MEASUREMENT METHOD OF NUCLEAR REACTOR REACTIVITY Russian patent published in 2013 - IPC G21C17/04 

FIELD: power industry.

SUBSTANCE: measurement method of nuclear reactor reactivity, at which signals from fission chamber are converted to a physical parameter. Reactivity is calculated as per the change in time of the value of that parameter, by solving the converted equation of the reactor kinetics, by means of a digital reactivity metre. Reactivity metre is pre-adjusted. When the reactor is being started again after reduction of its power to N level corresponding to pulse operating mode of reactivity metre, at which the share of mutual pulse superimpositions is inconsiderable. Reactivity metre is switched over in turn to pulse and current operating modes. Corresponding values of counting speed of current pulses and current of fission chamber are measured. Then, value of fission chamber current determined with neutrons is calculated as per the following formula: In=AFq, where F - measured counting speed of current pulses of fission chamber; q - average charge in current pulse of fission chamber; A - normalisation coefficient, and partial reverse compensation of measured current is entered so that equality of measured current to fission chamber current determined with neutrons can be provided at N power level; at that, partial reverse compensation is provided by supplying counter current to current input of reactivity metre simultaneously with current of fission chamber or by means of mathematical deduction of counter current from measured current at processing of signal in a digital channel of reactivity metre; after that, calculation of reactivity in current mode is performed as per compensated current.

EFFECT: invention allows sufficient improvement of monitoring reliability of nuclear reactor state.