NUCLEAR SAFETYHardy Transistor Material Could Be Game-Changer for Nuclear Reactor Safety Monitoring
The safety and efficiency of a large, complex nuclear reactor can be enhanced by hardware as simple as a tiny sensor that monitors a cooling system. That’s why researchers are working to make those basic sensors more accurate by pairing them with electronics that can withstand the intense radiation inside a reactor.
The safety and efficiency of a large, complex nuclear reactor can be enhanced by hardware as simple as a tiny sensor that monitors a cooling system. That’s why researchers at the Department of Energy’s Oak Ridge National Laboratoryare working to make those basic sensors more accurate by pairing them with electronics that can withstand the intense radiation inside a reactor.
The ORNL research team recently met with unexpectedly high success using a gallium nitride semiconductor for sensor electronics. A transistor made with the material maintained operations near the core of a nuclear reactor operated by research partner The Ohio State University.
Gallium nitride, a wide-bandgap semiconductor, had previously been tested against the ionizing radiation encountered when rockets hurtle through space. Devices with wide-bandgap semiconductors can operate at much higher frequencies, temperatures and irradiation rates. But gallium nitride had not faced the even more intense radiation of neutron bombardment. “We are showing it is great for this neutron environment,” said lead researcher Kyle Reed, a member of the Sensors and Electronics group at ORNL.
That could offer a big boost for equipment monitoring in nuclear facilities. The information gathered by sensors provides early warnings about wear and tear on equipment, allowing timely maintenance to avoid broader equipment failures that cause reactor downtime. Currently, this sensing data is processed from a distance, through yards of cable connected to electronics with silicon-based transistors.
“Our work makes measuring the conditions inside an operating nuclear reactor more robust and accurate,” Reed said. “When you have lengthy cables, you end up with a lot of noise, which can interfere with the accuracy of the sensor information. By placing electronics closer to a sensor, you increase its accuracy and precision.” To meet that goal, scientists need to develop electronics that can better tolerate radiation.
Researchers irradiated gallium nitride transistors for three days at temperatures up to 125 degrees Celsius close to the core of The Ohio State University Research Reactor. “We fully expected to kill the transistors on the third day, and they survived,” Reed said. The team pushed the transistors all the way to the reactor’s safety threshold: Seven hours at 90% power.
