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Hot Particle
A hot particle is a microscopic piece of radioactive material that can become lodged in living tissue and deliver a concentrated dose of radiation to a small area. A generally accepted theory proposes that hot particles within the body are vastly more dangerous than external emitters delivering the same dose of radiation in a diffused manner. Other researchers claim that there is little or no difference in risk between internal and external emitters, maintaining that individuals will likely continue to accumulate radiation dose from internal sources even after being removed from the original hazard and properly decontaminated, regardless of the relative danger from an internally sourced radiation dose compared to an equivalent externally sourced radiation dose. The theory has gained most prominence in debates over the health effects of nuclear accidents, dirty bombs or fallout from nuclear weapons, all of which can spread hot particles through the environment. The current ICRP ri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chernobyl Disaster
On 26 April 1986, the no. 4 reactor of the Chernobyl Nuclear Power Plant, located near Pripyat, Ukrainian Soviet Socialist Republic, Ukrainian SSR, Soviet Union (now Ukraine), exploded. With dozens of direct casualties, it is one of only two nuclear energy accidents rated at the maximum severity on the International Nuclear Event Scale, the other being the 2011 Fukushima nuclear accident. The response involved more than Chernobyl liquidators, 500,000 personnel and cost an estimated 18billion Soviet ruble, rubles (about $84.5billion USD in 2025). It remains the worst nuclear disaster and the List of disasters by cost, most expensive disaster in history, with an estimated cost of US$700 billion. The disaster occurred while running a test to simulate cooling the reactor during an accident in blackout conditions. The operators carried out the test despite an accidental drop in reactor power, and due to a design issue, attempting to shut down the reactor in those conditio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Qaanaaq
Qaanaaq (), formerly known as New Thule, is the main town in the northern part of the Avannaata municipality in northwestern Greenland. The town has a population of 646 as of 2020. The population was forcibly relocated from its former, traditional home, which was expropriated for the construction of a United States Air Force base (Thule Air Base, now Pituffik Space Base) in 1953. The inhabitants of Qaanaaq speak the local Inuktun language and many also speak Kalaallisut and Danish. Qaanaaq is one of the northernmost towns in the world. Within Greenland, it is the northernmost major town and the third northernmost public settlement, after nearby Qeqertat and Siorapaluk. Geography Qaanaaq is located in the northern entrance of the Inglefield Fjord. The village of Qeqertat is located in the Harvard Islands, near the head of the fjord. History The Qaanaaq area in northern Greenland was first settled around 2000 BCE by Paleo-Eskimos migrating from the Canadian Arctic. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boeing B-52 Stratofortress
The Boeing B-52 Stratofortress is an American long-range, subsonic aircraft, subsonic, jet-powered strategic bomber. The B-52 was designed and built by Boeing, which has continued to provide support and upgrades. It has been operated by the United States Air Force (USAF) since 1955 and was flown by NASA from 1959 to 2007. The bomber can carry up to of weapons and has a typical Range (aeronautics), combat range of around without aerial refueling. After Boeing won the initial contract in June 1946, the aircraft's design evolved from a straight wing, straight-wing aircraft powered by six turboprop engines to the final prototype YB-52 with eight turbojet engines and swept wings. The B-52 took its maiden flight in April 1952. Built to carry nuclear weapons for Cold War Nuclear strategy, deterrence missions, the B-52 Stratofortress replaced the Convair B-36 Peacemaker. The bombers flew under the Strategic Air Command (SAC) until it was disestablished in 1992 and its aircraft abso ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
BES-5
BES-5, also known as Bouk or Buk (), was a Soviet thermoelectric generator that was used to power 31 satellites in the US-A (RORSAT) project. The heat source was a uranium 235 fast fission nuclear reactor (FNR). Background Spacecraft nuclear reactors are typically fast reactors for the following reasons. First, normal moderator materials (carbon, water) add bulk and mass which is not desirable in a spacecraft. Second, for reasons of nucleonics the fuel must be highly enriched to have a lightweight critical mass (similar to small reactor designs on nuclear submarines). Note that some of the 238U (which is fertile and not fissile) will be converted to 239Pu during operation, and this is taken into consideration during the design and while estimating the power output and design life expectancy. Reactor design The design of the BES-5 FNR is such that a sub-critical assembly exists into which a rod of fissile material is inserted. Feedback and monitoring of the power level will ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kosmos 954
Kosmos 954 () was a reconnaissance satellite launched by the Soviet Union in 1977. A malfunction prevented safe separation of its onboard Nuclear reactor technology, nuclear reactor; when the satellite Atmospheric reentry, reentered the Earth's atmosphere the following year, it scattered radioactive debris over northern Canada, some of the debris landing in the Great Slave Lake next to Fort Resolution, Northwest Territories. This prompted an extensive multiyear cleanup operation known as Operation Morning Light. The Canadian government billed the Soviet Union for over 6 million Canadian dollars under the terms of the Outer Space Treaty, which obligates states for damages caused by their space objects. The USSR eventually paid 3 million Canadian dollars in compensation. Launch and operation The satellite was part of the Soviet Union's RORSAT programme, a series of reconnaissance satellites which observed ocean traffic, including surface vessels and nuclear submarines, using act ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plutonium Oxide
