Instrument calibration and measurement plan for the poorly measured/unmeasured211 category of highly enriched uranium at Lawrence Livermore National Laboratory

摘要

In partial response to a Department of Energy (DOE) request to evaluate the state211u001eof measurements of special nuclear material, Lawrence Livermore National 211u001eLaboratory (LLNL) evaluated and classified all highly enriched uranium (HEU) 211u001emetal and oxide items in its inventory. Because of a lack of traceable HEU 211u001estandards, no items were deemed to fit the category of well measured. A 211u001esubsequent DOE-HQ sponsored survey by New Brunswick Laboratory resulted in their 211u001epreparation of a set of certified reference material (CRM) standards for HEU 211u001eoxide (U(sub 3)O(sub 8)) that are projected for delivery during September of 211u001e1999. However, CRM standards for HEU metal are neither in preparation nor are 211u001ethey expected to be prepared within the foreseeable future. Consequently, HEU 211u001emetal working standards must be developed if the poorly measured/unmeasured 211u001eportion of the LLNL inventory is to be reclassified. This paper describes the 211u001eapproach that LLNL will take to (1) develop a set of HEU metal working standards; 211u001e(2) develop HEU metal and oxide calibration curves for the passive-active neutron 211u001e(PAN) shuffler that are functions of mass, enrichment, size, and shape; and (3) 211u001ereclassify the poorly measured/unmeasured inventory through direct measurement or 211u001ereprocessing of previously archived data.