Development of a method for measuring the effective fraction of delayed neutrons using a 240Pu spontaneous fission source

The article presents the results of determining the effective fraction of delayed neutrons beta(eff) for a BFS critical assembly whose fuel is composed of metallic plutonium and depleted uranium nitride and dioxide. The traditional method for determining beta(eff) by introducing the Cf-252 source into the core is supplemented by the Pu-240 source of spontaneous fissions in the fuel composition. The described modification simplifies the analysis, increases the reliability of results, and can be used in power reactors with plutonium of known composition in which it is impossible to use a Cf-252 source.