Investigation of Steady-State Operating Performance of Cr?O?-Doped UO?-Zircaloy Nuclear Fuel

Abstract:

Cr?O?-doped UO? pellets can promote grain growth and may improve fission-gas retention. This study coupled the fuel-performance code BEEs with the grain-scale fission-gas code SCIANTIX. BEEs transfers local temperature, burnup, fission rate, and grain size to SCIANTIX, while fission gas release (FGR) and gas swelling are returned to the rod-scale calculation. For the BR-3 36i8 rod, the coupled model predicted an end-of-life FGR of 28.49%, 15.7% below the measured value of 33.80%, and a void volume of 5.890×10?? m3, 26.8% below the measured value of 8.046×10?? m3. Because only one rod and endpoint measurements were available, this comparison establishes neither statistical significance nor general predictive accuracy. Deterministic sensitivity calculations for grain sizes of 10–50 μm showed lower FGR and gap pressure but higher retained-gas swelling at larger grain sizes under the adopted model settings.