Molten salt reactors powered by a liquid fuel rather than solid fuel rods could be the next big thing in nuclear energy, contends a consortium working under the aegis of the European Commission.
For years nuclear scientists have talked about a revival of molten salt reactors and recent developments indicate that this alternative nuclear power technology is finally making gradual progress toward commercialization.
The consortium – which includes the Technology University of Delft (TU Delft), in the Netherlands, France’s National Center for Scientific Research, and the Commission’s Joint Research Center, in Brussels – recently embarked on a four-year research program designed to demonstrate the safety benefits of molten salt reactors.
Called ‘Safety Assessment of the Molten Salt Fast Reactor’ (Samofar), the effort will lead to the building of a prototype reactor in the early 2020s if all goes as planned.
First built and tested in the 1960s at Oak Ridge National Laboratory, molten salt reactors could be the first genuinely new nuclear power generation technology to reach the market in the last three decades, the researchers contend. These reactors produce zero carbon, as they use a radioactive solution that blends nuclear fuel with a liquid salt.
Though the reactors run on uranium, they are also ideally suited for thorium, an alternative nuclear fuel that is cleaner, safer, and more abundant than uranium.
Molten salt reactors also offer inherent safety advantages: because the fuel is liquid, it expands when heated, thus slowing the rate of nuclear reactions and making the reactor self-governing. And they’re built like bathtubs, with a drain in the bottom that’s blocked by a ‘freeze plug.’ If anything goes wrong, the freeze plug melts and the reactor core drains into a shielded underground container.
On the plus side, they can operate as producers of thermal power or as ‘burner’ reactors that consume nuclear waste from conventional reactors – thus helping solve two problems that have bedeviled the nuclear power industry: safety and waste.
Samofar project will be primarily focused on fast reactors, which are more efficient than conventional light-water reactors and can breed fissile elements from nuclear waste. The researchers will build experimental laboratory facilities to test the geometry of the freeze plug, the coatings of vessel and pipe materials, the behavior of the liquid fuel during circulation and draining, and other key safety metrics.
The project represents “the first step towards large scale validation and demonstration of the technology,” says Jan-Leen Kloosterman, a professor of nuclear physics at TU Delft and the lead researcher on Samofar. “Hopefully the results will also lead to much more commitment from the large nuclear industry.”
Currently, the most advanced program for liquid-fuel, thorium-based reactors is in China, where the Shanghai Institute of Applied Physics – in collaboration with ORNL – reportedly plans to build a prototype in the next few years or so.
Image credits: ORNL/MIT Technology Review – Richard Martin