Apr 11, 2019

Ep 146: Tomasz Kozlowski - Associate Prof., Nuclear Engineering, University of Illinois

Associate Professor, Nuclear Engineering
University of Illinois
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Show notes

1- (0:22)
Interviewer name: Bret Kugelmass
Guest name: Tomasz Kozlowski
Title: Titans of Nuclear: Tomasz Kozlowski | Early Background in Nuclear and Path to Academia (Pt. 1)

Tomasz Kozlowski came to the US in 1993 and grew up in Northwestern Indiana. He took an early interest in science and technology, eventually attending Purdue University, the first school to accept him. Nuclear was intriguing to him, it was a mysterious attraction, and once he got started, he never looked back. Engineering and physics appealed to Tomasz, but not as much as nuclear did. Referencing the mysterious attraction of the field of “nuclear”, Bret commented, “What is happening inside an atom is an alien universe.”

After his Ph.D., Tomasz realized he had a preference for research. While looking for job opportunities, he found the Royal Institute of Technology, Nuclear Power Safety, in Stockholm, Sweden, and he served there from 2009 to 2011. Tomasz liked being a professor and mentoring students, it was personally satisfying to him.

After a few years and an assistant professorship, he came to the United States to further pursue a career in academia at the University of Illinois, where he is currently an Associate Professor of Nuclear, Plasma and Radiological Engineering.

2- (5:20)
Interviewer name: Bret Kugelmass
Guest name: Tomasz Kozlowski
Title: Titans of Nuclear: Tomasz Kozlowski | What is multiphysics? (Pt. 2)

Coolant is used to remove heat from nuclear systems. Tomasz specializes in multiphysics simulation for reactor safety. In his case, “multiphysics", means fluid flow and heat transfer combined, including analysis of neutronics and thermohydraulics coupled with the performance of the fuel. Tomasz solves simple analytical problems using metrics like "volumetric heat capacity", or the amount of energy required to raise the temperature of unit volume.

Water tends to be superior as a coolant since other industries and infrastructures are optimized to handle water. It is widely available and it’s easy to handle and transport.

However, due to certain constraints, different coolants, like sodium, lead, or water, may be “best” in different cases. A proper coolant may be determined based on the unique constraints and performance of the system.

3- (9:30)
Interviewer name: Bret Kugelmass
Guest name: Tomasz Kozlowski
Title: Titans of Nuclear: Tomasz Kozlowski | What are Molten Salt Reactors (Pt. 3)

Reactor physics is interesting and the academic field is robust, but molten salt reactors pose a unique challenge for contamination risk since the fuel is ground up into a fluid substrate. Enough released fission products from a system will make a nuclear plant shutdown due to radioactive contamination. Currently, it is necessary to contain radioactive material to a limited area.

In the example of automobile manufacturing in a large factory, it is difficult to absolutely prevent material leaks in an aging car engine. Likewise, absolute leak prevention in a nuclear power plant is nearly impossible. Some leaks in a nuclear reactor are expected and allowed, but the current question is, “How much leaking is acceptable?”

Theoretically, a simple cylindrical system can be hermetically sealed, but there are already small leaks in systems where fuel is hermetically sealed with high precision, so leakage prevention remains a hypothetical ideal rather than a standard of performance.

Molten salt nuclear systems present challenges. The biggest challenge from a regulatory standpoint is “safeguards,” or guaranteeing that no fuel is leaked, which is unrealistic but necessary to guarantee. Further, molten salt systems require volumetric calculations and exhibit a mechanism of extraction/insertion, which presents greater risks for tampering.

In Tomasz’s opinion, the best solution moving forward is “EBR-II”, or Experimental Breeder Reactor-II. It’s a sodium-cooled fast reactor at the Argonne National Laboratory National Reactor Testing Station in Idaho, USA, and it was shut down in 1994. EBR-II uses Uranium zirconium alloy rods as fuel, which can be electro-refined, melted, cast to alloy, and reused in a closed-loop system.

Sodium nuclear systems can be dangerous. When sodium leaks and comes into contact with water or air, it causes an explosion. Nevertheless, sodium is the best for reactors that require fuel reprocessing. However, if reprocessing is not required, water is the best coolant solution.

Molten salt reactors are not as prevalent because they are cost-prohibitive, even with recycled fuel, the cost of the power plant may be multiple billions of dollars.

4- (20:09)
Interviewer name: Bret Kugelmass
Guest name: Tomasz Kozlowski
Title: Titans of Nuclear: Tomasz Kozlowski | Purpose-driven Nuclear Technologies (Pt. 4)

Bret has been exposed to many different opinions on which reactors are better, e.g., lead, sodium, light, heavy, solid, etc. Tomasz uses the example of a car to demonstrate that nuclear reactors, like cars, have different designs based on their purpose. The best choice for a particular nuclear system is “purpose driven”, i.e., it depends on the purpose for the reactor and there are four different purposes a nuclear reactor may have, #1) electricity production, #2) heat production, #3) transmuting waste, or #4) breeding new fuel. For example, a light-water reactor is best for electricity production, gas or molten salt reactors are best for heat production, while fast reactors (lead or sodium) are best for waste transmuting and fuel breeding.

Bret asked “Why we aren’t building smaller light-water reactors or a new nuclear product altogether? Why haven’t companies in the oil industry developed nuclear solutions? Energy companies like Shell, BP, and Exxon are in the right industry and have the supply chain and resources to explore nuclear products.

Bret and Tomasz discuss the XKCD comic that displays the temperature of the earth over the last 20,000 years. Comic link: https://xkcd.com/1732/. Relative to changes that took thousands of years, major changes in climate have occurred in recent history.

5- (33:40)
Interviewer name: Bret Kugelmass
Guest name: Tomasz Kozlowski
Title: Titans of Nuclear: Tomasz Kozlowski | Renewable energy vs. Nuclear and Core Safety Analysis (Pt. 5)

How does Tomasz advise his students in order to help solve the problem of climate change?

Tomasz says that he tries not to give them his opinions, allowing them to investigate what they believe in. However, he is an advocate for large-scale nuclear energy production in contrast to other forms of “renewable energy” as alternatives to nuclear. Tomasz and Bret discuss confirmation biases and preconceived notions, and how they play a role in our own beliefs.

Tomasz’s current focus is core safety analysis, where he works to get the simulations to be as high-fidelity as possible. One key problem he is trying to solve is fuel failure mechanisms, specifically, in predicting when the cladding exterior around the fuel will crack and fail. Tomasz runs simulations at different cladding stress levels, including microcracks, grain morphology, and exposure to heat but these simulations do not always match experiments. The standard zirconium-cladding fuel rod in a light-water reactor lasts about six years, at which point, its ability to maintain production is mostly diminished.

6- (42:00)
Interviewer name: Bret Kugelmass
Guest name: Tomasz Kozlowski
Title: Titans of Nuclear: Tomasz Kozlowski | Simple Energy Production with the Light-water Reactor (Pt. 6)

Nuclear is easy to control and to construct, it does not harm the environment, and scalable mass production is possible. Even though nuclear energy is much simpler, cleaner, and less destructive than coal, there hasn’t been an intellectual drive towards 100% nuclear energy in past administrations of the US government.

China is relying more on nuclear and could be one of the countries to use 100% nuclear energy in the future. The Chinese will meet supply chain constraints before demand throttling.

Are we too timid to build enough nuclear power plants, similar to the scale of manufacturing automobiles? We tend to grow accustomed to the environment we’re used to and we must challenge our existing paradigms if full-scale nuclear is to become a reality. Mass production of nuclear reactors might be the only answer to clean energy and the reversal of climate change.

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