Initial MR Evaluation for Plants Shut Down for Extended Periods

Maintenance Effectiveness Monitoring Programs (known as MR) for CANDU plants have been developed since March 2007. KHNP is currently operating four CANDU plants and all the plants have their own MR programs. The first CANDU unit operated by KHNP has been in operation for 29 years and is to extend its lifetime. This plant was shut down for refurbishment from April 2009 to July 2011. Therefore, an initial evaluation must be conducted prior to implementing the program. The initial evaluation assesses the Systems, Structures and Components (SSCs) against the established performance criteria using historical plant data for a period of at least two fuel cycles or 36 months in order to determine if the SSCs meet the performance criteria. The initial evaluation period for Wolsong Unit 1 includes the refurbishment shut down period. The other KHNP plants, which are Pressurized Water Reactors (PWRs), were not shut down for longer than one operating cycle in their initial evaluation period. This paper presents the effect of the extended shut down period on the initial evaluation of the plant in order to determine which SSCs do not meet the performance criteria