Technical report on the boxed waste assay system

A boxed waste assay system (BWAS), accommodating boxes up to 5' x 5' x 8', has been built for the WRAP facility in Hanford, Washington. The system incorporates active and passive neutron imaging measurements along with imaging gamma measurements using both NaI and HPGe detectors. The system is currently undergoing acceptance testing at the TA-55 site at Los Alamos National Laboratory (LANL) with subsequent installation, scheduled when testing is completed, at the WRAP facility. This paper will present system performance results available to date. Currently, a substantial quantity of neutron data has been acquired with the system. The active neutron measurements show a detection sensitivity of approximately 1 nCi/g, for all matrices tested -- namely, a light matrix (4.6 lbs/ft3); a medium matrix (7.8 lbs/ft3); a heavy matrix (68.5 lbs/ft3). The passive measurements show an average detector efficiency of about 10% with a corresponding detection sensitivity of approximately 10 mg 240Pu. The 12 cm outside diameter x 5 cm thick NaI detectors (16 in system) display detection limits of better than 20 pCi/g for 137Cs and 60Co gamma lines. A 40% HPGe detector is used to characterize gamma hot spots