A new report by the OECD Nuclear Energy Agency (NEA), Long-Term Management and Actions for a Severe Accident in a Nuclear Power Plant, reviewed knowledge and experience gained through long-term management of the accidents (LTMA) at Three Mile Island (USA, 1979), Chernobyl (Ukraine, 1986) and Fukushima Daiichi (Japan, 2011), by identifying and ranking main issues and knowledge gaps. The 212-page report also looked at the existing regulations and guidance, practices, technical bases and issues considered in NEA member countries of related to long-term management of a severely damaged nuclear site.
The objectives of the working group that prepared the report were:
- To review the experience gained for LTMA from the TMI-2, Chernobyl and Fukushima Daiichi accidents;
- To review envisaged, planned or existing regulations, guidance and practices in NEA member countries for LTMA for a severe accident in an NPP;
- To suggest possible approaches for LTMA following a severe accident including methods for risk ranking and issues identification;
- To identify the main challenges and open issues faced during the long-term phase of a severe accident;
- To make recommendations to better address them in the future, including, for instance, orientation to where research and development efforts should be allocated, or improvement of methods to assess LTMA; and
- To make recommendations to enhance LTMA.
Following a detailed introduction, Chapter 2 described the state of the art of long-term management and actions based on: severe accidents experience (TMI-2, Chernobyl and Fukushima Daiichi); information compiled through a questionnaire on envisaged, planned or existing regulations, guidance and practices for LTMA for a severe accident in an NPP; and a review of relevant existing reports in the literature.
Chapter 3 suggests possible approaches to LTM and actions looking at diverse severe accident scenarios and used fuel pool accidents including methods for issues identification and risks ranking. Chapter 4 provides a summary and a discussion of main identified challenges and open issues faced during the long-term phase of a severe accident.
Chapter 5 makes recommendations.
The report proposes areas for future investigation to enhance LTM of an NPP with respect to necessary knowledge and provisions development, particularly for the optimisation of management of contaminated cooling waters.