Method and apparatus for the surveillance of the reactivity rate of a core in a nuclear reactor and for the diagnosis of changes in the core reactivity

摘要

1. Method for monitoring the reactivity balance of the core of a nuclear reactor, more particularly of a liquid metal cooled, fast breeder reactor, with a plurality of fuel elements and control rods, and for diagnosing reactivity disturbances, the reactivity measured directly, for example through the neutron flux, (rhomess1 ) being compared with a reactivity (rhomess2 ) determined from diverse measurements, characterized by the following features : a) The comparative value (rhomess2 ) is obtained as function of direct and indirect measured values by means of connection with all relevant reactivity parameters. b) All direct and indirect measured values are moreover used, periodically or as required, for the recalculation of the reactivity parameters by means of the adjustment of the comparative value (rhomess2 ) to the directly measured reactivity (rhomess1 ). c) With the exceeding of a tolerance threshold by the difference between the directly measured reactivity and the comparative value (DELTArho = rhomess1 - rhomess2 ), a revaluation of all parameters is started automatically (as opposed to an alarm being emitted), matching the directly measured reactivity (rhomess1 ), (with the result that DELTArho becomes small again). d) The reactivity parameters are monitored with the observance of certain desired value limits. e) If a reactivity parameter exceeds its limiting values, an alarm is then emitted, the emitting parameter being shown.