Development of the Inspection and Diagnosis Technology for the NSSS Components Integrity

This project is to develop and demonstrate new technologies for a monitoring, inspection, diagnosis and evaluation of the safety related components in nuclear power plants. These technologies are required to detect the defects in the components of nuclear power plants and to prepare thoroughly against accidents. We studied on the four issues recently focused. Thus we developed an impact analysis model of the reactor and steam generator, and diagnosis software of the reactor internals. As an on-line monitoring technology using an ultrasonic guided wave, we developed a new method enhancing the S/N ratio of the weak signal based on time reversal technique. A network based remote inspection system and an inspection robot for reactor vessel head penetration was developed. We also performed a lifetime estimation and degradation analysis of the NPP cables through accelerated degradation tests. The technologies developed in this project are applied to the components of nuclear power plants. The applications include a localization of the NSSS integrity monitoring system, replacement of an in-service inspection by on-line monitoring, remote inspection of the major components of the plants, lifetime estimation of the degraded plant cables, and so on