Nondestructive assay of highly enriched spent fuel

Passive gamma-ray and neutron measurements have been made on irradiated MTR fuel at the Omega West Reactor. Detectors utilized include a Ge(Li) for gamma spectroscopy, a /sup 235/U fission chamber for thermal neutrons, and a smaller /sup 235/U fission chamber with a beryllium photoneutron converter for detecting gamma-rays above 1.7 MeV. Measurements confirm that burnup can be closely correlated with the /sup 134/Cs//sup 137/Cs ratio. A comparison of activity profiles taken with the three detectors indicates that the method based on (..gamma..,n) reactions in beryllium is a promising technique.