Instrument for assaying the radionuclide concentrations in 208-l drums

The US Nuclear Regulatory Commission's 10CFR61 defines the concentrations of all radionuclides allowable within the various categories of low-level waste. Commercial low-level waste disposal sites can only accept wastes within the legally defined concentration limits and add surcharges to waste shipments having high curie contents. Waste generators must not verify that their waste packages conform to all legal requirements but also must pay disposal costs proportionate to the volume and curie content. An accurate, even through initially more expensive, assay technique may save money in the long run. To provide this accuracy, a portable instrument capable of nondestructively assaying 208-l drums for the concentrations of all radionuclides present has been assembled. The instrument utilizes segmented gamma-ray spectroscopy to determine the concentrations of most fission and activation products and incorporates neutron detectors to determine the concentrations of transuranic nuclides. The system also makes a direct determination of the 90Sr concentration in the drum by a unique method of measuring the bremsstrahlung radiation. All other radioactivities that cannot be measured directly are inferred by correlation factors appropriate to the waste stream represented by the drum. The computer data reduction system can print a shipping manifest that lists all individual, radioisotope concentrations including those required by 10CFR61