Operational limits of type 230 WWER-440 nuclear power plant

The main results and conclusions are presented of an investigation of operational limits of a nuclear power plant with a type 230 WWER-440 reactor. Described are the procedure, solution pre-requisites and safety criteria applied for evaluating the permissibility of processes brought about by an outage of the main circulating pumps. A permissible power output of the reactor for various groups of regimes was designed on the basis of the study. As compared with the project of limit operating regimes it was recommended that in three groups power output should be reduced by 5%, in three groups reserves were found allowing to increase the output by 10%, and in one group reserves were found for increasing the output by 5% of the rated power. An adverse effect of higher permissible output on operating safety was found in three groups of regimes. (J.B.)