Nuclear reactor poisons Nuclear fission product

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some fission products decay release of neutron. since there may short delay in time between original fission event (which releases own prompt neutrons immediately) , release of these neutrons, latter termed delayed neutrons . these delayed neutrons important nuclear reactor control.


some of fission products, such xenon-135 , samarium-149, have high neutron absorption cross section. since nuclear reactor depends on balance in neutron production , absorption rates, fission products remove neutrons reaction tend shut reactor down or poison reactor. nuclear fuels , reactors designed address phenomenon through such features burnable poisons , control rods. build-up of xenon-135 during shutdown or low-power operation may poison reactor enough impede restart or interfere normal control of reaction during restart or restoration of full power, possibly causing or contributing accident scenario.







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