b'temperature failures (PCMI driven)References: and high temperature failures[1.] Wagner A.R., Harp J.M., Ar-(swelling and rupture driven). Thechibald K.E., Ashby S.C., Watkins high temperature failure limit startsJ.K., Tolman K.R., Fabrication of at 711 J/g and decreases to 628 J/gstoichiometric U 3 Si 2fuel pellets with increasing fuel rod internalMethodsX Vol 6 (2019) pressure. The low temperature[2.] Stone J.G., Schleicher R., Deck (PCMI) limit is based on the stateC.P., Jacobsen G.M., Khalifa of environmental degradation in theH.E., Back C.A., Stress analysis cladding and starts at 628 J/g andand probabilistic assessment of decrease to 209 J/g [4]. Based onmulti-layer SiC-based accident these initial experiments, ATF rodstolerant nuclear fuel cladding that consist of U 3 Si 2fuel in ZircaloyJournal of Nuclear Materials Vol cladding or SiC-SiC cladding, fuel466 (2015)safety limits could start as high as 528 J/g for fresh fuel based on the[3.] U.S. Atomic Energy Commission, results of the experiments describedRegulatory Guide 1.77, no. above (SETH-G). While this is lowerMay, pp. 18, (1974)than the current limits for fresh[4.] Nuclear Regulatory Comission, fuel (628 J/g or 711 J/g), stayingDraft Regulatory Guide DG under this value should not pose an1327 Pressurized Water Reactor excessive burden on LWR reactivityControl Rod Ejection and Boil-control systems. These limits willing Water Reactor Control Rod likely need to be reexamined forDrop Accidents, (2016)the fuel as its burnup increases. The SETH-I test provides some insight into how this limit may change. The SETH-I test simulates pellet swelling during burnup and closure of the pellet cladding gap. The SETH-I test showed that for fuel rods with U 3 Si 2fuel and SiC-SiC cladding the fuel rod is likely able to retain its geom-etry at enthalpies up to 330 J/g even when PCI occurs.2020|AFC ACCOMPLISHMENTS 103'