HTGR Knowledge Base

Conference Article: Release behavior of metallic fission products from fuel for HTTR.

Hayashi, K.; Fukuda, K. (Japan Atomic Energy Research Inst., Tokai Research Establishment, Tokai, Ibaraki (Japan). Dept. of Fuels and Materials Research); Shiozawa, S. (Japan Atomic Energy Research Inst., Oarai Research Establishment, Oarai, Ibaraki (Japan). Dept. of HTTR Project)

Abstract

Model fuel assemblies of High Temperature Engineering Test Reactor (HTTR) were irradiated in an in-pile gas loop, OGL-1, and axial and radial distributions of metallic fission products were measured by gamma spectrometry. The in-pile diffusion coefficient of Cs determined from its radial profiles in the graphite sleeve was significantly smaller than that for the un-irradiated graphite, IG-110. Rapid release of Cs was observed for heating of irradiated TRISO particles at 2200 and 2300 deg. C, due to thermal deterioration of the SiC coating layer. Release experiments with BISO particles led to decision of the rate-determining steps in the release of metallic fission products, and to determination of their diffusion coefficients in the fuel kernel and pyrocarbon layer. These results have been reflected in the HTTR design analyses on the release under normal operating and accident conditions.

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key words: Gas Cooled Reactor, Nuclear Technology
Reference:
Behaviour of gas cooled reactor fuel under accident conditions. Proceedings of a specialists meeting held in Oak Ridge, 5-8 November 1990
International Atomic Energy Agency, Vienna (Austria). International Working Group on Gas-Cooled Reactors
IWGGCR--25, pp:61-67