Thorium Molten Salts Reactor

Innovation created by: various research centers

Presentation written by: Ruben Rochwerger, ruben.rochwerger@grenoble-inp.org

Presentation supervised by: Assoc. Prof. Dr. Elena M. BARBU, elena.barbu@univ-grenoble-alpes.fr

 

1. General information

In a world where the energy demand is getting higher every day, and where most of this energy is produced using fossil fuels which is a great threat to the environment (rising the greenhouse gases emissions and therefore rising of the greenhouse effect), it is paramount to find new ways to produce high amounts of energy without rejecting greenhouse gases in the atmosphere.

One way to realise this objective is investing into renewables energies. However, the amount of energy that it can produce compared to the cost is very low, and a lot of questions are raised concerning the lifetime, the maintenance, and the recycling of the products used (solar panels, wind turbine…).

Another way to produce a lot of energy with almost no impact on the environment is to use nuclear power plants. However, two great disasters (Tchernobyl and Fukushima) have been caused by this industry, and this energy is linked to nuclear weapons which are a threat to humanity. That is why nowadays nuclear energy is very badly perceived by public opinion.

Nevertheless, what if we could develop a nuclear power plant that avoids the drawbacks of the current ones?

That is precisely what a bunch of scientists from all over the world try to do. One of the proposals is to bring up to date with current technologies a 1950’s nuclear reactor design which was abandoned for the benefit of the widespread Pressurized Water Reactors (PWR): the Molten Salts Reactor (MSR).

 

2. The innovation and the benefits

In the figure below you can see the MSR innovation.

 

The main innovation when compared to the “classical” PWR, is that the fuel is no more solid but liquid. This characteristic confers a higher safety to the reactor, as in this case the fuel is also the cooling fluid: disasters due to the lack of coolant such as the Tchernobyl or the Fukushima accidents cannot happen.

Plus, as the fuel is in liquid form, it becomes possible to work on it during the operation cycles, thus to withdraw the fission products that are highly toxic and radioactive, which in “classical” PWR stay in the tank and are one of the big threats to the environment in case of accident.

Moreover, the reactor is intrinsically more stable than a classical one thanks to the liquid form of the fuel (chain reaction leading to the melting of the core cannot occur as the fuel is already “molten”). It is also important to note that thorium MSR will make far less high-level waste (~ a small percent of the actinide waste currently made by PWR reactors).

Because they run at atmospheric pressure there are no scenarios where thorium MSR can contaminate large areas as happened at Chernobyl and Fukushima.

Another benefit of this solution is that this kind of reactor could easily burn Thorium 232 instead of Uranium (238+235) in classical ones. As Thorium 232 is very abundant on earth, this innovation would be very durable. Thorium MSR could power the world’s electricity needs for millions years. There’s enough easily available thorium for that.

They also run at higher temperatures, so make more efficient use of the heat. Current PWR technology turns about 32% of heat into electricity. Thorium reactors running over 300ºC hotter will be able to turn 42%, or more of heat, into electricity.
Those higher temperatures would enable operators to do other things with the heat apart from make electricity (e.g. Thorium MSR could be used to make synthetic fuel for aircraft and other vehicles).

MSR are physically smaller for the same power output as current PWR so are more easily turned into mass-produced factory-made reactors. It is more scalable. The world could transition to MSR electricity within 10 years.

Last but not least, using Thorium 232 as fuel in this kind of reactor would make it not favourable to the proliferation of nuclear weapons (thanks to the production of Uranium 232).

According to this list of benefits, this innovation would be strategic and responsible, as it would make a better use of the natural resources, produce a lot of cheap electricity with multiple applications and no harm to the environment, and also a lot of jobs too to develop, build and do the maintenance of the reactors.

 

3. Negative impacts

Obviously there would be some drawbacks, first of all being the cost and the time to develop a reactor that can be sold and built on the industrial scale. However, a prototype has already been operated during the 1960’s, so that it would certainly be easier to run one nowadays thanks to the technological improvements that have been made in 50 years.

The second drawback is intrinsic to the nuclear fission reaction. In all cases it produces toxic and radioactive materials that have to be carefully handled, recycled and stored.

There is no absolutely “clean” way to produce energy. Apparently, this one could be one of the most appropriate solutions.

 

Websites and bibliography

https://fissionliquide.fr/tag/oak-ridge/

https://www.youtube.com/watch?v=tyDbq5HRs0o

https://www.environmentalleader.com/2016/08/chinas-research-into-thorium-will-have-implications-for-nuclear-energy-in-the-united-states/

http://www.world-nuclear.org/information-library/current-and-future-generation/molten-salt-reactors.aspx