High enrichment of 15N isotope by ion exchange for nitride fuel development

Two kinds of nitrogen-isotope enrichment experiments were conducted for the purpose of developing a process to obtain highly enriched 15N by ion-exchange chromatography. As the first stage experiments, high enrichment of 14N was carried out by displacement chromatography using columns packed with cation-exchange resin and feed ammonium ion of which 15N abundance is natural namely 0.36%. In the second stage, high enrichment of 15N was studied starting from ca. 80% enriched 15N feed material; after 30 m migration 99.67% 15N was obtained. The height equivalent to a theoretical plate (HETP) of ion-exchanges separation is usually very small, but the results clearly indicate that the HETP is enlarged when the high enrichment zone of 14N or 15N is developed at the front or the rear band boundary, respectively. The information obtained is very important and should be useful for designing when the plant for the high enrichment isotope separation is designed. (author)