Nondestructive Assay Measurements Can Be Traceable

The use of nondestructive assay (NDA) techniques for the analysis of Special Nuclear Materials is one of the keystones in the development of safeguards technology. Currently this effort to use NDA is being frustrated because of a lack of "demonstratable traceability." Presented here is a discussion of what traceability means and how it can be achieved. Specifically, traceability means far more than having a series of calibration standards for each individual NDA technique. It means defining the limits of uncertainty for both random and systematic error components of a set of measurements (i.e. precision and accuracy). Realizing this, an approach to these evaluations is suggested. In addition, the authors emphasize that the availability of standards is not holding back the use of NDA. The use of NDA is actually limited by the poor accuracy (possible systematic error) of many methods and the availability of real calibration standards would only tend to accentuate this point. Finally, the suggestion is made that calibration standards will only be available when the demonstrated need is limited to a finite number of sets.