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Image source: https://currentaffairs.adda247.com/hiroshima-day-facts-history-and-significance/

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On August sixth, 1945, during World War II, the United States dropped a 9,700 pound atomic bomb called “Little boy” on the city of Hiroshima, Japan, destroying 90% of the city. This was the first time a nuclear bomb had been used in warfare. The bomb was made of about 64 grams of highly enriched uranium-235. Within minutes of the explosion, 9 out of 10 people within half a mile of ground zero were killed,  and in total, over 200,000 people died due to the atomic bombing of Hiroshima. The massive release of energy from the bombs allowed them to have devastating effects. The energy caused fires, destructive blast pressure, extreme radiation exposure, and high temperatures immediately upon the blast, further killing locals. The dropping of this uranium based bomb marks one of the most devastating events in human history.

Sources - https://www.osti.gov/opennet/manhattan-project-history/Events/1945/hiroshima.htm

https://world-nuclear.org/information-library/safety-and-security/non-proliferation/hiroshima-nagasaki-and-subsequent-weapons-testin

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THE ATOMIC BOMBING OF HIROSHIMA(Hiroshima, Japan, August 6, 1945)
Events >Dawn of the Atomic Era, 1945

The War Enters Its Final Phase, 1945

Debate Over How to Use the Bomb, Late Spring 1945

The Trinity Test, July 16, 1945

Safety and the Trinity Test, July 1945

Evaluations of Trinity, July 1945

Potsdam and the Final Decision to Bomb, July 1945

The Atomic Bombing of Hiroshima, August 6, 1945

The Atomic Bombing of Nagasaki, August 9, 1945

Japan Surrenders, August 10-15, 1945

The Manhattan Project and the Second World War, 1939-1945

In the early morning hours of August 6, 1945, a B-29 bomber named Enola Gay took off from the island of Tinian and headed north by northwest toward Japan. The bomber's primary target was the city of Hiroshima, located on the deltas of southwestern Honshu Island facing the Inland Sea. Hiroshima had a civilian population of almost 300,000 and was an important military center, containing about 43,000 soldiers.

The bomber, piloted by the commander of the 509th Composite Group, Colonel Paul Tibbets, flew at low altitude on automatic pilot before climbing to 31,000 feet as it neared the target area. At approximately 8:15 a.m. Hiroshima time the Enola Gay released "Little Boy," its 9,700-pound uranium gun-type bomb, over the city. Tibbets immediately dove away to avoid the anticipated shock wave. Forty-three seconds later, a huge explosion lit the morning sky as Little Boy detonated 1,900 feet above the city, directly over a parade field where soldiers of the Japanese Second Army were doing calisthenics. Though already eleven and a half miles away, the Enola Gay was rocked by the blast. At first, Tibbets thought he was taking flak. After a second shock wave (reflected from the ground) hit the plane, the crew looked back at Hiroshima. "The city was hidden by that awful cloud . . . boiling up, mushrooming, terrible and incredibly tall," Tibbets recalled. The yield of the explosion was later estimated at 15 kilotons (the equivalent of 15,000 tons of TNT).

On the ground moments before the blast it was a calm and sunny Monday morning. An air raid alert from earlier that morning had been called off after only a solitary aircraft was seen (the weather plane), and by 8:15 the city was alive with activity -- soldiers doing their morning calisthenics, commuters on foot or on bicycles, groups of women and children working outside to clear firebreaks. Those closest to the explosion died instantly, their bodies turned to black char. Nearby birds burst into flames in mid-air, and dry, combustible materials such as paper instantly ignited as far away as 6,400 feet from ground zero. The white light acted as a giant flashbulb, burning the dark patterns of clothing onto skin (right) and the shadows of bodies onto walls. Survivors outdoors close to the blast generally describe a literally blinding light combined with a sudden and overwhelming wave of heat. (The effects of radiation are usually not immediately apparent.) The blast wave followed almost instantly for those close-in, often knocking them from their feet. Those that were indoors were usually spared the flash burns, but flying glass from broken windows filled most rooms, and all but the very strongest structures collapsed. One boy was blown through the windows of his house and across the street as the house collapsed behind him. Within minutes 9 out of 10 people half a mile or less from ground zero were dead.

