b'Westinghouse Cr coated Zr cladding.175; starting with unfueled SiGA The test simulated loss of coolantrodlets, followed by SiGA metal-bond accident (LOCA) conditions (5C/ rodlets, and concluding with SiGA UO 2second temperature rise with rodmetal-bond rodlets in ATR cycle 175.pressures of ~55 bar) but terminatedFurther, GA is completing fabrication at 1300C instead of the currentof six SiGA metal-bond rodlets with 1204C LOCA limit. Much lowersurrogate fuel (molybdenum pellets) oxidation was found at the peakfor water loop irradiations in ATR temperature of 1300C as comparedcycles 173A/B (Figure 2). In parallel, to uncoated Zr cladding. These testGA is collaborating with Westing-results will be used to validate thehouse to demonstrate autoclave beyond design basis accident (BDBA)robustness of this configuration performance models in the MAAP5through 120+ days of Westinghouse and MELCOR codes. The resultsautoclave exposure (Figure 3). Previ-of these codes and probabilityously, GA has delivered six unfueled safety analyses (PSA) which takeSiGA rodlets for ATR cycle 171A, advantage of FLEX capabilities, willcurrently scheduled to be inserted be used as the basis for the NRC tofall 2022.allow downgrading of some equip-ment classifications, resulting inPreliminary steam oxidation ultra-economic benefits for the utility. high temperature (UHT) testing at Lower length scale modeling (ASM)Westinghouse Churchill of SiGA clad-is being used to develop ADOPT andding resulted in minimal corrosion UN fuel properties. U15N with 5%at 1600C in a steam environment. enriched has a235 U content equiva- ORNL tests showed SiGA cladding lent to ~6.9% enriched UO 2and asurvived temperatures and pressures higher thermal conductivity thatfar above other materials and did not also aids in reducing or eliminatingburst when to design limits of the test fuel fragmentation, relocation, andapparatus (up to 1200C and 15 MPa dispersal (FFRD). internal pressure).GA has advanced SiC microstructureGA continues fabrication prepara-consistency and demonstrated favor- tion for batches of 3-foot SiC ceramic able out-of-pile corrosion resultsmatrix composites cladding as a of its baseline chemical vaporforerunner to fabricating full-length deposition (CVD) SiC coating and(12-foot) SiGA cladding. Corrosion has shown improved hermeticityand irradiation performance of 2-ft SiC and yields of the locally heated CVDmetal-bond fuel pins will be demon-endcap joining. Demonstration of strated in future ATR irradiations.SiGA cladding irradiation performance is scheduled for the upcoming ATR cycles 171, 173 and 2022|AFC ACCOMPLISHMENTS 109'