OP-ED: Solving climate change with thorium molten-salt reactors
We need to invest in safer forms of nuclear energy to protect the planet
Daily headlines make it clear that the world is headed for a climate catastrophe, with record heat and forest fires that burned much of Australia in the past year. Climate researchers are warning that there are only a decade or two left to avoid catastrophic global warming of over 2 ° C, which submerges all lower-lying areas under rising seas, creating millions of climate refugees, and endangering global food production and potentially major famines would cause.
Obviously, the world needs to stop using fossil fuels, which are the main cause of climate change. Super Fuel: Thorium, Richard Martin’s green energy source for the future, shows a way forward. We might have already lived in an alternative world powered by cheaper, safer, low-carbon nuclear energy if civilian nuclear energy could develop freely without military interference.
The terrible Chernobyl and Fukushima accidents could have been avoided if the safer alternative of molten salt reactors based on thorium had been chosen as the basis for civil nuclear power. Instead, we still use fossil fuels as the main source of energy, and the world continues to be at extreme risk of extreme global warming.
Martin’s book describes the evolution of the “light water reactor” design that dominates the world’s nuclear industry and how that design was driven by military concerns rather than the need for safe nuclear power. The light water reactor was used in 1957 for the first commercial nuclear reactor in Shippingport, Pennsylvania, and in 1958 for the first Nautilus nuclear submarine in the US Navy.
The joint reactor design was no coincidence, but the result of development decisions by Admiral Hyman Rickover: In the 1950s, he headed the US nuclear submarine research team and, as a member of the US Atomic Energy Commission, decided what form civil nuclear power should take to take.
The advantage of the light water reactor was obvious from Rickover’s point of view for the Navy: “The Navy had the best plumbers in the world. They knew how to design and operate pumps, bearings, and valves to move water, including water at the high pressure required for a nuclear reactor in a submarine ”(page 106).
However, the selection of water as the reactor coolant was dangerous; This created the possibility for water to escape as high temperature, high pressure steam, or worse, react with metals in the reactor to release hydrogen gas, which can then cause an explosion. Light water reactors therefore required large, expensive “containment” to prevent steam or hydrogen explosions from releasing radioactivity into the environment. A factor as arbitrary as the U.S. Navy’s comfort with aqueducts was critical in giving the world the inherently unsafe but expensive and difficult-to-build light water reactor that dominates nuclear power today.
Alvin Weinberg, director of Oak Ridge National Laboratories in the US and one of the original designers of the light water reactor, identified other safety issues. These reactors were built around a solid core containing uranium fuel rods in which the nuclear reactions take place. To slow the nuclear reaction, a mechanical control system is required to physically move “control rods” between the fuel rods. In a light water reactor, any problem with the mechanical control system can cause the core to overheat and melt catastrophically.
To solve these problems, Weinberg and his team designed the “molten salt reactor”. As Martin says, “The only truly inherently safe reactor is a liquid core reactor, like the molten salt reactor that was manufactured in Oak Ridge in the 1960s. For the purposes of a reactor designer, liquid – whether water, liquid metal, or some type of liquid fluoride [salt] – has a wonderful quality; it expands quickly when it gets hot … In a liquid nuclear reactor, it expands and naturally slows the response, making a runaway accident nearly impossible. When reactivity decreases, the reactor essentially turns itself off ”(page 73).
This type of passive safety (which does not require human or mechanical intervention to slow the response) is absent from the light water reactors that provide most of the world’s nuclear energy today.
While the thermal expansion of the liquid core of the Weinberg molten salt reactor allows passive cooling to slow the nuclear reaction, it is still conceivable that an accident could occur due to unforeseen natural disasters such as earthquakes. Even in the event of an earthquake or other accidents in a molten salt reactor, the release of radioactive material into the environment and the resulting damage to life and health is almost zero.
“Fluoride [salt]Liquid based fuels have another property that makes them ideal for reactor cores: they flow. Gravity, no sophisticated control systems or so-called passive safety systems, offers liquid fluoride-thorium reactors their ultimate protection against a serious nuclear accident. In the event of a power failure or breakdown, a specially designed freezer plug in the reactor vessel melts and the liquid core simply flows out of the reactor into an underground, shielded vessel, such as a bathtub, when the drain plug is pulled. The fission reactions stop quickly and the liquid cools down quickly… melting is impossible ”(page 74).
Again, earlier generations of light water reactors lacked such a passive safety measure to limit the release of radioactivity in nuclear accidents.
Weinberg’s design of the molten salt reactor featured another innovation; It could run on thorium-based nuclear fuel, which is not as rare as uranium, so it promises to be an affordable source of fuel for much longer. This is important because for developing countries, which are consuming ever more electricity, nuclear fuels need to be inexpensive and readily available in the long term.
A thorium-based molten salt reactor (also known as a Liquid Fluoride Thorium Reactor or LFTR for short) is also much more efficient with its nuclear fuel, as it converts almost all of the thorium fuel to uranium-233 and then burns almost all of it. In comparison, a light water reactor consumes only a tiny percentage of its uranium 235/238 nuclear fuel, producing many times the volume of nuclear waste.
The nuclear waste produced by molten thorium salt reactors is also much less durable. “While LFTRs, like any other nuclear reactor, produce highly radioactive fission products, their half-lives are typically measured in tens of years, not thousands.” (Page 77).
This means that thorium-based molten salt reactors do not present the radioactive waste storage problems for thousands of years that conventional nuclear power plants face. Indeed, new designs of molten salt reactors are currently being explored that could consume existing stocks of radioactive nuclear waste as fuel and thus permanently eliminate the need for long-term storage of nuclear waste (pages 78-79).
Unfortunately, the U.S. Navy has invested heavily in light water reactors for its nuclear submarine programs. Large companies like GE and Westinghouse also invested heavily in the marketing and construction of light water reactors around the world.
Both powerful groups opposed further research into alternatives such as the safer molten salt reactor. The Nixon government briefly stopped funding Weinberg’s research on molten salt reactors. Weinberg’s outspoken criticism of the dangers of light water reactor design eventually led to his being fired from his job as head of Oak Ridge National Laboratories. However, disasters in Chernobyl and Fukushima showed that Weinberg was right to be concerned about the safety of light water reactors.
Disasters in Fukushima and Chernobyl have caused panic and much public opposition to nuclear energy. This was a colossal mistake in terms of the environment as countries like Germany and Japan replaced carbon-free nuclear power with even more fossil fuels.
Many environmentalists also reject nuclear power in favor of wind and solar energy. However, these renewable sources are temporary and cannot replace continuous electricity from fossil fuels without making huge investments in electrical storage batteries that are both commercially and technologically unfeasible. Thorium-based molten salt reactors in any country (in fact, in any city) are therefore a much more realistic solution to the climate crisis.
The good news is that over the past decade around a dozen nuclear start-ups have sprung up in different countries developing new designs based on the thorium molten salt reactor. Extensive research has also been carried out at the government level in India and China. It is hoped that thorium molten salt reactors can soon be built in countries like Bangladesh, which are acutely prone to global warming and sea level rise and are in dire need of greener, cheaper and safer alternatives to fossil fuels and conventional uranium reactors.
One can only hope that this will happen before our reliance on coal, oil, and gas harms the earth’s climate beyond human survival.
Zeeshan Hasan is the director of Kazi Media, the company behind Deepto TV. He is also the managing director of Sysnova.