An inconel loop circulating fluoride fuel (62 1/2 make [unintelligible] NaF, 12 1/2 make [unintelligible] ZrF4, 25 make [unintelligible] UF4, 92 [unintelligible] enriched) was operated at 1485°F with a temperature difference of about 35°F in the Low Intensity Test Reactor for 645 hr. For 475 hr of this time the reactor was at full power, and fission power generation in the loop was 2.7 kw, with a max length power density of 0.4 kw/cc. The total volume of fuel was 1290 cc (5.o kg [unintelligible] and the the flow through the irradiated section was 8.6 fps (Reynolds number 5500). The loop has been disassembled and has been examined by chemical and metallographic analyses. Ne acceleration of corrosion of decomposition of fuel by irradiation was noted, although deposition of fission-product ruthenium was absorbed. Ne mass transfer of Inconel was formed, and the corrosive [unintelligible] was general and relatively light. The average corrosive generation, in the usual form of subsurface yields, was 0.5 [unintelligible], the maximum penetration was 2 to 3 miles.