FIELD: nuclear reactor physics; measuring reactivity of zero-power reactors and small-size reactors of space nuclear power plants in particular. SUBSTANCE: neutron source is placed in reactor nonfilled with fuel and component not correlated with fission neutrons is determined in terms of measuring channels. For reactor filled with fuel, relative power is measured including power drop curve upon removal of source from reactor to shielding container. Two sections are discriminated on power drop curve: first one corresponds to time of neutron source removal t2 and second section is chosen with time moment t2 and t4(t4 > t3); t3 is time moment (a few seconds) upon removal of neutron source and t4 may be any moment of power drop curve measurement until it reaches level Nψ. Then reactivity is computed according to algorithm using solution of point kinetics equation. Component not correlated with fission neutrons is subtracted from reactor power values and transient processes on time section are specially included (or excluded) according to neutron source displacement. EFFECT: improved measurement accuracy. 2 cl, 2 dwg
