A testing campaign led by the Department of Energy’s Oak Ridge National Laboratory (ORNL) has successfully validated a prototype high-temperature fission chamber, which is a critical component for the next generation of nuclear reactors.
“During the weeklong irradiation, the prototype maintained expected performance across all power levels while operating steadily at temperatures consistent with the maximum range of high-temperature reactors,” said ORNL in a press release.
The evaluation, conducted at The Ohio State University Research Reactor, confirmed that the sensor can maintain operational integrity at temperatures reaching 800 degrees Celsius (1,472°F).
Role of fission chambers in nuclear Safety
In nuclear power generation, fission chambers function as primary sensors responsible for detecting neutrons. This data is essential for starting a reactor and monitoring its power levels during operation.
While existing light-water reactors operate at relatively lower temperatures, many advanced reactor designs—such as molten salt or high-temperature gas-cooled reactors—are engineered to run at significantly higher thermal ranges to increase energy efficiency and provide process heat for industrial applications.
As these reactors operate in more extreme environments, the instrumentation must be capable of providing accurate data without mechanical or electrical failure.
The recent testing focused on ensuring that the fission chamber designed by nuclear equipment manufacturer Curtiss-Wright could withstand these specific conditions.
Technical evaluation and collaborative engineering
The testing process required a specialized environment capable of mimicking the interior of an advanced reactor. Brandon Wilson, an R&D staff member in the Nuclear and Extreme Environment Measurement Group at ORNL, led the effort to design a custom testing rig.
“Designing experiments that push these crucial sensors to their limits is something ORNL is uniquely equipped to do,” highlighted Wilson.
“Our expertise in recreating extreme environments is exactly why partners come to us when they need confidence in how a new component will perform.”
The team, which included experiment engineer Craig Gray and former ORNL staff member Padhraic Mulligan, engineered this rig to subject the prototype to both high thermal loads and constant reactor irradiation.
During a weeklong irradiation period, the prototype was monitored by a joint team from ORNL and Curtiss-Wright, including engineers Heather Shave and Chris Laidler. The sensor was tested across a full range of reactor power levels.
Data collected during the campaign indicated that the prototype performed according to technical expectations, showing no signs of degradation while operating steadily at the 800-degree Celsius threshold.
Supporting national energy infrastructure
This project was facilitated through the Department of Energy’s Gateway for Accelerated Innovation in Nuclear (GAIN) voucher program.
The GAIN program is designed to provide private sector technology developers with access to the technical expertise and specialized facilities available at national laboratories.
This specific collaboration aligns with the Office of Nuclear Energy’s Advanced Sensors and Instrumentation program, which seeks to remove technical barriers to the deployment of advanced nuclear systems.
The successful validation of this prototype provides a data-backed foundation for the commercial use of high-temperature sensors. For the nuclear industry, these results represent a necessary step toward licensing and operating new reactor types.