INL/US DOE Participation in the Coordinated Research Project FUMAC: Final Report

Abstract

This report summarizes the contribution of Idaho National laboratory (INL) to the IAEA Coordinated Research Project on Fuel Modeling under Accident Conditions FUMAC. In line with the original research agreement bewtween INL/US DOE/Battelle and IAEA, work at INL has focused on both (i) developments of INL's fuel performance code BISON for the analysis of loss-of-coolant accidents (LOCA) and (ii) simulation of selected FUMAC priority cases. With reference to code development efforts, models were implemented in BISON for high temperature cladding oxidation, Zircaloy solid-solid phase transformation, Zircaloy high temperature creep, cladding burst failure and axial fuel relocation. BISON, analyses were performed of the FUMAC cases (1) MTA-EK tests PUZRY, (2) QUENCH L1 rods 4 and 7, (3) Halden IFA-650.2 and ( 4) Halden IFA-650.10. In addition, the REBEKA separate effects tests were analyzed, including an effort to investigate 3D cladding response in presence of azimuthal temperature variations. In general, BISON predictions of burst temperature, pressure and time to burst are very reasonable. Predictions of cladding hoop strain are less satisfactory and require additional investigation. Finally, results of 3D simulations indicated that 3D effects are potentially important in fuel rod analysis during LOCAs. BISON results are made available to the FUMAC project as a contribution to the FUMAC benchmark exercise.