59 2006 TRISO Fuel Testing Tri-isotropic (TRISO) fuel is a specialized fuel intended for high-temperature gas reactors. An outer shell of carbon coats a layer of silicon carbide, which coats the uranium center so containment of the radioactive material is built right into the fuel itself. While the research dates back to 1980s Germany, it was abandoned in the early 1990s. A decade later, Generation IV reactor research resurrected interest and ATR irradiation began in 2006. In March 2008, researchers announced that TRISO particles consumed 9 percent of their fuel, far greater than the 3 or 4 percent burnup achieved by conventional light water reactor fuel. By September they had confirmed 12.5 percent burnup, and in 2013 they announced that the fuel could endure temperatures as high as 1,800 Celsius (more than 3000 F) with a burnup rate close to 20 percent. “ The ability of the fuel to retain fission products at such high temperatures translates directly to enhanced safety of the reactor.” — Paul Demkowicz, technical lead for post-irradiation examination of TRISO fuel