The passive gamma ray non-destructive assay method for verification of non-accessible nuclear material in spent fuel ponds

Measurements were performed at an LWR spent fuel pond for nuclear safeguards verification. The method is particularly helpful in situations where Cerenkov viewing cannot provide satisfactory verification, e.g. for low burnup or long cooled spent fuel. The other methods using instruments such as Cutie Pie, high sensitivity gamma monitor or GRAND-I/Fork require the movement of the item to be verified in order to isolate it from other spent fuel elements. These limitations could be avoided when using the elaborated method. 4 refs, 3 figs