United States Role in the Formulation of the 1992 International Target Values for Uncertainty Components in Fissile Isotope and Element Assay of Nuclear Materials

The continuing need to define international standards of measurement for the safeguarding of nuclear materials involving the independent quantitative verification of the accountancy of fissile materials prompted the International Atomic Energy Agency (IAEA) to convene a consultants' meeting in June 1991. The consultants determined that existing \"Target Values\" could be used as a starting point to develop International Target Values and agreed upon a format for publishing them in 1992. For over ten years the Target Value concept has been used for evaluating the results of quantitative measurements of fissile elements and isotopes. Recommendations arising from the consultants' meeting were to be discussed with a variety of regional technical meetings/groups for greater international participation. For the United States effort the INMM 5.1 Committee on Analytical Chemistry Laboratory Measurement Control, with the support of the Department of Energy (DOE) and the Nuclear Regulatory Commission (NRC), requested and received Target Value comments and data on the proposed 1992 Target Value tables from DOE and NRC facilities. The information has been evaluated and forwarded to the IAEA for use with other regional input in the formulation of the updated Target Values. A novel feature in the 1992 Target Value tables will be the inclusion of \"constructed\" assay methods which can provide a basis for upgrading measurement methods where needed or required.