b'Development of BISON Models for Coated CladdingPrincipal Investigator: Ryan Sweet, ORNLTeam Members/ Collaborators: Brian Wirth and Andy Nelson (ORNL)assessment of the integral thermal-mechanical performance of fuel rods with coated cladding.Project Description: The goal of this effort is twofold; to identify the constitutive behavior characteristics that a coating material must possess to remain beneficial, and to develop accurate coating analysis capabilities, which allow us to collabo-rate with industry partners on near-term accident tolerant fuel (ATF) solutions.For this project, the BISON fuel performance code is used due to its multi-dimensional and multi-physics capabilities, as well as its Figure 1. These simulationsT he motivation for developingextensive library of LWR performance demonstrate a minimal effect ofalternative cladding materials formodels. Constitutive properties for zirconium oxide coatings on thelight water reactor (LWR) fuelthe proposed coating materials are cladding hoop stress state a) howeversystems is to improve reactor safetyimplemented and simulations are the coating hoop stress b) varies aperformed to evaluate the behavior sizeable amount based on the propertyduring high-temperature transient mismatch with the cladding. conditions, where zirconium claddingof both the coating and cladding rapidly oxidizes. As the cladding reactsunder LWR conditions. Key cladding with the coolant, it both releasesperformance indicators, such as creep energy and produces hydrogen gas.down and stress development after gap Coatings applied to the exteriorclosure, are investigated to ensure that surface of zirconium cladding havethe coating is not negatively impacting Developed coatingthe cladding behavior. Correspondingly, analysis capabilitiesbeen identified as a possible solutionthe coating behavior itself is examined have garnered interestto help limit cladding oxidation atto identify if the coating is in danger of from several fuel vendorselevated temperatures. These coatingcracking, delamination, or spallation.for assessing their near- materials must remain adherent toAdditionally, parametric analyses of term accident tolerantthe cladding substrate to realize thecore thermomechanical properties fuel concepts. oxidation protection and are expectedallow us to determine where additional to modify the established behavior of the zirconium alloy cladding duringinvestigation is needed, and can help reactor operation. This work focuses oninform experimental conditions. the development of constitutive modelsAs material property testing for proposed coating materials and ancommences at Oak Ridge National Laboratory (ORNL), refinements to the constitutive models will be made 160 2019|AFC ACCOMPLISHMENTS'