Regulatory approach for the lifetime management of the nuclear power plants in Korea

Full text: There are 18 NPPs in operation and 2 NPPs under construction in Korea, since the first NPP started its commercial operation in 1978. Nine NPPs have been operating more than 10 years, and Kori unit 1 (which is the oldest PWR plant) approaches its design life of 2008. As the number of aged plants is increasing, public concern has been increased on the safety of operating NPPs. Systematic and comprehensive operational safety assessment and plant life management are necessary to maintain a high level of safety, taking into account improvements of safety standards and practices, the cumulative effects of plant ageing, operating experience, and the evolution of science and technology. In Korea, operating license is issued without a fixed term and design life is specified in Final Safety Analysis Report (FSAR). Institutional scheme for the plant life extension should be devised in the very near future, considering the remaining life of Kori unit 1 and the time required for the safety assessment. The technical and economic feasibility studies for the lifetime management of NPPs have been carried out for the last 10 years. However the licensing basis for ageing management (mainly apply to the long-lived and passive components) should be prepared for the institutionalization of the plant life extension of NPPs. Also different opinions between the regulatory authorities and stakeholders should be converged. On the other hand, a Periodic Safety Review (PSR) system was introduced and established with sound legal basis in order to evaluate the comprehensive and systematic safety of operating plants. The PSR review scope is based on the safety factors suggested by IAEA. The results of PSR with focusing on ageing assessment can be utilized for the life extension of NPPs. Also the Nuclear Safety Commission recommended to use the results of PSR in the life extension of NPPs. In this study, the PSR system enforced in Korea would be compared with the current periodic inspection system and the License Renewal of the USA in the aspect of procedural requirements on the plant life extension. Then basic factors for life management are considered in PSR and License Renewal. Considering the present status and the comparison results on the life extension of the NPPs in Korea, three possible models considered on the sound legal basis are: License renewal: limit license term and renew a license term (less than 20 years) beyond the established the licensed term. Typical example is the USA formulation; Approval for continued operation beyond design life: license a fixed term (10∼20 years) by the legal approval. Typical example is provided by Swiss or Hungarian regulation; Continued operation with PSR results without any procedural requirement: license every 10 years according to the PSR results. Typical example is provided by the UK or French regulation. In view of the safety assessment for the lifetime management of the NPPs in Korea, the above models would be seriously discussed in terms of characteristics, merits and demerits for each other. For any models, PSR results can provide useful information for the decision of continued operation. (author)