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376 - Nuclear Reactors 47 - New Molten Salt Reactor Design

          Molten salt reactors have been explored in the past. They were originally seen as a possible power source for airplanes because they could be small enough for that application. In one type of molten salt reactor, fuel in the form of uranium tetraflouride is mixed with other chemicals and the heat generated by nuclear reactions turns the mixture molten. A graphite core serves the moderator. The molten salt circulates through a heat exchanger to create steam to power turbines. While the reactor operates at high temperature, it also operates at low pressure which reduces the complexity of the reactor and the wear on the components. Unfortunately, the power density of the molten salt reactors is much lower than the light water reactors that currently supply commercial nuclear power. Although the U.S. and other countries including Russia and China have explored molten salt reactors they have never caught on for any major commercial application. The old designs for molten salt reactors are simply not cost competitive for power generation.

          Leslie Dawan has invented a new type of molten salt reactor and has started a company called Transatomic Power to develop the new design. In her design, with new materials and a new shape, she has managed to increase the power density thirty times to the point where her smaller molten salt reactors can compete in the market place with existing reactor designs. In her design, there is a plug made of the salt mixture that is cooled to keep it solid. If the power to the reactor fails, the plug melts and the molten salt fuel pours out into a big chamber under the reactor. The mixture spreads out and the nuclear fuel is no longer compact enough to react so the mixture cools and solidifies posing no threat of a meltdown. An additional benefit of her molten salt reactor is that it can burn nuclear waste. One ton of nuclear waste can be consumed in a year to generate power and only about eight pounds of waste will remain at the end of the year. This could help with the disposal of nuclear waste.

         At this point in time, the design only exists as a document, a series of computer simulations and some patent filings. Dawan needs about four million dollars to runs a series of experiments to validate her design. After that, if she wants to sell reactors in the U.S., it will take a decade and hundreds of millions of dollars to go through the certification and licensing process of the Nuclear Regulator Commission. Dawan has decided that her design is a better choice for carbon dioxide reduction than sustainable sources such as wind and solar. Unfortunately, climate change is accelerating and waiting ten years to even start selling her reactors may be too late to have a meaningful impact. She has decided that she might have better luck taking her design to China where they could move faster with implementation. While I admire her enthusiasm and engineering skills, she might be a bit naïve when it comes to the Chinese nuclear industry. As I outlined in my article yesterday, there are some serious problems in China that could interfere with her good intentions.