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Expert blog – October 2, 2023

Nuclear energy is often the subject of heated discussions. Some see it as an indispensable component in the energy transition, while others see too many objections. Jonathan Moed, nuclear energy expert at StartGreen, describes in this blog why he sees a future in the new generation of nuclear reactors.

Necessary base

A lot of solar and wind energy is now being generated. This will only increase in the coming years. That's great, but unfortunately energy generation from sun and wind fluctuates greatly. We still generate the basic energy we need from coal and gas-fired power stations in order to always have sufficient electricity. We want to get rid of that because of the relatively high greenhouse gas emissions.

Securing the base

You could store the energy from wind and sun in batteries. You will need an enormous amount of batteries for that. The question remains whether there are sufficient (affordable) raw materials for this. As you can read in Michael's blog storing sustainably generated electricity in hydrogen is an alternative solution. Nuclear energy is another alternative that can provide a stable supply.

In my view you have to do both: it's not one or the other. So you have to invest in storage as well as build nuclear power plants for a stable base. However, the current generation of nuclear power plants cannot quickly scale up and down energy production (to ramp it's called), as is possible with gas and coal-fired power plants. And that is not the only drawback of the current generation of reactors.

Third generation reactors

The current, third generation reactors ('gen three') that are now in use are so-called light water reactors, also known as LWRs. This technology uses solid fuel (uranium and plutonium). The heat released by nuclear fission is converted into steam. The steam drives turbines and thus generates electricity.

Disadvantages and risks gen three

However, LWRs have a number of drawbacks. They produce radioactive waste when uranium is burned, which requires long-term storage and management due to its long radioactivity. In addition, fuel efficiency is limited: LWRs can only extract a small portion of the energy from uranium before the fuel rods need to be replaced. The result is a significant amount of nuclear fuel waste. In addition, LWRs require large amounts of cooling water to function; water extracted from the natural environment.

In addition, the risks of LWRs are considerable. Although the uranium is low-enriched, it can still be used for nuclear weapons production. And then there's the risk of a nuclearmeltdown. When the cooling stops working, the fuel rods overheat and melt through everything into the ground.

Chernobyl and Fukushima

In any discussion about nuclear energy, the names Chernobyl and Fukushima quickly come up. The story of Chernobyl is now known to almost everyone, including through the wildly popular HBO miniseries Chernobyl from 2019. In Fukushima, on March 11, 2011, the three operational reactors at the plant were automatically shut down within seconds of the start of the earthquake. The subsequent tsunami damaged the emergency generator, preventing the reactor from being cooled. That led to a meltdown. No one died or became ill (so far) as a result of the meltdown itself. The seaquake claimed 18,000 victims.

Advantages of fourth generation reactors

As we speak, we are working hard on fourth-generation generators, which are based on much safer technology. I mainly see a future in the molten salt reactor (molten salt reactor, abbreviated as MSR). In this technology, the fuel (thorium) floats in molten salt. Thorium is much less radioactive than uranium, you cannot make weapons from it and there is much more of it available.

In addition, the risk of meltdown with molten salt is minimal. As mentioned, the thorium floats in molten salt. As soon as that salt gets too hot, the so-called freeze plug,  runs all the salt at once dump tank and stops the nuclear reaction. An MSR reactor also produces much less long-lasting nuclear waste: the waste from a gen-3 reactor is harmfully radioactive for 10,000 years, that from an MSR 'only' 300 years. That's still a long time, but not so long that no one in the future will know where it is stored.

Who has the best design?

Because molten salt reactors are smaller than light water reactors, they can scale up and down quickly. If we invest in fourth-generation reactors now, they will soon be able to do the aforementioned rampable baseload . Several start-ups are working on this. Please note that no party has yet built an MSR power station. All developing parties are all still working on paper. All calculations are based on simulations. The question then is: who has the design for something that actually works?

Solid and feasible

We have done extensive due diligence and the design of the Amsterdam-based Thorizon appears to be the most promising. Their design is sound and feasible and therefore has a good chance of being realized. The thorium-molten salt reactor developed by Thorizon also uses - in addition to thorium - long-lived nuclear waste as fuel.

More investors

When I saw Thorizon's design, I was immediately very enthusiastic. I talked a lot with the founders of Thorizon. In the end, PDENH decided to invest 3 million euros and we looked for other investors. The rest of the necessary EUR 12.5 million has been invested by Positron Ventures, Invest-NL, Impuls Zeeland, Huisman Equipment and several informal investors. Fortunately, more and more venture capital parties are investing in deeptech. So I have no doubts that we will be bringing new investors on board over the next four years.

You might want to read: PDENH invests in reactor that converts nuclear waste into CO2-free energy

Female CEO

As with every investment we make, we are deeply involved in Thorizon's growth. We helped them complete the team. At the beginning of May we found a new CEO: Kiki Lauwers. She has worked for commercial companies such as and McKinsey and has a background in aerospace engineering. The fact that Thorizon's new CEO is a woman fits well with StartGreen's impact objective to promote diversity.

No better alternative yet

If it is a success, theoretically 17 large MSR reactors with a capacity of 1000 MW could supply the whole of the Netherlands with electricity. Shouldn't we have started it earlier? Yes for sure. Experiments with molten salt were carried out as early as the 1960s. Now is the second best time to start. Maybe in 15 years there will be an even better alternative. But if you don't invest in this now, there is also a chance that you will not have a better alternative later. That is why we invest in Thorizon.

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