b'SiC/SiC Channel Box IrradiationPrincipal Investigator: Christian PetrieTeam Members/ Collaborators: Wilna Geringer, Adam James, Kurt Smith, Joseph R. Burns, Annabelle Le Coq, Nicholas Russell, Christian Deck, Takaaki Koyanagi, and Yutai Katohcant heating and hydrogen generation caused by exothermic steam oxidation reactions with Zr-based materials during severe accidents. However, there is concern that spatial variations in neutron flux and/or temperature could result in significant lateral bowing of a SiC/SiC channel box due to differ-ential radiation-induced swelling. This bowing could potentially interfere with coolant channels or control blade movements. While some recent models have predicted the extent of bowing for a SiC/SiC channel box, those models are lacking in validation from experi-mental irradiations.Project Description:The objective of this project is to experimentally evaluate the lateral bowing of a miniature SiC/SiC channel box and SiC/SiC tubes (for fuel clad-ding applications) following neutron irradiation under a fast neutron flux Figure 1. Design of theS ilicon carbide (SiC) fiberrein- gradient. General Atomics fabricated channel box experiment forced, SiC ceramic matrixa 38 cm long channel box with a 30 composites (SiC/SiC composites)mm30 mm cross-section as well have long been considered as a poten- as SiC/SiC composite tube specimens tial accident tolerant fuel (ATF) becausewith typical pressurized water reactor of their high-temperature strength,cladding dimensions. A novel irradia-dimensional stability under irradia- tion vehicle was designed (Figure 1) to tion, minimal neutron absorption, andaccommodate the specimens and allow superior oxidation kinetics comparedthem to bow and swell axially without to zirconium (Zr) alloys in steamconstraint during neutron irradiation and air environments. In addition,in Oak Ridge National Laboratory SiC/SiC materials could be a nearer(ORNLs) High Flux Isotope Reactor term replacement for current Zr alloy(HFIR). Within the permanent reflector channel boxes in boiling water reactorsof the reactor, the fast neutron flux (BWRs) that could mitigate the signifi- decreases by ~35% moving from the 68 2021|AFC ACCOMPLISHMENTS'