Material degradation and related managerial issues at nuclear power plants. Proceedings of a technical meeting

The world's fleet of nuclear power plants (NPPs) is, on average, more than 20 years old. Even though the design life of an NPP is typically 30 to 40 years, it is quite feasible that many NPPs will be able to operate in excess of their design lives, provided that nuclear power plant engineers demonstrate by analysis, trending, equipment and system upgrades, increased vigilance, testing, ageing management that the nuclear power plant will operate safely. In the operation of nuclear power plants, safety should be always the prime consideration. Plant operators and regulators must always ensure that plant safety is maintained, and where possible enhanced, during a plant's operating lifetime. After the secondary system pipe rupture at Unit 3 of the Mihama nuclear power plant in Japan, which occurred on August 9, 2004, the IAEA recognized the increasing importance of material degradation and related managerial aspects, and held a technical meeting from 15 to 8 February 2005 in Vienna, Austria. The purpose of the technical meeting was to provide an international forum to share recent knowledge and experience, and to share lessons learned. The discussion included lessons from recent events, results from research programmes, experiences and practices, ownership and responsibility, managing operational experience and regulatory aspects. The quality of the papers and presentations in the technical meeting was high, and they provided good technical and managerial insights to materials degradation issues. The main results and lessons learned from the technical meeting were compiled in this publication. By evaluating common aspects of the issues presented, one can conclude that the initiating technical issue was rarely the root cause of the resulting problem. That is, each technical issue was relatively well understood at least in some segments of the industry and frequently had been experienced to some degree at other nuclear power plants. What complicated each issue and was at the root of most of the problems, was some shortcoming in the facilities' management process combining a gradual decrease in safety culture