Recently, I have been focusing on nuclear breeder reactors which can generate more fissile material than they burn. Today I am going to talk about thermal breeder reactors (TBR). These reactors utilize moderated neutrons which have been slowed down by some moderator.
A liquid fluoride thorium reactor design was first researched at the Oak Ridge Laboratory Molten-Salt Reactor Experiment in the 1960s. This design has advantages such as being able to drain its fuel into a catch basin under the reactor where it will cool without danger. It is also is simpler to fuel because precisely machined fuel rods are not necessary. And, there is the possibility of removing some of the fuel mix during operation to be reprocessed. There is interest in some nuclear countries in pursuing this technology.
A pressurized light water thermal breeder reactor was put into operation at the Shippingport Atomic Power Station in Beaver County Pennsylvania. The reactor was testing a design for naval vessels and commercial power generation. It was fueled by pellets that were a mixture of thorium oxide and U-233 oxide. There were three different sections in the reactor that contained thorium. The "seed" area in the core, the "blanket" area surrounding the core and the reflector area around the blanket. U-233 is used as the initial fuel to provide neutrons to the thorium. In the seed area in the core, the percent of U-233 is about five or six percent. In the blanket area, there is about one and one half percent U-233. As the U-233 decays, it emits neutrons some of which are absorbed by the thorium. Then the thorium atom emits electrons and is transmuted into U-233. When the core was taken out after five years of operation, it was found that there was about one and one half percent more fissile material that was originally put into the reactor thereby proving the design for breeding fissile materials.
India has great interest in thermal breeder reactors fuel with thorium. India has chronic power outages and desperately needs more electricity. India has been a nuclear nation for some time and has created over one hundred nuclear warheads. However, India does not have any uranium resources. It does have huge reserves of thorium. If they could deploy thermal breeder reactors that were fueled with thorium and a little U-233, they could get power from the reactors and also breed more U-233 that could be used to fuel additional reactors. Thorium thermal breeder reactors cannot be used to make weapons grade nuclear materials although that is a moot point because India already has nuclear weapons.
Core of the Molten Salt Reactor Experiment:
