OPERATING THE WAND AND HERCULES PROTOTYPE SYSTEMS

摘要

Two prototype systems for low-density Green is Clean (GIC) waste at Los Alamos NationalrnLaboratory (LANL) have been in operation for three years at the Solid Waste Operation’srn(SWOs) non-destructive assay (NDA) building. The Waste Assay for Nonradioactive Disposalrn(WAND) and the High Efficiency Radiation Counters for Ultimate Low Emission Sensitivityrn(HERCULES) are used to verify the waste generator’s acceptable knowledge (AK) that lowdensityrnwaste is nonradioactive.rnGIC waste includes all non-regulated waste generated in radiological controlled areas (RCAs)rnthat has been actively segregated as “clean” (i.e., nonradioactive) through the use of wasterngenerator AK. GIC waste that is verified clean can be disposed of at the Los Alamos CountyrnLandfill. It is estimated that 50-90% of the low-density room trash from RCAs at LANL mightrnbe free of contamination. To date, with pilot programs at five facilities at LANL, 3000 cubic feetrnof GIC waste has been verified clean by these two prototype systems.rnBoth the WAND and HERCULES systems are highly sensitive measurement systems optimizedrnto detect very small quantities of common LANL radionuclides. Both of the systems use a set ofrnphoswich scintillation detectors in close proximity to the waste, which have the capability ofrndetecting plutonium-239 concentrations below 3 pCi per gram of low density waste. Bothrnsystems detect low-energy x-rays and a broad range of gamma rays (10-2000 keV), while thernWAND system also detects high energy beta particles (>100 keV).rnThe WAND system consists of a bank of six shielded detectors which screen low densityrnshredded waste or stacked sheets of paper moving under the detectors in a twelve inch swath onrna conveyor belt. The WAND system was developed and tested at the Los Alamos PlutoniumrnFacility in conjunction with instrument system designers from the Los Alamos SafeguardsrnScience and Technology group.rnThe HERCULES system consists of a bank of three shielded detectors, which screen low-densityrnwaste in two cubic foot cardboard boxes or in bags sitting on a turntable. Waste that does notrnpass the verification process can be examined within the facility to determine the type andrnquantity of the contamination and its origin within a waste container. The paper discussesrnlessons learned that have helped generators improve their AK segregation.