Solving climate change with Thorium Molten Salt Reactors (MSRs)

First published on 22nd June 2020 in the Dhaka Tribune.

The daily headlines make it clear that the world is headed for climate catastrophe, with record heat and wildfires burning much of Australia in the past year. Climate scientists warn that only a decade or two is left to avoid catastrophic global warming of over 2C, which would submerge all low-lying areas under rising seas, creating millions of climate refugees, and endanger global food production, potentially causing huge famines. 

Obviously, the world has to stop using fossil fuels, which are the root cause of climate change; Super Fuel: Thorium, The Green Energy Source for the Future by Richard Martin shows a path forward. We might have been already living in an alternate world powered by cheap, safe, and zero-carbon nuclear power if civilian nuclear energy had been allowed to develop freely without military interference. 

The terrible accidents of Chernobyl and Fukushima could have been avoided if the safer alternative of thorium-based molten salt reactors had been chosen as the basis of civilian nuclear power. Instead, we still use fossil fuels as our main energy source, and the world remains at dire risk of extreme global warming.

Martin’s book outlines the development of the “light water reactor” design which dominates the world’s nuclear industry, and how this design was driven by military concerns rather than the need for safe nuclear power. The light water reactor was used for the first commercial nuclear reactor at Shippingport, Pennsylvania in 1957, as well as the first Nautilus nuclear submarine of the US Navy in 1958. 

The common reactor design was no accident, but the result of development decisions by Admiral Hyman Rickover: In the 1950s, he headed the US naval nuclear submarine research team and also decided as a member of the US Atomic Energy Commission what shape civilian nuclear power would take. 

The advantage of the light water reactor was obvious from Rickover’s naval perspective: “The Navy had the best plumbers in the world. They knew how to design and operate pumps, bearings and valves to transport water, including water at the high pressure required for a nuclear reactor inside a submarine” (page 106). 

The selection of water as reactor coolant was dangerous, however; it created the possibility of water escaping as high-temperature, high-pressure steam, or even worse reacting with metals in the reactor to release hydrogen gas, which could then cause an explosion. So light water reactors needed large, expensive “containment vessels” to prevent steam or hydrogen explosions from releasing radioactivity into the surroundings. Thus a factor as arbitrary as the US Navy’s comfort with water-based plumbing was decisive in giving the world the inherently unsafe, yet expensive and difficult to build, light water reactor which dominates nuclear power today.

Alvin Weinberg, the head of Oak Ridge National Laboratories in the US and one of the original designers of the light water reactor, identified further safety problems; these reactors were built around a solid core containing uranium “fuel rods” which host the nuclear reactions. Slowing down the nuclear reaction requires a mechanical control system to physically move “control rods” in between the fuel rods. In a light-water reactor, any problem with the mechanical control system can cause the core to overheat and catastrophically melt down. 

To solve these issues, 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 created at Oak Ridge in the 1960s. For the purposes of a reactor designer, liquid -- whether it’s water, liquid metal, or some type of liquid fluoride [salt] -- has a marvelous characteristic; it expands rapidly when it gets hot … In a liquid core reactor, as the energy of the liquid rises, it expands and naturally slows down the reaction, making a runaway accident nearly impossible … When the reactivity goes down, the reactor is essentially turning itself off”(page 73). 

This sort of passive safety (which does not require human or mechanical intervention to slow down the reaction) is missing from the light water reactors which now provide most of the world’s nuclear power.

While thermal expansion of the liquid core of Weinberg’s molten salt reactor provides passive cooling to slow the nuclear reaction, it’s still conceivable for an accident to happen due to unforeseen natural disasters such as earthquakes. However, even in the event of an earthquake or other accidents at a molten-salt reactor, the release of radioactive material into the environment and consequent damage to life and health is almost zero. 

“Fluoride [salt]-based liquid fuels have one other characteristic that makes them ideal for reactor cores: They flow. Gravity, not elaborate control systems or so-called passive safety systems, gives liquid fluoride thorium reactors their ultimate protection against a serious nuclear accident. In a power outage or mishap, a specially designed freeze plug in the reactor vessel melts and the liquid core simply drains out of the reactor into an underground shielded container, like a bathtub when the drain plug is pulled. The fission reactions quickly cease, and the fluid cools rapidly … Meltdown is impossible”(page 74).

Again, earlier generations of light water reactors lacked such a passive safety measure to limit the release of radioactivity from nuclear accidents.

Weinberg’s molten salt reactor design had another innovation; it could be run on thorium-based nuclear fuel, which is not as rare as uranium, and consequently promises to be an affordable fuel source for much longer. This is important, as nuclear fuel has to be inexpensive and readily available in the long-term for developing countries which consume increasing amounts of power.

A thorium-based molten salt reactor (also known as Liquid Fluoride Thorium Reactor, or LFTR for short) is also much more efficient with its nuclear fuel, in that it converts almost all of its thorium fuel to uranium-233 and then burns almost all of it. By comparison, a light water reactor utilizes only a tiny percentage of its uranium-235/238 nuclear fuel and so produces many times the volume of nuclear waste. 

