The System Prioritization Method (SPM) is a decision analysis tool initially developed to provide the Waste Isolation Pilot Plant program with a defensible basis for regulatory compliance by integrating experimental site characterization activities with performance assessment (PA) and repository design options. The SPM is designed to provide an quantitative basis for programmatic decisions regarding activities to be undertaken to support a regulatory compliance application associated with the long-term performance of waste disposal sites.
The SPM is an iterative process whose goal is to involve the total project team, the public, and the regulator in arriving at a common understanding and acceptance of the current state of knowledge for a waste disposal site, the use of that knowledge in assessing regulatory compliance, and then, if regulatory compliance is not achieved, the identification of the most cost-effective and timely activities that, if completed, are most likely to lead to regulatory compliance.
The SPM strategy and overall process is illustrated below. These activities are designed to define and develop the necessary information for a compliance application to be submitted to the Environmental Protection Agency. The basic foundation of the SPM is that to support a compliance application, the information in the application must ultimately be acceptable to all project staff, to the public, and to the regulator. To achieve an acceptable compliance application, SPM analyzes important combinations of activities or activity sets. For each combination considered, it determines the likelihood that
completing the selected activities will satisfy the regulatory criteria. The following steps are used:
Identify the models and data that the project participants believe address regulatory requirements, are acceptable to project participants, the regulators, and other interested parties, and are supported by existing information. These models and data become the PA technical baseline.
Estimate system performance using models and data from the PA technical baseline. If the performance measures indicate compliance with quantitative standards, prepare and submit a compliance application.
If the performance measures do not indicate compliance, identify those activities available to the project that have the potential to shift performance measures into compliance. These activities may include experiments, alternative engineering designs, and alternative waste acceptance criteria. It may be necessary to aggregate these activities into activity sets of logically related activities.
Elicit from the project participants their beliefs about what new models and data might evolve if specific activities (e.g., experiments to reduce uncertainty in a particular process or parameter value) were completed. These "expected outcomes" should be as realistic and unbiased as possible, but all parties must recognize that they are essentially informed estimates provided before the activity has been completed.
Estimate performance of the system using the likely outcomes of the activities. These new performance measures are conditional on the assumption that the specific activities are actually completed and that the results of the activities are within their likely outcomes. Therefore, the likelihood of each activity being successfully completed along with the uncertainty of the experimental outcome must be estimated and included in the analysis.
Create a decision matrix of activity sets showing cost, schedule, and the associated likelihood of satisfying the regulatory criteria.
The decision maker will use the information in the decision matrix to select activities to complete based on cost, time required, and the likelihood that they will result in a successful compliance application.
Implement the selected activities. Update the PA technical baseline when activities are complete and new defensible data are obtained.
Repeat step 2, and iterate as necessary to demonstrate compliance, including the public and the regulator in assessing the defensibility of the baseline at each iteration.
Future Work
Future work will investigate the potential for using the SPM for integrating site characterization, risk assessment, and regulatory compliance for low-level waste disposal, decontamination and decommissioning, and environmental restoration.
For further information, contact:
Paul A. Davis
Sandia National Laboratories, MS-1345
Albuquerque, NM 87185-1345
Phone: (505) 848-0754
email: padavis@sandia.gov
Submitted October 1996 Layout design by Wanda Mar.
Submitted October 1996