People farther from the point of detonation experienced first the flash and heat, followed seconds later by a deafening boom and the blast wave. Nearly every structure within one mile of ground zero was destroyed, and almost every building within three miles was damaged. Less than 10 percent of the buildings in the city survived without any damage, and the blast wave shattered glass in suburbs twelve miles away. The most common first reaction of those that were indoors even miles from ground zero was that their building had just suffered a direct hit by a bomb. Small ad hoc rescue parties soon began to operate, but roughly half of the city's population was dead or injured. In those areas most seriously affected virtually no one escaped serious injury. The numerous small fires that erupted simultaneously all around the city soon merged into one large firestorm, creating extremely strong winds that blew towards the center of the fire. The firestorm eventually engulfed 4.4 square miles of the city, killing anyone who had not escaped in the first minutes after the attack. One postwar study of the victims of Hiroshima found that less than 4.5 percent of survivors suffered leg fractures. Such injuries were not uncommon; it was just that most who could not walk were engulfed by the firestorm.

Even after the flames had subsided, relief from the outside was slow in coming. For hours after the attack the Japanese government did not even know for sure what had happened. Radio and telegraph communications with Hiroshima had suddenly ended at 8:16 a.m., and vague reports of some sort of large explosion had begun to filter in, but the Japanese high command knew that no large-scale air raid had taken place over the city and that there were no large stores of explosives there. Eventually a Japanese staff officer was dispatched by plane to survey the city from overhead, and while he was still nearly 100 miles away from the city he began to report on a huge cloud of smoke that hung over it. The first confirmation of exactly what had happened came only sixteen hours later with the announcement of the bombing by the United States. Relief workers from outside the city eventually began to arrive and the situation stabilized somewhat. Power in undamaged areas of the city was even restored on August 7th, with limited rail service resuming the following day. Several days after the blast, however, medical staff began to recognize the first symptoms of radiation sickness among the survivors. Soon the death rate actually began to climb again as patients who had appeared to be recovering began suffering from this strange new illness. Deaths from radiation sickness did not peak until three to four weeks after the attacks and did not taper off until seven to eight weeks after the attack. Long-range health dangers associated with radiation exposure, such as an increased danger of cancer, would linger for the rest of the victims' lives, as would the psychological effects of the attack.

No one will ever know for certain how many died as a result of the attack on Hiroshima. Some 70,000 people probably died as a result of initial blast, heat, and radiation effects. This included about twenty American airmen being held as prisoners in the city. By the end of 1945, because of the lingering effects of radioactive fallout and other after effects, the Hiroshima death toll was probably over 100,000. The five-year death total may have reached or even exceeded 200,000, as cancer and other long-term effects took hold.

At 11:00 a.m., August 6 (Washington D.C. time), radio stations began playing a prepared statement from President Truman informing the American public that the United States had dropped an entirely new type of bomb on the Japanese city of Hiroshima -- an "atomic bomb." Truman warned that if Japan still refused to surrender unconditionally, as demanded by the Potsdam Declaration of July 26, the United States would attack additional targets with equally devastating results. Two days later, on August 8, the Soviet Union declared war on Japan and attacked Japanese forces in Manchuria, ending American hopes that the war would end before Russian entry into the Pacific theater. By August 9th, American aircraft were showering leaflets all over Japan informing its people that "We are in possession of the most destructive explosive ever devised by man. A single one of our newly developed atomic bombs is actually the equivalent in explosive power to what 2,000 of our giant B-29s can carry on a single mission. This awful fact is one for you to ponder and we solemnly assure you it is grimly accurate. We have just begun to use this weapon against your homeland. If you still have any doubt, make inquiry as to what happened to Hiroshima when just one atomic bomb fell on that city." Meanwhile, Tibbets's bomber group was simply waiting for the weather to clear in order to drop its next bomb, the plutonium implosion weapon nicknamed "Fat Man" (left) that was destined for the city of Nagasaki.

