Research Programs

Nuclear Systems Performance

Outage Performance Evaluation of Operating US Light Water Reactor

Investor confidence in new reactor orders depends significantly on the satisfactory operation of the existing fleet. Consequently, the industry must set goals that promote performance improvement, but are still within reach for currently well-performing plants.

In establishing such goals, however, there must be some way to measure the performance of the nuclear fleet that not only allows for comparisons between plants, but also for comparison of a plant’s current performance against its past performance. There are two indicators that provide a clear measure of a plant’s performance. Both of these deal with the length of time a plant is forced to shut down, but it is important to distinguish whether the outage is due to the cyclical refueling process, which plant managers can plan for, or whether the outage is due to some unplanned event or equipment failure.

The goal of this research is three-fold. First is the development of a way to judge each plant’s current and historical performance record based on these two factors. Second is the assessment of the performance of the industry overall, taking the historical record of the fleet into consideration. Third is the identification of the strategies plants have adopted to improve their outage characteristics in a rapid and sustainable manner.

The Institute for Nuclear Power Operations (INPO) in Atlanta, Georgia has provided a set of data giving the quarterly percentages of losses sustained by every nuclear power plant in America from January 1996 to September 2004. INPO categorized the percentage of lost capacity into unplanned, planned, and extension losses. Planned losses are primarily sustained for refueling and can be projected by plant managers far in advance. Unplanned losses are due to shutdowns that occurred during an operating cycle and were not expected by the operator. Extension losses are the losses incurred due to additional time the plant was shut down after a refueling cycle to make necessary repairs and/or replacements that could not be made during the planned refueling period. When analyzing this data, extension losses were treated as equivalent to unplanned losses since they are both losses incurred due to equipment problems.

Using this data the planned and forced outage history of plants in the US fleet was determined and displayed. The trajectory of this historical performance by operating cycle was evaluated to assess the effectiveness and consistency of management action. Goals of less than 5% planned outage rate and 2% forced outage rate were established. It was found that both PWR and BWR fleet averages were trending to those goals, although many plants (80% of the 69 plants that had data available for 5 cycles) were still either relatively short of achieving those goals or were exhibiting inconsistent performance and far from achieving these goals. Further, of those plants which exhibited marked performance improvement, the strategy employed was to first control unplanned outages and then address the high planned outage rate.

This work is continuing and will evaluate the recent plant data made available to us by INPO for September 2004 through early 2005.