Irradiation performance of FBR Monju-type fuel with modified type 316 stainless steel at high burnup
- PNC, Oarai (Japan)
In the last three decades, extensive effort has been devoted to the development of austenitic stainless steels for the liquid-metal fast breeder reactor in Japan. In the driver fuels of the Joyo MK-II experimental fast reactor core, which has been operated successfully at 100 MW(thermal) since 1982, 127 fuel pins are assembled with wrapping wire into the hexagonal duct. The material for cladding, duct, and wire is 20% cold-worked modified Type 316 stainless steel (PNC316) and mixed-oxide (MOX) fuel pellets, with 29 wt% Pu content and 94% theoretical density (TD). The peak burnup and neutron dose at the current Joyo MK-II core has reached 84 GWd/tonne U and 50 dpa, respectively. The postirradiation examination of those assemblies showed excellent performance of the MOX fuel and a negligible pin diameter increase, which demonstrates that the conservative design for the Joyo MK-II driver fuels is satisfactory. A life-limiting factor of the austenitic steel fuel assemblies was demonstrated to be dominated by the swelling-induced bundle distortion in a duct. Specifically, for characterizing swelling of PNC316 materials, microstructure changes of the irradiated cladding and duct were extensively analyzed by means of transmission electron microscopy. In PNC316 the improvement of swelling resistance had been conducted by adjusting 20% cold working and by adding minor alloying elements such as P, B, Ti, and Nb within the specification range of chemical compositions in the standard Type 316 stainless steel.
- OSTI ID:
- 298292
- Report Number(s):
- CONF-981106-; ISSN 0003-018X; TRN: 99:001923
- Journal Information:
- Transactions of the American Nuclear Society, Vol. 79; Conference: American Nuclear Society winter meeting, Washington, DC (United States), 15-19 Nov 1998; Other Information: PBD: 1998
- Country of Publication:
- United States
- Language:
- English
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