Koroush Shirvan, John Clark Hardwick Career Development Professor in the Department of Nuclear Science and Engineering (NSE), knows that the nuclear industry has traditionally been wary of innovations until they prove proven useful. As a result, he has relentlessly focused on the practical applications of his research, work that has earned him the 2022 Reactor Technology Award of the American Nuclear Society. “The award has generally recognized practical contributions to the field of reactor design and hasn’t gone to academia often,” says Shirvan.
One of these “practical contributions” is in the field of accident tolerant fuels, a program launched by the US Nuclear Regulatory Commission in the wake of the 2011 Fukushima Daiichi incident. The goal within this program, Shirvan says, is to develop new forms of nuclear fuel that can tolerate heat. His team, with students from more than 16 countries, is working on numerous possibilities that vary in composition and production method.
Another aspect of Shirvan’s research focuses on how radiation affects heat transfer mechanisms in the reactor. The team found that fuel corrosion was the driving force. “[The research] it informs how the nuclear fuels in the reactor work, from a practical point of view,” says Shirvan.
Nuclear reactor design optimization
A summer internship when Shirvan was a college student at the University of Florida in Gainesville seeded his drive to focus on practical applications in his studies. A nearby nuclear company was losing millions due to dirt accumulating on fuel rods. Over time, the company worked around the problem by using more fuel, before all the life had been extracted from the previous batches.
Fuel rod placement in nuclear reactors is a complex problem with many factors (lifetime of fuel, location of hot spots) affecting results. Nuclear reactors change their fuel rod configuration every 18 to 24 months to optimize about 15 to 20 constraints, leading to about 200 to 800 assemblies. The mind-bending nature of the problem means plants must rely on experienced engineers.
During his internship, Shirvan optimized the program used to place fuel rods in the reactor. He found that certain rods in assemblies were more prone to dirt deposits and modified his settings, optimizing the performance of these rods rather than adding assemblies.
In recent years, Shirvan has applied a branch of artificial intelligence (reinforcement learning) to the configuration problem, creating a software program used by the largest nuclear company in the United States. “This program gives even a layman the ability to reconfigure the fuels and the reactor without having specialized knowledge,” says Shirvan.
From advanced math to counting jelly beans
Shirvan’s own background in nuclear science and engineering developed quite organically. He grew up in Tehran, Iran, and when he was 14 the family moved to Gainesville, where Shirvan’s aunt and family live. He recalls an awkward couple of years at the new high school where he was grouped with newly arrived international students and placed in entry-level classes. “I went from doing advanced math in Iran to counting jelly beans,” he laughs.
Shirvan applied to the University of Florida for his undergraduate studies as it made financial sense; the school awarded full scholarships to Florida students who received a certain minimum score on the SAT. Shirvan qualified. Shirvan’s uncle, who was then a professor in the department of nuclear engineering, encouraged Shirvan to take classes in the department. Tutored by his uncle, the courses Shirvan took and his internship cemented his love for the interdisciplinary approach the field demanded.
Since he always knew he wanted to teach (he remembers finishing his math exams early in Tehran so he could earn the reward of being the class monitor), Shirvan knew graduate school was next. His uncle encouraged him to apply to MIT and the University of Michigan, home to renowned programs in the field. Shirvan chose MIT because “only at MIT was there a program on nuclear design. There were professors dedicated to designing new reactors, looking at multiple disciplines and bringing it all together.” He continued his MSc and PhD studies at NSE under the supervision of Professor Mujid Kazimi, focusing on compact boiling and pressurized water reactor designs. When Kazimi passed away suddenly in 2015, Shirvan was a research scientist and became a starter to lead the professor’s team.
Another project Shirvan took on in 2015: directing the MIT course on nuclear reactor technology for utility executives. Offered solely by the Institute, the program is an introduction to nuclear engineering and safety for personnel who may not have much experience in the area. “It’s a great course because you can see what the real problems are in the energy sector… like grid stability,” says Shirvan.
A multi-pronged approach to saving
Another very real problem facing nuclear companies is cost. Contrary to what you hear on the news, one of the biggest obstacles to building new nuclear facilities in the United States is the cost, which today can be up to three times that of renewables, Shirvan says. While many approaches, such as advanced manufacturing, have been tried, Shirvan believes the solution to lower costs lies in designing more compact reactors.
His team has developed advanced open source software nuclear cost tool and has focused on two different designs: a small water reactor with compact steam technology and a horizontal gas reactor. Compactness also means making fuels more efficient, as Shirvan’s work does, and improving the heat exchange device. It’s about going back to basics and bringing “commercially viable arguments with his research,” Shirvan explains.
Shirvan is excited about the future of the US nuclear industry and that the Cut Inflation Act of 2022 provides the same subsidies for nuclear power as it does for renewables. On this new level playing field, advanced nuclear power still has a long way to go in terms of affordability, he admits. “It’s time to move forward with a cost-effective design,” says Shirvan, “I look forward to supporting this by continuing to guide these efforts with my team’s research.”
