UMaine builds sensors that can withstand the next generation of nuclear reactors

Nuclear power plants provide 20% of the nation’s energy. To ensure they remain functional and safe to operate, plant engineers rely on sensors to provide feedback on a wide range of parameters, including temperature; reactor power, or neutron flux; and strain on vessel walls. 

A new fleet of advanced reactors are in development to support the U.S.'s expanding nuclear energy infrastructure, but they lack commercial sensors that can withstand the highest temperatures that these new reactors can reach, which range from 500-1,000 degrees Celsius.  

Following two years of testing and development, University of Maine scientists and engineers created a microelectronic sensor that can withstand both the in-core radiation levels and the extreme temperatures that exist within these advanced nuclear reactors. The nanotechnology-based microchip at the heart of this sensor system not only survives the harshest reactor environments, it also provides operational data in real-time. This can help nuclear power plant engineers and operators identify technical issues faster and reduce maintenance costs.

“This is the first demonstration of a microchip technology capable of measuring reactor power up to 800 degrees Celsius, or about 1,500 degrees Fahrenheit,” said Mauricio Pereira da Cunha, the Roger Clapp Castle and Virginia Averill Castle Professor of Electrical and Computer Engineering and principal investigator on this project. “Since many advanced reactors currently under development operate at these temperatures, there is a high demand on the sensors to monitor them.”

Advanced high-temperature reactors, which include microreactor technologies, can generate more energy from the same amount of nuclear fuel as compared to conventional reactors due to the higher thermal efficiencies that are attained at higher temperatures. That’s why this sensor technology, which has been refined over nearly two decades by UMaine engineers, can address a critical gap in instrumentation for the next generation nuclear reactors.

“The commercially available sensors that measure power in nuclear reactors do not operate up to 800 degrees Celsius,” said Pereira da Cunha. “We have now proven that it can be done.” 

The UMaine team’s recent accomplishments have also caught the attention of the Advanced Sensors and Instrumentation group at the Department of Energy’s Idaho National Laboratory, and was recently featured in their newsletter.

“Opportunity: that’s the word of the day,” said the project’s senior research scientist and R&D program coordinator, Luke Doucette. “We’ve got a chance to be a leading institution in this area, but we need to act now.”

From 2013-2024, the team installed similar sensors in other power plant environments, such as the UMaine steam plant, the Penobscot Energy Renewable Company power plant in Orrington, Maine and a coal plant in West Virginia to monitor plant operations for three years. The technology has now been retooled to be resilient against high doses of gamma radiation and intense neutron flux for applications in advanced reactors.

“In addition to extreme temperatures, we’re now also exposing these sensors to intense, in-core levels of nuclear radiation at the same time. This adds an entirely new dimension of difficulty in terms of what types of sensor materials can survive in these conditions and remain functional,” said Doucette.

The research team, which also includes UMaine’s Frontier Institute for Research in Sensor Technologies research scientist Morton Greenslit, has already conducted two week-long tests at the Ohio State University Nuclear Research Laboratory (OSU NRL). This test reactor is part of the Nuclear Science User Facilities network managed by the Idaho National Laboratory. 

During these preliminary tests, their sensor technology demonstrated the capability to continuously operate for the entire test period with no significant degradation in performance. The UMaine researchers are currently refining their sensor technology to withstand even higher reactor powers and be tested over longer deployments.

The team also plans to extend their nuclear sensor technology for wireless connectivity, which requires no batteries, and is powered and operated entirely by the wireless interrogation signal.

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

Collaborations with Idaho National Laboratory and testing at OSU NRL have positioned UMaine as a major player, with potential applications including microreactors and commercial energy for high-performance computing and data storage centers.

The researchers hope to move beyond shorter trials to simulate years of continuous reactor operation at higher radiation levels. They also aim to work with other Maine-based industrial and academic organizations, and have already initiated planning discussions with some of these parties. Their long-term goal is to establish a formal laboratory dedicated to sensors and materials for microreactor and advanced reactor applications. 

“The successful development of these sensors will address and alleviate technology barriers that currently hinder the rollout of advanced nuclear reactors”, said Pereira da Cunha. “Continued support to our work will enable UMaine to play a major role in this emerging area and help to meet our nation’s growing energy needs.”

The project was supported with funding from the U.S. Department of Energy’s (DOE) Established Program to Stimulate Competitive Research (EPSCoR) program, the DOE Nuclear Science User Facilities program and U.S. Nuclear Regulatory Commission.