has been detected in the environs of Chernobyl, that cannot otherwise be explained as an artifact of the globally well documented Screening effect. In 2004, the UN collaborative, Chernobyl Forum, revealed thyroid cancer among children to be one of the main health impacts from the Chernobyl accident. This is due to the ingestion of contaminated dairy products, along with the inhalation of the short-lived, highly radioactive isotope, Iodine-131. In that publication, more than 4,000 cases of childhood thyroid cancer were reported. It is important to note that there was no evidence of an increase in solid cancers or leukemia. It said that there was an increase in psychological problems among the affected population. The WHO's Radiation Program reported that the 4,000 cases of thyroid cancer resulted in nine deaths.

According to the United Nations Scientific Committee on the Effects of Atomic Radiation, up to the year 2005, an excess of more than 6,000 cases of thyroid cancer had been reported. That is, over the estimated pre-accident baseline thyroid cancer rate, more than 6,000 casual cases of thyroid cancer have been reported in children and adolescents exposed at the time of the accident, a number that is expected to increase. They concluded that there is no other evidence of major health impacts from the radiation exposure.

Well-differentiated thyroid cancers are generally treatable, and when treated the five-year survival rate of thyroid cancer is 96%, and 92% after 30 years. the United Nations Scientific Committee on the Effects of Atomic Radiation had reported 15 deaths from thyroid cancer in 2011. The International Atomic Energy Agency (IAEA) also states that there has been no increase in the rate of birth defects or abnormalities, or solid cancers-such as lung cancer-corroborating the assessments by the UN committee. UNSCEAR raised the possibility of long term genetic defects, pointing to a doubling of radiation-induced minisatellite mutations among children born in 1994. However, the risk of thyroid cancer associated with the Chernobyl accident is still high according to published studies.

The German affiliate of the anti-nuclear energy organization, the International Physicians for the Prevention of Nuclear War suggest that 10,000 people are affected by thyroid cancer as of 2006, and that 50,000 cases are expected in the future.

Other disorders

The report went into depth about the risks to mental health of exaggerated fears about the effects of radiation. According to the IAEA the "designation of the affected population as 'victims' rather than 'survivors' has led them to perceive themselves as helpless, weak and lacking control over their future". The IAEA says that this may have led to behaviour that has caused further health effects.

Long-term radiation deaths

The number of potential deaths arising from the Chernobyl disaster is heavily debated. The World Health Organization's prediction of 4,000 future cancer deaths in surrounding countries is based on the Linear no-threshold model (LNT), which assumes that the damage inflicted by radiation at low doses is directly proportional to the dose. Radiation epidemiologist Roy Shore contends that estimating health effects in a population from the LNT model "is not wise because of the uncertainties".

According to the Union of Concerned Scientists the number of excess cancer deaths worldwide (including all contaminated areas) is approximately 27,000 based on the same LNT.

Chernobyl: Consequences of the Catastrophe for People and the Environment is a 2007 Russian publication that concludes that there were 985,000 premature deaths as a consequence of the radioactivity released. The results were criticized by M. I. Balonov from the Institute of Radiation Hygiene in St. Petersburg, who described them as biased, drawing from sources that were difficult to independently verify and lacking a proper scientific base. Balanov expressed his opinion that "the authors unfortunately did not appropriately analyse the content of the Russian-language publications, for example, to separate them into those that contain scientific evidence and those based on hasty impressions and ignorant conclusions".

According to U.S. Nuclear Regulatory Commission member and Professor of Health Physics Kenneth Mossman, the "LNT philosophy is overly conservative, and low-level radiation may be less dangerous than commonly believed." Yoshihisa Matsumoto, a radiation biologist at the Tokyo Institute of Technology, cites laboratory experiments on animals to suggest there must be a threshold dose below which DNA repair mechanisms can completely repair any radiation damage. Mossman suggests that the proponents of the current model believe that being conservative is justified due to the uncertainties surrounding low level doses and it is better to have a "prudent public health policy".

Another significant issue is establishing consistent data on which to base the analysis of the impact of the Chernobyl accident. Since 1991, large social and political changes have occurred within the affected regions and these changes have had significant impact on the administration of health care, on socio-economic stability, and the manner in which statistical data is collected. Ronald Chesser, a radiation biologist at Texas Tech University, says that "the subsequent Soviet collapse, scarce funding, imprecise dosimetry, and difficulties tracking people over the years have limited the number of studies and their reliability".

