Density, Porosity and Grain Size, (II) Irradiated ROX Fuels to Burn-up of 28%FIMA

概要

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The irradiation of ROX fuels to a burn-up of 28%FIMA in JRR-3M was made. Obtained results from post-irradiation examinations are: (1) The fuel bulk density of the ROX-SZR decreased by irradiation from 4.6g/cc (82%TD) to 3.4g/cc (61%TD), while that of the ROX-ThO2 also decreased from 5.2g/cc (83%TD) to 3.4g/cc (55%TD). (2) The porosity of the ROX-SZR increased from 18 to 39%, while that of the ROX-ThO2 also increased from 17 to 46%. The increase of porosity, that is, the unconstrained gas bubble swelling in the present case might be attributed to the agglomeration of pores, where Al2O3 and PuAl11O18 of ROX components took an important role. (3) The rate of unconstrained gas bubble swelling was estimated to be 0.8%ΔV/V per 1%FIMA for the ROX-SZR and 1%ΔV/V per 1%FIMA for the ROX-ThO2, respectively. For UO2, it was about 1%ΔV/V per 1%FIMA. Hence, with respect to the rate of unconstrained gas bubble swelling between the ROX fuels and UO2, the difference was insignificant. (4) The average grain size of the ROX-SZR increased from 2 to 6μm, while that of the ROX-ThO2 increased from 2 to 4μm. A grain growth occurred slightly.
社団法人日本原子力学会の論文
1999-12-25