US nuclear fission chamber passes extreme heat stress test at 1,472°F

The Department of Energy’s Oak Ridge National Laboratory (ORNL) has successfully tested a prototype high-temperature nuclear fission chamber capable of operating reliably at 800°C (1,472°F), a temperature consistent with advanced reactor designs like molten salt and high-temperature gas-cooled reactors. This weeklong irradiation test, conducted at The Ohio State University Research Reactor, demonstrated that the sensor maintained expected performance across all reactor power levels without degradation. The fission chamber, developed by Curtiss-Wright, is critical for detecting neutrons to safely start and monitor reactor power, especially in reactors operating at higher temperatures than conventional light-water reactors. The testing involved a custom rig engineered by ORNL experts to simulate extreme reactor environments, combining high thermal loads with constant irradiation. The collaborative effort between ORNL and Curtiss-Wright engineers validated the sensor’s mechanical and electrical integrity under these conditions. This successful validation supports the Department of Energy’s Advanced Sensors and Instrumentation program and was facilitated through the GAIN voucher program, which