Failure mechanism of silicide and aluminide fuels during power transient

Yanagisawa, Kazuaki

An influence of fuel core density (2.2, 3.0 and 4.0 g/cc) on a fuel failure was studied comparing the silicide fuel (4.8 g/cc) as the reference. (1) The DNB value of the test specimens (below 4.8 g/cc) was 175 24 C, having no difference to the reference (180 14 C). (2) The reference fuel failed at the large temperature drop (above 94 C) and the short time to quench (below 0.13 s). The test specimens did not fail until 106 cal per gram fuel plate due to the enhanced plasticity of the aluminum matrix. The lower the fuel density, the more the plasticity enhanced. (3) Irrespective to fuel density, the bow was increased with the increasing PCST. Experimental fact revealed that maximum bow at JRR-3 operating (below 228 C) is 15% (0.4 mm), where the almost data are within 4% (0.1 mm). (4) For axial permanent strain evaluated by the plate thickness, the test specimens were expanded but the references were shrunk.