Analyzing Nuclear Reactor Safety Systems

Analyzing Nuclear Reactor Safety Systems reactor ... 

ABSTRACT Technological advancements in area of sensor-based online maintenance systems have made the possibility of repairing some failed safety support systems of Nuclear Power Plants (NPP) such as electrical supply, I C systems, ventilation systems. However, the possibility of repair during accident situation is yet to be included into PSA level-1. Therefore, this paper presents a scheme of PSA level-1 by implementing an integrated method of Repairable Event Tree (RET) and Repairable Fault Tree (RET) analysis. The Core Damage Frequency (CDF) is calculated from consequence probabilities of the RET. An initiating event of Decay Heat Removal (DHR) systems of ASTRID reactor is analyzed. The proportionate CDFs estimated with repair and without repair have been compared and found that the recoveries can reduce CDF. In sum, this paper attempts to deal with the possibility of repair of some safety systems in PSA and its impacts on CDF of the NPP. 

As a rule, the main reactor systems are scrutinized more carefully than the auxiliary reactor systems and the order actions are existed for eliminating and mitigating of consequences of main reactor system fails. Therefore the auxiliary reactor system fails may impact on the main reactor systems through places of its contact in significant measure. The influence of auxiliary reactor system fails on main reactor systems and its possible consequences for behavior of the main reactor systems have been analyzed on the basis of the above-mentioned occurrences. Significance of the above-mentioned occurrences for nuclear safety BN-350 NPP have been analyzed too. 

Criticality safety analysis is a discipline aimed at the prevention or termination of inadvertent nuclear chain reactions in nonreactor environments. Although the physics and mathematics are the same as for reactor analysis, the basic approach is different because the goal is different. Because the analysis goal of criticality safety exclusively is to establish a conservative assessment of the criticality state of a given proposed operation, and the systems being analyzed have so much variety, the methodology takes a completely different form than reactor analysis methodology. 

---