Verification of exp 235 U Enrichment in SNM Receipts at the DOE Feed Materials Production Center

摘要

A diversity of uranium-bearing, nonirradiated materials with exp 235 U assays from fully depleted to a maximum of 10 wt % exp 235 U, is routinely returned to this DOE site for reprocessing. It is necessary to confirm the exp 235 U isotopic content of Special Nuclear Material (SNM) receipts both for accountability and nuclear criticality safety purposed. Methods and instrumentation have been developed for an isotopic verification facility by which exp 235 U isotopic content is rapidly and nondestructively determined. The 185 keV gamma photon emitted by exp 235 U is measured using a dual-channel gamma spectrometer which incorporates automatic background subtraction and an optimized collimator/NaI(Tl) detector assembly. Measured activities are then related to exp 235 U isotopic content by means of appropriate standards that have been destructively analyzed in the laboratory. Use of the described facility for the past seven years has resulted in improved nuclear safety procedures, better use of storage space and more stringent nuclear materials accountability. (ERA citation 03:039362)