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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Here are my comments to an article in Oil Price, “6 Things to do with Nuclear Waste: None of them Ideal” at

There is another possibility you did not mention, a way of eliminating nuclear waste: fission it!

Very few people realize it, but there are other types of nuclear reactors than we’ve been using. We’ve only used light water reactors (LWR) for political reasons from decades ago, but our priorities have changed since then.

In LWR, fission byproducts absorb neutrons stopping fission; fuel rods get damaged by radiation; only ~2% of the fuel gets fissioned.

Molten Salt Reactors, e.g. LFTR, use molten uranium dissolved in a molten salt coolant, and fission byproducts are easily removed; over 99% of the fuel fissions.

We successfully operated a Molten Salt Reactor for 5 years, decades ago. If we completed development of these reactors (bringing power generation capacity above 100MW), they would exceed environmental standards for radioactive contamination, for reduction of existing nuclear waste, for reducing global warming pollution, for environmental impact. They would provide low-pollution base-load power supplementing solar and wind power, getting us off coal/oil sooner. (I know, the oil and coal industries don’t want that…)

Molten salt reactors use a special salt for coolant. The coolant won’t boil (operating temperature far below salt boiling point), so there’s no high pressure, no risk of “loss of coolant accidents”. The reactor uses no water, so there is no risk of steam or hydrogen explosions. This is inherently much safer, eliminating almost all the (water-based) risks of current reactors.

LFTRs would even cost a lot less to build than LWRs. No water, so no steam containment building. No high pressure, so no high pressure piping.

Liquid fuel allows use of a “freeze plug” (frozen fuel in a section of pipe — cut power to cooling and it quickly melts, fuel drains from the core to passive cooling tanks where nuclear reaction is impossible). This is much simpler, safer and less expensive than what LWRs need — LWR needs complex emergency systems to over-ride everything that normally happens in the core.

To make a gigawatt-year electricity, LWRs leave 35,000kg uranium/plutonium (and other transuranic elements) to somehow safely store for 100,000+ years. That’s not counting the 215,000kg depleted uranium left from making 35,000kg enriched uranium.

Only a properly designed nuclear reactor can Consume nuclear waste. A fast-spectrum molten-salt reactor could use nuclear waste from LWRs as fuel, 800kg to make 1 gigawatt electricity for a year. Since an MSR consumes 99%+ of the uranium (or plutonium or plentiful thorium) fuel, waste is much easier to take care of — most MSR waste would be harmless in 10 years (83%, radiation levels below background levels). The rest (17%) would be safe in 350 years. We know how to safely store 135kg (300 lbs) of waste for 350 years.

(Molten Salt Reactors can be fast-spectrum simply by eliminating the moderator, and adjusting the fuel density and other parameters physicists know. All the basic design features — molten fuel circulating, fission product removal, very high fuel usage, freeze plug, strong fission rate regulation by thermal expansion of the salt — remains the same.)

MSR waste, once no longer radioactive, is chemicals we use in industry, to make solar panels and wind power generators, headphones, LCD screens.

Eliminate nuclear waste, inherent safety much better than LWR, lower construction cost. Smaller sites, no water needed, so build where electricity is needed. High temperature operation allows us to make CO2-neutral vehicle fuels. Best base-load power to replace coal and oil.

See for what they are, how they’re different, what ways they are so much safer, how they can consume nuclear waste, how they would fare in accidents or terrorist attacks, how much less they would cost, how long it will take us to build them.

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