Application of CR-39 detectors in spent reactor fuel assay

Abstract

Fast neutrons from reactor fuel were monitored with CR-39 track detectors, using energy discrimination by shape selection to reduce the number of disturbing events. The detectors were irradiated in a steel container placed on the top of assemblies. Exposure time was optimized for providing acceptable statistics and keeping ??-dose low enough -below 6 kGy - to prevent the material from damage due to the huge intensity ??-background. As the effect of the adjacent assemblies in a hexagonal lattice of 160 mm storage distance is rather high, individual assay on isolated fuel assemblies is recommendable.