Scenarios for the Evaluation of the Criticality Potential of High Actinide Glasses

Vitrification is one of the leading options for immobilization of actinide-containing materials no longer needed for national defense. For these glasses to be suitable for disposal, it must be established that a significant potential for a nuclear criticality involving these glasses does not exist. The vitrification working group within the nuclear materials disposition program has been given the responsibility for developing scenarios to be evaluated. In this report, potential bounding scenarios for disposal of high actinide glasses in a geologic setting are described. These scenarios are being provided to the Department of Energy`s Office of Civilian Radioactive Waste Management (OCRWM) so that the potential for criticality can be evaluated. If the evaluation of these scenarios by OCRWM reveals a significant potential for criticality then a sensitivity analysis to numerical values should be used to determine whether more precise definitions of any parameter is warranted. It is anticipated that there will need to be extensive interactions between the working group and the personnel performing the criticality evaluations