by John Preedy
“So, why are you against nuclear power?”
“Because it’s so dangerous! Look at what happened at Chernobyl and Fukushima!”
“Yes. Chernobyl was the worst nuclear accident that the world has seen, and in the area affected by the fallout there have been about 4,000 documented cases of thyroid cancer among children and at least 9 deaths. There are also the expected premature deaths among the over 600,000 people who were directly involved in making the remains of the power station safe, which have been variously estimated at between 4,000 and 6,000 individuals.
If you look on the internet you can find whatever figure you wish for subsequent long-latency premature deaths. Accurate numbers are impossible to deduce but the World Health Organisation and the IAEA have agreed on a figure of 4,000. All energy production incurs risks, accidents and fatalities, and as the graphic below shows, coal is among the worst.
Coal contains uranium and its radioactive breakdown products. It's a fact that a typical coal fired power station releases 100 times more radioactivity into the surrounding area than a nuclear power station and they are not monitored or controlled. The figures quoted above are just fatalities caused directly by accidents. They don't consider the more general effects on health associated with air pollution and the release of radioactivity as particulates in the fly ash - a by-product from burning coal for electricity."
“OK, but don’t forget the upheaval to people who lived in the exclusion zones around Chernobyl and Fukushima, where radioactivity is going to remain high for thousands of years. They’ve lost everything - their homes, their jobs, their whole way of life!”
“Yes I agree. And on top of that many of them live in constant fear for their health and that of their families. The WHO report states that the psychological damage is the real harm done to the health of residents in areas affected by the Chernobyl accident.”
“So just taking the case of Chernobyl you agree that it’s resulted in major economic losses and political upheavals, as well as direct physical health effects and indirect psychological harm?”
"Yes and the same is true for Fukushima, although since there was much less radioactive material released, the direct health effects have been orders of magnitude lower. Also, after the Fukushima nuclear plant failures, which seem to have eclipsed the fact that 23,000 people died as a result of the tsunami, it’s such an obviously attractive and vote-winning posture for environmentalists and politicians to be against nuclear power.”
Satisfying the Base Load “So why do you still support nuclear power?”
“Because, in spite of having many reactors in operation worldwide which are inherently unsafe, there have been very few accidents. Even then, with the exception of Chernobyl, which was an RBMK plant which didn't even have a reactor containment structure, their effects have mostly been local. I also believe that there are no fully viable alternatives, capable of continuous running, that don't contribute greenhouse gases to the atmosphere. Nuclear power is a source of energy which is available all day and every day, not only during daylight hours or depending on weather conditions, but unlike fossil fuels, it doesn’t contribute to climate change.”
“But surely energy conservation and renewable energy is the way forward.”
“I agree that both have a place in any future energy strategy, but there are limits to energy conservation; and renewable energy, like all of the options, has associated problems and disadvantages.”
“Such as what?”
“Well the fundamental problem with most renewable sources is that they can’t supply the continuous base load of power generation that’s necessary in developed countries. Of course, if you think that we should all change our lifestyle to be like that of someone living in a religious order, you could go to bed when it gets dark, do without street lights, television, washing machines, computers and electric cookers after dark and get up when it’s light to work on your vegetable garden. I like cooking with charcoal or wood but I would miss my computer and my TV!”
“ I still don’t get it! Why can’t renewables satisfy the base load?”
“Well, photovoltaic power only works during daylight hours; and on cloudy days in Northern latitudes it produces very little. Solar thermal power has the same problem, although versions exist where heat is stored to allow overnight generation. Wind power only works when, and where, there is wind. And wave power needs a coastline. Hydroelectricity needs water to be able to run, but when river flows dry up in the summer it often can’t be used. You could burn wood or biofuels to generate electricity, but then you’d need huge areas of sustainably-managed forests or agricultural land dedicated to raising fuel crops. There have been some power stations built to run on biomass fuels, and there are circumstances where it’s feasible, but it’s not a universal solution for most developed economies. Or for highly-populated countries that use as much of their land as possible for agriculture, like China and India.
There are also the problems associated with transmitting electricity from one region to another. In Germany the wind is in the North and people are objecting to transmission lines being installed from North to South across the country.” The Problem of Energy Storage “Well, they will just have to get used to the new ways. But why can’t we store the energy somehow? What about having lots of electric batteries?”
