On Measurement of Subcriticality of Reactors with Statistical Methods

Abstract

The possibility of measurement of subcriticality of reactors of nuclear power plants by statistical methods in the performance of requirements of Regulations NP-082-07 is discussed. The statistical methods, in particular, the Feynman method, make it possible to measure the subcriticality of shutdown reactors and at initial start-ups within the required range of 0.01–0.02 at the level of neutron detector counting of about one pulse per second. The Feynman method was perfected at the critical assembly of the high-temperature gas-cooled nuclear reactor PROTEUS at the Paul Scherrer Institute (Switzerland). The measurement results of subcriticality are presented. The conditions which should be ensured to obtain an acceptable result of experiment are formulated.