The War Enters Its Final Phase, 1945

Debate Over How to Use the Bomb, Late Spring 1945

The Trinity Test, July 16, 1945

Safety and the Trinity Test, July 1945

Evaluations of Trinity, July 1945

Potsdam and the Final Decision to Bomb, July 1945

The Atomic Bombing of Hiroshima, August 6, 1945

The Atomic Bombing of Nagasaki, August 9, 1945

Japan Surrenders, August 10-15, 1945

The Manhattan Project and the Second World War, 1939-1945

Next
Sources and notes for this page.

Portions of the text for this page were adapted from, and portions were taken directly from the Office of History and Heritage Resources publication: F. G. Gosling, The Manhattan Project: Making the Atomic Bomb (DOE/MA-0001; Washington: History Division, Department of Energy, January 1999), 51-53. Also used was the report on "The Atomic Bombings of Hiroshima and Nagasaki" in the official Manhattan District History, produced by the War Department in 1947 at the direction of Leslie Groves, especially pages 1-19; the "Atomic Bombings" document is available in the University Publications of America microfilm collection, Manhattan Project: Official History and Documents (Washington: 1977), reel #1/12; the report itself is a government document. Tibbets's description is from Paul W. Tibbets, "How to Drop an Atom Bomb," Saturday Evening Post 218 (June 8, 1946), 136. The estimate of Little Boy's yield is fromUnited States Nuclear Tests, July 1945 through September 1992 (DOE/NV-209-REV 15; Las Vegas, NV: Nevada Operations Office, Department of Energy, December 2000), vii. Summaries of Hiroshima and Nagasaki casualty rates and damage estimates appear in Leslie R. Groves, Now It Can Be Told (New York: Harper & Row, 1962), 319, 329-330, 346, and Vincent C. Jones, Manhattan: The Army and the Atomic Bomb, United States Army in World War II (Washington: Center of Military History, United States Army, 1988), 545-548. A translation of the leaflets dropped on Japan in between Hiroshima and Nagasaki can be found in Dennis Merrill, ed., Documentary History of the Truman Volume 1, The Decision to Drop the Atomic Bomb on Japan (Bethesda, MD: University Publications of America, 1995), 194-195. The photograph of the mushroom cloud is courtesy the United States Air Force (USAF) (via the National Archives (NARA)). The photographs of Little Boy and Fat Man are courtesy the U.S. Army Corps of Engineers (via NARA). The photograph of the Enola Gay landing at Tinian Island is courtesy the USAF. The photograph of the woman with burns on her back is courtesy the U.S. Army Corps of Engineers (via NARA). The photographs of the mushroom cloud taken from the ground and of the debris (including the Hiroshima Peace Memorial (Genbaku "A-bomb" Dome) are courtesy the Federation of American Scientists. The photographs of the hospital and of the lone soldier walking through an almost-completely leveled portion of the city are courtesy the Department of the Navy (via NARA); the former was taken by Wayne Miller.

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Manhattan Project: The Atomic Bombing of Hiroshima, August 6, 1945

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THE ATOMIC BOMBING OF HIROSHIMA (Hiroshima, Japan, August 6, 1945) Events >Dawn of the Atomic Era, 1945 The War Enters Its Final Phase, 1945 Debate Over How to Use the Bomb, Late Spring 1945 The Trinity Test, July 16, 1945 Safety and the Trinity Test, July 1945 Evaluations of Trinity,

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A nuclear reaction is a process that changes the structure of an atom’s nucleus by changing the number of neutrons and protons of one element and transforming it into another. The change of the number of protons is especially important because they dictate which element an atom is. Unlike chemical reactions, nuclear reactions take place inside the nucleus and change the number of neutrons and protons while chemical reactions do not, they only share and transfer electrons around the nucleus. There are two types of nuclear reactions: Nuclear fusion and nuclear fission. Both of these nuclear reactions are very powerful and release much more energy that chemical reactions do and they aren't as impacted by environmental factors such as temperature and pressure like chemical reactions are. Nuclear reactions not only release energy, but they emit radioactive decay particles as well. For example, when uranium-235–like used in the atomic bomb dropped on Hiroshima– goes through alpha decay, it emits helium nucleus and becomes thorium-231. This shows how nuclear reactions transform elements in the process of a reaction.

