MSR Benefits

Molten Salt Reactor Advantages

  • Molten Fuel - Fuel circulates through the reactor, fission products get removed, for over 99% fuel use (vs. LWR ~3%). No long-term radioactive waste.
  • Salt Cooled - Coolant far below boiling point, reactor operates at atmospheric pressure. Fuel dissolved in stable salt (no water), no loss of coolant accident possible. No need for high-pressure safety systems.
  • High Inherent Safety - No water, no high pressure, nothing that could propel radioactive materials into the environment. Thermal expansion/contraction of molten fuel salt strongly regulates fission rate; MSR is a very stable reactor. Simple safety systems work even if no electricity or operators.
  • Easy Construction and Siting - Low pressure operation, so no high-pressure safety systems. No water, so no steam containment building. Reactor factory assembled, with modern quality control, sensors and communication.
  • Lower Cost - Even with exotic materials, construction costs will be dramatically lower than LWR — factory construction, minimal manual on-site preparation. No long-term radioactive waste, so no long-term storage.
  • High Temperature Operation - Heat to generate electricity, desalinate water, produce CO2-neutral vehicle fuel, etc.
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In the March 24, 2012 issue, page 27 of Science News (90th Anniversary Issue: 1950s) they mention this as one of the science predictions that “never quite came to fruition” under “The future’s so bright”:

1955 “Atomic plants do not pose the ‘disposal’ problems that many laymen often think… Fifty years would perhaps be the right time to let the hottest radiations die away” (8/27/55 p.131)

I sent Science News this response:

Our current 100,000+ year storage time for waste from atomic plants is due to the specific atomic plants we are using, not inherent to nuclear power itself. Solid fueled reactors keep fission byproducts trapped in the fuel rods, so only 1-2% of the fuel can be used. The rest of the uranium is left as waste with the fission byproducts. But using solid fuel is not necessary.

Molten fueled reactors, such as the reactor operational from 1965-1969 in the Molten Salt Reactor Experiment, allow easy separation of fission byproducts from the fuel. 83% by mass of these will decay to below background levels of radiation within 10 years; the remaining 17% are elements that decay within 350 years. (Uranium and transuranic elements would be kept circulating through the reactor until they fission.)

The Atomic Energy Commission knew of other reactor designs than the pressurized water reactor we still use, including molten salt reactors. See Civilian Nuclear Power–1962 Report to Kennedy and Congress.

Also see which quotes Alvin Weinberg (1947 patent holder of the PWR) “Both the fast breeder based on the 239Pu-238U cycle and the thermal breeder based on the 233U-232Th cycle figured prominently in the report. Indeed, the report implied that both systems should be pursued seriously, including large-scale reactor experimentation. It particularly favored molten uranium salts for the thermal breeder.”

Especially specifying “hottest radiations” (those that are most radioactive, with the shortest half-lives), the 1955 statement was accurate.

One type of Molten Salt Reactor favored today is the Liquid Fluoride Thorium Reactor, using plentiful thorium as fuel. Other types of MSR can use as fuel the spent uranium, depleted uranium, or plutonium from solid fueled reactors, converting that long-term waste to 10 year and 350 year waste. Plus, loss of coolant accidents are physically impossible (salt coolant stays liquid more more than 400 degrees C above the reactor temperature), no water means no high pressure so steam/hydrogen explosions are impossible, “nuclear meltdown” is standard operation, and electricity is needed to Prevent shutdown of the reactor; without electricity a simple “freeze plug” melts and the fuel dumps to cooling tanks where fission is impossible, to passively cool without water.

For more on Molten Salt Reactors, and the Liquid Fluoride Thorium Reactor, see
and the main LFTR sites, and

We could implement modern designs of a molten salt reactor, in less than 5 years (the MSRE began in 1960, the reactor was operational in 1965, we have all their research and what we’ve learned since; they didn’t have nuclear modeling software, CAD software, our material testing methods, etc.). Estimated development cost, including validation of modern materials, is $1billion, and estimated construction of factories for assembly line production of LFTRs (like Boeing has for airplanes) is $5billion, less than the $10-12billion for construction of a single new PWR. A 100MW LFTR would cost around $200 million.

Flibe Energy plans to have a LFTR operational by 2015, and the Chinese Academy of Sciences has LFTR plans — in 2010 they visited Oak Ridge National Laboratory where the MSRE was done; and Chinese New Year in 2011 they announced they would be starting a Thorium Molten Salt Reactor program (and patenting every advance they make).

To a bright future,
George Lerner

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