Head of Waste Management, Safety, and Radiation Research
Karlsruhe Institute of Technology
Oct 30, 2019
KIT explained (0:41)
0:41-5:56 (Walter explains what KIT is and how the Institute plans to restart a program to introduce school children to infrastructure to attract new engineering students.)
Q. Can you explain what the KIT is?
A. KIT is the Karlsruhe Institute of Technology in Germany and is the merger of the nuclear research center and the University of Karlsruhe. Walter Tromm is head of the Nuclear Safety Research program here, which covers all aspects of nuclear safety.
As an 18 year old student, Walter visited both a coal and nuclear power plant and noticed the difference in cleanliness between the two energy sources. Walter had planned to study mechanical engineering before the visit and decided to follow this path into the nuclear industry. Introducing students to infrastructure was a uniquely German thing but stopped in Germany about 10 to 15 years ago. Walter believes ending these programs is one of the reasons why Germany has a problem attracting engineers to universities. KIT hopes to start a program to introduce children to technology and physics with the aim of attracting students to the university to study technical areas.
Modeling severe accidents and core catchers (5:57)
5:57-10:46 (Walter describes his research career and the questions that still exist regarding molten core accidents.)
Q. What was your first job out of school?
A. Walter went on to pursue a Masters in severe accident research and a PhD focusing on core catchers. The research group used MELCOR code and other models to predict the interaction between the molten core when it leaves the reactor vessel and the surrounding concrete. There are still open questions regarding the effect of concrete destruction.
This research does not have to be purely theoretical and can be simulated in a controlled setting. An experiment in the US heated depleted uranium with a plasma torch to understand the molten core reaction and measured the released gas. This modeling is complicated and is still ongoing. One open question is determining the amount of time it takes for the 6 meter concrete basement to be eroded to the groundwater level. Another question is what direction the erosion moves in when the release spreads.
Blockers to adopting new methods and relaxing regulations (10:47)
10:47-20:46 (Walter explains how materials other than concrete can be used in containment. He also explains how some methods may be better than others, but adopting new measures relies on relaxing regulations.)
Q. Why can’t we use steel plates instead of concrete?
A. Decay is long term and steel can melt upon immediate contact with the molten core. A large ceramic layer could be used to release the heat to the containment. This heat, however, becomes another issue where the fission products could be released during an accident. Coming into contact with groundwater stops the core meltdown because it creates a glassy layer. The fission products are then released into the groundwater, but it takes a long time for the products to reach a river. Sand acts as a filter and groundwater level and flow direction vary throughout the year, creating somewhat stable conditions for fission products. It may therefore be better to allow the molten core to come into contact with a less stable basement layer and let it reach the groundwater to avoid pressure buildup.
Rather than stopping a meltdown, the goal is to stop the spread of source term. It can be argued that Defense in Depth may not be as necessary and core catcher decisions should be economical rather than one of public safety. Because of the filters in place, the release to the environment would be minor. However, adopting this approach is an issue of trust. Walter believes the 9/11 terrorist attacks which pushed for additional safety measures to be put in place to protect against the potential of an attack on a nuclear facility increase public concern over nuclear safety. Overall, there are always reasons to be found to generate a lack of trust in the ability for safety requirements to be relaxed. For Germany, the regulator is complicated. Each state has the power of regulation in addition to the head regulator, meaning regulations are not uniform and political power often dictates how relaxed a regulator is.
Germany’s nuclear industry and the need for education (20:47)
20:47-28:43 (Walter explains why German’s nuclear industry failed and how education can decrease radiation ignorance.)
Q. What happened to the nuclear industry in Germany?
A. Walter thinks the German nuclear industry made many mistakes. In the 1950’s and 60’s, the attitude from within the nuclear industry was one of arrogance and not one of inclusiveness or wide communication. People in Germany accepted nuclear as a clean alternative to coal and supported the building of facilities. However, Three Mile Island (TMI) and Chernobyl changed the public’s perception of nuclear and they felt as if the industry never communicated the dangers to the public. This caused the industry to become defensive, adopting more safety standards. The antinuclear movement strengthened this, making nuclear more expensive. Nuclear then become uneconomical. The industry failed to fight for nuclear power support and did not demonstrate the advantages to the public.
Additionally, Walter does not believe that we have a good enough knowledge of radiation exposure. A lack of radiation education on the industry’s side has lead to ignorance in politicians and researchers. Changing this requires the industry to educate people about how radiation exposure is natural as it occurs around the globe and in our bodies. Education must occur early and now and must be offensive rather than defensive.
Research at KIT (28:44)
28:44-33:01 (Walter discusses KIT’s research and his research interests.)
Q. What are some of the fields studied at KIT and what is some of the research that you produce?
A. KIT researches solar, batteries and nuclear. Specifically, KIT is researching nuclear waste disposal, decommissioning and reactor physics. In addition, KIT researches reactor safety and radiation. Walter studies reactor safety but is becoming more engaged with decommissioning. Walter wants to look into at reactor construction cycles and designing reactors with deconstruction in mind. Walter also sees the need for more robotic research to understand how robots could replace human activity in reactor facilities, such as using laser technology to remove aerosol contaminants from concrete.
Decommissioning and waste (33:02)
33:02-43:36 (Walter discusses decommissioning and Germany’s nuclear waste storage strategy.)
Q. Why decommission at all? Why not refurbish instead?
A. After a certain period of time, the concrete will begin to deconstruct, threatening the stability of a facility. It may also be more expensive to refurbish a facility than to decommission it and build a new one.
When dealing with waste, there is an argument to create long term storage to allow for future innovations to implement better waste management solutions. This is true in Germany, where the state is currently looking for an underground repository to store waste for at least a thousand years. This storage facility would not be permanently closed to allow for future generations to repurpose the waste with new innovations. It is forbidden in Europe to dilute nuclear waste in the ocean because waste is only diluted locally, not throughout the entire ocean. While dilution will not be a solution, Walter foresees Europe coming together for a European or regional repository. It is also important to remember that waste products can be used for other purposes, including fuel for fast reactors. This could create an incredibly long term energy source for at least 10,000 years.
The future of nuclear for Europe (43:37)
43:37-48:34 (Walter explains how the ending of Germany’s nuclear program may influence the future of nuclear in Europe.)
Q. What do you think could happen with nuclear in the future?
A. The last German reactor will be shut down in 2022, ending the nuclear discussion in Germany. The prospect of nuclear is still alive in Eastern Europe. Walter thinks other countries will look to Germany to see what will happen after ending a zero carbon electricity source. Walter foresees that if Germany’s transition away from nuclear is not a success, other European countries will learn from this and maintain their nuclear programs. Walter also believes small modular reactors may help create a balance between renewable and nuclear power.