Sources - https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Fundamentals_of_General_Organic_and_Biological_Chemistry_(LibreTexts)/11%3A_Nuclear_Chemistry/11.01%3A_Nuclear_Reactions

https://drive.google.com/file/d/12_OB-6ahMZxzemUjWWvPORLASCRPheST/view (Unit 2 textbook pages)

Lesson 8.5 -https://drive.google.com/file/d/1BA3CLxnGi0dbxj8r-xwCUAZWAEE63kKk/view

Picture credit - https://www.nagwa.com/en/videos/502190958497/

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What Type of Nuclear reaction happened at Hiroshima? 

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What Type of Nuclear reaction happened at Hiroshima? 

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The atomic bomb that was dropped on Hiroshima used nuclear fission to split the uranium-235 when it was hit by a neutron. The split of the nucleus released large amounts of energy, more neutrons, and radiation. The released neutrons of the reaction then struck other uranium atoms and caused a chain reaction of the bomb and multiplied its force in seconds. Unlike fusion, where particle combine, the fission reactants combined to make a destructive blast. This uncontrolled nuclear reaction release about 16,000 tons of energy and devastated the population in Hiroshima, killing over 200,000 due to the bomb.

Sources - https://world-nuclear.org/information-library/safety-and-security/non-proliferation/hiroshima-nagasaki-and-subsequent-weapons-testing

(textbook pages about nuclear fusion and fission) - https://drive.google.com/file/d/12_OB-6ahMZxzemUjWWvPORLASCRPheST/view

(image) -https://www.britannica.com/event/atomic-bombings-of-Hiroshima-and-Nagasaki

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Two atomic bombs made by the allied powers (USA and UK) from uranium-235 and plutonium-239 were dropped on Hiroshima and Nagasaki respectively early in August 1945. These brought the long Second World War to a sudden end.

The immense and previously unimaginable power of the atom had been demonstrated. In the following years several governments joined the arms race, while internationally, efforts were focused on constraining the threat of nuclear weapons proliferation.

From the 1950s the power of the atom was harnessed increasingly for peaceful uses, notably electricity generation and medicine. Nowhere is the transition from weapons of destruction to power for good better displayed than Hiroshima and Nagasaki in Japan which have come to depend substantially on electricity from nuclear energy.

Today, as the main nuclear arsenals are being dismantled and a comprehensive test ban treaty is in sight, commercial nuclear power provides a significant portion of the world's electricity. Several factors suggest that nuclear power has a much larger role to play in supplying the world's future energy needs, and this is supported by every reputable projection.

The first two atomic bombs in 1945

The Hiroshima bomb was made from highly-enriched uranium-235. This was prepared by diffusion enrichment techniques using the very small differences in mass of the two main isotopes: U-235 (originally 0.7% in the uranium) and U-238, the majority. As UF ₆ , there is about a one percent difference in mass between the molecules, and this enables concentration of the less common isotope. About 64 kilograms of highly-enriched uranium was used in the bomb which had a 16 kiloton yield ( i.e. it was equivalent to 16,000 tonnes of TNT). It was released over Hiroshima, Japan's seventh largest city, on 6 August 1945. Some 90% of the city was destroyed.

The 21 kiloton explosive charge for the bomb detonated over Nagasaki three days later was provided by about 6.2 kilograms of plutonium-239 (>90% Pu-239), and its preparation depended on the operation of special nuclear reactors built for the purpose. During 1942, under conditions of wartime secrecy, the first human-designed reactor* had been constructed, in a squash court at the University of Chicago. It used highly purified graphite to slow the neutrons released in fission to enable further fission. This paved the way for more substantial production reactors at Hanford. The plutonium-239 generated in these could be separated by simple chemical methods, with no need for the complexities of isotope separation.

* Several natural nuclear reactors functioned about 2 billion years ago in Africa.

However, the design of a plutonium bomb is very much more complex than one using enriched uranium. Hence the need to test it, and in fact the plutonium was first used for a test explosion at Alamogordo in New Mexico on 16 July 1945, ushering in the nuclear age with all its threat and promise.

