Application of a Burnup Verification Meter to Actinide-Only Burnup Credit for Spent PWR Fuel

A measurement system to verify reactor records for bumup of spent fuel at pressurized water reactors (PWR) has been developed by Sandia National Laboratories and tested at U.S. nuclear utility sites. The system makes use of the Fork detector designed at Los Alamos National Laboratory for the safeguards program of the International Atomic Energy Agency (IAEA). A single-point measurement of the neutrons and gamma-rays emitted from a PWR assembly is made at the center plane of the assembly while it is partially raised from its rack in the spent-fuel pool. The objective of the measurements is to determine the variation in bum up assignments among a group of assemblies, and to identify anomalous assemblies that might adversely affect nuclear criticality safety. The measurements also provide an internal consistency check for reactor records of cooling time and initial enrichment. The burnup verification system has been proposed for qualifying spent fuel assemblies for loading into containers designed using burnup credit techniques. The system is incorporated in the U.S. Department of Energy's \"Topical Report on Actinide-Only Burnup Credit for PWR Spent Nuclear Fuel Packages\" (DOEIRW 1995).