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 β_eff for a BFS critical assembly whose fuel is composed of metallic plutonium and depleted uranium nitride and dioxide. The traditional method for determining β_eff by introducing the ²⁵²Cf source into the core is supplemented by the ²⁴⁰Pu 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 ²⁵²Cf source.