Ukraine joins the world practice of using risk-informed approaches in making decisions on nuclear power plant (NPP) safety. The introduction of risk-informed NPP configuration management tools allows the operating organization to justify that maintenance of systems important to safety, conventionally performed within refueling outages, is possible when NPP units operate at full power. This in turn reduces the length of refueling outages and, accordingly, increases the installed capacity factor.
Thus, on 11 January 2021, the State Nuclear Regulatory Inspectorate of Ukraine approved a technical decision "On Introduction of Risk-Informed NPP Configuration Management into Trial Operation to Improve Safety and Optimize Maintenance of Systems Important to Safety" along with a trial operation program, temporary changes to the ZNPP Unit 2 Technical Specifications for Safe Operation, and changes to standard maintenance procedures for NPP units.
The project on maintenance optimization for systems important to safety using plant configuration risk management has been implemented, as a pilot one, at Zaporizhzhia NPP Unit 2 since 2017.
The project is being implemented with assistance and financial support of the US Department of Energy with involvement of the Argonne National Laboratory (USA), and the beginning of trial operation is its final stage.
The main goal of the project is to enhance safety of NPP units by applying the risk-informed approach in:
- analysis and determination of the need to reassess restrictions on the allowed outage time of systems and equipment established in the technical specifications for safe operation;
- identification of equipment that has a dominant impact on NPP safety to focus maintenance efforts on ensuring the efficiency of this NPP equipment;
- justification of the optimal configuration of NPP equipment during maintenance;
- reduction of dose loads on personnel through maintenance optimization;
- reduction of excessive conservatism during maintenance.