FIELD: physics.
SUBSTANCE: invention relates to physics of nuclear reactors and namely to provision of nuclear safety at operation of nuclear power plants (NPP) - nuclear reactors and NPP critical assemblies. Method for subcriticality determination of NPP stopped without transfer into emergency condition lies in measurement of counting rate v(t) in time from NPP by neutron detectors before, during and after disturbance introduction into neutron current emitted by NPP and in calculation of NPP subcriticality. Count number (T1ST2) of each neutron detector is measured within range of (T1÷T2), where T1 is end time of disturbance introduction into neutron current and T2 is end time of counting rate measurements. Average counting rates v(0) are measured for each neutron detectors at NPP initial stationary condition and v(T2) NPP final stationary condition. By measured values v(0) and v(T2) for each detector counting rate v(t) and number groups of counts (T1CT2)j are calculated by point kinetics equation in range (T1÷T2) at variation of effective multiplication factor k0j in initial NPP condition in range from 0.99 up to 0.95. Subcriticality is determined through the unknown keff=k0j, at which (T1CT2)j has minimum deviation of T1ST2.
EFFECT: provision of subcriticality evaluation in all modes of stopped NPP, reliability enhancement of subcriticality evaluation and increase of NPP safety.
8 cl, 6 dwg
