TL;DR

While nuclear power is often surrounded by controversy, we are unlikely to decarbonize electricity production without it. New advancements in nuclear are promising cheaper costs, safer operation, and less waste to deal with. Challenges still lie in proving some of the technology beyond theory, improving the public perception of nuclear, and financing the nuclear ecosystem.

The Basics

• Fission vs Fusion Overview
• Radioactive material (fuel)
• Traditional reactors

Next-generation fission reactors

The next generation of nuclear reactors is aiming to be more cost-effective, reliable and safer to operate than older generations.

• Molten salt reactors (MSR): Can be built anywhere and are considered safer, but are more expensive to build. Allows operation at higher temperatures (more efficient) and lower pressure (less risk of explosion).
  • Concerns:
    • Salt can be corrosive to the structure of the reactor at high temperatures and under radiation
    • Reprocessed waste as fuel: A more expensive fuel source than fresh uranium and requires the construction of additional (expensive) facilities for reprocessing and management. It also introduces new forms of waste that we don’t really know how to deal with yet.
    • Liquid sodium: It is opaque—making safety inspections more difficult; sodium reacts violently with water; if the temperature gets too high it can create a positive feedback loop leading to rapid increases in temperature and pressure
• Small modular reactors (SMR): Produce 50-300 MW (versus the 600 MW - 1.5 gigawatts of average reactors). Constructed in a factory and installed on-site, rather than needing to build on location. Smaller in size, and lower cost to build.
• Microreactors (MMR): 1-50 MW; Meant for industrial applications and replacing expensive and unreliable diesel generators in remote communities. Microreactors are designed for easy setup and operation, can go years without needing to be refueled, and do not require active cooling systems.
  • There is one 5 MW test unit under construction in Canada (Chalk Rivers), scheduled to be finished by 2026. It is designed to operate for 20 years and then the core can either be replaced, or the plant can be shut down.

Why don’t we have fusion yet?

No one has been able to produce a fusion reactor that generates more power than it consumes.

The fusion reaction happens when two atoms are combined. In the sun, this happens when two hydrogen atoms (one proton each) combine to form helium (two protons). The problem is that protons repel each other because they have identical charges, so very high temperatures are needed to force them together.

We don’t have a reliable fuel source.

Hydrogen always has one proton, but for fusion reactions, we need the hydrogen isotopes with extra neutrons—Deuterium w/ one neutron and Tritium w/ two neutrons. The problem here is that Tritium is radioactive and very rare (it represents only trace amounts of naturally occurring hydrogen). Helium-3 is a possible substitute for Tritium. It is also incredibly rare, but we can artificially produce tritium by irradiating Lithium.

Arguments against nuclear power

A small snapshot of some of the arguments against nuclear power and counterpoints to those arguments.

1. It’s dangerous, just look at Chernobyl (1986), Three Mile Island (1979), and Fukushima (2011).

   Besides these disasters, mining uranium releases carcinogenic radon gas and is heavily polluting soils, air, and groundwater.

   Counterargument: Air pollution from fossil fuels has claimed millions of lives, making nuclear a much safer alternative. The problem is that when nuclear fails, it fails spectacularly and so people tend to remember that very clearly. However, every major nuclear disaster has been related to cooling failures in water-based thermal reactors, and many of the next-generation reactors are moving away from these systems.

   

   Source: Our World in Data, 2020