Accelerator driven subcritical reactor

In my last post, I wrote about some drawbacks or flaws in the current design of nuclear fission reactors. In this blog post, I will be writing about an accelerator driven subcritical reactor. I feel that this type of reactor is superior in multiple ways. I will compare this to the current fission reactor design in three main ways. The first of which is safety.

The accelerator driven subcritical reactor would be much safer than current nuclear fission reactors. In normal fission reactors, the reaction is self-sustaining, meaning that if the reactor lost power, it would continue to generate heat, making it possible to cause a nuclear meltdown. The accelerator driven subcritical reactor, however would, in the event of a loss of power, become inert by no longer producing heat. Fission reactors produce heat by splitting atoms. The conventional fission reactor uses a fuel that can sustain a chain reaction. One atom will split and give off more than one neutron. These neutrons will cause other atoms to split, giving off more neutrons, and the cycle continues. In an accelerator driven subcritical reactor, the fuel is not able to sustain a chain reaction. Instead, it is split by high energy neutrons from a particle accelerator. If the particle accelerator has no power, it will stop splitting atoms, and therefore stop producing heat.

An accelerator driven subcritical reactor would not produce the long half-life nuclear waste that is produced in a conventional fission reactor. As an addition to not producing these dangerous and long-lived isotopes, it would also be able to use these as fuel, solving most of the problems with nuclear waste. The only nuclear waste that would be produced by the accelerator driven subcritical reactor would be short half-life isotopes that would be highly radioactive, but for a shorter period of time. The high radioactivity could be used in a second reactor to generate power. This would remove the need for expensive long term storage, empty existing long term storage, and generate more power.

Lastly, in conventional fission reactors, the fuel is rare and expensive to process. This is not the case for accelerator driven subcritical reactors. Other than being able to use nuclear waste as fuel, which would actually gain money, as it costs money to store it otherwise, it can also use thorium. Thorium is estimated to be three to four times as abundant in the earth’s crust as uranium. This, along with the fact that less than .4-.6% of uranium can be used in reactors, makes thorium hundreds of times as abundant as uranium. Also, thorium only occurs as one natural isotope, so it does not need the expensive enrichment process required by uranium. It is also thought that thorium will give more energy per weight than enriched uranium. This, if implemented, would make power substantially cheaper, safer, and environmentally friendly.