The nuclear waste produced by thorium molten salt reactors is also much less long-lived. “While LFTRs, like every other nuclear reactor, generate fission products that are highly radioactive, their half-lives tend to be measured in dozens of years, not thousands.” (page 77). 

This means thorium-based molten salt reactors will not present the problems of storing radioactive waste for thousands of years that conventional nuclear plants face. In fact, new designs of molten salt reactors are now being researched which could consume existing stocks of radioactive nuclear waste as fuel, thus permanently removing the need for long-term storage of nuclear waste (pages 78-79).

Unfortunately, the US Navy invested heavily in light water reactors for its nuclear submarine programs; big corporations like GE and Westinghouse likewise invested heavily in marketing and constructing light water reactors around the world. 

Both these powerful groups opposed further research into alternatives like the safer molten salt reactor. The US government under Nixon short-sightedly terminated funding for Weinberg’s molten salt reactor research. Weinberg’s outspoken criticism of the dangers of the light water reactor design ultimately led him to be fired from his job as head of Oak Ridge National Laboratories. However, disasters at Chernobyl and Fukushima have shown that Weinberg was correct to be apprehensive about the safety of light water reactors.

Disasters at Fukushima and Chernobyl created panic, and have resulted in much public opposition to nuclear energy. This was a colossal mistake in environmental terms, as it has meant that countries like Germany and Japan have been replacing carbon-free nuclear power with yet more fossil fuels. 

Many environmentalists also reject nuclear power in favour of wind and solar power; however, these renewable sources are intermittent, and can’t replace continuous fossil fuel-based power without colossal investments in electrical storage batteries which are both commercially and technologically infeasible. Thorium-based molten salt reactors in every country (in fact, in every city) are thus a much more realistic solution to the climate crisis.

The good news is that in the last decade, around a dozen nuclear start-up companies in various countries have emerged, developing new designs based on the thorium molten salt reactor, with considerable research taking place at the government level in India and China as well. Hopefully, thorium molten salt reactors will soon be available to be built in countries like Bangladesh which are acutely vulnerable to global warming and sea-level rise, and desperately need greener, cheaper, and safer alternatives to both fossil fuels and conventional uranium reactors. 

One can only hope this happens before our dependence on coal, oil, and gas damages the earth’s climate beyond the capacity for human survival.

Saving the world with carbon taxes

This article was published in Dhaka Tribune on 25th August, 2019.

Every day, the news brings fresh stories about the urgency of stopping climate breakdown. The number of record hot years over the past decade keeps climbing, along with reports of severe storms, summer heat waves and melting polar ice. And yet we continue burning coal, oil and gas every day, generating more carbon dioxide emissions and making the planet hotter. Sometimes the scale of the climate problem seems overwhelming. But the fact remains that stopping global warming is simple; it only requires implementing a policy of global carbon taxes.

Economist have acknowledged for decades that global warming is essentially a failure of the market to price fossil fuels correctly. The abundance of coal, oil and gas means their minimum price is largely determined by extraction costs from the earth, which generally results in a low price (particularly for coal, which is cheap to mine). Unfortunately, the low prices of fossil fuels don’t reflect their true cost to society: if global warming is allowed to raise the Earth’s temperature by 4 or 5 degrees Celsius over the next century as projected by scientists, it could mean the end of much of the world’s population through droughts, crop failure, famines and ultimately warfare over food and water (a pattern already seen in Syria). The long-term cost of unmitigated climate change would be almost incalculable.

The rational, economic solution is to tax fossil fuels at point of extraction or import by coal, oil and gas companies. This would increase prices of coal, oil and gas and reduce their use, and thus slow down carbon emissions and global warming. However, governments have been wary of carbon taxes as a political liability which could create both unemployment and public dissatisfaction. In France, Macron’s attempt to impose a carbon tax at the beginning of 2019 sparked the violent ‘yellow vest’ protests among low-paid workers who could not afford higher transport and heating bills.

However, there is a refinement of carbon tax policy which can solve the problem of imposing any tax burden on the poor, namely 'carbon dividends'. This is the subject of economist James Boyce’s excellent new book, ‘The case for carbon dividends’. A ‘carbon dividend’ simply returns carbon tax revenue to the public as a flat payment per taxpayer. If all carbon tax revenue is returned this way, the net economic burden of the carbon tax will be zero, and it will not create unemployment. An example is helpful here; consider a simplified population of 100 people consisting of 5 wealthy people and 95 lower-income people. As wealthy people buy more carbon-intensive goods like cars and aeroplane flights, the wealthiest 5% may have 100 times the carbon footprint and thus might each pay $1000 carbon tax (as opposed to $10 for a lower-income person who doesn't fly or drive). Total carbon tax revenue for a sample population of 100 people would be (5 wealthy people x $1000 per person carbon tax) + (95 lower-income people x $10 per person carbon tax) = $5,950. However, all taxpayers would receive an averaged equal carbon dividend of $5950/100 or $59.50 each. That means that the wealthiest 5% of people would pay a net tax of ($1000 carbon tax - $59.50 carbon dividend) = $940.50 each, which gives them a powerful incentive to reduce their fossil fuel consumption. On the other hand, the lower-income 95% would receive a net benefit of ($59.50 carbon dividend - $10 carbon tax = $49.50). This net benefit will help low-income people to pay for higher costs of fossil fuels (due to carbon taxes) without falling further into poverty, and thus help prevent political backlash against the carbon tax. Even though it doesn’t cause any net tax burden, the carbon tax will make all use of fossil fuels more expensive and speed up the transition to renewable energy. The higher the carbon tax, the faster the transition will be.

