The new reactor design, which so far exists only on paper, produces 20 times as much power for its size as Oak Ridge’s technology. That means relatively small, yet powerful, reactors could be built less expensively in factories and shipped by rail instead of being built on site like conventional ones. Transatomic also modified the original molten-salt design to allow it to run on nuclear waste.

via A New Molten-Salt Reactor Could Halve the Cost of Nuclear Power | MIT Technology Review.

In the event of a power outage, a stopper at the bottom of the reactor melts and the fuel and salt flow into a holding tank, where the fuel spreads out enough for the reactions to stop. The salt then cools and solidifies, encapsulating the radioactive materials. “It’s walk-away safe,” says Dewan, the company’s chief science officer. “If you lose electricity, even if there are no operators on site to pull levers, it will coast to a stop.”