Jun 13, 2018

Ep 25: Brady Hanson - Used Fuel Expert, Pacific Northwest National Laboratory

Used Fuel Expert
Pacific Northwest National Laboratory
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Show notes

"Q1: How did you become interested in nuclear energy?

A1: Brady Hanson was naturally attracted to the news in kindergarten during the Apollo moon landings and saw coverage about new nuclear power plants being built north of Milwaukee. When Hanson got older, he started reading up on the topic, especially related to acid rain, which was the main environmental concern in the 70’s. In 8th grade, Hanson heard about Three Mile Island on the news, around the same time that the “China Syndrome” film was released which fed into misinterpretations surrounding nuclear energy. Hanson knew he wanted to work with nuclear, specifically on the back end of the fuel cycle, and became a chemical engineer in pursuit of this study. Plants had been built around the concept of reprocessing, but Presidents Ford and Carter banned the process due to fears about proliferation.

Q2: Were you still interested in reprocessing at the graduate level?

A2: Brady Hanson attended graduate school at the University of California at Berkeley in the nuclear engineering program. Utilities were shutting down nuclear plants due to larger than anticipated storage costs, since the plants were originally planned around using reprocessing. Pools and dry storage are temporary storage before it goes to long-term storage. Gov was supposed to take ownership of spent fuel in 1998 with Yucca Mountain, but cells are still in pools and dry storage for the time being. Hanson completed a project in graduate school looking at the effects of water contacting fuel in storage and also had a fellowship with the DOE Office of Civilian Radioactive Waste Management in charge of Yucca Mountain. Upon graduation, Hanson accepted a job offer from PNNL working on determining mechanisms and kinetics of oxidation in spent fuel.

Q3: By adding different elements, you can change the fundamental properties. These changes can be intentional or unintentional. How do we know the changes inside fuel itself?

A3: Brady Hanson utilizes radiochemistry to dissolve fuel in order to determine what makes it up. Hanson determined that higher fissions in fuel rods are more resistant to oxidation. DOE started the Nuclear Energy Research Initiative (NERI) which accepted proposals for projects. Hanson started designing reactor fuel that would be more resistant to oxidation, and was chosen to receive three years of funding. Hanson and his team made their own fuel pellets and observed how the properties changed. For Yucca Mountain, he looked at dissolution, in which a waste package buried in the mountain fails and water contacts it. They worked to determine how long will it take for fuel to dissolve in this condition. Hanson discovered that fissions have a remarkable stabilizing effect, on the fuel cells.

Q4: Where do you see Yucca Mountain going, considering it was mostly political issues, not technical issues, that kept it from opening in the first place?

A4: Brady Hanson would like to see Yucca Mountain move forward through the whole process, since so much work has already been put into it. The project got a license from the NRC, and stakeholders, such as the State of Nevada, put in contentions. If and when Yucca Mountain comes back, the NRC has to set up a court to resolve the contentions. Hanson is a firm believer that Yucca Mountain is a good site and, despite its oxidizing environment, the amount of moisture is miniscule. The public understanding of the site needs to be addressed so they can understand the technology. Hanson collaborated with Sandia National Labs, Spain, and South Korea to conduct an experiment to understand the stresses and strains that the spent fuel rods undergo during multiple forms of transportation. They determined they cells are very robust and able to withstand all forms of transportation safely.

Q5: Explain more about the reaction between water and the zirconium alloy cladding. The oxygen from water reacts with the outermost layer of the zirconium alloy, and the hydrogen atom is left.

A5: Some of Brady Hanson’s work has focused on the reaction between water and the zirconium alloy cladding of the fuel cells. Zirconium likes hydrogen, so some is taken up by the cladding and if the solubility is exceeded, some zirconium hydrides are precipitated out. If spent fuel assemblies are placed into a dry storage canister, a vacuum removes all of the water and the temperature goes up. Pressure in the rods cause the zirconium hydrides to reorient in the radial direction, which look like cracks under the microscope. Hanson is finding that the pressures are not high enough to cause the hydrides to reorient, designers of cells have been overly conservative, and therefore, there is a high confidence that the fuel will stay together and is able to be transported safely.

Q6: What other topics do you focus on at PNNL?

A6: Brady Hanson also works on novel fuel designs at PNNL, taking lessons learned from the back end of the fuel cycle and applying it to the front end. He also works with tank waste at the Hanford site to see how it behaves. Hanson notices that utilities pay millions of dollars a year to maintain, inspect, and provide security for spent fuel cells on decommissioned sites. These non-operating sites are still being used for temporary storage for spent fuel and can’t be turned back over to the public.

Q7: How do we teach the public about the safety of nuclear energy?

A7: Brady Hanson is passionate about sharing the safety of nuclear energy with others. Hanson is a strong proponent of nuclear energy because it is clean and the waste is small, but he also supports other energy sources that pursue cleaner air and cleaner water. Politics play an influential role in public perception of nuclear energy.

Q8: What can we look forward to in the nuclear power industry?

A8: While Brady Hanson looks forward to technology such as advanced reactors and new fuel cycles, he is most excited about the DOE’s Accident Tolerant Fuel Program. He hopes to do things to prove that future generations won’t ever have an event like Fukushima, even if we power is lost, which was the catalyst for that event. Hanson hopes to move forward with centralized interim storage and a repository. He recognizes that electricity efficiency is getting better, but in order to reduce poverty, energy is needed and industry leaders, such as Bill Gates, are looking towards nuclear power to provide this support.

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