Implementation of technical conservatism in the development of nuclear waste repositories

The Department of Energy (DOE) waste management program is committed to assuring the safe disposal of radioactive waste. It is recognized that long-term disposal concepts will contain inherent uncertainties in predictive techniques and scientific information. Accordingly, conservative approaches ae being followed to enhance levels of confidence that the disposal system will perform in such a manner that the established performance requirements will be met. Limiting values of critical parameters will be established for each site based on its inherent characteristics prior to beginning site development. The performance limits will be established for each geometric region of the repository system and be applied simultaneously to assure that no single limit is violated over the repository life cycle. A site-specific set of specifications will be determined when the site is fully characterized, establishing a conservative design basis to increase confidence in safe system performance. The implementation of the NWTS program policy on technical conservatism, as discussed in this document, takes two forms--(1) conservatism in the conduct of the program and (2) conservatism in the performance of the disposal system. The first is achieved by a stepwise approach to system development and operation, the systems viewpoint, the retrievability requirement, and the extensive use of peer reviews throughout the conduct of the program. The second is achieved by the proper selection and application of conservative design and operational limits