A Coupled Experimental and Simulation Approach to Investigate the Impact of Grain Growth, Amorphization, and Grain Subdivision in Accident Tolerant U₃Si₂ Light Water Reactor Fuel

Technical Report · Mon Mar 30 00:00:00 EDT 2020

DOI:https://doi.org/10.2172/1607368· OSTI ID:1607368

Walters, William ^[1]; Tonks, Michael R.  ^[2]; Lian, Jie ^[3]; Zhang, Yongfeng ^[4]; Harp, Jason ^[5]

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1. Pennsylvania State Univ., University Park, PA (United States)
2. Univ. of Florida, Gainesville, FL (United States)
3. Rennselaer Polytechnic University, Troy, NY (United States)
4. Univ. of Wisconsin, Madison, WI (United States)
5. Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

Triuranium disilicide (U₃Si₂) is being considered as an alternative accident tolerant fuel (ATF) due to its higher thermal conductivity. However, there is uncertainty in its use due to a lack of irradiation data at light water reactor (LWR) conditions. In this project, we used an integrated experimental and simulation approach to answer two significant questions pertaining to U₃Si₂ that were not investigated by the Fuel Cycle Research and Development (FCRD) and Nuclear Energy Advanced Modeling and Simulation (NEAMS) programs: (1) Will grain growth in the hotter portions of the fuel significantly impact U₃Si₂ LWR fuel behavior? (2) Under what conditions do grain subdivision and amorphization occur in U₃Si₂ and will either occur at LWR conditions? Our approach to answer these questions used in situ ion irradiation and annealing to investigate grain growth, grain subdivision, and amorphization, along with mesoscale simulations using the MARMOT tool. We found that while the grain boundary mobility of U₃Si₂ is larger than that of UO₂, grain growth in U₃Si₂ fuel pellets will be less than in UO₂ and may be neglected due to the lower thermal conductivity and thus lower centerline temperature. We also found that amorphization will not occur in U₃Si₂ above 600 K, such that it is not likely to occur at typical LWR operating conditions. Grain subdivision will occur at LWR conditions and will likely occur at lower burnups than in UO₂.

• Research Organization: Pennsylvania State Univ., University Park, PA (United States)
• Sponsoring Organization: USDOE Office of Nuclear Energy (NE)
• DOE Contract Number: NE0008564
• OSTI ID: 1607368
• Report Number(s): DOE-PSU-08564; 16-10667; TRN: US2103848
• Country of Publication: United States
• Language: English

Related Subjects

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
U3Si2
Grain growth
Grain Subdivision
Amorphization