Engineers build sensors that can withstand next-generation nuclear reactors

Nuclear power plants provide 20% of the country’s energy. To ensure plant functionality and safe operation, plant engineers rely on sensors to provide feedback on a wide range of parameters, such as temperature. Reactor power or neutron flux. And it puts a strain on the blood vessel walls.

New advanced nuclear reactors are being developed to support America’s expanding nuclear energy infrastructure, but there is a lack of commercial sensors that can withstand the maximum temperatures of 500 to 1,000 degrees Celsius that these new reactors can reach.

After two years of testing and development, scientists and engineers at the University of Maine have created a microelectronic sensor that can withstand both the in-core radiation levels and extreme temperatures present within these advanced nuclear reactors.

At the heart of this sensor system is a nanotechnology-based microchip that not only withstands the harshest nuclear reactor environments, but also provides operational data in real time. This allows nuclear power plant engineers and operators to identify technical issues faster and reduce maintenance costs.

“This is the first demonstration of microchip technology that can measure reactor power down to 800 degrees Celsius or about 1,500 degrees Fahrenheit,” said Mauricio Pereira da Cunha, Roger Clapp Castle and Virginia Averill Castle Professor of Electrical and Computer Engineering and principal investigator on the project.

“Many new nuclear reactors currently in development will operate at these temperatures, putting a high demand on sensors to monitor them.”

Modern high-temperature nuclear reactors, including microreactor technology, can produce more energy from the same amount of nuclear fuel compared to conventional nuclear reactors due to the higher thermal efficiency achieved at higher temperatures. That’s why this sensor technology, refined over nearly two decades by UMane engineers, addresses a critical gap in next-generation nuclear reactor instrumentation.

“Commercially available sensors that measure reactor power do not work up to 800 degrees Celsius,” Pereira da Cunha said. “We have now proven that it is possible.”

The UMaine team’s recent work has also attracted the attention of the Advanced Sensors and Instrumentation Group at the Department of Energy’s Idaho National Laboratory.

“Opportunity: That’s the word of the day,” said Luke Doucette, the project’s senior research scientist and research and development program coordinator. “We have an opportunity to be a leading institution in this field, but we need to act now.”

The team installed similar sensors in other power plant environments from 2013 to 2024, including the Penobscot Energy Renewable Company power plant in Orrington, Maine, and monitored plant operations for three years. This technology is currently being recalibrated to be resistant to high doses of gamma rays and intense neutron fluxes for use in advanced nuclear reactors.

“In addition to extreme temperatures, we are now simultaneously exposing these sensors to reactor-level intense nuclear radiation. This adds a whole new dimension of difficulty in terms of what kinds of sensor materials can withstand and remain functional under these conditions,” Doucette said.

The research team, which includes Morton Greenslit, a sensor technology researcher at the University of Maine’s Frontier Research Institute, has already conducted two weeks of testing at the Ohio State University Nuclear Research Laboratory (OSU NRL). The test reactor is part of the Nuclear Science Utilization Facility Network managed by the Idaho National Laboratory.

During these preliminary tests, the company’s sensor technology demonstrated its ability to operate continuously throughout the test period without significant performance degradation. Researchers at the University of Maine are currently refining the sensor technology to withstand even higher reactor power and test it over extended deployments.

The team also plans to extend nuclear sensor technology for wireless connectivity. The wireless connection requires no batteries and is powered and operated entirely by wireless interrogation signals.

Both graduate and undergraduate engineering students play key roles in the project, gaining hands-on experience in one of UMane’s clean rooms. The skills they acquire are highly transferable and prepare them for careers in the microelectronics and semiconductor industries.

Collaboration with the Idaho National Laboratory and testing at OSU NRL have established UMane as a major player with potential applications such as microreactors and commercial energy for high-performance computing and data storage centers.

Researchers hope to go beyond shorter-term tests to simulate years of continuous reactor operation at higher radiation levels. They also aim to collaborate with other Maine-based industry and academic groups, and have already begun discussions on plans with some of these groups.

Their long-term goal is to establish a formal laboratory specializing in sensors and materials for microreactor and advanced reactor applications.

“Successful development of these sensors could address and alleviate the technical barriers that currently prevent the deployment of advanced nuclear reactors,” Pereira da Cunha said.

“With continued support for our work, Umine will be able to play an important role in this emerging field and help meet our country’s growing energy needs.”