Batteries are being replaced by nuclear reactors

By Christian J. Meier

Maybe Walt Disney took inspiration from a tennis ball for his film "Our Friend the Atom". One tennis ball is enough to supply 20,000 households with electricity for a year. All you have to do is fill it with uranium.

That was exactly what Walt Disney was about in 1957: a film was intended to convince mankind of the blessings of nuclear energy. It worked well at first, then not at all. But since climate change has intensified, some scientists have changed their view of nuclear energy again. Young researchers in particular rely on them because they hope that it will stop global warming. At least in areas where there is little wind and solar energy is insufficient to replace oil, gas or coal.

The renaissance of nuclear power should not bring the old reactors, but new reactors, they belong to the so-called fourth generation. Allegedly, the power plants are exactly what conventional ones are no longer or never were: clean, economically efficient - and safe.

In Canada, for example, Terrestrial Energy has cleared the first hurdles. In the next few years she wants to put a new type of molten salt reactor into operation. Instead of solid fuel rods, the power plant uses a liquid nuclear fuel - uranium in salt form. This flows in a circle, similar to water in a heater. At one point the uranium is split in a chain reaction. The molten salt then removes the heat, which can now be used to generate electricity.

Why laboriously change fuel rods when you can also refuel with uranium?

The liquid fuel should make the entire energy production cheaper, simpler and more flexible. Instead of laboriously replacing the spent fuel rods as was previously the case, the fuel can be refueled while the system is in operation.

The molten salt reactor has another advantage: it can theoretically also be operated with nuclear waste or the naturally abundant thorium. The fissile metal thorium is an alternative nuclear fuel that is ten times as abundant as uranium in the earth's crust. The new nuclear age could last correspondingly long.

The Canadian authorities have already approved Terrestrial Energy's concept for the time being. Allegedly there are supposed to be some investors who are interested in the model. The company is not an isolated incident. The British company Moltex is pursuing a similar plan in Canada and has received approval for a demonstration reactor. Scientists are also working on prototypes for new types of nuclear power plants elsewhere. They are supported by private donors who are apparently ready again to invest in the unpopular nuclear energy. The American think tank Third Way estimates that nuclear start-ups have raised $ 1.3 billion in venture capital in North America alone.

The majority of the power plants in operation worldwide are still classified as second generation. They are so-called pressurized water reactors. After the Chernobyl accident, this series of power plants was given a security update - since then they have been running under the heading of "third generation". But the core technicians of the future will no longer be satisfied with a simple further development. They know that this is not the way to breathe new life into nuclear power.

The new power plants should work much more efficiently. Essentially, it is about making better use of the limited uranium resource. Molten salt reactors could, for example, be operated as so-called fast breeders. As such, they would then convert the uranium, which a pressurized water reactor leaves largely unused, into fissile plutonium. The new fuel can then be withdrawn at any time and used again - or it remains in the cycle and is burned.

If you speak to the proponents of the molten salt reactor, its "inherent safety" is particularly praised. What is meant is a kind of protection by natural laws against construction defects and all human error. At least a core meltdown like the one that took place in Fukushima in several reactors should be ruled out for the future.

To understand this, an analogy from everyday life helps: a water glass that narrows towards the top will not tip over when you hit it, because its center of gravity is low. The new power plants work on a similar principle: an overheated reactor or an uncontrolled chain reaction would subside by itself.