A team of Pacific Northwest National Laboratory (PNNL) scientists with extensive operations and maintenance (O&M) backgrounds has developed a simple, straightforward methodology for evaluating and categorizing plant equipment maintenance in specific action categories. The method is risk based, and accounts for expected equipment residual life, expected service duty, criticality of equipment function, necessary preventive maintenance (PM) scope and frequency considerations, and regulatory compliance aspects of the maintenance action.
The total PM craft maintenance man-hour reduction from the eliminated, frequency, and scope change categories was documented as approximately 3500 hours per year based on plant work control records. This total includes those PMs that were added during the review. For a total investment of approximately $150K (project development and implementation cost), it is conservatively estimated that a minimum of $980K in maintenance and associated engineering resources (impact on parts savings was not estimated) will be saved in the next 5 years of operation. When the spent nuclear fuel (SNF) mission is complete, large additional savings can be garnered from a re-review of the PM set. The thorough review provided by this project appreciably reduces costs and maintenance related risks to the SNF cleanup mission by applying a sound approach to identify essential and to eliminate unnecessary maintenance.
The East and West K Basins are located on the south bank of the Columbia River near the north end of the Hanford Site. The K Basins, built in the early 1950s, are two large basins for underwater storage of irradiated fuel produced by the K Reactors. The basins presently store a large quantity of N Reactor SNF that has been deteriorating for many years. A small amount of single pass reactor fuel is also stored in the basins.
The U.S. Department of Energy (DOE) established the SNF Project to address safety and environmental issues associated with the deteriorating fuel presently stored underwater in the basins. Recommendations for a series of projects to construct and operate systems and facilities to manage the safe removal of SNF fuel were made in WHC-EP-0830, Hanford Spent Nuclear Fuel Recommended Path Forward, and its subsequent update, WHC-SD-SNF-SP-005, Hanford Spent Nuclear Fuel Project Integrated Process Strategy for K Basin Fuel. The integrated process strategy recommendations include the following steps:
In December of 2000, the first MCO was processed from the K West Basin through the CVD and successfully stored in the CSB repository. This marked a transition point for all three facilities, in that they had now completed construction for meeting the SNF goals and had become true process facilities. At this time, an examination of the PM tasking revealed that the existing maintenance staff would be extremely hard pressed to perform all the time-based PM tasks for these facilities that were scheduled, and would have no time to perform any corrective maintenance. Subsequent to a January 2001 presentation on Decision Support for Operations and Maintenance (DSOM®) technology, SNF personnel requested that PNNL assist in analyzing the appropriateness and necessity for the 1536 PMs that existed for the three SNF facilities. In February, through a PNNL - Fluor technology transfer agreement, a PNNL team initiated site information reviews and personnel interviews at the K Basins, CVD, and CSB. The initial scope involved the development and validation of a methodology for examining the existing PMs with regard to their requirements (drivers) and the potential for reducing the resource requirements necessary for safe maintenance of the facilities. At SNF request, this scope was then expanded to include the facilitation of the PM reviews and an analysis of the resulting manpower and cost impacts.
The project was conducted in a short time frame because the product was needed in the short-term. The active working time for initiation, development, information gathering, and analysis was about 10 weeks.
The Hanford DSOM application was featured recently in The Hanford Reach: SNF Project saves a million with condition-based maintenance (PDF format, 43k).
WHC-SD-SNF-SP-005, 1995, Hanford Spent Nuclear Fuel Project Integrated Process Strategy for SNF's Fuel, Rev. 0, Westinghouse Hanford Company, Richland, Washington.
WHC-EP-0830, 1994, Hanford Spent Nuclear Fuel Recommended Path Forward, Rev. 0, Westinghouse Hanford Company, Richland, Washington.