World’s first reactor was built in 1942 in Chicago by Enrico Fermi and his team. Since then several hundred nuclear reactors were built, shut downed and rebuilt. For the future, six types of Generation 4 fission machines wait to be born. The world needs the energy to develop and maintain life but above all these reasons there is an essential one: going to Mars and supplying all energy that is needed for life. That’s my priority motivation and purpose for choosing the nuclear area to work. History tells us that “never forget to take lessons from past” and future tells us that “enlighten your ways from your mistakes”. The nuclear accidents that happened in the past led us to Gen 4 designs. As students, we are the ones who determine the nuclear reactor’s destiny. One of the Gen 4 designs is Molten Salt Reactor. We are trying to understand what can we do to design and build a molten salt reactor. We do this by interviewing nuclear experts, engineers all over the world. Come and join our story!
The Student Guild’s first interview was with Professor Akira Tokuhiro. He recently stepped down as the Dean of the Faculty of Energy Systems and Nuclear Science at Ontario Tech University in Canada. Also, he was in the American Nuclear Society’s President’s Committee on the 2011 Fukushima Daiichi nuclear power plant accident in Japan. He is an international nuclear energy expert.
President of the Student Guild
The Thorium Network
What does nuclear energy expert do?
We do many things. We design Generation 4 (IV) systems. We look at the safety issues of current reactors and reactors that will be constructed. We are always looking for continuous safety improvements. We have 4 questions to be answered about safety and accidents, “what can happen, how often can it happen, how does it happen and what are the consequences?”. We ask these questions and we do the engineering design, safety analysis for that. Now nuclear engineering requires computer programming and engineering analysis. Applications of virtual reality, augmented reality, new applications of artificial intelligence, and machine learning will be used by new nuclear engineers to design and operate reactors.
In one of your interviews, you said “Nuclear reactors are challenging, that’s why I choose the nuclear energy area to work”. What is the most complex and challenging thing in the nuclear area or reactor physics?
For me, the most interesting and challenging thing is you have to know many things. You may find the solution for a small area but nuclear power plant is many different things. If you find a solution for a small area, it may impact other things. That’s why you have to look at many different things and you have to integrate them. That’s challenging for me. That integration that I teach to my students. How do you design a reactor? You design from the reactor core and then outward from the core.
What are the most common safety design features for Gen 4 that at the same time can be used for Gen 3 or Gen 2 reactor safety designs?
We have learned from Generation 2, 3 and 3+ about human factors engineering. There are two things about human beings, one is human beings are unreliable, other is unpredictable. When you apply these to safety systems, you want to design the reactor that minimizes probability for human error. Gen 4 and small modular reactors are designed so that cooling is assured, and do not rely on human operators because they can make mistakes under pressure. You have to design the reactor so that after shutdown decay heat can be removed without human intervention.
What is the biggest problem about safety that must be redesigned immediately now? For example, for PWR Generation 2 designs, what is the biggest safety problem about that reactor, and how can it be redesigned?
My opinion is reactor is designed so that it can shut down when a postulated event occurs. Even if an earthquake happens, the reactor can shut down like the reactors are located at Fukushima. The reactor was shut down after the earthquake. To remove the decay heat that’s remaining, pumps may be required to facilitate cooling for the first 72 hours. After two weeks the decay heat has to be much less. That has to change in all plants. Cooling after shut down is possible, we can do that but we have to make sure that even if we have a terrible earthquake, sufficient cooling has to remove thermal energy from the core. In SMR’s we don’t need pumps, like large reactors; when you have a pump, you also need a source of water in order to maintain cooling to take the heat. The safety problem of Gen 2 and Gen 3 designs is to prevent the meltdown of the core.
When do you think the first Gen 4 reactor will be built and where will it be built and which design will be built?
I think by 2030 or 2035 some Gen 4 reactors will be built. It may be Gen 4 large reactors but it is also possible that small modular reactor may be built too. It depends on the country. Russia and China have their designs and they are being constructed. It is difficult to call them Gen 4 but recent VVER is an improved design. China is building different kinds of reactors and operating them. So by 2030 or 2035 Gen 4 large reactors or small modular reactors will be built by Russia or China. In the west, new reactors very much depends on investment. For example, in North America before 2035 there will be a small modular reactor constructed and ready to operate as well.