“They’re not yet viable on a grid scale, and they won't be until new technologies allow batteries to be built with a much greater energy density. At present they're expensive, they need replacing after a few years and they use toxic metals, like lithium, manganese and cobalt, for their construction. Using batteries as a large scale storage option is being done in South Australia at Hornsdale Power Reserve but output is currently limited to 3 hours at 30MW, not enough to substitute for a lack of wind power generation on a calm day."
“But there must be other ways of storing energy.”
“There is a pumped storage scheme at Port Dinorwig in Wales that was completed in 1984. It works by pumping water up to a high level when electricity is abundant or cheap, then releasing it down through turbines to generate power when electricity is scarce and expensive. This simple article explains it. It’s possible to use schemes like this to store renewable energy, but they don’t store much energy, Port Dinorwig, for example, can only run for six hours, and they are expensive. Firstly you need to have the right location where you can construct a power station between two lakes, separated vertically by a few hundred metres, and after you’ve built the station, you have the problem of efficiency.”
What do you mean by that?”
“Any pump can only convert a percentage of the supplied electrical power into hydraulic power. For a typical pump you might get 70% of the electrical energy back in terms of mechanical/hydraulic work. The rest is lost as heat in the motor or the pumped fluid. But with a pumped storage scheme you have the same efficiency problem in both directions. When you convert the water stored at high level back to electricity using turbines, you once again lose about 30% as heat. So overall you are left with 0.7 x 0.7 = 0.49 or about 50% of the energy that you started with.”
“So we would need twice as many wind turbines?”
“Well it’s not as simple as that, because it depends on when the wind is blowing, what the demand is at the time and how many pumped storage schemes you can build. But you would certainly need extra generation capacity and you can see that it would be a lot more expensive than satisfying the base load with power stations capable of generating the base load requirements in the first place. Assuming that all your electricity is generated from renewable sources and ignoring the cost, I don't believe that there is any European country where it would be possible to find enough pumped storage sites to satisfy the base load at night, if there was no wind.
There are many other possible ways of storing energy and proposals to use surplus power from wind and solar to generate hydrogen that could be stored, and then used to power vehicles and fuel cells are interesting, but the concept is still being considered in feasibility studies."
“But we don’t want to build any more gas, oil or coal fuelled power plants, which are the only other power stations capable of running 24/7.”
“Yes I agree. Climate change is a threat to the well-being of everyone on the planet! In addition I don't like the fact that fossil fuels have finite reserves and are mostly under the control of undemocratic regimes. So why not re-examine nuclear power?”
Inherently Safe Nuclear Reactors “But you‘ve already agreed that it’s not safe!”
“What I actually said was that '.... in spite of having many reactors in operation worldwide which are inherently unsafe, there have been very few accidents and even then, with the exception of Chernobyl, their effects have been local'.”
“So you do agree that nuclear power is not safe!”
“Yes at the moment, with the existing fleet of 50-60 year-old reactor designs. But what if there was a type of inherently safe nuclear reactor that can’t explode, can’t meltdown, can’t overheat and shuts itself down safely if there’s a total power failure?”
“But we all know that nuclear power stations aren't like that, and if that was possible someone would have built one by now!”
“Someone did! Alvin Weinberg built one in the sixties at the Oak Ridge National Nuclear Laboratory in the USA, and it operated between 1965 and 1969. It’s described here in this Wikipedia article about the Molten Salt Reactor Experiment (MSRE). It was a small 10MW reactor and it was the first of its kind. In spite of that, it operated successfully and demonstrated that the technology was feasible. Alvin Weinberg ran a very well-managed research laboratory and the design, with all of the results, operational experience and engineering detail, were written up in a series of papers. They’re available here. (be patient the pdf’s take a while to load)!
The MSRE used molten liquid fluoride fuel running at high temperature, but at atmospheric pressure, so it couldn't explode. Since its fuel was already molten it couldn't melt down. In addition this demonstration reactor used air cooling, not water cooling, so it didn't need to be near the sea or a river.
They didn’t want to staff it at the weekends, so they used to switch off the power, which stopped the fan cooling a 'freeze valve'. This allowed the liquid reactor contents to discharge by gravity into a set of tanks. These tanks had no neutron moderator and a geometry that didn't permit a critical chain reaction to continue. Since it was a small reactor the decay heat was limited and it needed no special cooling systems. Basically they let it shut itself down on a Friday afternoon. It was walk-away safe!”
“That’s amazing! But why wasn't this work pursued further?”
