Professor, Health Physics
Nov 18, 2019
Biology and Nuclear Engineering (0:31)
0:31-9:03 (Jason Harris reflects on how his early interest in biology led to a career in nuclear engineering)
Q: Where did you grow up?
A: Jason Harris grew up in Baltimore, Maryland. As the oldest of four from a blue collar family, Jason was the first in his family to go to college. Originally, he wanted to go to med school and started out studying biology and chemistry. Jason took a job in the environmental toxicity testing field after graduating and his wife-to-be took a job at an R&D start-up working in the clean energy sector. They needed scientists to work specifically on radioactive waste amelioration and tritium separation, so Jason was hired to work in the lab. It was this job that shifted Jason’s trajectory as he started to understand nuclear energy and nuclear waste. One of the consultants for the company was Dr. George Miley, a professor at the University of Illinois at Urbana-Champaign in the nuclear engineering department. He was the inspiration for Jason and his wife-to-be to pursue graduate school, both receiving their Master’s and PhD’s.
Tritium is radioactive hydrogen and is a product in the nuclear generation process, as a fission product and through other neutron activation reactions. There are three forms, or isotopes, of hydrogen: protium, or regular hydrogen; deuterium, which has a neutron; and tritium, which has two neutrons. Because hydrogen is such a small element, it is very hard to separate. The start-up Jason worked at developed a hollow-core fiber with a mesh inside, a semipermeable membrane. Tritiated water could be drawn through it and separated. Tritiated water and normal water also have different freezing points, so it could be separated that way, but it was very energy intensive.
Environmental Distribution of Radionuclides (9:03)
9:03-24:47 (Jason leans into health physics and how radionuclides are distributed throughout the environment)
Q: What did you focus your efforts on in grad school?
A: Jason Harris and his wife were brought into the University of Illinois for grad school by Dr. Miley. Dr. Miley’s area was fusion and low energy nuclear reactions (LENR). Jason worked for Dr. Miley at first, but realized his interests were tied to biology looking at the potential health effects from nuclear and went to do his Master’s with a different advisor in the health physics area. The linear no-threshold (LNT) model for radiation protection is still controversial because research has shown that it doesn’t hold in all situations. However, it has its place for regulatory purposes because it is a clean, easy-to-use model. If one looks at individual scenarios or situations, such as cancer development, it’s been shown that LNT is not the model in the initiation, promotion, and development of tumors. It has been very expensive for a lot of industries to follow the LNT model because the assumption is that any dose of radiation has an effect. The stance of the Nuclear Regulatory Commission (NRC) is that they don’t support any industry and don’t show any favoritism. There are some changes, like NRC’s process of going to a risk-informed approach, but it is not increasing the speed at which regulations are changed or new reactors are designed. There are still some debates and differences in the science on which models hold. There are conflicting studies that have shown some detriment at the cellular level that may or may not create an adaptive response. What’s keeping LNT around and alive is that there is still not a biomarker or mechanism for cancer development.
Jason is a health physicist, nuclear engineer, and biologist. There is risk versus benefit for everything related to radiation. In a lot of technologies in which radiation is emitted, there is some byproduct. Some radionuclides have long enough half-lives that they stick around in the environment, such as cesium-137. With a thirty year half-life, it will be down to a percent of what’s left after about seven half-lives, but is still in the environment for hundreds of years. After they are released, the way they distribute through the environment depends on their chemical form. Cesium bonds to different types of soils and clays, limiting uptake by people in most cases. Iodine is taken up readily by the thyroid gland, but it has a much shorter half-life. Radioactive waste is really a political problem. There are still fission products and transuranics that will last hundreds or thousands of years, but they are not the ones that should be worried about. Nuclear power operations dilute a waste stream that is deemed not harmful, which will have to be done at Fukushima to release the water.
Nuclear Power Plant Emissions (24:47)
24:47-39:23 (A comprehensive look at nuclear power plant emissions and the birth of the nuclear security field)
Q: Tell me about your research now and what you focus on.
A: Jason Harris did some work looking at the dose impact from nuclear power emissions, which is minimal. He partook in studies, over the course of a decade, looking at every nuclear power plant in the U.S. and what they release through gaseous, liquid, and waste effluence. Each power plant has a comprehensive monitoring program to make sure what they release is not accumulating in the environment and not creating harm to the environment or individuals. Jason also compared these results to some of the accidents like Chernobyl and Fukushima. People are focused on Fukushima and the reactor and what was released there. The earthquake and the flooding harmed and impacted the local industry and chemical plants. The releases on those sites were much worse in terms of health effects than Fukushima. There is still some fear and concerns people have with radiation, but Jason sees that changing. People are starting to accept the technology and see that it is safe.
Jason’s work has also taken him into the nuclear security area. Before he came back to Purdue as a professor, Jason was at Idaho State University and had a joint appointment with the Idaho National Lab. He was also the associate director for the Center for Advanced Energy Studies. Jason got a call out of the blue from someone at the International Atomic Energy Agency (IAEA) who was putting together an education program in nuclear security, which did not exist. After 9/11, there was a real concern about the possibility of using nuclear, radiological materials for malicious purposes like a terrorist attack. Four scenarios are considered for security against a substate actor: getting ahold of an intact nuclear weapon, getting enough nuclear material to build an improvised nuclear device, getting radiological material to make dirty bombs or radiological dispersal device, and sabotage. Jason’s group specializes in risk analysis and assessment for radiological security. They developed one of the most comprehensive models that looks at every possible parameter that determines risk at a radiological facility. This model looks at both physical parameters and human factors that could affect the facility’s security, such as weather or a power outage.
The Human Factor in Nuclear Security (39:23)
39:23-48:20 (Methods of analyzing and assessing security culture at organizations and how it impacts risk at a nuclear facility)
Q: How do you include the human factor in risk models?
A: It is very difficult to model human factor, so Jason Harris and his team focuses on assessment of the security culture at each organization. It’s hard to pinpoint on an individual, but looking at a facility as a whole, they can determine whether people are happy at work or whether workers are disgruntled. Another thing being developed is the use of algorithms in concert with sensors and AI to track individuals and detect very subtle differences in behavior, which has both safety and security applications. An algorithm could be developed to see if the reactor operator is doing things they shouldn’t be doing, by looking at their actions, behaviors, or devices they are manipulating that are not typical behavior. Nuclear is getting close to operating without operators, but there might be some scenarios in which have an experienced person to make a call is wanted.
Jason is optimistic about nuclear power in the U.S., even though plants are shutting down. The turn needs to happen soon, however, especially from an economic standpoint. A lot of people thought that regulations would kick in for natural gas and would help soften the blow in the difference in cost. Climate change is very important and people must get on that ship and steer it the right way very soon. Part of the problem with large scale nuclear is, not only cost, but the time it takes to build a new plant. There is hope for moving towards advanced nuclear like small modular reactors (SMR) and microreactors, but they need to be able to get through the regulation process quickly. Nuclear throughout the world is flourishing and people see nuclear as the energy of the future because of their own energy security needs and lack of resources.