Maintenance activities for sodium leak detection system in Monju

Muto, Keitaro 

Monju is sodium cooled fast breeder reactor. Monju resumed operations on May 5th, 2010 after an intermission for about 14 years following a sodium leak accident. During the shut-down period, sodium system was operated and there were some troubles of sodium leak detectors. To improve leak detectors performance and reliability, detectors modification and improved maintenance activities were applied. For example, a contact type sodium leak detector (CLD) in the secondary sodium system was modified to increase to ion-migration resistance and periodical insulation measurement was added to the maintenance activities. Based on the maintenance and operation experience and the technology development will be reflected to the improvement of the performance and reliability of sodium leak detectors.