One of many beneficiaries of the run-up to a possible federal election has been the nuclear vitality trade, particularly corporations which might be touting new nuclear reactor designs referred to as small modular reactors. The most important two monetary handouts have been to 2 corporations, each growing a particular class of those reactors, referred to as molten salt reactors (MSRs).
First, in October 2020, Canada’s minister of innovation, science and trade introduced a $20-million grant to Ontario-based Terrestrial Power and its integral molten salt reactor (IMSR) design. In March 2021, New Brunswick-based Moltex obtained $50.5 million from the Strategic Innovation Fund and Atlantic Canada Alternatives Company.
As a physicist who has analyzed completely different nuclear reactor designs, together with small modular reactors, I consider that molten salt reactors are unlikely to be efficiently deployed anytime quickly. MSRs face tough technical issues, and can’t be counted on to supply electrical energy constantly.
How they work
Molten salt reactors use melted chemical substances like lithium fluoride or magnesium chloride to take away the warmth produced throughout the reactor. In lots of MSRs, the gasoline can also be dissolved in a molten salt.
These designs are very completely different from conventional reactor designs — presently, the Canada Deuterium Uranium (CANDU) design dominates Canada’s nuclear vitality panorama. CANDU makes use of heavy water (water with deuterium, the heavier isotope of hydrogen) to move warmth, decelerate or “reasonable” neutrons produced throughout fission, and pure uranium fabricated into strong pellets as gasoline. Slower neutrons are more practical in triggering fission reactions as in comparison with extremely energetic, or quick, neutrons.
Terrestrial’s IMSR is fuelled by uranium which comprises greater concentrations of uranium-235, a lighter isotope as in comparison with uranium present in nature (pure uranium), which is utilized in CANDU reactors. The enriched uranium is dissolved in a fluoride salt within the IMSR. The IMSR additionally makes use of graphite, as a substitute of heavy water utilized in CANDU reactors, to reasonable neutrons.
Moltex’s Steady Salt Reactor (SSR), however, makes use of a mix of uranium and plutonium and different parts, dissolved in a chloride salt and positioned inside a strong meeting, as gasoline. It doesn’t use any materials to decelerate neutrons.
Due to the completely different sorts of gasoline used, these MSR designs want particular services — not current in Canada presently — to manufacture their gasoline. The enriched uranium for the IMSR have to be produced utilizing centrifuges, whereas the Moltex design proposes to make use of a particular chemical course of referred to as pyroprocessing to supply the plutonium required to gasoline it. Pyroprocessing is extraordinarily expensive and unreliable.
Each processes are intimately linked to the potential to make fissile supplies utilized in nuclear weapons. Earlier this 12 months, 9 non-proliferation consultants from the US wrote to Prime Minister Justin Trudeau expressing critical issues “in regards to the expertise Moltex proposes to make use of.”
Expertise with MSRs has not been very encouraging both. All present designs draw upon the one two MSRs ever constructed: the 1954 Plane Reactor Experiment that ran for simply 100 hours and the Molten Salt Reactor Experiment that operated intermittently from 1965 to 1969. Over these 4 years, the latter reactor’s operations have been interrupted 225 occasions; of those, solely 58 have been deliberate. The remaining have been as a consequence of numerous unanticipated technical issues. In different phrases, the reactor needed to be shut down at the least as soon as each 4 out of 5 weeks — that isn’t what one would count on of a dependable energy plant.
Even the U.S. Atomic Power Fee that had funded the U.S. MSR program for practically twenty years raised tough questions in regards to the expertise in a devastating 1972 report. Most of the issues recognized proceed to be technical challenges confronting MSR designs.
One other primary downside with MSRs is that the supplies used to fabricate the assorted reactor elements will probably be uncovered to scorching salts which might be chemically corrosive, whereas being bombarded by radioactive particles. Thus far, there isn’t a materials that may carry out satisfactorily in such an surroundings. A 2018 evaluation from the Idaho Nationwide Laboratory might solely really useful that “a scientific growth program be initiated” to develop new alloys which may work higher. There’s, in fact, no assure that this system will probably be profitable.
These issues and others have been recognized by numerous analysis laboratories, starting from France’s Institut de radioprotection et de sûreté nucléaire (IRSN) to the Nuclear Innovation and Analysis Workplace in the UK. Their conclusion: molten salt reactors are nonetheless removed from confirmed.
Because the IRSN put it in 2015: “quite a few technological challenges stay to be overcome earlier than the development of an MSR could be thought of,” going so far as saying that it doesn’t envision development of such reactors “in the course of the first half of this century.”
Ought to an MSR be constructed, it’s going to additionally saddle society with the problem of coping with the radioactive waste it’s going to produce. That is particularly tough for MSRs as a result of the waste is in chemical varieties which might be “not recognized to happen in nature” and it’s unclear “which, if any, disposal surroundings might accommodate this high-level waste.” The Union of Involved Scientists has additionally detailed the security and safety dangers related to MSR designs.
The Liberal authorities’s argument for investing in molten salt reactors is that nuclear energy is important to mitigate local weather change. There are good causes to doubt this declare. However even when one have been to disregard these causes, the issues with MSRs laid out right here present that they can’t be deployed for many years.
The local weather disaster is much extra pressing. Investing in applied sciences which might be confirmed to be problematic is not any option to take care of this emergency.
MV Ramana receives funding from the Social Sciences and Humanities Analysis Council.