Evaluation of Reduced Order Model for HT-9 Creep and Modifications to Current HT-9 Creep Model in BISON

Abstract

In order to leverage existing reduced-order models (ROM) for material modeling, Los Alamos National Laboratory (LANL)-developed HT-9 cladding mechanistic-based constitutive models have been implemented into BISON. It is posited that the increased fidelity of the ROM will show improvement over engineering-scale models in terms of comparison against experimental measurements. Idaho National Laboratory will assist LANL in implementing an HT-9 ROM in BISON. Once the HT-9 mechanistic constitutive model can be leveraged in nuclear performance simulations, the numerical results of fast reactor models will be analyzed and compared against the Fuels Irradiation & Physics Database and separate effects tests to attempt a validation process. Idaho National Laboratory and LANL will work together to perform any necessary improvement identified during the implementation and use processes. Successful milestone completion will enable the general use of validated mechanistic ROMs for HT-9 cladding in BISON.This report provides a brief introduction to the Los Alamos Reduced Order Model Applied to Nonlinear Constitutive Equations (LAROMance) code, mechanical testing used to illustrate its creep and plastic deformation predictions for HT-9 cladding, and a comparison with existing models implemented into BISON. Current models have been modified to more appropriately account for primary thermal creep, and results for corresponding testing are included in this report.