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Cladding is the outer layer of the fuel rods, standing between the coolant and the nuclear fuel. It is made of a corrosion -resistant material with low absorption cross section for thermal neutrons , usually Zircaloy or steel in modern constructions, or magnesium with small amount of aluminium and other metals for the now-obsolete Magnox reactors .
Spent nuclear fuel, occasionally called used nuclear fuel, is nuclear fuel that has been irradiated in a nuclear reactor (usually at a nuclear power plant). It is no longer useful in sustaining a nuclear reaction in an ordinary thermal reactor and, depending on its point along the nuclear fuel cycle , it will have different isotopic ...
The nuclear fuel cycle, also called nuclear fuel chain, is the progression of nuclear fuel through a series of differing stages. It consists of steps in the front end , which are the preparation of the fuel, steps in the service period in which the fuel is used during reactor operation, and steps in the back end , which are necessary to safely ...
Control rod assembly for a pressurized water reactor, above fuel element Control rods are used in nuclear reactors to control the rate of fission of the nuclear fuel – uranium or plutonium . Their compositions include chemical elements such as boron , cadmium , silver , hafnium , or indium , that are capable of absorbing many neutrons without ...
The back-end of the nuclear fuel cycle, mostly spent fuel rods, contains fission products that emit beta and gamma radiation, and actinides that emit alpha particles, such as uranium-234 (half-life 245 thousand years), neptunium-237 (2.144 million years), plutonium-238 (87.7 years) and americium-241 (432 years), and even sometimes some neutron ...
Control rods are a series of rods that can be quickly inserted into the reactor core to absorb neutrons and rapidly terminate the nuclear reaction. [2] They are typically composed of actinides, lanthanides, transition metals, and boron, [3] in various alloys with structural backing such as steel. In addition to being neutron absorbent, the ...
Hydrogen embrittlement may also occur in the reactor materials and volatile fission products can be released from damaged fuel rods. Between 1,300 and 1,500 °C (2,370 and 2,730 °F), the silver-indium-cadmium alloy of control rods melts, together with the evaporation of control rod cladding. At 1,800 °C (3,270 °F), the cladding oxides melt ...
Worker examines a pond for storing spent fuel rods at the Leningrad nuclear power plant in Sosnovy Bor. The maximum temperature of the spent fuel bundles decreases significantly between two and four years, and less from four to six years. The fuel pool water is continuously cooled to remove the heat produced by the spent fuel assemblies.