What are your thoughts about thorium molten salt reactors?
Thorium Molten Salt reactors combine interesting reactor design with a fresh look at a new type of fuel. In the least next 3-5 years, we need much more engineering to finish the design and to get the regulatory approval of the completed design. Since my background is from the US, I am familiar with US Nuclear Regulatory Commission and they will importantly ask safety questions about design basis accidents. If you don’t have a pump, as part of the design natural convection cools the reactor so it may be a preferred design. Molten salt reactors are an interesting design and thorium is a different type of fuel. Perhaps by analogy, the nuclear industry is very similar to a restaurant or the automotive sector. You have to have customers and people come to eat at a restaurant. You have to make a popular automobile and people have to trust the safety and they are buying the safety in design that comes with it. Thorium Molten Salt design has to be finished and the design has to convince the regulator that it is a sufficiently safe design and that is constructed.
You are an expert on nuclear safety. Do you think passive safety systems designed for molten salt reactors are sufficient? Are there any other passive systems projects running? Can you please give us the details?
The molten salt reactor concept came from the 1950s and 1960s. Modernized design of the MSR started with Oak Ridge Molten Salt Reactor. (MSRE) They operated a research and demonstration reactor for a few years so fifty years later we are updating this design. I think the concept is solid but needs details; safety cases are convincing. If you have the money and engineers the first step to building a reactor is making a research and demonstration reactor to show that the reactor is very safe. For example, in molten salt reactors, fuel flows in a tank by gravity when an unanticipated event occurs. That is when a PS may be needed. So this means no operator, no human error.
About thorium molten salt reactors, what can students do?
Now in the last five years, I think it is very important for students to find friends all over the world and to be interested in solving the challenges posed by climate change. We need to reach net-zero as quickly as possible: even before 2050. I think we have to make progress every five years or it will become very difficult to meet our net-zero carbon economy. We have to make as much progress by 2030. By 2050 we have to make substantial progress or net-zero carbon economy. If we don’t have any progress by 2030 reaching a net-zero carbon economy becomes increasingly difficult. Now we have the power of social media. Students have to ask many questions to old people like me about safety, design. We have to change and seek from the regulator, approval of the new reactors designs. We have a lot of experts from many countries. We already have about 440 nuclear power plants in the world but we need as many as ten times as many reactors to tackle climate change. We need more nuclear power plants because we need a quick transition to a lower CO2 economy or scale. It is not the ultimate solution for climate change but it is a solution that we have now. Young people can become involved through social media and by asking good questions. We need to convince people that by combining nuclear energy, wind, and solar we can reach a net-zero carbon economy. We need nuclear power, it may be risky, but risk and fear are a spectrum. If you think the benefit is greater than the risk then you would do it. People are usually afraid when they don’t understand the risk so they think the risk is very big and the benefit is not so big.
How did you decide to join the Thorium Network? What was the most attractive thing that impressed you about Thorium Network?
I contacted one of the founders Jeremiah Josey. I thought the thorium molten salt reactor is interesting and thorium is an alternative to uranium. It is a network. This network includes many people all around the world. That’s why I joined. The network is a new way to design a reactor.
I had a great time while talking with Professor Tokuhiro. I would like to thank him for his time and perfect answers.
Thorium Network Student Guild continues to inspire people all around the world. Come and join our team! You can find the Student Guild application on this page:
Links and References
- Professor Akira Tokuhio on LinkedIn
- Rana on Linkedin
- The interview on YouTube
- Ontario Technical University
- Generation IV Fission Technology
- Chicago Pile 1
- ANS Committee Report: Fukushima Diiachi
- Launching “Leading to Nuclear, Interviews by the Thorium Network Student Guild”
- The Thorium Student Guild
#ThoriumStudentGuild #LeadingToNuclear #Interview #AkiraTokuhiro #OTU