Yes! Clean Nuclear Power Exists

Next generation nuclear reactors consume nuclear waste

Terrestrial Energy Molten Salt Reactor
Terrestrial Energy Molten Salt Reactor

There are two key oppositions to nuclear power:

  1. It is unsafe. You could have reactor meltdowns spreading nuclear waste wide and far.
  2. They produce nuclear waste we have no clue where to store.

What if there was a way to make both of those problems go away? And I am not talking about Nuclear Fusion which is always 50 years away. No, I am talking about technology which was already proven decades ago in 1965 at Oak Ridge National Laboratory called Molten Salt Reactors (MSR).

Highly toxic radioactive waste goes in, and out comes tons of cheap energy

Both companies are making reactors which will almost literally run on garbage. Highly toxic radioactive waste goes in, and out comes tons of cheap energy and significantly less dangerous waste, which can easily be disposed. Oh and for the pedantics out there, Energy is obviously not measured in tons but in Joule. Although for this industry kilo watt hours (kWh) are more practical.

But Are They Safe?

Convinced yet? Okay, I can almost hear you thinking about Chernobyl and Fukushima. What if that kind of accidents happen again?

This is almost good to be true, but those kinds of accidents are physically impossible to happen in a Molten Salt Reactor. The laws of physics would not allow it.

Using Water as Coolant is a Safety Hazard

Both Chernobyl and Fukushima used water as coolant. That is the very scary part of these reactors. Uranium gets insanely hot and when water is heated up and turns into steam it expands 1000x times. It is almost as if current nuclear reactors are pressure cookers where lots of engineering goes into keeping the pressure under control and prevent the whole thing from blowing up. And it is not just the pressure which makes these reactors “fun” but the fact that if you make the water hot enough it will react with the Zirconium cladding on fuel rods and produce massive quantities of hydrogen. When that hydrogen gets vented out the core to prevent the pressure from building up too much, you got another huge problems on your hands.

That was what happened in Fukushima. After reactor shut down, there is a lot of residual heath in the fuel rods. They must be continuously cooled. Except the Tsunami killed the backup generators and and the coolant stopped flowing. Thus eventually the water got hot enough to produce hydrogen and later the hydrogen caught fire and blew the roof off the building.

Solution: Use Non-Water Coolant

In short the use of water is the source of almost all problems with modern nuclear reactors. Get rid of the water and you have solved a huge chunk of the safety issues. That is what Molten Salt Reactors do. Salt requires very high temperatures to melt and insanely high temperatures to boil. For this reason MSR reactors are not under pressure. They are not pressure cookers waiting to blow.

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The salt in MSR reactors turns into rock hard solids when cooled which cannot spread radioactive contamination far. Contamination will always be limited to the power-plant site.

Should electricity, pumps and pretty much anything fail in a MSR reactor, have no fear. The usual design uses power to constantly cool part of the salt at the bottom of the reactor forming a plug (freeze plug). As soon as power fails or the reactor gets too hot, this plug melts and the molten salt flows into separate containers (emergency dump tanks), which space out the salt so that it is no longer in concentrations which can sustain fission.

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A Molten Salt Reactor Schematic showing safety systems such as the freeze plug and Emergency dump tanks.

Sure you still would want to cool these containers. But even if this cooling fails it isn’t a huge problem. No dangerous pressure develops blowing anything up. If the hot salt pierce the tanks that hold them the spillage does not get far. It it quickly turns into rock hard salt crystals.

This means nuclear fallout will never get dispersed far and wide like with Chernobyl or Fukushima. Radioactive material is locked inside fluoride salt which does not dissolve in water. So you got no radioactive clouds nor do you have radioactive water pouring into rivers or ground water.

Basically you cannot go wrong. Sure you can end up wrecking the reactor, but you cannot spread radioactive waste beyond the reactor and that is what is key.

It is a Win-Win

For these reasons it is madness to be categorically against nuclear power. Yes we should oppose huge complicated light water reactor, which require massive complex active safety systems and where failure could case radioactive fallout to get thrown wide and far. But not every type of reactor is like that. As I hope I have convinced you here. We can build reactor types which are really safe.

One has to keep in mind that wind and solar power does not have zero environmental impact.

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Material usage of different power sources excluding Uranium ore mining

The amount of concrete, steel and other materials required to construct various power plants per kWh of power generated actually favors nuclear power. Although this does depend on the type of reactor used. Current reactors used are not fueled with nuclear waste but with fuel from uranium mining. These reactors are not that favorable in comparison.

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You can see in this case the amount of materials required for wind power is about the same as required for nuclear power due to the uranium mining. The reason for this is that there is very little Uranium in Uranium ore.

However if we use modern Molten Salt Reactors, the advantage of Nuclear Power is clear. The use of steel and concrete will be even less than shown in the first diagram because you don’t need massive containment structures as there is not massive pressure to contain.

Thus MSR reactors can give us much smaller environmental footprint than wind and solar power. We require less resources to build these reactors per kWh, and they produce negative waste. The longer they run, the less waste we got. Wind and solar power in contrast lasts 20–30 years after which time we got waste we need to dump or recycle and these quantities will be a lot larger.

Should We Go All Out Nuclear Then?

This may sound so good that one would be tempted to ditch wind and solar power all together, however I think this would be wrong for a few simple reasons. Molten Salt Reactors are not yet commercialized and produced in quantities. Most likely we are looking at 2030 before that happens.

In the meantime we cannot just sit on our hands and let coal plants keep polluting. Instead we can use the years until Molten Salt Reactors become available to replace as much fossil fuel power generation with renewable energy.

Renewables can never completely replace fossil fuels as there will be times when the sun doesn’t shine and the wind doesn’t blow. This is where Molten Salt Reactors come to the rescue. They are the final piece of the puzzle which will completely remove the need for fossil fuels.

Written by

Geek dad, living in Oslo, Norway with passion for UX, Julia programming, science, teaching, reading and writing.

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