Delayed gamma studies from photo-fission of 237Np for nuclear waste characterization

An active and non-destructive method is being established for detection of 237Np in nuclear waste barrels. The unique high energy decay gamma signature produced after photo-fission is analysed to deduce decay time parameters. A high purity 237Np sample was irradiated with bremsstrahlung photons and high energy gamma decay spectra were measured with BGO detectors for various irradiation durations. The analysis of decay spectra resulted in the formation of five decay groups, which can reproduce the experimental decay spectra within 10% accuracy. These parameters together with neutron decay groups are absolutely essential to quantify the nuclear material in waste barrels by photo-fission. The delayed decay gamma groups for 237Np nucleus are being reported for the first time.