Assessment of Buffer-IPyC Thermomechanical Debonding Behavior Using New Experiment Strength Data in BISON

Krajewska-Travar, Zuzanna [Idaho National Laboratory]; Skerjanc, William F [Idaho National Laboratory]; Stempien, John D [Idaho National Laboratory] (ORCID:0000000166320785); Jiang, Wen [North Carolina State University]

DOE OSTI · 3030821

Assessment of Buffer-IPyC Thermomechanical Debonding Behavior Using New Experiment Strength Data in BISON

Krajewska-Travar, Zuzanna [Idaho National Laboratory]·Skerjanc, William F [Idaho National Laboratory]·Stempien, John D [Idaho National Laboratory] (ORCID:0000000166320785)·Jiang, Wen [North Carolina State University]

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Abstract

TRIstructural ISOtropic (TRISO) single sub-millimeter-diameter nuclear fuel particle consists of a spherical fuel kernel surrounded by four coating layers. During reactor operation, the TRISO coating layers are subjected to irradiation-induced dimensional changes and the associated thermomechanical behavior of each layer. One of the observed behaviors is gap formation between the buffer and IPyC layer due to the porous buffer’s irradiation-induced shrinkage exceeding that of the IPyC layer. To predict TRISO thermomechanical performance, multi-physics models have been built that are continually updated and refined. The BISON code is a finite element-based nuclear fuel performance code that may be used for TRISO particle simulations. One of the recent additions to the BISON code is the ability to model the process of layer debonding. This paper will focus on the simulation results of the improved BISON debonding model that will utilize updated strengths measured from irradiated TRISO fuel particles. The new experimental strength data from micromechanical tests of irradiated TRISO fuel samples were exercised in the BISON simulations and compared to baseline strength data to assess their applicability in the models. This also includes updated buffer-IPyC bond strengths to simulate layer delamination. Based on current experimental observations it is noted that the buffer-IPyC separation occurs not exactly at the junction of these two layers, but more on the side of the buffer layer. This improved modeling approach using experimental strength data to characterize buffer-IPyC debonding and its potential subsequent cracking will be presented in the paper along with comparisons to available experimental observations.

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Krajewska-Travar, Zuzanna [Idaho National Laboratory], Skerjanc, William F [Idaho National Laboratory], Stempien, John D [Idaho National Laboratory] (ORCID:0000000166320785), Jiang, Wen [North Carolina State University]. 2025-10-06. Assessment of Buffer-IPyC Thermomechanical Debonding Behavior Using New Experiment Strength Data in BISON. https://www.osti.gov/biblio/3030821

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