Utilization of 3D fuel modeling capability of BISON to derive new insights in performance of advanced PWR fuel concepts

The Internally and eXternally cooled Annular Fuel (IXAF) and Lightbridge's metallic Helical Cruciform Fuel (HCF) are two innovative fuels, which could allow significant power uprate (similar to 20%) in current Pressurized Water Reactors (PWRs) while maintaining or improving safety margins. Both fuels would substantially benefit from 3D modeling to properly assess their performance in a PWR core and to further their technology readiness level. For IXAF, the possible misalignment of the annular pellets creates a mismatch in inner and outer gap size, which will result in an azimuthally asymmetric temperature distribution and different heat split between the inner and outer channel. For HCF, the fuel deformation requires 3D consideration due to its inherit helical geometry. In this work, the first attempt of building thermo-mechanical capability for analysis of these fuels was made in BISON fuel performance code. The 3D fuel behavior under normal operation along with loss of coolant accident (LOCA) and reactivity initiated accident (RIA) were simulated. The preliminary key insights derived from the 3D fuel performance modeling were the potential excessive ballooning of IXAF during LOCA and excessive swelling of HCF during RIA. However, overall both fuels did show promising and improved performance at 20% uprated conditions compared to traditional solid fuel geometry and material. (C) 2019 Elsevier B.V. All rights reserved.