Three Virginia Tech professors from nuclear engineering, physics, and industrial engineering are bringing together their expertise and inventions to create a highly innovative technology for high-fidelity, real-time monitoring of nuclear power plant cores.

The project would increase the safety and economy of nuclear reactors and has received funds from the National Science Foundation, the U.S. Department of Energy (DOE), the Nuclear Regulatory Commission, and the Virginia Tech Institute for Critical Technology and Applied Science, for a total of more than $2.6 million.

The nuclear power picture

Among all current types of energy sources, nuclear energy produces the highest amount of energy from its resources. According to the DOE, nuclear power plants operate at high capacity more than 90 percent of the time, more than double the output capacity of wind or coal and triple the capacity of solar.

Nuclear power is also clean, producing no air pollution or carbon dioxide while operating. Within a nuclear core, atoms are split through nuclear fission to release energy, which is then recovered by a coolant to produce steam. The steam spins large turbines, generating electricity for homes and businesses.

To sustain efficiency and safety at nuclear power plants, technicians must monitor many operating components, which requires a tremendous amount of instrumentation. H.M. Hashemian, president and CEO at Analysis and Measurement Services Corporation, has reported 10,000 sensors and detectors and 5,000 kilometers of instrumentation and control cables, representing a total mass of 1,000 tons within the control system of a typical nuclear plant unit.

According to a 2015 article in Nature, several of these sensors also must be duplicated for redundancy in case they cannot withstand the harsh conditions inside a reactor. Replacing sensors can be expensive and often involves shutting down the entire nuclear power plant, causing a dip in the energy available to customers and incurring costs for replacement parts and lost business.

The Virginia Tech research team’s combined efforts could circumvent this problem entirely with innovative sensors that operate outside the reactor, eliminating the need for installations and removals that cause shutdowns.

Bringing the team together

Jonathan Link, professor in the Department of Physics at Virginia Tech, together with departmental colleagues Patrick Huber and Camillo Mariani, developed a novel detection system that caught the attention of a nuclear engineer. That system is called CHANDLER, a boxed set of materials that detects the presence of particles called antineutrinos.

The CHANDLER mechanism uses a series of cubes containing a scintillating material that produces light when interacting with energy. That phenomenon occurs because of energy deposition within particle interactions. Different particles give off light in different timings, which helps researchers identify them. The mechanism also contains photomultiplier tubes that detect the light and measure the positions of energy depositions and the time between illuminations, thus relaying the nature of each interaction.

Antineutrinos are tiny, harmless particles carrying no charge, subatomic in size, that nuclear power plants emit in large numbers. They are created during the process of nuclear fission and pass through the reactor's structure uninhibited due to their small size and lack of charge.

Detecting antineutrinos is difficult because interfering charged particles are everywhere. They travel the galaxy and even come from our sun. In sensors, charged particles create interference as additional “noise” that muddies the picture when interpreting results.

Link’s device cuts through the noise. While CHANDLER was originally envisioned as a way to deter rogue nations from developing nuclear weapons by finding hidden diversions of nuclear material, the system’s ability to detect particles and filter out the ambient noise offers opportunities beyond that purpose. This potential sparked a conversation between Link and Alireza Haghighat, director of the nuclear engineering program within the Department of Mechanical Engineering.

Over the past 36 years, Haghighat and his group have been developing advanced particle transport simulation methods and codes. Their efforts produced a computer code called RAPID, which renders a visual representation of neutron distributions in high fidelity. Haghighat and his students have been working for many years within the nuclear industry, engaged in projects with the Jozef Stefan Institute and Dominion Energy to perform validation studies using their system. With RAPID, they have created entire virtual versions of nuclear power plants and their reactors.

After joining efforts with Link’s team, Haghighat was able to extend those partnerships to include further development of CHANDLER. Dominion Power agreed to support the research by providing data for modeling of the North Anna Power Station, Unit 2, using RAPID, in-core and out-of-core neutron measurement data, and access for performing CHANDLER measurements. In that environment, Haghighat and Link were able to determine new ways of filtering through the noise to accurately identify the previously elusive antineutrinos and create a more complete picture of their presence in and around a reactor. The resulting information precisely illustrates what the reactor core is doing.

“If I can measure antineutrino flux with high precision, I know the amount of fission,” said Haghighat. “If I know the amount of fission, I know the power generated in the reactor. If I know the fission and the power, I know the material. When combined with RAPID solutions, this gives us the full picture of a nuclear core without needing to be inside the core itself.”

Also involved in the project is Nathan Lau, associate professor in the Grado Department of Industrial and Systems Engineering. Lau and his group have been studying how to design nuclear power plant control rooms to support situational awareness and reduce human errors. Lau’s expertise has bridged the gap between detecting the particles and communicating the information for operators to understand what’s going on in the core and take necessary actions. The collaboration enables the team to determine how to identify antineutrinos, how to translate the data into an intuitive display, and how to put those tools in the hands of people who need them.

“The fact that we know exactly what is happening in the core is enormous because there are many methods used to establish how much fuel is left in a nuclear core,” said Haghighat. “Fuel is used at different amounts throughout a reactor core, which creates a more complicated process to calculate the exact information from within a core. We have the tools to overcome these difficulties.”

Haghighat added that this effort may eliminate the need for in-core neutron detectors, which can significantly benefit Small and Micro modular reactor design and operation.

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