This radioactive metal is three to four times more common than uranium, and, unlike uranium, it doesn’t generate weapons-grade nuclear material after it’s burned in a reactor. (The United Stated experimented with thorium reactors as early as the 1950s, before the element lost out to uranium.) Virginia-based Lightbridge aims to capitalize on thorium’s potential by marketing a thorium nuclear-fuel assembly that could be used in today’s light water fission reactors. Further down the road, thorium could also be dissolved in a mixture of liquid salts and used to power so-called molten salt fission reactors. These reactors aren’t yet ready for widespread rollout, but their creators say they will be able to reburn radioactive waste products generated from thorium, yielding cheaper power as well as smaller waste piles.
Traveling Wave Reactors
Enriched uranium — a compound high in the radioactive uranium-235 isotope — has long been the fuel of choice for civilian nuclear reactors. But traveling wave reactors (TWR) currently being designed could convert less rarified radioactive materials into fuel. “The traveling wave reactor stands apart because it will use waste uranium as its basic fuel, amplifying the basic fuel supply by 10,” says John Gilleland, the CEO of Bellevue, Wash. – based TerraPower, which is perfecting a TWR prototype. The completed reactors should also be able to extract large amounts of power from other “nonoptimal” fuels, including unrefined natural uranium and thorium. Bill Gates, Vinod Khosla and other investor heavyweights love the concept; a VC funding round last year netted TerraPower $35 million.
Most traditional nuclear power plants are expensive behemoths, producing a consistent supply of power that doesn’t change based on population fluctuations in the surrounding area. Oregon-based NuScale Power’s proposed 45-megawatt mini reactors, on the other hand, are the Lego bricks of the nuclear power world: These self-contained reactor/containment structure combos can be stacked together or separated as regional need dictates. “You install a module as the power demand increases — it’s a plug-and-play sort of model,” says Jose Reyes, chief technology officer at NuScale. Since the entire reactor assembly sits in a concrete bunker underground, mini reactors could prove ideal for use in areas that have a history of seismic activity — a need that Japan’s earthquake-and tsunami-induced nuclear disaster has proved all too well.
Could bite-size nuclear plants become go-to power sources for off-grid homes and businesses? They will if Denver-based Hyperion Power Generation can make good on its vision. About the size of an outdoor hot tub, Hyperion’s 25-megawatt fission batteries potentially could be installed just about anywhere, and they need to return to Hyperion for refueling with enriched uranium only about once every eight to ten years. They’re optimized for safety too: Because liquid metal cools the reactors instead of pressurized water (which is what large fission reactors use), radioactive material would not likely spew into the air in case of an accident, says Deborah Blackwell, Hyperion’s vice president of public policy. “The fuel would just sit in the bottom of the reactor and become a big paperweight, containing the radioactivity.