Q: How did you become interested in nuclear?
A: Ville Tulkki started being interested in climate change while in high school and even considered himself anti-nuclear during his time at university. Tulkki studied engineering physics with the intent of pursuing the renewable energy industry. After learning the scientific facts, Tulkki determined that some of the information he had been taught and heard from leaders was false. He started a summer job in fusion research at a lab on campus and switched to Generation IV nuclear for his master’s program, which includes gas-cooled and molten salt reactors. This generation is supposed to be safer, more versatile, and more economical.
Q: What work were you doing around Generation IV nuclear reactors?
A: Ville Tulkki first worked on a supercritical water nuclear reactor, in which water is pressurized to a point at which it doesn’t boil, but instead transitions from a liquid state to fluid state and is used in turbines to improve efficiency. He then started working on nuclear fuel safety for currently operating nuclear reactors. Tulkki joined VTT and started working on fuel behavior analysis, which looks at the state of the fuel in terms of characteristics such as thermoconductors, mechanical effects of changing temperatures, and stresses and strains on pellets and cladding.
Q: What happens to fuel rods over time?
A: Ville Tulkki analyzes how the state of fuel rods change over time and how accidents could affect the fuel. These tests are modeled based on data from materials testing reactors. Tulkki is the Finnish technical delegate to Halden project, which is a fifty year old boiling water reactor in Norway. He is also a working group member on Jules Horowitz reactor in France which is a new materials testing reactor. This reactor is available for use by researchers worldwide and has very high capabilities. Tulkki is modeling the response to the pressure differential between the fuel rod and the cladding.
Q: How did you get involved in small modular reactors (SMR’s)?
A: Ville Tulkki was asked to coordinate an EU proposal on licensing small modular reactors (SMR’s) and learned a lot about the technology during his research. Tulkki proposed some initial internal projects for SMR’s focused on gaining expertise that got privately funded, which leads to involvement in public projects and then, eventually, commercial projects. SMR’s currently being proposed are expensive, but have the possibility of more reliable production and construction. Some designs have been intentionally agile in the amount of electricity they can deliver to the grid, in order to adapt to many different purposes. Large nuclear plants can do some load following, but smaller reactors have even more capability for load following and at a quicker pace. Nuclear-powered icebreakers, such as used on some Russian ships, can ramp up extremely quickly.
Q: What are some other things you look into with regards to SMR’s?
A: Ville Tulkki is researching small modular reactors (SMR’s) for heat use. Only a fraction of heat produced at large nuclear reactors can be used since it is created at such a large quantity. Smaller reactors create heat at a level that can actually be used by consumers, such as chemical production that use catalytic processes and drying pulp at paper mills. District heating is also a possible use of SMR’s. Tulkki’s high level studies analyzes why people should be interested in SMR’s, focusing on the self-sufficiency, low carbon footprint, and cost of electricity. After publishing a paper on the possibility of district heating through the use of SMR’s, Tulkki became highly sought after in Finland for his knowledge of the technology. In his role, Tulkki tries to bring the most factual information forward for the public to make their own decision and form their own opinions.
Q: What’s next for you and what do you see coming down the line in the nuclear field?
A: Ville Tulkki is currently working on submitting proposals and funding applications for new projects around small modular reactors. Tulkki’s technical research has involved the future of district heating, which is currently serviced by traditional industries such as coal, biomass, and gas. Projects in the U.S., like NuScale, and the Chinese gas-cooled nuclear reactor are examples of new technologies that could be used for district heating.