Why molten salt reactors are problematic and Canada investing in them is a mistake via The Conversation

MV Ramana

One of the beneficiaries of the run-up to a potential federal election has been the nuclear energy industry, specifically companies that are touting new nuclear reactor designs called small modular reactors. The largest two financial handouts have been to two companies, both developing a specific class of these reactors, called molten salt reactors (MSRs).


As a physicist who has analyzed different nuclear reactor designs, including small modular reactors, I believe that molten salt reactors are unlikely to be successfully deployed anytime soon. MSRs face difficult technical problems, and cannot be counted on to produce electricity consistently.[…]

Because of the different kinds of fuel used, these MSR designs need special facilities — not present in Canada currently — to fabricate their fuel. The enriched uranium for the IMSR must be produced using centrifuges, while the Moltex design proposes to use a special chemical process called pyroprocessing to produce the plutonium required to fuel it. Pyroprocessing is extremely costly and unreliable.

Both processes are intimately linked to the potential to make fissile materials used in nuclear weapons. Earlier this year, nine non-proliferation experts from the United States wrote to Prime Minister Justin Trudeau expressing serious concerns “about the technology Moltex proposes to use.”


Another basic problem with MSRs is that the materials used to manufacture the various reactor components will be exposed to hot salts that are chemically corrosive, while being bombarded by radioactive particles. So far, there is no material that can perform satisfactorily in such an environment. A 2018 review from the Idaho National Laboratory could only recommended that “a systematic development program be initiated” to develop new alloys that might work better. There is, of course, no guarantee that the program will be successful.

These problems and others have been identified by various research laboratories, ranging from France’s Institut de radioprotection et de sûreté nucléaire (IRSN) to the Nuclear Innovation and Research Office in the United Kingdom. Their conclusion: molten salt reactors are still far from proven.

As the IRSN put it in 2015: “numerous technological challenges remain to be overcome before the construction of an MSR can be considered,” going as far as saying that it does not envision construction of such reactors “during the first half of this century.”


Problematic solutions

Should an MSR be built, it will also saddle society with the challenge of dealing with the radioactive waste it will produce. This is especially difficult for MSRs because the waste is in chemical forms that are “not known to occur in nature” and it is unclear “which, if any, disposal environment could accommodate this high-level waste.” The Union of Concerned Scientists has also detailed the safety and security risks associated with MSR designs.

The Liberal government’s argument for investing in molten salt reactors is that nuclear power is necessary to mitigate climate change. There are good reasons to doubt this claim. But even if one were to ignore those reasons, the problems with MSRs laid out here show that they cannot be deployed for decades.

The climate crisis is far more urgent. Investing in technologies that are proven to be problematic is no way to deal with this emergency.

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