“Because at the time of the Cold War the priority was to generate nuclear material suitable for weapons, and this type of reactor doesn’t do that! Unlike the MSRE, those reactor development programmes which bred plutonium from uranium continued to be fully supported and Alvin Weinberg, who wanted to work on the thorium fuel cycle, which he considered was inherently safer, was asked to leave his post. He was subsequently reticent to continue promoting this type of reactor in the US because he was concerned about what the nuclear establishment of the period might do to his career.”
“Ah, where would we be without politics!? But what’s thorium?”
“Without going into too much nuclear physics, thorium is a naturally occurring radioactive element, about four times as abundant as uranium and it's geographically widespread. As thorium 232 it can be used to breed uranium 233, which is what was used to fuel Alvin Weinberg’s Molten Salt Reactor Experiment.”
The Oak Ridge Molten Salt Reactor Experiment
What About Nuclear Waste? “Hang on, what about the nuclear waste issue. Nobody has found an answer to that. It stays radioactive for thousands of years!”
“Ah that’s where it gets even better. If thorium is used, the amount of waste is drastically reduced. Thorium-powered reactors generate about 35 times less waste from spent fuel, a fraction of the nuclear waste generated by a uranium-fuelled reactor, with only 17% of the waste having a long half-life, and in the case of thorium that means about 300 years instead of tens of thousands.
Liquid fluoride thorium reactors can burn most of their fuel instead of the 1% consumed by a uranium-based plant before the solid fuel elements need reprocessing. This slide tells the waste story better than I can!
In addition the wastes generated from thorium are radioactive for only hundreds of years and don’t decay into plutonium. If you bury spent nuclear fuel from the uranium fuel cycle, after thousands of years the other radioactive components decay, leaving plutonium. In effect you create a plutonium mine for future generations of terrorists! This 40 minute video presentation from Kirk Sorensen explains it well.
But Kirk Sorensen also suggests that a liquid chloride reactor could be designed to burn weapons and reactor grade plutonium in the fast spectrum, and at the same time the neutrons could be captured in a thorium blanket to generate U233 for burning in Liquid Fluoride reactors. We could permanently get rid of redundant plutonium stocks whilst producing energy and new fuel, but I should say that the research work on that hasn’t been done yet.”
“Now you’ve lost me in technical detail!”
“Sorry! It’s a complicated and technical subject. I think that’s one of the reasons why not many people know about it yet.” Not in My Backyard? “So you wouldn’t be concerned if a Liquid Fluoride Thorium fuelled nuclear power plant was built near you?”
“As long as I couldn’t see it or hear it and I had had the opportunity to satisfy myself about the safety aspects of the design before it was built, it wouldn’t worry me. A couple of kilometres away would be no problem. It might even slow down the house-building that’s happening all around us. What a shame that would be!”
“So you think that inherently safe nuclear power is possible? “
“Yes, not only possible, but investment in safe nuclear power is essential if, thinking globally, we are to avoid expanding the burning of fossil fuels to fulfil the rapidly growing energy needs of countries like China, India and Brazil. I’m far from alone in thinking this way, because, as well as nuclear enthusiasts, there are a number of environmental campaigners who’ve publicly stated that this is also their opinion, and they’ve accepted that Liquid Fuelled Thorium reactors are the best choice.“
“I’m still not completely convinced.” Back to the Future “Well others are, and it’s a case of back to the future! Alvin Weinberg, if he was still with us, would be very pleased, although he would probably be campaigning for more active US government involvement. China has announced that it’s pursuing the development of Liquid Fluoride Thorium Reactors ( LFTRs), the US has a number of private companies promoting them, Russia and France are doing research work and India has already built reactors fuelled with metallic thorium. Even Japan has people promoting LFTRs but after Fukushima they are having a tough job doing so !
This review from the World Nuclear Association, written in 2020, gives a detailed account of the many different research programmes associated with molten salt reactors and also explains many aspects of the technology. If you want to read more, here’s a list of links that might help you, but be prepared to put some effort in! “
Websites promoting thorium and LFTRs: http://energyfromthorium.com/ Kirk Sorensen http://www.thoriumenergyalliance.com/ http://sites.google.com/site/rethinkingnuclearpower/aimhigh Robert Hargreaves Other posts about thorium nuclear power written by the author: Thorium - Safe, Clean, Cheap Nuclear Power Who is Developing Thorium Power? Thorium- A New Direction in Power Generation Thorium- Energy Cheaper than Coal The Chinese Thorium Programme