ASSAY OF LOW LEVEL PLUTONIUM IN SOFT DRUMMED WASTE

The Atomic Weapons Establishment (AWE) at Aldermaston has traditionally stored plutonium (Pu) contact wastes on site, in 205 l steel drums, because of difficulties in demonstrating compliance with the Drigg Repository Conditions For Acceptance (CFA) for Low Level Waste (LLW) (less than 100 Bq/g total plutonium alpha). This paper presents a procedure for germanium gamma-ray detector assay of low level plutonium in soft drummed waste, utilising the 60 keV Am-241 signature, which meets the stringent Drigg requirements. The technique is valid for drums containing up to 72 kg of low atomic number wastes, such as: polythene, PVC, rubber, plastics, wood, paper, cotton etc. Errors due to non-uniform distributions of contamination and counting statistics are quantified. Significant cost savings are projected for routine application of the procedure.