This carbon dividend policy is not invented by Boyce; he has just written the first book devoted to it. In fact, carbon dividends are the policy advocated by Citizens’ Climate Lobby (www.citizensclimatelobby.org) a worldwide group of volunteers dedicated to educating the public and politicians about how to stop climate breakdown by implementing carbon taxes and dividends. The imposition of a carbon tax and dividend policy in Canada at the beginning of 2019 was largely the outcome of years lobbying by this group. This initial success in Canada needs to be replicated in every country if climate breakdown is to be prevented. Since Bangladesh is one of the countries most vulnerable to climate change, and there is now a large expatriate Bangladeshi population around the globe, one hopes that Bangladeshis wherever they are will join the campaign to stop global warming through carbon taxes and dividends.

Climate Changed: A graphic novel by Philippe Squarzoni

This article was published in Dhaka Tribune on February 9th, 2019.

French cartoonist Philippe Squarzoni has taken on the huge task of trying to convey the complex science of climate science and the global emergency that it implies in the form of his autobiographical/documentary graphic novel, Climate Changed. Hopefully this will enable the general public, which does not always seem inclined to wade through dense texts on scientific topics, to get a better appreciation of the challenges of global warming.
The book starts with the author contemplating the difficulties of tackling the subject of global warming in comic book form; unlike most comic book stories, it’s a scientific phenomenon without the conventional beginning and end of most stories. His solution is to place a fairly detailed exposition of climate science in the context of an autobiography. The end result is illuminating. It serves to remind the reader that climate change is not just happening to the globe. It’s happening to all of us, since we all live on this planet that is rapidly heating up, and is already presenting us with real consequences in the form of record high temperatures, droughts and deadlier storms. His visit to his childhood home and his observation of how much smaller and how different it seems as an adult illustrates that the comfortable planet we knew even a few decades ago is gone forever; the climate has changed, and it’s a now a new, more dangerous world that we live in.
As a low-lying country which is both densely populated and incredibly vulnerable to sea level rise, Bangladesh gets two mentions in the book. Squarzoni quotes climatologist and World Bank economist Stephane Hallegatte: with ‘a rise in sea level of a little over 3 feet (1 metre)… numerous densely populated coastal regions such as the Ganges and Nile deltas could be flooded. Millions of people will be driven out, and agricultural production will be severely affected. 20% of Bangladesh could be flooded.’ Bangladesh comes up again when Hallegatte discusses the potential effect of millions of climate refugees on the international arena: ‘If 20 million people leave Bangladesh and head for India, what do we do?… What will the India and Bangladesh of 2060 be like? Will tensions between them have eased? Or will they be at war?’. Even in Bangladesh, such long-terms concerns are rarely addressed in the short-term new cycle.
Unfortunately, the effects of climate change will be felt disproportionately by the poor; this is made clear by Squarzoni’s account of the severe flooding caused by Hurricane Katrina hitting New Orleans in 2005. The wealthier sections of the populace all evacuated upon hearing storm warnings a day in advance. The poor had no means to escape, and had to survive for days on the roofs of their submerged houses with most of the city being flooded with up to 23 feet of water. 30,000 people took shelter above the flood waters in the city stadium, until being finally evacuated by the government to the surrounding states. Desperate people started looting shops for supplies, with the result that a curfew was imposed; US soldiers freshly returned from Iraq were called in with orders from the state governor to shoot to kill. Total deaths numbered 1293, and 2 million were displaced; hundreds of thousands for over a year. Immense numbers were left in financial ruin with no means of rebuilding their ruined homes. All this in the richest country in the world. The question arises as to how poorer countries would deal with similar storms and floods, which will grow more common everywhere as global warming adds heat and power to storm systems. Will wealthy countries treat poor countries any better than they treat the poorest of their own citizens?
‘So, how to end this book?’ Squarzoni asks as he draws to a close. He observes that so far humanity has failed to deal with the existential threat of climate change by curbing fossil fuel use, and thus nearly closes on a pessimistic note; but as he says, ‘The story isn't over’. Everything depends on how successfully we the public are able to lobby governments of the world to act over the next decade (which according to the 2018 International Panel on Climate Change report is all the time we have left to make severe cuts to fossil fuel use and thus prevent catastrophic climate change of over 1.5C).