TOTAL SYSTEM PERFORMANCE ASSESSMENT (TSPA) FOR THE SITE RECOMMENDATION

The U.S. Department of Energy (DOE) has been evaluating the feasibility of disposing high level radioactive wastes at a potential repository at Yucca Mountain, Nevada. These wastes consist of spent fuel from commercial nuclear reactors around the U.S. as well as defense and other high level wastes in the form of vitrified glass or spent fuel stored at DOE facilities. An important milestone in the decision making process is the determination of the suitability of the Yucca Mountain site as a long-term repository for these wastes. The DOE has been conducting numerous scientific and engineering investigations at the site for the last 20 years to evaluate the suitability of the site. If the site is found suitable, the Secretary of Energy may decide to recommend the site to the President. An important element in the determination of site suitability is the evaluation of the performance of the site and the associated engineered barriers following repository closure. A total system performance assessment (TSPA) for the Yucca Mountain repository system has recently been completed. This TSPA has been documented by the Civilian Radioactive Waste Management System Management and Operating (CRWMS M&O) contractor in a technical report entitled Total System Performance Assessment for the Site Recommendation (1). The purpose of this paper is to briefly summarize the approach, results and conclusions contained in this document.