Gaseous swelling of U3Si2 during steady-state LWR operation: A rate theory investigation

• Published in: Nuclear engineering and design 2017-10, Vol.322, p.336-344
• Main Authors: Miao, Yinbin, Gamble, Kyle A., Andersson, David, Ye, Bei, Mei, Zhi-Gang, Hofman, Gerard, Yacout, Abdellatif M.
• Format: Article
• Language: English
• Subjects: Fission gas behavior; Light water reactor (LWR); Rate theory; Silicide fuels; Steady-state operation
• ISSN: 0029-5493; 1872-759X
• DOI: 10.1016/j.nucengdes.2017.07.008

•Rate theory model for U3Si2’s fission gas behavior in LWRs was developed.•Sensitivity of the key parameters was analyzed to examine the model reliability.•Fission gas behavior was evaluated under various steady-state LWR conditions.•U3Si2 shows controllable fission gas behavior during steady-state LWR operation.•A fission gas behavior correlation was developed for higher-scale simulations. Rate theory simulations of fission gas behavior in U3Si2 are reported for light water reactor (LWR) steady-state operation scenarios. A model of U3Si2 was developed and implemented into the GRASS-SST code based on available research reactor post-irradiation examination (PIE) data, and density functional theory (DFT) calculations of key material properties. The reliability of the model was examined by performing sensitivity analysis of the key parameters. Simplified peripheral models were also introduced to capture the fuel-cladding interaction. The simulations identified three regimes of U3Si2 swelling behavior between 390K and 1190K. Under typical steady-state LWR operating conditions where U3Si2 temperature is expected to be below 1000K, intragranular bubbles are dominant and fission gas is retained in those bubbles. The consequent gaseous swelling is low and associated degradation in the fuel thermal conductivity is also limited. Those predictions of U3Si2 performance during steady-state operations in LWRs suggest that this fuel material is an appropriate LWR candidate fuel material. Fission gas behavior models established based on this work are being coupled to the thermo-mechanical simulation of the fuel behavior using the BISON fuel performance multi-dimensional finite element code.