The safety of repositories for highly radioactive wastes

Abstract

Many authors have studied the safety of disposal of highly radioactive wastes in excavated cavities beneath the earth. 'Work has been concentrated in three areas: prediction of future events and processes which could aA'ect waste containment, mathematical modeling of failure scenarios, and estimation of uncertainties in model predictions. The results of past safety assessments are reviewed and compared in this paper. Anything but a very small release of radioactivity from a repository would appear to be quite unlikely; a quantitative evaluation of the probabilities of small releases has not proved possible. CONTENTS III. IV. V. VIII.Refe similar to those encountered elsewhere in the mining and nuclear industries (GEIS, 1980); the principal safety issue is the possibility that radioactivity would leak from a repository and cause damage at some time in the future. have addressed the safety of disposal at particular sites.More commonly, one studies a hypothetical "generic" site. Studies of generic sites are of considerable value in identifying the role of different elements of a repository

Methods of calculating the post-closure performance of high-level waste repositories

“…The 7 years since the preparation of tile review by Koplik et aL (1982) bave been notable for the lack of new iniriatives in the area of calcularing scenario probabilities. This is especially noteworthy in view of the need for such calculations created by the U.S.…”

“…There are indications that more quantitative data may be forthcoming in such areas as alteration of natural basaltic glass, near-field hydrogeochemistry, sorption, mineral alteration, and radionuclide migration . Koplik et al (1982) define a scenario as "a possible sequence of processes and events which is describable by equations involving specified physical parameters.~' Any repository safety analysis requires the identification of scenarios to analyze. In selecting scenarios, and in evaluating the significance of the consequences one calculates for each scenario, the analyst must also take into account the likelihood of the various scenarios.…”

“…event trees, and judgment. Koplik et al (1982) describe the concepts behind these methods and review work on them through the summer of 19&0. This section will summarize developments since that time.…”

“…The 7 years since the preparrttion of the review by Koplik et a\. (1982) have been notable for the lack of new initiatives in the area of calculating scenario probabilities.…”

The Enhanced Plan for Features, Events, and Processes (FEPS) at Yucca Mountain

“…Suggested checklist of phenomena similar to Burkholder (1980) and Koplik et al (1982) Potentially disruptive events and processes The chronological development chains produced the following "end of chain" lists:…”