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.

The United State Department of Energy (US DOE) disposes of low-level radioactive waste in near-surface disposal facilities. Safety of the disposal operations is evaluated for operational safety as well as long-term safety. Operational safety is evaluated based on the perceived level of hazard of the operation and may vary from a simple safety assessment to a safety analysis report. Long-term safety of all low-level waste disposal systems is evaluated through the conduct of a radiological performance assessment. The US DOE has established radiological performance objectives for disposal of low-level waste. They are to protect a member of the general public from receiving over 25 mrem/y, and an inadvertent intruder into the waste from receiving over 100 mrem/y continuous exposure or 400 mrem from a single exposure. For a disposal system to be acceptable, a performance assessment (PA) must be prepared which must be technically accurate and provide reasonable assurance that these performance objectives are met. Technical quality of the performance assessments is reviewed by a panel of experts. A number of lessons have been learned from conducting several preliminary reviews of performance assessments. These lessons are shared among the various US DOE sites to improve the process of evaluating low-level waste disposal sites for long-term performance.