A non-destructive assay system for the verification of uranium fuel rods

This paper describes a Non-Destructive Assay System for the verification of uranium fuel rods used in nuclear reactors. The system is based on gamma-ray spectroscopy technique. It employs a NaI(Tl) Detector, a Photo-multiplier tube, a Multi-channel Pulse-height Analyzer, associated electronics and a lead collimator. Two segments of well-known enrichments are used as "Standards". By selecting certain gamma-rays peaks in the uranium spectra, the U-235 enrichment can be measured. Measurements performed on the verification of fuel rods of a gave U-235 enrichment with relative accuracy of about /spl plusmn/5%. The obtained results showed that the system can be very useful for the physical inventory verification, accountability and control, of uranium fuel rods at nuclear reactors and at the fuel fabrication stage as well.