Plant life extension of first generation CANDU plant (KANUPP) experience and challenges

Karachi Nuclear Power Plant (KANUPP) is a 137 Mwe CANDU plant. It started commercial operation in 1972 with nominal conceptual design life of 30 years. During three decades of operation, plant safety has been assessed / reviewed by IAEA, COG and WANO expert missions in different areas. Based on assessments made by these missions and the results of periodic inspections, the critical components of the plant have been found in good health. KANUPP is in the process of extending plant life by 10-15 years. The challenges associated with extended life operation are to maintain the margin of safety by ensuring reliability of safety related systems, to reduce plant unavailability due to obsolescence and age-related component failures and to minimize the cost of repair/replacement. The plant was shutdown in December 2002 to undertake major safety upgrades, equipment maintenance / refurbishments etc. to meet the regulatory requirements for operating beyond the 30 years of plant life. The objective of this paper is to present different phases of plant life extension and implementation of major system / equipment modifications during the current re-licensing outage. (author)