Rapid determination of transuranium nuclides in the primary coolant of a nuclear power plant by using nuclear track micro filters and investigation of α-emitting particles on the loaded filters by α-autoradiography

Abstract

Nuclear Track Micro Filters (NTMF) have been applied to analyze the primary coolant of a nuclear power plant for its content of transuranium elements and solid contaminants. The obtained sample, i.e. the loaded filter, has been investigated for its α- and γ-activity, as well as for studies of solid contaminants of the primary coolant using SEM (scanning electron microscope) attached with EDXA (energy dispersive X-ray analysis). The comparison of the results of the chemical analysis of the filtrate and the results of the filtration method shows, that the NTMF made of Kapton are capable to retain (90 ± 10) % of the total transuranium α-activity. However, the actual content of such α-activities varied considerable from sample to sample. In order to get an explanation of this variation in samples taken at the same time from the reactor cooling circuit, it was tried to find out, whether the transuranium elements are evenly distributed in the coolant or occure point-like (“hot spots”). For this purpose α-autoradiography using CR-39 exposed to the loaded filters was employed. The observed, uneven distribution of tracks on the surface of the CR-39 indicates, that the transuranium elements are adsorbed at the surface of small solid particles, possibly consisting of zirconium and other elements of the fuel elements and the structural material of the nuclear reactor cooling circuit. An other possibility could be the occurence of the transuranium elements in large agglomerates or “clusters” in the primary coolant.