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Conference Article: Study on storage and reprocessing concept of the high temperature engineering test reactor (HTTR) fuel

Sawa, K.; Yoshimuta, S.; Shiozawa, S.; Fujikawa, F.; Tanaka, T. (Japan Atomic Energy Research Inst. (Japan)); Watarumi, K.; Deushi, K.; Koya, F. (Nuclear Fuel Industries Ltd, Ibaraki (Japan))

Abstract

The Japan Atomic Energy Research Institute (JAERI) is proceeding with the construction of High Temperature Engineering Test Reactor (HTTR), which is the first High Temperature Gas-cooled Reactor in Japan. The first criticality of the HTTR, will be attained in the end of 1997. A fuel assembly of the HTTR is so-called pin-in-block type, which consists of fuel rods and a hexagonal graphite block. A fuel rod contains fuel compacts in which coated particles are dispersed. The coated fuel particle consists of a microsphere of low enriched UO2 with the TRISO coating. All fuel assemblies are discharged from the core after about three years operation. The spent fuels are transferred to air-cooled spent fuel storage racks after two years cooling in the fuel storage pool in the reactor building. According to basic Japanese concept, all spent fuel shall be reprocessed, although the coated fuel particle is considered to be able to retain fission products during long period. Then a calculation study has been carried out to investigate the fission products release behavior from the HTTR fuel during long-period repository and/or disposal. In addition, some head-end reprocessing techniques have been investigated to apply the conventional Purex process to the HTTR fuel. JAERI studied graphite-CO2 reaction and jet grind method as a head-end reprocessing technique. In fuel fabrication process, burn-crush-leach method is employed to recover uranium from the fuel compacts. This experience is supplying useful data to investigate the head-end reprocessing method. This report describes the fuel storage system of the HTTR and present status of the storage and reprocessing study in JAERI.

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key words: Gas Cooled Reactor, Nuclear Technology
Reference:
Technical committee meeting on technologies for gas cooled reactor decommissioning, fuel storage and waste disposal. Juelich (Germany) 8-10 Sep 1997
International Atomic Energy Agency, Vienna (Austria)
IAEA-TECDOC--1043, pp:177-189