Advanced Reactor Modeling
Argonne National Lab
July 12, 2018
Q1: How did you end up at University of Wisconsin in Madison?
A1: Tom Fanning was first exposed to nuclear energy during a project in his high school physics class. As a Wisconsin native, UW-Madison’s nuclear engineering program was a natural fit. Fanning became interested in the safety side of the industry following both the Challenger and Chernobyl incidents. Fanning pursued his doctorate degree with a focus on numerical methods for neutron transport. In 1986, Argonne conducted one-of-a-kind testing of the inherent safety of EBR-II, a sodium-cooled reactor. These tests, called the Shutdown Heat Removal Tests, included unprotected loss of flow, which simulated pump failure, and unprotected loss of heat. Inherent safety is achieved because expansion shuts the reaction down and natural circulation removes the heat from the system. Fanning now works at Argonne National Laboratory.
Q2: How have you collaborated around the world with your work?
A2: Tom Fanning is the U.S. representative for the Sodium Fast Reactor Safety and Operations project management board and meets with countries around the world to share research in this technology. Fanning also represented the U.S. on the Generation IV Expert Group, which advises the policy group that manages Generation IV activities around the world. Each country has different design preferences, such as fuel type or core supports, and regulatory environments. Being involved and engaged in the international community allows the U.S. the understand and share different approaches in the industry.
Q3: As you engage with different countries, do you notice core differences in fundamentals and design philosophy?
A3: Tom Fanning engages with different countries to share approaches on nuclear fundamentals, design, and also regulation. South Korea is very aligned with the U.S. fundamentals and philosophies and is partnering with Argonne on development of the Prototype Gen Four Sodium Fast Reactor (PGSFR). Sodium has better thermal conductivity boiling margin than water. One fundamental design option is the decay heat removal system, which may be a pool type system. U.S. preference is to utilize the cold pool and other countries utilize the heat pool, which require different complexities of modeling.
Q4: Why is there such a focus on removing the heat from a sodium pool?
A4: Tom Fanning sees a focus on heat removal in sodium-cooled reactors to improve the ability to respond in the event something goes wrong. if the heat is left alone to rise, it will eventually creep out. Using sodium buys you time, but industry also want to make reactors small and compact. Fast reactors have a high power density and are more compact than other units. Having decay heat removal systems, which consist of just pipes and heat exchangers, designed to the right capacity, allows buy incident response time.
Q5: What nuclear work have you modeled in simulation?
A5: Tom Fanning’s models are characterized by codes, as used in computer programming and also as used as codes and standards. Some of these codes were developed at Argonne specially for fast reactors. One example is MC-Squared, which completes cross-section processing for fast spectrum systems, which feeds into a variational modal transport code for calculating the reactor physics calculation. Multiple levels of code create a workflow of tools allowing the team to take data into the design space and plant modeling space. Many of the codes, such as the Safety Analysis System (SAS) are decades old and have gone through many different versions.
Q6: Who is using your codes, such as the SAS system?
A6: A number of companies in the U.S. have licenses for Tom Fanning’s modeling codes as they pursue fast reactor concepts. The Japanese Atomic Energy Agency has also used the model in the past, as well as the Korean Atomic Energy Research Institute. The U.S. likes to benchmark their codes with other countries’ codes through the International Atomic Energy Agency. If nuclear energy is going to be pursued worldwide, Fanning believes fast reactors are the best option. Fast reactors have better resource utilization of uranium than water-cooled reactors, which includes recycling and reusing the fuel. By burning all of the fuel to completion, the nuclear waste is minimized and need to be contained and stored for much shorter time. Passive safety is also integral in fast reactor technology.
Q7: What is the importance of nuclear technology?
A7: Tom Fanning sees nuclear power as a disruptor in the industry and promising base load source of power (bottom 80%), even though the variability of demand (top 20% of power) is a technical hurdle for nuclear at this point. In China, their first and foremost priority is building big reactors to take care of the base load and will figure out the variability details once the infrastructure is in place. Nuclear can play a role in modernization and social and economic improvements across the globe.