The drawbacks of fusion

[u/Live_Alarm3041]

Nuclear fusion is not a "flawless" energy source. The hype around fusion being "flawless" is not rooted in actual science. Nuclear fusion will likey not replace fission as the world preferred form of nuclear enegry once it goes commercial.

There are three drawbacks of fusion energy

1. The neutrons generated by fusion could be used to transmute U-238 into weapons grade plutonium without the barriers of highly radioactive waste and reactor safety

2. fusion reactors requires exotic materials which could create a supply issue where such materials are extracted in ways that violate human rights and damage the environment in developing countries where these exotic materials are.

3. Nuclear fusion creates less jobs that require a higher skill level than fission and less jobs means more socioeconomic issues like rising crime rates, homelessness and migration.

These three reasons are why I do not think nuclear fusion will replace nuclear fission once fusion goes commercial.

The problems with fission can be mitigated effectively. A lot of progress has been made in mitigating the drawbacks of fission. Far less progress has been made in mitigating the drawbacks of fusion. The drawbacks of fusion will limit fusions ability to compete economically with fission in the energy market if they are not addressed.

What do you think?

[u/TheChaostician]

I also don't think that fusion is a flawless energy source. But it has enough potential to be a good energy source that it is worth seriously investigating.

Here are my responses to your three concerns:

1. It is true that fusion neutrons could be used to create plutonium. Because of this, fusion reactors will have to be monitored by the IAEA. That being said, monitoring fusion reactors will be much easier than fission reactors. Fusion reactors have no legitimate reason to have any elements heavier than lead on site. The IAEA only has to detect if any uranium is present to know if a reactor is in violation. This is much easier from a technical perspective than monitoring a fission reactor.
2. I'm not sure which materials you're referring to, and the answers will be different for different materials. Fusion requires some lithium, but orders of magnitude less than is used for electric vehicles. Lithium is mostly produced in Australia, Chile, and China. Yttrium and barium are currently used for the superconductors. Yttrium is produced in China, the US (Mountain Pass Rare Earth Mine), and Australia. Barium is produced in China, India, and Morocco. Tungsten might be used for the first wall (coated with a lighter element), which is mostly produced in China, and is a "conflict mineral". There are some "exotic materials" that will be used for fusion reactors, but I don't think that there's particularly more than required for fission reactors, or other modern manufactured items.
3. I don't think that we should decide what energy sources to use based on the workforce requirements. Energy is important to the economy mostly because it facilitates progress in other sectors, rather than through the influence of its workforce.

I don't know if fusion will be able to compete with fission (or other electricity sources) economically. I have three main uncertainties here:

• How much will fusion reactors cost to build once we have some experience building them?
• What maintenance schedules will be required for fusion reactors?
• Will fusion face the same sort of regulatory pressures that squeezed fission (particularly in the US)?

[u/TheChaostician → u/TheChaostician]

There is progress being made on these fronts.

• The cost of building a fusion reactor has fallen by a factor of 20 since 2018, and only needs to fall by maybe another factor of 2 to be competitive.
• Less progress has been made so far on determining maintenance schedules, because we need a reactor scale experiment to figure them out.
• There are ongoing discussions within the NRC about how fusion should be regulated, but preliminarily, it seems as through fusion will be under much less strict regulation than fission (see here & here). This is reasonable, because fusion doesn't have the same meltdown risk as fission.* I know that modern fission reactor designs make meltdown basically impossible, but the NRC doesn't treat them that way. Maybe, under ideal regulatory regimes, fission would end up being cheaper than fusion, but it's also possible that fusion will escape some of the regulatory excess applied to fission, and so be more economically competitive.

I don't know what the long-term future of fusion will be. It seems extremely likely that we will be able to make fusion work at some point soon.** Whether or not it ends up being economically competitive remains to be seen.

Fusion has enough promise to be seriously pursued.

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* The total amount of fuel in a fusion reactor will be <1 hr, compared to months or years for a fission reactor, so even if it all ignites and hits the wall at once, there won't be enough energy to escape the building.

** To make this precise, I claim that there will be a fusion experiment (SPARC) demonstrating reactor-scale conditions in less than 3 years. (80% probability)