Socio-economic impact

It is difficult to establish the total economic cost of the disaster. According to Mikhail Gorbachev, the Soviet Union spent 18 billion Rbls (the equivalent of US$2.5 billion at that time, or $5.32 billion in today's dollars) on containment and decontamination, virtually bankrupting itself. In 2005, the total cost over 30 years for Belarus which includes the monthly payments to liquidators, was estimated at US$235 billion; about $318 billion in today's dollars given inflation rates. Gorbachev in April 2006 wrote "The nuclear meltdown at Chernobyl 20 years ago this month, even more than my launch of perestroika, was perhaps the real cause of the collapse of the Soviet Union."

Ongoing costs are well known; in their 2003-2005 report, The Chernobyl Forum stated that between five and seven percent of government spending in Ukraine is still related to Chernobyl, while in Belarus more than $13 billion is thought to have been spent between 1991 and 2003, with 22% of national budget having been Chernobyl-related in 1991, falling to six percent by 2002. In 2018, Ukraine spent five to seven percent of its national budget on recovery activities related to the Chernobyl disaster. Overall economic loss is estimated at $235 billion in Belarus. Much of the current cost relates to the payment of Chernobyl-related social benefits to some seven million people across the three countries.

A significant economic impact at the time was the removal of 784,320 ha (1,938,100 acres) of agricultural land and 694,200 ha (1,715,000 acres) of forest from production. While much of this has been returned to use, agricultural production costs have risen due to the need for special cultivation techniques, fertilizers and additives. Politically, the accident gave great significance to the new Soviet policy of glasnost, and helped forge closer Soviet-US relations at the end of the Cold War, through bioscientific cooperation. The disaster also became a key factor in the dissolution of the Soviet Union in 1991, and a major influence in shaping the new Eastern Europe.

Ukrainians viewed the Chernobyl disaster as another attempt by Russians to destroy them, comparable to the Holodomor. Meanwhile, commentators have argued that the events of the Chernobyl disaster were uniquely inclined to occur in a communist country versus a capitalist country. It has been argued that Soviet power plant administrators were not empowered to make crucial decisions when time was of the essence.

Long term site remediation

Portraits of deceased Chernobyl liquidators used for an anti-nuclear power protest in Geneva

Following the accident, questions arose about the future of the plant and its eventual fate. All work on the unfinished reactors No. 5 and No. 6 was halted three years later. However, the trouble at the Chernobyl plant did not end with the disaster in reactor No. 4. The damaged reactor was sealed off and 200 cubic meters (260 cu yd) of concrete was placed between the disaster site and the operational buildings. The work was managed by Grigoriy Mihaylovich Naginskiy, the deputy chief engineer of Installation and Construction Directorate - 90. The Ukrainian government allowed the three remaining reactors to continue operating because of an energy shortage in the country.

Decommissioning of other reactors

In October 1991, a fire broke out in the turbine building of reactor No. 2; the authorities subsequently declared the reactor damaged beyond repair, and it was taken offline. Reactor No. 1 was decommissioned in November 1996 as part of a deal between the Ukrainian government and international organizations such as the IAEA to end operations at the plant. On 15 December 2000, then-President Leonid Kuchma personally turned off reactor No. 3 in an official ceremony, shutting down the entire site.

No. 4 reactor confinement

Soon after the accident, the reactor building was quickly encased by a mammoth concrete sarcophagus in a notable feat of construction under severe conditions. Crane operators worked blindly from inside lead-lined cabins taking instructions from distant radio observers, while gargantuan-sized pieces of concrete were moved to the site on custom-made vehicles. The purpose of the sarcophagus was to stop any further release of radioactive particles into the atmosphere, isolate the exposed core from the weather and provide safety for the continued operations of adjacent reactors one through three.

The concrete sarcophagus was never intended to last very long, with a lifespan of only 30 years. On 12 February 2013, a 600 m ² (6,500 sq ft) section of the roof of the turbine-building collapsed, adjacent to the sarcophagus, causing a new release of radioactivity and temporary evacuation of the area. At first it was assumed that the roof collapsed because of the weight of snow, however the amount of snow was not exceptional, and the report of a Ukrainian fact-finding panel concluded that the collapse was the result of sloppy repair work and aging of the structure. Experts warned the sarcophagus itself was on the verge of collapse.