The effects of the Hiroshima and Nagasaki bombs

The devastating effects of both kinds of bombs depended essentially upon the energy released at the moment of the explosion, causing immediate fires, destructive blast pressures, and extreme local radiation exposures. Since the bombs were detonated at a height of some 600 metres above the ground, very little of the fission products were deposited on the ground beneath. Some deposition occurred however in areas near to each city, owing to local rainfall occurring soon after the explosions. This happened at positions a few kilometres to the east of Nagasaki, and in areas to the west and north-west of Hiroshima. For the most part, however, these fission products were carried high into the upper atmosphere by the heat generated in the explosion itself. The majority would have decayed by the time they landed around the globe.

In Hiroshima, of a resident civilian population of 250,000 it was estimated that 45,000 died on the first day and a further 19,000 during the subsequent four months. (Another figure is 78,500 fatalities, with 5 to 15% of the short-term ones being from radiation.) In Nagasaki, out of a population of 174,000, on the first day 22,000 died and another 17,000 within four months. Unrecorded deaths of military personnel and foreign workers may have added considerably to these figures. About 15 square kilometres (over 50%) of the two cities was destroyed.

It is uncertain what proportion of these 103,000 deaths, or of the further deaths in military personnel, were due to radiation exposure rather than to the very high temperatures and blast pressures caused by the explosions - 15 kilotons at Hiroshima and 25 kilotons at Nagasaki. From the estimated radiation levels, however, it is apparent that radiation alone would not have been enough cause death in most of those exposed beyond a kilometre of the ground zero below the bombs. Most deaths were from blast injuries or burns rather than the radiation. Beyond 1.5 km the radiation risk would have been much reduced (and 24 Australian prisoners of war about 1.5 km from the Nagasaki ground zero survived and many lived to a healthy old age).

In comparison, during the period of February 1945 to August 1945, the US bombing of Japanese cities - notably Tokyo, Nagoya, Osaka and Kobe - by B-29s delivered about 100 kilotons of high explosives and incendiaries to urban areas in hundreds of raids, resulting in a large number of deaths and causing widespread destruction. Some 80,000 to 100,000 people were killed in a single 300-bomber raid on Tokyo. About 80 square kilometers of those four cities was destroyed in ten days during March. Overall 67 Japanese cities were partly destroyed, 500,000 people were killed and 5 million more made homeless.

To the 103,000 deaths from the blast or acute radiation exposure at Hiroshima and Nagasaki have since been added those due to radiation induced cancers and leukaemia, which amounted to some 400 within 30 years, and which may ultimately reach about 550. (Some 93,000 exposed survivors were still being monitored 50 years later.) There was an increase in leukaemia beginning about two years later and peaking at four to six years later, and other cancers beginning about ten years later. There was no evident to suggest an increase in leukaemia at less than 500 mSv acute dose. At an acute dose of 100 mSv, an increased cancer risk of 1.05 times normal was calculated. There was concern about ingestion or inhalation of radionuclides, but fires released far higher levels of non-radioactive carcinogens. Additionally, no genetic damage has been detected in survivors' children, despite careful and continuing investigation by a joint Japanese-US foundation.

The major source of exposure in both cities was from the penetrating gamma radiations, and to a lesser extent from the neutrons (mostly at Hiroshima), emitted during and shortly after fission. There were two further, and smaller, sources of exposure. One, already mentioned, was due to the 'black rain' which fell in some areas, carrying down radioactive materials from within the rising cloud of fission products. The exposures due to these depositions are in general estimated to have been small, but some increased activity from the fission product radionuclide caesium-137 remained detectable for many years in soil and farm products in the Nishiyama district east of Nagasaki.

The second additional form of exposure resulted from the effect of neutrons in inducing radioactivity in various stable chemical elements such as in iron or concrete structures or roofing tiles. The total absorbed doses of radiation from these activation products are estimated to be less than one per cent of that from the neutrons which induced them. They could however have caused a significant exposure of people who entered the city within a few days of the explosions.

Subsequent atmospheric weapons tests

The atmospheric testing of some 545 nuclear weapons up to 1963 caused people to be exposed to radiation in a quite different way. The Japanese atomic bombs had caused lethal exposures locally from radiation at the time of the explosions, but very little radiation more than a few kilometres away. On the other hand, subsequent atmospheric tests did not cause any substantial direct exposures of people at the time of the tests. However, the fission products released into the atmosphere caused the whole world population to be exposed to very low but continuing annual doses from fallout. In at least two instances these fission products also caused substantial irradiation to small populations exposed to local fallout close to the site of testing.

