Nuclear Science & Technology
Idaho National Labs
Feb 14, 2018
Q - Early Exposure to Nuclear at National Labs
Bret Kugelmass: How did you find your way into a nuclear profession?
John Wagner: John Wagner bounced around the different engineering departments at the University of Missouri-Rolla before getting excited about nuclear physics and engineering. During his undergrad, Wagner spent a summer at Oak Ridge National Laboratory working on the High Flux Isotope Reactor. Between undergrad and graduate school, went to Los Alamos National Laboratory where he got involved in Monte Carlo radiation transport methods. That summer was a career changing experience and took him to graduate school at Penn State to receive his Master’s and PhD with a focus on Monte Carlo. If you want to know a person’s dose rate of radiation exposure and design the safety of a system, such as shielding, you have to understand how radiation moves through matter. The principle ionizing radiation protected against are neutrons and gammas. Radiation transport is a computational or analytical tool for simulating the dose rate in different parts of a system. Monte Carlo follows individual neutrons and, based on the statistics, infers the average behavior of all the neutrons in a system. Wagner combined Monte Carlo radiation transport methods with traditional deterministic transport methods into hybrid transport method. After grad school, John Wagner joined Holtec International working on criticality safety analyses for spent fuel rocks, which are steel rocks that sit in a spent fuel pool. When fuel is initially taken out of the reactor core, it sits in pools to cool and water provides shielding from radiation. From there it is transferred into dry storage casks. Dry casks are certified for 20 years for commercial spent nuclear fuel. As on-site storage in the industry grew, Holtec had a market to put higher density racks in the pool to increase the capability of the pools. The Nuclear Regulatory Commission (NRC) worked with the industry in terms of what they saw as requirements for ensuring the safety and continued performance of the systems, allowing extension of the licenses up to 40 years. The industry has active aging management programs in which people inspect the canisters and casks to ensure they are continuing to perform and look for signs of degradation.
13:12 Q - Storage Options for Spent Fuel
Bret Kugelmass: After Holtec, where did you go?
John Wagner: After a couple years at Holtec, John Wagner was offered the opportunity to return to Oak Ridge National Laboratory (ORNL) and get back into his radiation transport work. A few different codes being used around the world were developed at ORNL using those methods. These codes are pieces of software that are executed to solve a problem. These methods enabled calculations that were previously computationally prohibitive. While at ORNL, Wagner got involved with the Nuclear Regulatory Commission (NRC), ultimately working on the proposed repository at Yucca Mountain. John Wagner was part of the Yucca Mountain team that submitted the license application in June 2008. The NRC has reviewed it and issued safety reports that are favorable. The program has since been defunded, but from a technical standpoint, the repository is very viable. There are efforts on both sides of the political aisle to support or not support Yucca Mountain. The local community is supportive and wants the license to go all the way to go through the system and get executed if it is safe. Interim storage is needed, but the industry struggles with the social and political aspects of the technology. The dose rates at the storage casks are very, very small. The Nuclear Regulatory Commission (NRC) focuses on the site boundary does, approximately one-third of what a cross-country airplane. The people that would be close to the casks may be security, maintenance, or aging management personnel. Due to radiation decay, the radiation dose rates get lower.
20:26 Q - Idaho National Laboratory
Bret Kugelmass: How did you get involved at Idaho National Laboratory (INL)?
John Wagner: Idaho National Laboratory (INL) has complex tools and facilities for the Advanced Test Reactor, such as the fuel examination facility and the irradiated materials characterization lab. INL had all the ingredients and abilities on-site to make different fuel types and materials. Test fuels go through pre-irradiation characterization, get sent to the Advanced Test Reactor, go back to the hot fuels examination facility, and get sample prepped to go into different microscopes. By understanding how fuels and materials behave in a radiation environment allows scientists to inform their computational models. Research is pushing in the direction of getting data to develop predictive capabilities so that experiments are used to confirm what codes are telling us. Experiments are expensive and time consuming. John Wagner runs a directorate which is made up of five different divisions, which are Domestic Programs, Nuclear Fuels and Materials, Fuel Cycle Technology, Nuclear Systems and Analysis, and Regulatory Safety. The Regulatory Safety division informs current or new regulations and helps them understand technical bases for different regulations.
25:47 Q - Advanced Reactor Research
Bret Kugelmass: Tell me about some of the advanced reactor work going on at Idaho National Lab.