In 1997, the international Chernobyl Shelter Fund was founded to design and build a more permanent cover for the unstable and short-lived sarcophagus. It received €864 million from international donors in 2011 and was managed by the European Bank for Reconstruction and Development (EBRD). The new shelter was named the New Safe Confinement and construction began in 2010. It is a metal arch 105 metres (344 ft) high and spanning 257 metres (843 ft) built on rails adjacent to the reactor No. 4 building so that it could be slid over the top of the existing sarcophagus. The New Safe Confinement was completed in 2016 and slid into place over top the sarcophagus on 29 November. The huge steel arch was moved into place over several weeks. Unlike the original sarcophagus, the New Safe Confinement is designed to allow the reactor to be safely dismantled using remotely operated equipment.

Waste management

Used fuel from units 1-3 was stored in the units' cooling ponds, and in an interim spent fuel storage facility pond, ISF-1, which now holds most of the spent fuel from units 1-3, allowing those reactors to be decommissioned under less restrictive conditions. Approximately 50 of the fuel assemblies from units 1 and 2 were damaged and required special handling. Moving fuel to ISF-1 was thus carried out in three stages: fuel from unit 3 was moved first, then all undamaged fuel from units 1 and 2, and finally the damaged fuel from units 1 and 2. Fuel transfers to ISF-1 were completed in June 2016.

A need for larger, longer-term radioactive waste management at the Chernobyl site is to be fulfilled by a new facility designated ISF-2. This facility is to serve as dry storage for used fuel assemblies from units 1-3 and other operational wastes, as well as material from decommissioning units 1-3 (which will be the first RBMK units decommissioned anywhere).

Fuel-containing materials

According to official estimates, about 95% of the fuel in reactor No. 4 at the time of the accident (about 180 tonnes (180 long tons; 200 short tons)) remains inside the shelter, with a total radioactivity of nearly 18 million curies (670 PBq). The radioactive material consists of core fragments, dust, and lava-like "fuel containing materials" (FCM)-also called " corium"-that flowed through the wrecked reactor building before hardening into a ceramic form.

It has been reported that the degradation of the lava is likely to be a slow, gradual process, rather than sudden and rapid. The same paper states that the loss of uranium from the wrecked reactor is only 10 kg (22 lb) per year; this low rate of uranium leaching suggests that the lava is resisting its environment. The paper also states that when the shelter is improved, the leaching rate of the lava will decrease. As of 2021, some fuel had already degraded significantly. The famous elephant's foot, which originally was so hard that it required the use of an armor piercing AK-47 round to remove a chunk, had softened to a texture similar to sand.

Exclusion zone

Mass media sources have provided a variety of generalized estimates for when the Zone could be considered habitable again. These informal estimates have ranged from approximately 300 years (corresponding to 10 half-lives of the widespread radionuclides Cesium-137 and Strontium-90), to multiples of 20,000 years, referring to the half-life of Plutonium-239 which contaminates the central portion of the Zone.

In the years following the disaster, residents known as illegally returned to their abandoned homes to regain their lives. Most people are retired and survive mainly from farming and packages delivered by visitors. As of 2016, 187 locals had returned to the zone and were living permanently there.

In 2011, Ukraine opened up the sealed zone around the Chernobyl reactor to tourists wishing to learn more about the 1986 tragedy. Sergii Mirnyi, a radiation reconnaissance officer at the time of the accident, and now an academic at National University of Kyiv-Mohyla Academy, has written about the psychological and physical effects on survivors and visitors, and worked as an advisor to Chernobyl tourism groups.

Forest fire concerns

During the dry season, forest fires are a perennial concern in areas contaminated by radioactive material. Dry conditions and build-up of debris make the forests a ripe breeding ground for wildfires. Depending on prevailing atmospheric conditions, smoke from wildfires could potentially spread more radioactive material outside the exclusion zone. In Belarus, the Bellesrad organization is tasked with overseeing food cultivation and forestry management in the area.

