Sampling Strategies for Physical Inventories and Confirmation/Verification Measurement Programs

Department of Energy (DOE) Order 5633.3 requires that physical inventories of nuclear materials be conducted with varying frequencies, and that programs be established to verify or confirm the presence of nuclear materials in items. The order permits facilities to utilize statistical sampling techniques to comply with these requirements. The sampling strategy that is developed is based on the desired confidence statements and the composition of the population of interest. In order to assure that sampling is conducted consistent with the concept of graded safeguards (i.e. applying more emphasis on the more important material), alternatives to simple random sampling may be required such as stratified or probability proportional to size sampling. Other techniques such as cluster sampling may be incorporated into the strategy for some storage configurations. Sampling is an extremely useful tool that enables more efficient expenditure of resources, such as time, manpower, radiation exposure, etc. This is very important in the face of budget reductions and the increased attention focussed on safety.