This blog was written to inform people interested in the world’s energy future about the prospect of the element Thorium, and how it can be used in nuclear reactors to create electricity. There are many fears about the nuclear industry as a whole because of the threat of proliferation, accidents, and so on. However, nuclear power is widely misunderstood as it is a very safe form of electricity production, with no loss of life for ‘disasters’ such as Three Mile Island. Fukushima was a very real disaster, but the general consensus is that Japan would have been better off not building the reactor on a fault zone on a coast that historically has seen tsunamis for hundreds of years.
Current reactors used Uranium-235 or Plutonium as the fuel. This fuel reacts and heats some type of liquid, either water or molten-salt or others, that drives turbines to generate electricity. Two main types of these nuclear reactor power plants currently exist. One is the Pressurized Water Reactor (PWR), and the other is the Boiling Water Reactor (BWR). The PWR is the most common type found in the world today.
A few weeks ago, I watched a TED conference in which an engineer, Kirk Sorensen, was involved with NASA was working on trying to design a feasible power plant on the moon for a moon base. His video is shown on the link below. This video is about 10 minutes long, and I encourage you to take the time to watch it:
This video outlines how with liquid fuel reactors, we could get electrical power without the need for extremely high pressure vessels as we need with water cooled reactors like PWR and BWR. In addition, thorium is a fuel that is extremely abundant on earth (about 4 times as abundant as uranium).
I did some more research on thorium and its advantages and disadvantages. This included an hour long lecture by Dr. Joe Bonometti who has worked with the government for many years concerning energy and other such matters:
This video is very interesting if the reader has an hour to kill. In it, Dr. Bonometti describes huge advantages with this fuel.
Thorium is abundant, reusable, energy dense, and can be used in smaller (cheaper) reactors. In the reactor, one does need a starter fuel such as Uranium-233, which is fissile. But the thorium reactor would react first starting with this Uranium-233. It would emit an electron that would hit the Thorium-232 (acting as a neutron shield and absorber) inside the reactor and turn this Thorium-232 into thorium-233. Thorium-233 then decomposes first to Protactinium-233 and then decays into Uranium-233 again. So basically it is an energy cycle that breeds its own fuel with minimal waste.
Another fantastic advantage has to do with the safety of the reactor. The reactor uses a liquid fuel molten-fluoride salt mix that contains the uranium and thorium. This fuel is also able to freeze at reasonable temperatures. In the bottom of the reactor unit, there would be a freeze plug (basically just the frozen fuel mix). This freeze plug would be maintained by flowing air or water over the pipes in order to keep it frozen. If the reactor ever got too hot or if there was a loss of power, the plug would melt, dumping all of the contaminated radioactive material into a containment vessel in the ground that would be controlled, monitored, and safe from contamination. Also, if the reactor was engineered correctly, the fluid from this containment vessel could be pumped back into the reactor once the problem was fixed and an ‘all clear’ signal was given.
There are a few disadvantages to this, however. One of the biggest one is that this type of technology typically needs governmental support. The government today has already invested billions of dollars into the conventional nuclear reactor technologies for the navy vessels, weapons, and so forth. In order for thorium to gain more research and development, either the government would have to step up funding or private industry would have to take over (which could be extremely daunting for small time entrepreneurs). Also, the current nuclear industry already has infrastructure, history, and political clout that naturally oppose switching gears from Uranium and Plutonium to Thorium.