Recovery projects

The Chernobyl Trust Fund was created in 1991 by the United Nations to help victims of the Chernobyl accident. It is administered by the United Nations Office for the Coordination of Humanitarian Affairs, which also manages strategy formulation, resource mobilization, and advocacy efforts. Beginning in 2002, under the United Nations Development Programme, the fund shifted its focus from emergency assistance to long-term development.

The Chernobyl Shelter Fund was established in 1997 at the G8 summit in Denver to finance the Shelter Implementation Plan (SIP). The plan called for transforming the site into an ecologically safe condition through stabilization of the sarcophagus and construction of a New Safe Confinement (NSC) structure. While the original cost estimate for the SIP was US$768 million, the 2006 estimate was $1.2 billion. The SIP is being managed by a consortium of Bechtel, Battelle, and , and conceptual design for the NSC consisted of a movable arch, constructed away from the shelter to avoid high radiation, then slid over the sarcophagus. The NSC was moved into position in November 2016 and was expected to be completed by late 2017.

In 2003, the United Nations Development Programme launched the Chernobyl Recovery and Development Programme (CRDP) for the recovery of affected areas. The programme was initiated in February 2002 based on the recommendations in the report on Human Consequences of the Chernobyl Nuclear Accident. The main goal of the CRDP was supporting the Government of Ukraine in mitigating long-term social, economic, and ecological consequences of the Chernobyl catastrophe. CRDP works in the four most affected Ukrainian areas: Kyivska, Zhytomyrska, Chernihivska and Rivnenska.

The International Project on the Health Effects of the Chernobyl Accident was created and received US$20 million, mainly from Japan, in hopes of discovering the main cause of health problems due to iodine-131 radiation. These funds were divided among Ukraine, Belarus, and Russia, the three main affected countries, for further investigation of health effects. As there was significant corruption in former Soviet countries, most of the foreign aid was given to Russia, and no results from the funding were demonstrated.

In 2019, it became known that the Ukrainian government in power at the time aimed to make Chernobyl a tourist attraction.

Nuclear debate

The Chernobyl accident attracted a great deal of interest. Because of the distrust that many people had in the Soviet authorities, which engaged in a major cover-up of the disaster, a great deal of debate about the situation at the site occurred in the First World during the early days of the event. Because of defective intelligence based on satellite imagery, it was thought that unit number three had also had a dire accident. Journalists mistrusted many professionals, and they in turn encouraged the public to mistrust them.

The accident also raised concerns about the cavalier safety culture in the Soviet nuclear power industry, slowing industry growth and forcing the Soviet government to become less secretive about its operating procedures. The government coverup of the Chernobyl disaster was a catalyst for glasnost, which "paved the way for reforms leading to the Soviet collapse." Numerous structural and construction quality issues, as well as deviations from the original plant design, had been known to KGB since at least 1973 and passed on to the Central Committee, which took no action and classified the information.

In Italy, the Chernobyl accident was reflected in the outcome of the 1987 referendum. As a result of that referendum, Italy began phasing out its nuclear power plants in 1988, a decision that was effectively reversed in 2008. A 2011 referendum reiterated Italians' strong objections to nuclear power, thus abrogating the government's 2008 decision.

In Germany, the Chernobyl accident led to the creation of a federal environment ministry, after several states had already created such a post. The post has been held, among others, by Angela Merkel who would later become leader of the opposition and then chancellor. The German environmental minister was given the authority over reactor safety as well, a responsibility the current minister still holds today. The Chernobyl disaster is also credited with strengthening the anti-nuclear movement in Germany, which culminated in the decision to end the use of nuclear power made by the 1998-2005 Schröder government. A temporary reversal of this policy was in turn reverted after the Fukushima nuclear disaster.

In direct response to the Chernobyl disaster, a conference to create a Convention on Early Notification of a Nuclear Accident was called in 1986 by the International Atomic Energy Agency. The resulting treaty has bound signatory member states to provide notification of any nuclear and radiation accidents that occur within its jurisdiction that could affect other states, along with the Convention on Assistance in the Case of a Nuclear Accident or Radiological Emergency.

The Chernobyl disaster, along with the space shuttle Challenger disaster, the Three Mile Island accident, and the Bhopal disaster have been used together as case studies, both by the US government and by third parties, in research concerning the root causes of such disasters, such as sleep deprivation and mismanagement.

