A surveillance strategy for a four year operating cycle in commercial pressurized water reactors

Abstract

If the U. S. nuclear industry hopes to remain competitive and grow into the next century, it must be willing to expand the goal of each plant from safe performance, to safe and economic performance, and apply this type of thinking in all its decision making processes. A surveillance strategy necessary to achieve a 48 month life cycle was developed. The primary goals and objectives of the strategy were to overcome the regulatory and investment protection barriers to extended cycle lengths, provide a systematic surveillance resolution procedure, and provide a framework for addressing plant forced outage rates. As part of the strategy, a detailed methodology for determining the surveillance performance options necessary to achieve a 48 month fuel cycle was produced. The methodology was applied at an operating Westinghouse Pressurized Water Reactor to demonstrate the viability of a 48 month cycle within the nuclear industry. Of the 3108 regulatory and investment protection surveillances studied, 3054 would likely support an extended full cycle. The framework for reducing forced outage rates was applied to a key plant component, the Main Feed Pump. The framework concluded that the Main Feed Pump is likely to operate reliably over 48 months and not have a significant impact on the overall plant forced outage rate. One of the key concepts discussed is the use of the Limiting Plant Event Frequency (LPEF) as a measure of expected loss in making surveillance program economic decisions. The LPEF includes the Core Damage Frequency (CDF), but also recognizes the importance of other transient end states not affecting CDF whose economic consequences are so severe that they must be avoided with the same urgency applied to core damage.