The U-M Department of Nuclear Engineering and Radiological Sciences has received $5.1 million funding for three projects to advance nuclear technology. 

The department is also collaborating on three more of the 74 projects that the U.S. Department of Energy is supporting with a total of $61 million. 

Smaller, robust heat exchangers

The biggest project U-M leads—funded with $4 million from the Integrated Research Projects program—is focused on compact heat exchangers, which would transfer heat from a nuclear reactor to the systems that use the heat directly or convert it to electricity. They are much smaller and thus less expensive than traditional designs.

Diffusion bonding, the process used to create compact heat exchangers, involves stacking grooved plates and pressing them together, causing the grooves to form channels. This new manufacturing technique creates a large number of small channels, which maximize the contact between the metal and the heated fluid, allowing more heat to pass through than in conventional heat exchangers.

However, high temperatures weaken the bonds between plates, limiting the heat exchangers to a lower temperature and eliminating the gains made by making them small. This project’s goal is to improve the knowledge of the bonding process to enable strong bonds at high temperatures.

“By bringing together the top experts from around the country, the research from this project will improve our ability to make lower-cost and efficient heat exchangers that will decrease the overall costs associated with nuclear energy,” said Todd Allen, principal investigator of the project and the Glenn F. and Gladys H. Knoll Department Chair of Nuclear Engineering and Radiological Sciences. 

Another U-M contributor is Fei Gao, professor of nuclear engineering and radiological sciences. The project includes collaborators at the University of Wisconsin, Idaho National Laboratory, Argonne National Laboratory, Electric Power Research Institute and engineering firm MPR.

Better reactor physics modeling

Funded with $600,000 by the Nuclear Energy University Partnerships program, Brendan Kochunas, U-M assistant professor of nuclear engineering and radiological sciences, will lead an effort to speed up the modeling of neutron physics for the software tools developed under the Nuclear Energy Advanced Modeling and Simulation program. 

Determining the distribution of neutrons in a reactor is critical to understanding the energy output, including how to ramp it up and how to shut it down. 

Kochunas and his team will focus on developing new simulation methods that can be applied to advanced nuclear technologies based on SPn theory. The renewed interest in the almost 60-year-old SPn method comes in part from recent theoretical breakthroughs that improve the method’s accuracy.

“lt is humbling, and I feel grateful for this opportunity to lead an outstanding team of researchers in developing the next generation of SPn methods,” Kochunas said.

If successful, the new methods could substantially reduce advanced reactor design cycle times and lead to safer designs. Other U-M contributors are Brian Kiedrowski, associate professor of nuclear engineering and radiological sciences, and Krishna Garikipati, professor of mechanical engineering and mathematics. The project includes collaborators at the Argonne National Laboratory, Oak Ridge National Laboratory and Naval Nuclear Laboratory.

Understanding how reactor components degrade

Funded with $500,000 from the Nuclear Energy University Partnerships program, professor emeritus Gary Was and associate professor Kevin Field, both of nuclear engineering and radiological sciences, lead a study of how radiation damage evolves through creep, which can shorten the lifespan of a nuclear power plant by potentially affecting all components of a nuclear reactor’s core. 

Coupled with heat and neutron radiation in the reactor core, the mechanical stress causes metal components to slowly deform by a process known as creep. Because of these contributing factors, creep is extremely difficult to assess, and traditional testing cannot assess them independently. This project will use ion beam experiments to develop an understanding of how each individual factor affects creep, which will provide guidelines for the development of creep-resistant alloys.

“Thermal and irradiation creep are deformation mechanisms that can limit the long-term sustained operation of a nuclear power plant,” Was said. “However, traditional irradiation creep testing using neutron beams involves high costs and long lead times.”

The advantage of ion beams is that they can produce radiation damage much faster, and with additional computer modeling and simulation, they enable industry to predict when and how creep damage will progress. While data exists to make these predictions about radiation creep for current reactors, this project will produce both data and an understanding of radiation creep that is applicable to advanced reactor applications, for which the data is largely absent. 

Other U-M contributors on this work are Fei Gao, professor of nuclear engineering and radiological sciences, and Priyam Patki, a former U-M postdoctoral research fellow and current process engineer at Intel Corp.

Award announcements: 

• ​Advancing Diffusion Bonding for Compact Heat Exchangers
• Fast and Rigorous Methods for Multiphysics SPn Transport in Advanced Reactors
• Accelerated irradiation creep testing coupled with self-adaptive accelerated molecular dynamics simulations for scalability analysis