The Little Nuclear Reactor You’ve Never Heard About: A Thorium Molten Salt Breeder Reactor (MSBR)

Dr. Frank Shu is a celebrated astrophysicist and Shaw Prize winner now dedicated to making an impact on climate change. He has developed a process that converts biomass to carbon neutral (or negative) coal that can be enhanced by a molten salt nuclear reaction.

Sponsored by: National Tsing Hua University
Executive Producer: Mitchell Block
Producer: Keri Kukral, Donald Goldsmith
Director/Editor: Brian Weidling


Photo: Thorium Energy Alliance

1 Comment

  • Reply February 17, 2015

    Keri Kukral

    Response to Turner Davis (YouTube):

    You are really raising two issues here: (1) burners versus breeders, and (2) thorium versus uranium.

    On issue 1, these are the facts. Let us abbreviate million metric ton = MMT and year = yr. According to the Nuclear Energy Association, the proven reserves of uranium in the world is 5.5 MMT. The once-through rate usage of the fleet of present-day LWRs, which are burners, that supply 4.8% of the world’s primary energy supply is 0.070 MMT/yr. Simple division then yields that the proven supplies of uranium can last 5.5/0.070 = 79 yr if nuclear remains to hold its present percentage of primary energy use. Climate change would then overwhelm us in a few decades. On the other hand, if we build enough LWRs to supply 100% of the world’s primary energy use, the uranium would last only (4.8%/100%)79 yr = 3.9 yr.

    Clearly, therefore, burners are unsustainable if nuclear energy is to supply anything close to 100% of the world’s primary energy use. We must go to breeders that consume nearly 100% of the natural fuel rather than 1%. If uranium is that fuel, and the reactors are fast uranium/plutonium breeders, proven reserves could last (100%/1%) 3.9 yr = 390 yr, which would give us enough time to develop fusion as the ultimate energy resource.

    On the other hand, if we were to go to the thorium fuel cycle, the proven reserves are 6.4 MMT according to the World Nuclear Association. Theoretically, there should be 4 times as much Th as U, but to be conservative, let us stick to proven reserves. In that case, thorium breeder reactors would supply (6.4 MMT/5.5 MMT) 390 yr = 440 yr of today’s primary energy use, not much different from 390 yr.

    In either case, one needs to convert a 4.8% fleet of present-day LWRs to 100% fleet of breeder reactors. So you are right that the argument about conversion expense is specious. In either case, most of the expense, necessary to make nuclear energy sustainable over the long term, is the difference in cost between a large fleet of breeders and a small fleet of burners, not on whether we choose to use uranium/plutonium cycle versus the thorium cycle. The merits of the latter case should be argued on whether thorium (thermal spectrum) breeders are safer, superior (in cost), and securer (in weapons proliferation) than uranium/plutonium (fast spectrum) breeders. That argument requires another post.

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