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Portal:Nuclear technology

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This symbol of radioactivity is internationally recognized.
Nuclear technology is technology that involves the nuclear reactions of atomic nuclei. Among the notable nuclear technologies are nuclear reactors, nuclear medicine and nuclear weapons. It is also used, among other things, in smoke detectors and gun sights.
A nuclear weapon (also called an atom bomb, nuke, atomic bomb, nuclear warhead, A-bomb, or nuclear bomb) is an explosive device that derives its destructive force from nuclear reactions, either fission (fission bomb) or from a combination of fission and fusion reactions (thermonuclear bomb). Both bomb types release large quantities of energy from relatively small amounts of matter. The first test of a fission ("atomic") bomb released an amount of energy approximately equal to 20,000 tons of TNT (84 TJ). The first thermonuclear ("hydrogen") bomb test released energy approximately equal to 10 million tons of TNT (42 PJ). A thermonuclear weapon weighing little more than 2,400 pounds (1,100 kg) can release energy equal to more than 1.2 million tons of TNT (5.0 PJ). A nuclear device no larger than traditional bombs can devastate an entire city by blast, fire, and radiation. Since they are weapons of mass destruction, the proliferation of nuclear weapons is a focus of international relations policy.

Nuclear weapons have been used twice in war, both times by the United States against Japan near the end of World War II. On August 6, 1945, the U.S. Army Air Forces detonated a uranium gun-type fission bomb nicknamed "Little Boy" over the Japanese city of Hiroshima; three days later, on August 9, the U.S. Army Air Forces detonated a plutonium implosion-type fission bomb nicknamed "Fat Man" over the Japanese city of Nagasaki. These bombings caused injuries that resulted in the deaths of approximately 200,000 civilians and military personnel. The ethics of these bombings and their role in Japan's surrender are subjects of debate.

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Polaris missile launch from HMS Revenge (S27) 1983.JPEG
The United Kingdom's Polaris programme, officially named the British Naval Ballistic Missile System, provided its first submarine-based nuclear weapons system. Polaris was in service from 1968 to 1996.

Polaris itself was an operational system of four Resolution-class ballistic missile submarines, each armed with 16 Polaris A-3 ballistic missiles. Each missile was able to deliver three ET.317 thermonuclear warheads. This configuration was later upgraded to carry two warheads hardened against the effects of radiation and nuclear electromagnetic pulse, along with a range of decoys.

The British Polaris programme was announced in December 1962 following the Nassau Agreement between the US and the UK. The Polaris Sales Agreement provided the formal framework for cooperation. Construction of the submarines began in 1964, and the first patrol took place in June 1968. All four boats were operational in December 1969. They were operated by the Royal Navy, and based at Clyde Naval Base on Scotland's west coast, a few miles from Glasgow. At least one submarine was always on patrol to provide a continuous at-sea deterrent.

In the 1970s it was considered that the re-entry vehicles were vulnerable to the Soviet anti-ballistic missile screen concentrated around Moscow. To ensure that a credible and independent nuclear deterrent was maintained, the UK developed an improved front end named Chevaline. There was controversy when this project became public knowledge in 1980, as it had been kept secret by four successive governments while incurring huge expenditure. Polaris patrols continued until May 1996, by which time the phased handover to the replacement Trident system had been completed.

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Army-Navy E Award.jpg
Credit: Los Alamos National Laboratory

Los Alamos ranch house,16 October 1945. Robert Oppenheimer (left), Leslie Groves (center) and Robert Sproul (right) at the ceremony to present the Los Alamos Laboratory with the Army-Navy E Award

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Haroutune Krikor Daghlian Jr. (May 4, 1921 – September 15, 1945) was an American physicist with the Manhattan Project, which designed and produced the atomic bombs that were used in World War II. He accidentally irradiated himself on August 21, 1945, during a critical mass experiment at the remote Omega Site of the Los Alamos Laboratory in New Mexico, resulting in his death 25 days later.

Daghlian was irradiated as a result of a criticality accident that occurred when he accidentally dropped a tungsten carbide brick onto a 6.2 kg plutonium–gallium alloy bomb core. This core, subsequently nicknamed the "demon core", was later involved in the death of another physicist, Louis Slotin.

Nuclear technology news

18 November 2019 – Fukushima nuclear disaster
The Japanese government authorizes a release of contaminated water from the plant into the Pacific Ocean. Officials say that the release represents a "significantly small" risk to human health. (Kyodo News English)
6 November 2019 – Nuclear program of Iran
French media reports that Iranian nuclear scientists began injecting uranium into centrifuges in the presence of International Atomic Energy Agency inspectors at the Fordow Fuel Enrichment Plant. Effectively it turns the plant from a research site into an active nuclear site, in further violation of the Joint Comprehensive Plan of Action. (Al Jazeera)

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