Performance assessments for near-surface low-level radioactive waste disposal facilities

Abstract

The goal of a performance assessment for a low-level radioactive waste (LLW) disposal facility is to determine the proposed facility`s projected compliance with regulatory limits in terms of doses to the general public and to protect inadvertent intruders. A set of exposure scenarios must be evaluated for each of the various institutional phases of the facility; a quantitative evaluation must be performed for the most probable scenarios. Evaluation of the final conceptual model of the facility and site should involve the use of appropriate computer code and site-specific data. Code selection for a performance assessment should be based on code capabilities as well as on site-specific needs and characteristics. Generally, a single code will not be capable of simulating all relevant scenarios. A review of performance assessments for confirmation of regulatory compliance will be conducted by the NRC or the appropriate Agreement State regulatory agency. Performance assessment codes are tools for evaluating a proposed LLW disposal facility`s regulatory compliance. This evaluation should objectively assess the physical properties of the facility and its environment. Calculations in support of this evaluation must be conservative yet realistic and they must also be technically defensible and supported by adequate data.