Codes and standards in repair and replacement process. Concern on the technical evaluation by Nuclear Regulatory Agency

As described in the IAEA Safety standards both No. SSG-25 'PSR for NPPs' and No. NS-G-2.12 'Ageing Management for NPPs', maintenance activities for SSC is very important. Physical ageing of SSCs may increase the probability of common cause failures, which could result in the impairment of one or more levels of protection provided by the defense in depth concept. Therefore, Inspection, evaluation and repair and replacement in 'Standards for Nuclear Power Generation Equipment (Maintenance Standards) for JSME' is also a very important standard. Nevertheless, only repair and replacement chapter has been in the out of scope of the technical evaluation and it has not been endorsed as the parts of technical standards of the Japanese NRA. This document is intended to propose how to do technical evaluation of this chapter, with describing the reason why only this chapter has been out of scope of technical evaluation. (author)