John Wagner: There is a lot of external and private interest in advanced reactors. The nuclear community has transformed in the last 5-10 years from a few very big companies, like Westinghouse, to a lot of small startup companies that are focused on advanced reactor designs. Some advanced reactor designs include high temperature gas reactors and fast reactors. The Transient Reactor Test Facility (TREAT) shut down in 1994 and initially went critical in November, meaning steady state, and that reactor is intended to be a pulse or a transient reactor. A transient is a spike in power. A normal commercial reactor does not want transients, but instead wants to run steady state. In the event you did have a power spike, you need to understand how the fuel behaves. If your fuel doesn’t perform well under that environment, you may have to replace the assembly or it may have a big impact on the reactor core and is very important for licensing. Light water reactors use water to cool and moderate the neutrons. Advanced reactors are looking at different concepts that are more passively safe. A less mature class of advanced reactors is molten salt reactors. It is the only design that has the fuel in a liquid form. This offers the ability to continually operate and replenish salt. Fast reactors, fast spectrum neutrons, are better suited for fuel recycling. The Experimental Breeding Reactor 2 (EBR-2) was linked with a fuel conditioning facility and demonstrated full fuel recycling. Fast neutrons turn uranium-238 into plutonium-239 which is a fissile isotope. All the light water reactors in the U.S. have uranium-235 as the core ingredient in their fuel, which releases on average 2.5 neutrons out which go out to have another chain reaction. Plutonium-239 production was done at the Hanford site to create nuclear weapons. In civil applications, you can get to a point in which you are making more fissile isotopes than you are burning, creating an unlimited energy source. John Wagner got into nuclear energy from the standpoint of abundant, reliable clean energy. Energy conservation is helpful, but is not the answer to energy poverty. Nuclear is effectively an infinite source of energy. The facilities at Idaho National Laboratory drew Wagner in, but he was also attracted to the focus on nuclear energy.
36:22 Q - New Fuel Development at INL
Bret Kugelmass: What are some things you see coming out of the Idaho National Lab in the future?
John Wagner: The number of nuclear reactors in the U.S. is declining and there are a lot of challenges in cost, especially compared to wind, solar, and gas. Idaho National Lab (INL) wants to help nuclear plants reduce their operating cost. At the end of the day, we want to see the nation use diverse clean energy sources, but there is a commercial market and they must be cost competitive. Wagner is excited about the small startup companies in advanced nuclear and the push on innovation in technology, methods, and approaches. Accident tolerant fuels are more robust in the event of an off-normal situation, such as Fukushima, and provide as much time as possible to mitigate a situation. This fuel has the potential to be less expensive and more efficient, which will help with reactor operating cost. INL is getting ready to put three different concepts into the Advanced Test Reactor later in 2018. They are making uranium silicide fuel at the Materials and Fuels Complex which is targeted to go into a commercial reactor in 2019. One of the challenges with nuclear is how long it takes and all parts of the equation need to be more efficient. When designing new materials, it must be made and you must understand the material. Then it is exposed to radiation, high temperatures, or corrosion environments, whichever end use environment it will be exposed to. Higher flux research reactors are used to accelerate the process, but it still takes time. After taking it out of a reactor, it is both very radioactive and hot. By the time you get data, there is a chance it may not be the data you need. Innovation must be faster and rely more on modeling and simulation and get creative about how to create environments that can accelerate testing.
41:22 Q - Economic Uncertainty of Nuclear
Bret Kugelmass: What’s your vision for the future of nuclear energy?
John Wagner: A typical nuclear energy plant in the U.S. is very big, on the order of one gigawatt electric, take 8-10 years build, and are many billions of dollars. This is a big hurdle for a utility to commit to. The uncertainties and risks are significant. Right now, the economics drive them to putting natural gas or other sources on. Research at Idaho National Laboratory (INL) fits in three buckets: helping the existing fleet stay viable, advanced reactors, and the fuel cycle. Microreactors are very small reactors that could be built in a factory. INL is working with private companies and intend to demonstrate a microreactor on-site by 2021. Its characteristics are intrinsically safe and its systems are based on technologies that have been developed over decades. Interest for microreactors is in remote communities and special purpose type applications, such as the Department of Defense. INL wants to demonstrate that microreactors are possible and open up the future for nuclear in a small, modular way.