The Woodruff School

SUMMARY

Theoretical models are used in support of the I2S-LWR project for a direct comparison of fuel swelling and fission gas bubble formation between U3Si2 and UO2 fuels. Uranium silicide is evaluated using a previously developed model with the fuel in an amorphous state. The uranium dioxide is examined with two separate models developed using a number of papers. One model calculates the swelling behavior with a fixed grain radius while the second incorporates grain growth into the model. Uranium silicide rapidly becomes amorphous under irradiation. The different mechanisms controlling the swelling of the fuels are introduced including the “knee point” caused by the amorphous state for the U3Si2. The outputs of each model are used to compare the fuels.

SUBJECT:	M.S. Thesis Presentation

BY:	Thomas Winter

TIME:	Monday, February 22, 2016, 11:00 a.m.

PLACE:	Boggs, 3-47

TITLE:	Comparison of Fission Gas Swelling Models for Amorphous U3Si2 & Crystalline UO2

COMMITTEE:	Dr. Chaitanya Deo, Chair (NRE) Dr. Bojan Petrovic (NRE) Dr. Preet Singh (MSE)

SUMMARY Theoretical models are used in support of the I2S-LWR project for a direct comparison of fuel swelling and fission gas bubble formation between U3Si2 and UO2 fuels. Uranium silicide is evaluated using a previously developed model with the fuel in an amorphous state. The uranium dioxide is examined with two separate models developed using a number of papers. One model calculates the swelling behavior with a fixed grain radius while the second incorporates grain growth into the model. Uranium silicide rapidly becomes amorphous under irradiation. The different mechanisms controlling the swelling of the fuels are introduced including the “knee point” caused by the amorphous state for the U3Si2. The outputs of each model are used to compare the fuels.