A new nondestructive assay system combining both neutron and gamma-ray detectors

A novel nondestructive assay system (four separate identical units) has been constructed which combines a neutron coincidence counter and a high-resolution gamma-ray detector for the simultaneous measurement of plutonium items. The measurement systems have been developed to be used in an unattended mode with the items being presented to the detector automatically as part of the routine handling arrangements in a remotely operated facility. The neutron coincidence counter has been designed to acquire spectra during the neutron coincidence measurement. Particular attention has been paid to the detector layout, shielding collimation, and support and housing. The gamma-ray detector operates continuously in an unattended mode using a closed-cycle helium refrigerator. The neutron counter has been calibrated for the assay of multi-can containers of PuO/sub 2/ powder.<
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