The atomic bombs used in Japan in 1945, and the bombs or devices testing during the following seven years, depended on the fission of uranium-235 or plutonium-239, mostly the latter. The explosive effect of each was equal to that of up to a few tens of thousand tonnes of the conventional explosive TNT. On this basis of comparison, the Hiroshima bomb was of about 15 kilotons - that is, of 15 thousand tonnes of TNT equivalent - and that at Nagasaki was of 25 kilotons ( ca. 65 and 105 GJ respectively). In addition, the total equivalent of all atmospheric weapon tests made by the end of 1951 was in the region of 600 kilotons.

After 1951, however, devices were being tested which had explosive effects about a thousand times greater, and by the end of 1962 the total of all atmospheric tests had risen from the 1951 value of 0.6 million tonnes of TNT equivalent, to about 500 million tonnes equivalent. This vast increase in scale was due to the testing of 'thermonuclear' weapons or 'hydrogen bombs', which depended, not on the fission of a critical mass of fissile material alone, but on a two or three-stage process initiated by this reaction.

In a thermonuclear bomb, an initial fission, such as occurred in the 'atomic' bomb, momentarily creates conditions of enormously high temperature and atomic disturbance that allows the fusion together of the nuclei of atoms of low atomic number, such as lithium and hydrogen. This fusion liberates further large amounts of energy explosively, such as occurs in the similar reactions in the sun and stars.

In some such bombs, the high-energy neutrons released are used to set off a third stage, making it a fission-fusion-fission process. The third stage consists of the fission of a surrounding 'blanket' of uranium-238 isotope which is fissionable by neutrons of this high energy. This third stage provides about half of the yield of such a weapon.

The release of fission products is approximately proportional to the explosive power unleashed, although fusion as such does not give rise to them. From 1952 to 1962 therefore, with a thousand times more energy released in atmospheric testing than previously, the amounts of fission products discharged into the atmosphere would have increased by a much lesser factor.

To complete this tally of the total fallout to date, all atmospheric tests since 1962 appear to have increased by rather less than 20 percent the total of fission products that had been deposited by previous tests, as judged by the measured deposition of strontium-90 in successive years.

The most important radionuclides remaining from weapons testing are now carbon-14, strontium-90 and caesium-137. The global average dose from these is about 0.005 mSv/yr, compared with a peak of 0.113 mSv average in 1963. Residual dose rates at test sites are mostly low (< 1 msv/yr), apart from at Semipalatinsk in Kazakhstan.

Australian tests

Twelve atmospheric nuclear explosions comprised the main part of UK weapons testing in Australia. Three were at Monte Bello Islands (WA) in 1952 & 1956, two at Emu Field (SA) in 1953 and seven at Maralinga (SA) in 1956-57.

Underground tests and the NPT

Since the 1963 atmospheric test ban treaty, weapons tests have been mostly underground, the exceptions being by France and China. The underground tests have had no immediate environmental effect and are generally seen as relatively benign compared with the atmospheric tests.

In 1970 the Nuclear Non-Proliferation Treaty (NPT) was signed, and now has five weapons states: USA, UK, Russia, France and China. The basis of the NPT was that other states which were signatories eschewed the nuclear weapons option and in return were promised assistance in civil nuclear power development by the weapons states.

Today, 187 states have signed the NPT. The only states with significant nuclear facilities that are not party to the NPT or equivalent safeguards agreements are India and Pakistan , which exploded several nuclear devices in 1998, and Israel, which is generally believed to have nuclear capability. South Africa developed some nuclear weapons but then dismantled them, under international scrutiny, and has joined the NPT. Iraq and North Korea sought to circumvent their obligations under the NPT and this was thwarted by international pressure, but North Korea subsequently resigned from the NPT and then exploded a nuclear device underground in 2006.

From 1957 to 1989 the USA and USSR conducted about 150 explosions underground as part of their peaceful nuclear explosion programmes. A bilateral treaty covering these was signed in 1976. See also information page on Peaceful Nuclear Explosions.

