Innovations to Improve the Reliability of Actuation of the «Primary to Secondary Leak» Algorithm During Accidents at Nuclear Power Plants with WWER-1000 Reactor Units

Modern approaches to enhancing the safety of nuclear power plant operations are based on the assumption that safety can be improved by analyzing numerical safety indices, the frequency of core damage, and the frequency of radioactivity release. Design and actions are implemented with the goal of reducing the likelihood of reactor core damage and limiting are mitigated and the release of radioactivity. This study evaluated safety analysis for primary-to-secondary loop leakage accidents with leakage of less than 6% as well as probable core damage and higher leakage in the primary loop collector around 11%, in the reactor type WWER-1000. The frequency values of core damage were found to be higher due to the inadequate performance of the primary-to-secondary loop leakage algorithm. If this algorithm does not function automatically operators are required to run procedures to provide limitation conditions for the damaged steam generators. This ensures integrated heat removal from the core through the healthy steam generators, with no coolant release from the primary loop through the damaged steam generator into the secondary loop. This scenario was investigated using the RELAP5-3.2 code.