Development of the maintenance technologies for the future high-temperature gas cooled reactor (HTGR) using operating experiences acquired in high-temperature engineering test reactor (HTTR)

Abstract

This paper describes the lessons learned of the maintenance technologies, which have been and will be developed by using the high-temperature engineering test reactor (HTTR), which should be expected to apply to the future high-temperature gas cooled reactors (HTGRs). For example, the periodical maintenance for the future HTGRs is planned to carry out in each two years. The duration of periodical maintenance is planned about 60 days to satisfy the availability of operation up to 90%, in which decay heat removal, refueling and maintenances of equipment and components are carried out. As the key issue is to make a practical application of the technologies to the future HTGRs, shortening the duration of the periodical maintenance is expected to be important by excluding the maintenance related to the reactor equipment from the critical path by shifting the time-based maintenance, which is defined to be carried out in certain time interval, to the condition-based maintenance, which is defined to be carried out when a parameter exceeds its criteria, by using the experience and data acquired in HTTR, which is expected to make the maintenance interval significantly longer than that of the time-based maintenance as the operation experiences are accumulated.The maintenance technologies for the reactor system, which have been developed by using HTTR, are categorized as the following. (1) Establishment of the maintenance technologies specific to the HTGRs. (2) Development of the maintenance technologies for the future HTGRs. (3) Efficient maintenance works for the general equipment.