Plutonium(IV) oxide, or plutonia, is a chemical compound with the formula Pu O2. This high melting-point solid is a principal compound of plutonium. It can vary in color from yellow to olive green, depending on the particle size, temperature and method of production. Structure PuO2 crystallizes in the fluorite motif, with the Pu4+ centers organized in a face-centered cubic array and oxide ions occupying tetrahedral holes. PuO2 owes its utility as a nuclear fuel to the fact that vacancies in the octahedral holes allows room for fission products. In nuclear fission, one atom of plutonium splits into two. The vacancy of the octahedral holes provides room for the new product and allows the PuO2 monolith to retain its structural integrity. At high temperatures PuO2 tends to lose oxygen, becoming sub-stoichiometric PuO2−x, with the introduction of lower valence Pu3+. This continues into the molten liquid state where the local Pu-O coordination number drops to predominantly 6-fold, co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fissile Material
In nuclear engineering, fissile material is material that can undergo nuclear fission when struck by a neutron of low energy. A self-sustaining thermal chain reaction can only be achieved with fissile material. The predominant neutron energy in a system may be typified by either slow neutrons (i.e., a thermal system) or fast neutrons. Fissile material can be used to fuel thermal-neutron reactors, fast-neutron reactors and nuclear explosives. Fissile vs fissionable The term ''fissile'' is distinct from ''fissionable''. A nuclide that can undergo nuclear fission (even with a low probability) after capturing a neutron of high or low energy is referred to as ''fissionable''. A fissionable nuclide that can undergo fission with a high probability after capturing a low-energy thermal neutron is referred to as ''fissile''. Fissionable materials include those (such as uranium-238) for which fission can be induced only by high-energy neutrons. As a result, fissile materi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cold War
The Cold War was a period of global Geopolitics, geopolitical rivalry between the United States (US) and the Soviet Union (USSR) and their respective allies, the capitalist Western Bloc and communist Eastern Bloc, which lasted from 1947 until the dissolution of the Soviet Union in 1991. The term ''Cold war (term), cold war'' is used because there was no direct fighting between the two superpowers, though each supported opposing sides in regional conflicts known as proxy wars. In addition to the struggle for ideological and economic influence and an arms race in both conventional and Nuclear arms race, nuclear weapons, the Cold War was expressed through technological rivalries such as the Space Race, espionage, propaganda campaigns, Economic sanctions, embargoes, and sports diplomacy. After the end of World War II in 1945, during which the US and USSR had been allies, the USSR installed satellite state, satellite governments in its occupied territories in Eastern Europe and N ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Induced Radioactivity
Induced radioactivity, also called artificial radioactivity or man-made radioactivity, is the process of using radiation to make a previously stable material radioactive. The husband-and-wife team of Irène Joliot-Curie and Frédéric Joliot-Curie discovered induced radioactivity in 1934, and they shared the 1935 Nobel Prize in Chemistry for this discovery. Irène Curie began her research with her parents, Marie Curie and Pierre Curie, studying the natural radioactivity found in radioactive isotopes. Irene branched off from the Curies to study turning stable isotopes into radioactive isotopes by bombarding the stable material with alpha particles (denoted α). The Joliot-Curies showed that when lighter elements, such as boron and aluminium, were bombarded with α-particles, the lighter elements continued to emit radiation even after the α−source was removed. They showed that this radiation consisted of particles carrying one unit positive charge with mass equal to that of an el ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neutron Activation
Neutron activation is the process in which neutron radiation induces radioactivity in materials, and occurs when atomic nuclei capture free neutrons, becoming heavier and entering excited states. The excited nucleus decays immediately by emitting gamma rays, or particles such as beta particles, alpha particles, fission products, and neutrons (in nuclear fission). Thus, the process of neutron capture, even after any intermediate decay, often results in the formation of an unstable activation product. Such radioactive nuclei can exhibit half-lives ranging from small fractions of a second to many years. Neutron activation is the only common way that a stable material can be induced into becoming intrinsically radioactive. All naturally occurring materials, including air, water, and soil, can be induced (activated) by neutron capture into some amount of radioactivity in varying degrees, as a result of the production of neutron-rich radioisotopes. Some atoms require more th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclear Test
Nuclear weapons tests are experiments carried out to determine the performance of nuclear weapons and the effects of their explosion. Nuclear testing is a sensitive political issue. Governments have often performed tests to signal strength. Because of their destruction and fallout, testing has seen opposition by civilians as well as governments, with international bans having been agreed on. Thousands of tests have been performed, with most in the second half of the 20th century. The first nuclear device was detonated as a test by the United States at the Trinity site in New Mexico on July 16, 1945, with a yield approximately equivalent to 20 kilotons of TNT. The first thermonuclear weapon technology test of an engineered device, codenamed Ivy Mike, was tested at the Enewetak Atoll in the Marshall Islands on November 1, 1952 (local date), also by the United States. The largest nuclear weapon ever tested was the Tsar Bomba of the Soviet Union at Novaya Zemlya on October 30, 19 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
