Designer, builder, operator, administrator, and teacher, Gordon Kohse, deputy director of research and services for MIT’s Nuclear Research Laboratory (NRL), delights in wearing many hats. After nearly 40 years at the facility, Kohse continues to relish the daily duties of ensuring the smooth operation of experiments at the NRL, and the longer-term challenges of advancing the latest nuclear engineering technologies.
“It’s really nice for me to do something that I really believe is worthwhile,” says Kohse. “I also have a lot of fun doing it, and find it hard to imagine trading this life for anything else.”
Driving Kohse’s dedication to his work is an unflagging commitment to nuclear energy. He dates the start of his interest in the field to his college years at the University of Calgary. The son of a geophysicist who worked on seismic surveys for Mobil in the remote regions of Alberta, Kohse initially thought that he would become a chemical engineer. Like most of his university classmates, he foresaw a future in oil and gas. But from his perch in the woody, western reaches of Canada, Kohse became aware of the impacts of fossil fuel.
“It was the mid ‘70s, acid rain was a problem, and I began to have environmental concerns,” he says. “Nuclear energy seemed like an idea whose time had come—it was a good option for getting away from burning stuff, especially coal.”
Although the University of Calgary did not offer a nuclear engineering option, Kohse took nuclear physics classes, and soon decided to break decisively from his original career plan and his old life. “Going to graduate school, starting in a field I didn’t know much about, and moving away from home for the first time was a leap into the unknown for me in many respects,” he says.
That leap landed Kohse at MIT. “I started off very excited about fusion energy,” he recalls. “Like many researchers at the time, I figured if fission was good, fusion was even better.” He was interested in the effects of neutron radiation on material used in fusion reactors, and there was only one viable place for him to perform experiments. “My research relied on using the reactor lab,” he says.
Kohse was specifically interested in testing the fatigue properties of stainless steel in conditions that simulated plasma, the churning, radioactive environment of a fusion reactor. He helped develop an experimental set-up within the NRL that involved bombarding pressurized steel tube samples with ions produced by neutron interactions with boron. After cycling the tubes through these trials, he would remove them, and examine the samples of steel for cracks—evidence of metal fatigue.
As compelling as he found the science, Kohse was even more energized by the design and construction enabling the research. “I learned how to use the reactor to do a complicated experiment, how to take radioactive samples out, and examine them in remote facilities,” he says. “”It’s what I still do today.”
Although his interest in fusion faded, Kohse continued with the NRL as a research scientist, transitioning to fission-based nuclear energy experiments, and steadily expanding his repertoire of skills. He invented protocols for irradiating materials in the reactor core. “I helped create the first research hot cell at the reactor,” says Kohse. This is a heavily shielded enclosure large enough to accommodate the long apparatus that lifts radioactive samples from the reactor core, and within which robot arms manipulate samples for analysis.
“This set-up is more typical of a national energy lab and unusual for a university,” he says. “But that’s the theme here: We decided we wanted to do this, and figured out how to make it happen.”
Among Kohse’s research accomplishments is the NRL’s participation in efforts to solve the problem of radioactive corrosion product transport. Nuclear plant operators are sometimes exposed to small amounts of radiation from contact with parts of the plant that are not made radioactive by direct exposure to the core, such as heat exchangers and pumps, but where circulating coolant water has deposited radioactive metallic particles. “We wanted to figure out how to reduce the amount of radioactive stuff and remove it once it was already deposited,” says Kohse.
Through a suite of experiments, Kohse’s group was able to verify new guidelines for controlling water chemistry in reactors—guidelines that much of the nuclear energy industry using water-cooled reactors eventually adopted. “Our work led to the reduction of radioactive doses, more reliable operation of plants, shorter shutdowns, and higher capacity factors,” says Kohse.
More recent NRL research highlights for Kohse involve improving the cladding used in nuclear fuel assemblies to prevent the possibility of hydrogen explosions and meltdowns of the type experienced at Fukushima in 2011. He also has a hand in developing next-generation molten salt-cooled reactors.
“What drives me is the idea of keeping current plants operating safely, contributing to technology in places adopting nuclear power on a larger scale, and helping reduce the carbon intensity of electricity,” he says.
Kohse is convinced that the NRL’s impact on nuclear energy research and technology is disproportionate to its size. “As a smaller reactor, we have greater flexibility, meaning we can do tests that are difficult, bordering on the impossible,” he says. This means a constant stream of requests not just from Department of Energy laboratories, but industry as well. “Because we do things quickly and efficiently, people see that it’s worthwhile checking things out in our reactor first.”
Today, as well as designing and implementing large, collaborative experiments taking place inside the NRL year-round, Kohse carries a significant instructional load. In addition to one-on-one mentoring of Nuclear Science and Engineering (NSE) students for lab and thesis work, he co-teaches the foundational NSE lab course, 22.09 Principles of Nuclear Radiation Measurement and Protection. A communications intensive class, 22.09 represents “for a lot of students their first exposure to rigorous science writing,” says Kohse. He takes particular pleasure in the speed with which his students catch on. “The improvement from first reports to the end of the course, in just a few months, is remarkable,” he says. The satisfaction runs both ways: Kohse received the 2015-2016 PAI Outstanding Faculty Award, presented by the student chapter of the American Nuclear Society.
Kohse also supervises student research projects of all levels, and organizes outreach activities that expose a range of young minds to the NRL, including Korean student groups and high school girls interested in STEM fields.
“I like the variety I get day to day, from brainstorming new experiments, and hands-on work, to one-on-one mentoring,” says Kohse. “Put it all together, and I really feel that I can have some impact on the understanding and advancement of nuclear power.”