Operating experience feedback from incidental fluctuations of the power measurement channel at ETRR-2

This paper provides analysis of the operating experience feedback from two events of incidental fluctuations of the power measurement channels at Egypt Second Research Reactor (ETRR-2). In the first event, the fluctuation was due to improper functioning of the secondary cooling system, while in the second one the fluctuation was associated with a leakage of a gadolinium nitrate solution into chambers surrounding the reactor core (which are part of a diverse second shutdown system of the reactor). The paper describes these events, including observation of the reactor operation performance and operators' actions, and provides the root causes analysis of these events along with the corrective actions. Lessons learned from these events, which are generically applicable to other research reactors, are also identified and presented. The analysis showed the vital role of continuing training of reactor operators, consideration of human factors in all activities during the reactor lifetime, and quality checks and field verifications during operation and post-maintenance works to the safety and availability of research reactors. The analysis also showed that underperformance of non-safety components could have an effect on those important to safety and could negatively impact the availability and the operational performance of the reactor.