OPERATING THE WAND AND HERCULES PROTOTYPE SYSTEMS

Two prototype systems for low-density Green is Clean (GIC) waste at Los Alamos National Laboratory (LANL) have been in operation for three years at the Solid Waste Operation's (SWOs) non-destructive assay (NDA) building. The Waste Assay for Nonradioactive Disposal (WAND) and the High Efficiency Radiation Counters for Ultimate Low Emission Sensitivity (HERCULES) are used to verify the waste generator's acceptable knowledge (AK) that low-density waste is nonradioactive. GIC waste includes all non-regulated waste generated in radiological controlled areas (RCAs) that has been actively segregated as ''clean'' (i.e., nonradioactive) through the use of waste generator AK. GIC waste that is verified clean can be disposed of at the Los Alamos County Landfill. It is estimated that 50-90% of the low-density room trash from RCAs at LANL might be free of contamination. To date, with pilot programs at five facilities at LANL, 3000 cubic feet of GIC waste has been verified clean by these two prototype systems. Both the WAND and HERCULES systems are highly sensitive measurement systems optimized to detect very small quantities of common LANL radionuclides. Both of the systems use a set of phoswich scintillation detectors in close proximity to the waste, which have the capability of detecting plutonium-239 concentrations below 3 pCi per gram of low density waste. Both systems detect low-energy x-rays and a broad range of gamma rays (10-2000 keV), while the WAND system also detects high energy beta particles (>100 keV). The WAND system consists of a bank of six shielded detectors which screen low density shredded waste or stacked sheets of paper moving under the detectors in a twelve inch swath on a conveyor belt. The WAND system was developed and tested at the Los Alamos Plutonium Facility in conjunction with instrument system designers from the Los Alamos Safeguards Science and Technology group. The HERCULES system consists of a bank of three shielded detectors which screen low-density waste in two cubic foot cardboard boxes or in bags sitting on a turntable. Waste that does not pass the verification process can be examined within the facility to determine the type and quantity of the contamination and its origin within a waste container. The paper discusses lessons learned that have helped generators improve their AK segregation