Australian news, and some related international items

Dispelling the myth about why thorium nuclear reactors were never commercially developed

Thorium-pie-in-skyThorium Reactors: Fact and Fiction, Skeptoid  These next-generation reactors have attracted a nearly cultish following. Is it justified?   by Brian Dunning  Skeptoid Podcast #555  January 24, 2017

Podcast transcript     “………True or False? Thorium reactors were never commercially developed because they can’t produce bomb material.

This is mostly false, although it’s become one of the most common myths about thorium reactors. There are other very good reasons why uranium-fueled reactors were developed commercially instead of thorium-fueled reactors. If something smells like a conspiracy theory, you’re always wise to take a second, closer look.

When we make weapons-grade Pu239 for nuclear weapons, we use special production reactors designed to burn natural uranium, and only for about three months, to avoid contaminating it with Pu240. Only a very few reactors were ever built that can both do that and generate electricity. The rest of the reactors out there that generate electricity could have been any design that was wanted. So why weren’t thorium reactors designed instead? We did have some test thorium-fueled reactors built and running in the 1960s. The real reason has more to do with the additional complexity, design challenges, and expense of these MSBR (molten salt breeder) reactors.

In 1972, the US Atomic Energy Commission published a report on the state of MSBR reactors. Here’s a snippet of what was found:

A number of factors can be identified which tend to limit further industrial involvement at this time, namely:

  • The existing major industrial and utility commitments to the LWR, HTGR, and LMFBR.
  • The lack of incentive for industrial investment in supplying fuel cycle services, such as those required for solid fuel reactors.
  • The overwhelming manufacturing and operating experience with solid fuel reactors in contrast with the very limited involvement with fluid fueled reactors.
  • The less advanced state of MSBR technology and the lack of demonstrated solutions to the major technical problems associated with the MSBR concept.

In short, the technology was just too complicated, and it never became mature enough.

It is, however, mostly true that, if we’re going to use a commercial reactor to get plutonium for a bomb, recycling spent fuel from a uranium reactor is easier, and you can get proper weapons-grade plutonium this way. It is possible to get reactor-grade plutonium from a thorium reactor that can be made into a bomb — one was successfully tested in 1962 — but it’s a much lower yield bomb and it’s much harder to get the plutonium.

The short answer is that reduced weapons proliferation is not the strongest argument for switching from uranium fuel to thorium fuel for power generation. Neither reactor type is what’s typically designed and used for bomb production. Those already exist, and will continue to provide all the plutonium that governments are ever likely to need for that purpose.

There’s every reason to take fossil fuels completely out of our system; we have such absurdly better options. If you’re like me and want to see this approach be a multi-pronged one, one that major energy companies, smaller community providers, and individual homeowners can all embrace, then advocate for nukes. You don’t need to specify thorium or liquid fuel or breeders; they’re already the wave of the future — a future which, I hope, will be clean, bright, and bountiful.


February 1, 2017 - Posted by | Uncategorized

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