Hiroshima and Nagasaki since 1945

Both cities were rebuilt soon after the war and have become important industrial centres. The population of Hiroshima has grown to over one million and that of Nagasaki to 440,000. Major industries in Hiroshima today are machinery, automotive (Mazda) and food processing, those in Nagasaki are associated with its international port, particularly Mitsubishi Heavy Industries, now a major nuclear reactor supplier.

References:

Edward Pochin, Nuclear Radiation: Risks and Benefits, Clarendon Press Oxford (1983)
UNSCEAR, Sources and Effects of Ionizing Radiation ( 1977 and 1994)
F. Barnaby, The Effects of a Global Nuclear War: The Arsenals, Ambio XI, #2-3 (1982)
International Atomic Energy Agency, Radiation, People and the Environment (February 2004)
US Strategic Bombing Survey - summary report (July 1946)
Jane Orient, Fukushima and Reflections on Radiation as a Terror Weapon, Journal of American Physicians and Surgeons, 19, 2, p48 (summer 2014)
Information on weapons matters and tests can be found on the Nuclear Files project website
Note: Being opposed to the spread of nuclear weapons and their testing, the World Nuclear Association does not normally comment on such. However, due to pubic interest and to complement information pages on safeguards and countering weapons proliferation, this page endeavours to complement the factual information normally provided by the Association on the peaceful uses of nuclear power.
India, China & NPT
Nuclear Proliferation Case Studies
Safeguards to Prevent Nuclear Proliferation

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Hiroshima, Nagasaki, and Subsequent Weapons Testing

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Two atomic bombs made from uranium-235 and plutonium-239 were dropped on Hiroshima and Nagasaki respectively early in August 1945. The atmospheric testing of some 545 nuclear weapons continued up to 1963.

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Nuclear fission is when a low-energy free floating neutron hits a larger, fissible atomic nucleus and splits it into two smaller nuclei. This creates a self-sustaining nuclear reaction that emits a large release of energy and even defies the typical law of conservation of matter by converting mass into energy to become a product of the fusion reaction. Nuclear fission releases a lot of energy, but it doesn't release as much as nuclear fusion. Nuclear fission is able to be used on Earth for weapons and nuclear power plants to generate power, unlike nuclear fusion, which is still too unsafe to be confidently used.

Source -

Unit 2 textbook pages - https://drive.google.com/file/d/12_OB-6ahMZxzemUjWWvPORLASCRPheST/view

Lesson 8.5 -https://drive.google.com/file/d/1BA3CLxnGi0dbxj8r-xwCUAZWAEE63kKk/view

Image- https://nrl.mit.edu/reactor/fission-process/

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Nuclear fusion occurs when two or more atoms combine to cream a different atomic nucleus and subatomic particles. Like nuclear fission, some mass of the atoms is converted into energy, but unlike nuclear fission, fusion is able to absorb energy as well. To create a fusion reaction, the fused particles have to go through extreme heat and pressure to force them to fuse. The amount of energy needed to create a fusion reaction is the same as a fission reaction but a key difference is the amount of energy released. A nuclear fusion releases three to four times more energy than a fission reaction. Fusions naturally occur in stars like the sun, which constantly undergoes the fusion process until it creates too many larger elements and will collapse and die over billions of years. Using nuclear fusion on earth would be way more efficient than nuclear fission because it creates three to four times the amount of energy fission does, which means more power. Also, it would further cut the use of gas and coal to make energy. The best part is that nuclear fusion is actually considered to be safer than fission due to its short term danger of its waste.

Sources - Lesson 11 Article vhttps://docs.google.com/document/d/1CLmiNujq4Lc9iRReuuWTD6B8CX7toGh5pnR0qA_KuOU/edit?tab=t.0
Picture - https://www.atomicarchive.com/science/fusion/index.html

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https://www.icanw.org/hiroshima_and_nagasaki_bombings

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https://www.aljazeera.com/gallery/2015/8/6/atomic-bomb-in-1945-a-look-back-at-the-destruction

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https://www.youtube.com/watch?v=0TFijosdjbU

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https://www.reddit.com/r/Infographics/comments/u6darz/detonating_an_atomic_bomb_in_this_case_little_boy/