Analysis of accuracy of reactivity balance components in BN-600 power fast reactor - 212

Reactivity balance is a key element for nuclear safety substantiation for reactor facilities of any type. Commercial operation of BN-600 power fast reactor in Beloyarsk NPP stimulated work on finding optimal balance between conservative safety margins and reactor performance. This paper is devoted to the studies on the possibility of achieving high indices on the accuracy of reactivity balance justification. It is described calculation and experimental methods for determination of components of BN-600 reactivity balance. Results of comparison calculation and experimental data are presented. Taking into account experimental data and verification of codes facilitates increase of accuracy of max excess reactivity forecast up to 0.2%Δk/k. Forecast of the BN-600 reactor core subcriticality after SR setting can be made to the accuracy of 0.2-0.4%Δk/k, accuracy of SHR system worth forecast is 7%, single SR and reactor safety system 7-8%. These values make it possible to significantly decrease (by a factor of 2) conservatism of evaluation of these parameters justifying nuclear safety of the BN-600 reactor core. (authors)