Verification of 235U enrichment of fresh VVER-440 fuel assemblies.

Abstract Enrichment of uniformly and non-uniformly enriched (“profiled”) fuel assemblies in a range of 1.6–4.4% was verified by gamma-ray spectrometry at a nuclear power plant (NPP). HPGe detectors and a CdZnTe (CZT) detector, the latter fitting into the central tube of the assemblies, were used for obtaining information from outer and inner fuel rods. A procedure which has minimal impact on the NPP work was developed for verifying freshly arrived assemblies under normal operational conditions, and is now in routine use.