Cultural impact

The Chernobyl tragedy has inspired many artists across the world to create works of art, animation, video games, theatre and cinema about the disaster. The HBO series and the book Voices from Chernobyl by the Ukrainian-Belarusian writer Svetlana Alexievich are two well-known works that talk about the catastrophe that destroyed millions of lives. The Ukrainian artist Roman Gumanyuk created a series of artworks called "Pripyat Lights, or Chernobyl shadows" that includes 30 oil paintings about the Chernobyl accident. The series of artwork was exhibited at the National Fine Art Museum of Kyrgyzstan in Bishkek, the Kasteev State Museum of Arts of Kazakhstan in Almaty, the Vashchenko Art Gallery of Gomel in Belarus, and at the Museum of Chernobyl in Kharkiv in Ukraine in the years 2012-2013.

The video game S.T.A.L.K.E.R.: Shadows of Chernobyl released by THQ in 2007, is a first-person shooter set in the Exclusion Zone. A prequel called S.T.A.L.K.E.R.: Clear Sky was released in 2008 following with a sequel S.T.A.L.K.E.R.: Call of Pripyat released in 2010. Finally, the horror film Chernobyl Diaries released in 2012 is about six tourists that hire a tour guide to take them to the abandoned city of Pripyat where they discover they are not alone.

Filmmakers have created documentaries that examine the aftermath of the disaster over the years. Documentaries like the Oscar-winning Chernobyl Heart released in 2003, explore how radiation affected people living in the area and information about the long-term side effects of radiation exposure over the years that include mental disabilities, physical disabilities, and genetic mutations after the disaster. The Babushkas of Chernobyl released in 2015, is a documentary that explores the story of the three women who decided to return to the exclusion zone after the disaster. In the documentary, the Babushkas show the polluted water, their food from radioactive gardens, and explain how they manage to survive in this exclusion zone despite the radioactive levels of it. The documentary The Battle of Chernobyl, released in 2006, shows a rare original footage a day before the disaster in the city of Pripyat, then through different methods the documentary goes in depth on the chronological events that led to the explosion of the reactor No. 4 and the disaster response in which 50,000 men from Soviet Union engaged to liquidate the radioactivity of the damaged reactor.

In July 2019, Ukrainian president Volodymyr Zelenskyy announced that the Chernobyl site would become an official tourist attraction. Zelenskyy said, "We must give this territory of Ukraine a new life," after Chernobyl saw an increase in visitors since the HBO mini-series. Dr. T. Steen, a microbiology and immunology teacher at Georgetown's School of Medicine, recommends tourists to wear clothes and shoes they are comfortable with throwing away. Most importantly, Steen suggests to avoid plant life, especially the depths of the forest due to the high levels of radiation. Because the areas were not cleaned in the aftermath of the disaster, they remain highly contaminated. Research showed that fungus, moss, and mushrooms are radioactive. Drinking or eating from there could be dangerous. Generally speaking, Chernobyl can be a safe place, Dr. Steen said, "but it depends on how people behave."

References

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The Chernobyl disaster began on 26 April 1986 with the explosion of the No. 4 reactor of the Chernobyl Nuclear Power Plant, near the city of Pripyat in the north of the Ukrainian SSR, close to the border with the Byelorussian SSR, in the Soviet Union.

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End of the Iran–Iraq War.

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Fall of the Berlin Wall; Revolutions of 1989 and collapse of the Soviet Bloc in Europe.

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1991 Dissolution of the Sovietc Union and independence of 15 former Sovietic republics

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La caída de la Unión Soviética en imágenes

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FOTOGALERÍA El 8 de diciembre de 1991, el ruso Boris Yeltsin (ya fallecido), el bielorruso Stanislav Shushkevich y el ucranio Leonid Kravchuk dieron el tiro de gracia a la URSS.

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Diana, Princess of Wales is killed in a car accident in Paris.

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Google is founded by Larry Page and Sergey Brin.

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Euro is introduced to the financial markets.

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1989

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1989 Demolition of The Berlin Wall
After several weeks of civil unrest, the East German government announced on 9 November 1989 that all GDR citizens could visit West Germany and West Berlin.

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The murder of the King Frank Joseph is the starting point to World War I

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Russian Revolution (
Russian Revolution (1905)

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