Engineering Study of Frequent Refueling for Improved Uranium Utilization in Pressurized Water Reactors

摘要

The most practical alternative to annual refueling appeared to be semiannual refueling, with a short midyear refueling-only outage scheduled during minimum power demand and an annual outage during which maintenance outage tasks would be performed. A method for economic evaluation of frequent refueling was developed using fuel loading requirements, refueling frequency, replacement power costs and the price of uranium oxide as parameters and the economics evaluated with the costs anticipated for the year 1995. It was determined that to obtain breakeven energy costs, the extra semiannual refueling outage would have to be accomplished in six to nine days for most plants. Although it could not practicably be reduced to that level, proposed changes to arrangement, procedures and equipment indicated that an outage of from eleven to thirteen days was possible. Total cost of implementing these changes is estimated at less than 4% of the overall physical plant cost. This cost can be justified based on the time saved during refueling outages over the reactor lifetime. These changes were generally defined while a detailed design review was made of a fuel-handling system which utilizes two cantilever-supported refueling machines and two transfer systems, allowing independent and simultaneous handling of two fuel assemblies during the refueling sequence. A review of the critical path annual maintenance items indicated that these items would probably control the length of the annual refueling outage. (ERA citation 06:033297)