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Interview with Janne Wallenius

Published Sep 28, 2022

Tell us a bit about yourself and your educational background; what inspired your interest in your field?

I studied engineering physics at Chalmers and made my PhD in Quantum Chemistry at Uppsala University. I have spent time at Tartu University (MSc thesis) and Kyushu University in Fukuoka as guest PhD student. When the Three Mile Island accident happened I was 12 years old, and decided to solve the problems of nuclear power.

What is your research about?

I develop small lead-cooled reactors with nitride fuel, intended for commercial production of power and carbon-neutral energy carriers. In the longer term, these reactors can recycle their own spent fuel.

Receiving a new award must be exciting. Can you elaborate on what you received the award for, and what is your plan been in utilizing it?

I believe I received the award for having through patience and difficulties brought breakthrough research conducted at KTH towards a commercial product that can address major challenges of our time, such as global warming and energy security.

What are the long-term goals/aspirations of your work, if any?

To see 1000 of my reactors installed all over the world by 2050.

What are the biggest challenges your work/research combats?

To prove that the pump impeller material that we have developed can operate for at least one year without suffering erosion damage.

Are you planning to develop your research in new directions?

Possibly I will undertake research on uranium enrichment and small modular recycling plants.

Can you give us, and example of the size, cost, and CO2 emissions and waste of the typical generation 3 reactor plant compared to a small modular reactor plant (SMR) and a conventional fossil fuel plant?

A Gen-III reactor (as currently deployed) produces a power between 1200 – 1600 MW, costs between 50-100 billion Euros to build and emits a few grams of CO2 per kWh. The waste is used UO2 fuel assemblies where 1% of the original uranium source has been fissioned.

SMRs typically have a power between 50 and 300 MW, cost 0.2-0.5 M€ to build and emit the same amount of CO2 per kWh. Water cooled SMRs have the same waste as current reactors. Liquid metal cooled SMRs are capable of recycling their own used fuel. If so, they will produce vitrified fission product waste that must be stored for 1000 years, instead of 100 000 years.

Fossil fuel plants emit 800-1200 g CO2 per kWh.

Can you explain what nuclear scientists mean when they say, ‘Gen 4 reactors can utilise the spent nuclear fuel we currently have in storage’?

Fissionable elements can be separated from the spent fuel and recycled into new fuel elements for liquid metal or helium cooled reactors. The use of such fuel is what makes a Gen-IV reactor a Gen-IV reactor.

What do you view as your most important research accomplishment?

Example given the successful irradiation of (Pu,Zr)N fuel in the Netherlands, my revised definition of fuel breeding ratio, and the understanding of how gas release from nitride fuels is depending on the oxygen impurity.

What advice would you give to youngsters interested in becoming scientists?

Read in on literature and initiate your own collaborations with scientists in other countries.

How could we attract more young minds into the field of sciences? Are there any actions taken by your work environment about it?

Increase presence on public arenas and social media, visit schools, write popular science books and apps, communicate with journalists.

Nuclear energy is often a controversial topic on its own. Is it important for you to communicate your research to the world? If yes, what are, in your opinion, the means to approach the public?

Yes, see the above.

Text: Elina Charatsidou