BISON: A Flexible Code for Advanced Simulation of the Performance of Multiple Nuclear Fuel Forms Richard L. Williamson, a * Jason D. Hales, a Stephen R. Novascone, a Giovanni Pastore, a Kyle A. Gamble, a Benjamin W. Spencer, a Wen Jiang, a Stephanie A. Pitts, a Albert Casagranda, a Daniel Schwen, a Adam X. Zabriskie, a Aysenur Toptan, a Russell Gardner, b Christoper Matthews, c Wenfeng Liu, d and Hailong Chen e a Idaho National Laboratory, Computational Mechanics & Materials Department, P.O. Box 1625, Idaho Falls, Idaho 83415 b Kairos Power, 707 W. Tower Avenue, Alameda, California 94501 c Los Alamos National Laboratory, Materials Science in Radiation and Dynamics Extremes, Los Alamos, New Mexico 87545 d Structural Integrity Associates Inc., 9710 Scranton Road, Suite 300, San Diego, California 92121 e University of Kentucky, 185 Ralph G. Anderson Building, Lexington, Kentucky 40506-0503 Received July 10, 2020 Accepted for Publication October 12, 2020 Abstract — BISON is a nuclear fuel performance application built using the Multiphysics Object-Oriented Simulation Environment (MOOSE) finite element library. One of its major goals is to have a great amount of flexibility in how it is used, including in the types of fuel it can analyze, the geometry of the fuel being modeled, the modeling approach employed, and the dimensionality and size of the models. Fuel forms that can be modeled include standard light water reactor fuel, emerging light water reactor fuels, tri-structural isotropic fuel particles, and metallic fuels. BISON is a platform for research in nuclear fuel performance modeling while simultaneously serving as a tool for the analysis of nuclear fuel designs. Recent research in BISON includes techniques such as the extended finite element method for fuel cracking, exploration of high-burnup light water reactor fuel behavior, swelling behavior of metallic fuels, and central void formation in mixed-oxide fuel. BISON includes integrated documentation for each of its capabilities, follows rigorous software quality assurance procedures, and has a growing set of rigorous verification and validation tests. Keywords — Finite element, BISON, MOOSE. Note — Some figures may be in color only in the electronic version. I. INTRODUCTION Nuclear fuel performance modeling is used for a variety of purposes, including fuel design and optimization, experi- ment planning and interpretation, and operational and safety analysis. Such modeling is typically performed using dedi- cated fuel performance codes, a number of which have been developed for specific fuel types. Fuel vendors, utilities, safety authorities, and research organizations develop or use these codes to predict the behavior and lifetime of fuel during standard operation, accidental transients, and post- irradiation storage. A comprehensive review of nuclear fuel performance modeling was recently published. 1 *E-mail: richard.williamson@inl.gov This material is published by permission of a contractor of the U.S. government under Contract No. DE-AC07-05ID14517. The U.S. government retains for itself, and others acting on its behalf, a paid-up, non-exclusive, and irrevocable worldwide licence in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the government. This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives License (http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited, and is not altered, transformed, or built upon in any way. NUCLEAR TECHNOLOGY · VOLUME 207 · 954–980 · JULY 2021 © 2021 The Author(s). Published with license by Taylor & Francis Group, LLC. DOI: https://doi.org/10.1080/00295450.2020.1836940 954