APPLICATION OF CR-39 DETECTORS IN SPENT REACTOR-FUEL ASSAY

Fast neutrons from reactor fuel were monitored with CR-39 track detect ors, using energy discrimination by shape selection to reduce the numb er of disturbing events. The detectors were irradiated in a steel cont ainer placed on the top of assemblies. Exposure time was optimized for providing acceptable statistics and keeping gamma-dose low enough bel ow 6 kGy - to prevent the material from damage due to the huge intensi ty gamma-background. As the effect of the adjacent assemblies in a hex agonal lattice of 160 mm storage distance is rather high, individual a ssay on isolated fuel assemblies is recommendable.