Nuclear Redux
Nuclear Redux
March 2, 2012 by Taylor Studios
Nuclear power has always been nightmare material to me. Maybe it was being a child during the Three Mile Island era, or equating Cold War nuclear weapons with nuclear power, but my kneejerk reaction has been to just say no. Fortunately, I’m not in charge of nuclear research.
The majority of current nuclear reactors are Light Water Reactors, or LWRs. Companies already building nuclear reactors have focused on making them more economical, longer lasting, easier to maintain, and (hopefully) safer. But these are only evolutionary steps, improving aspects of the designs without actually dealing with the scarcity of the uranium used, the extreme radioactivity of the waste products, or the sheer size of the installations necessary. Since the vast majority of nuclear power is used to generate electricity, this issue ties in directly with coal-fired power plants and carbon dioxide in our atmosphere. Nuclear has been pushed as a carbon-neutral alternative to coal power. The uranium mining is less harmful to the landscape than coal mining. Coal-fired power plants emit ash, mercury, other trace metals, and massive amounts of carbon dioxide. However, spent nuclear fuel is dangerous to be near for millennia, and no one wants it anywhere near them.
It’s the classic complaint, “If we can put a man on the moon, why can’t we do better than this?” We can, and people have been working on this since the beginning of nuclear power. is the new wave of reactor designs, but this is quite the alphabet soup to deal with. I’d like to focus on one called the or LFTR.
This type of reactor is based upon research done in the 1960s. It uses Thorium-232 (which is about as common as lead in the Earth’s crust) to create Uranium-233 very efficiently. The thorium is contained in a molten salt mixture that circulates through a reactor chamber. This chamber is the only location the reaction can take place. Once the reaction heats up the molten salt to a set point, it is circulated out of the reactor and through a heat exchanger. This heat exchanger transfers the molten salt’s heat to a carrier liquid that either directly or indirectly runs a turbine to generate electricity.
One of the advantages of a LFTR is its ability to be designed as a passively . This means, if some aspect of the system fails, the nuclear reaction will stop without operator input. Current reactors run the risk of their reactor cores becoming more active in an emergency, or they depend on secondary cooling systems that can also fail in emergencies. This is part of what caused the Fukushima disaster in Japan. The systems that should have cooled the fuel also failed.
A LFTR would create much less radioactive waste per gigawatt than current reactors. Thorium itself packs more punch than Uranium-238, which is the most common nuclear fuel today. More than 99% of the thorium used in a LFTR would convert to useable material in the reactor. One more advantage is that a LFTR could use hazardous waste from older reactors as fuel, converting it to less radioactive materials with shorter half-lives.
While the concepts are exciting, the actual engineering will be a lot of work, and no one expects to see a LFTR running on a commercial scale for a couple decades. This is one field I look forward to following.