Last fall I blogged about Transatomic Power, a startup founded by a couple of MIT grad students that aims to build innovative molten salt nuclear reactors that can consume spent fuel from existing conventional reactors.  Transatomic got a big boost when it took the top prize at this year’s ARPA-E Innovation Summit.

ARPA-E is the advanced R&D arm of the U.S. Department of Energy, the counterpart to DARPA at the Pentagon.  Transatomic, whose technology is based on work done at Oak Ridge National Laboratory in the 1960s, under Alvin Weinberg (a period covered in detail in my book, SuperFuel), won out from around 200 clean energy startups.  Among the finalists were BDL Water, which aims to treat water used for fracking; Hevo, which is developing a wireless charging system for electric vehicles; and Altenera, which uses “oscillating reeds” to harvest wind energy.

Called a “Waste Annihilating Molten Salt Reactor,”  Transatomic’s system sustains nuclear fission in a liquid, molten-salt fuel, rather than in solid fuel rods.  Liquid-fuel reactors have several advantages over conventional solid-fuel rods, including safety – they operate at atmospheric pressure, obviating the need for huge pressurized containment vessels, and if the reactor begins to overheat, a “freeze plug” at the bottom of the core melts, draining the liquid fuel into a radiation-proof underground tank.

Thorium Shift

Molten-salt reactors are also the preferred technology for shifting to thorium, an alternative nuclear fuel that is cleaner, safer, and more abundant than uranium.  Leslie Dewan and Mark Massie, the founders of Transatomic, say that their design is “fuel-agnostic” in the sense that it can run on either uranium or thorium.  Using spent fuel from conventional light-water reactors, to help solve the nuclear waste-disposal problem, is a good way to get the initial reactors built.  CEO Russ Wilcox told Mark Halper, of Smart Planet, that the uranium reactor would serve as “a stepping stone” to a thorium-fueled version.

It will probably cost $2 billion or so to get the first Transatomic reactor built.  Winning a DOE contest is a long way from getting serious funding, but ARPA-E has an increased emphasis on commercialization, and the judges are largely drawn from big Silicon Valley venture capital firms.  So the ARPA-E win is a big step for a small company that hopes to transform the nuclear power industry.