Reactor 4 at Chernobyl [Image source: Carl Montgomery, Flickr]
Whenever someone writes an article advocating renewable energy as the way ahead for a society determined to solve climate change while also preserving the relatively economic and fairly comfortable (at least for industrialized nations thus far) stability of our present global society, invariably there will be someone questioning it on the basis that nuclear is the way ahead. For all the reasons presented below, this conclusion is unrealistic.
There are two types of nuclear energy – nuclear fission and nuclear fusion. Fission is what we use currently in modern reactors, using uranium 235 (U235). Fusion isn’t with us yet, if it will be at all.
In his book Sustainable Energy – Without The Hot Air, David MacKay points out that the nuclear energy available in just one atom is roughly 1 million times bigger than the chemical energy per atom of other fuels. This in turn means that the amount of fuel and waste can be up to 1 million times smaller than that of a conventional fossil fuel power station.
Unfortunately, as MacKay further points out, almost all the recoverable uranium is in the oceans not in the ground. This is a problem because no-one yet has demonstrated an ability to recover uranium from the oceans on an industrial scale.
Conventional ‘once through’ water cooled reactors
The nuclear power stations we have at the moment are water-cooled PWR’s (Pressurised Water Reactors) that McKay, and others, call ‘once through’ reactors. A conventional 1 GW nuclear power station will use 162 tons of uranium per year. MacKay says that the known mineable resources of uranium, shared between 6 billion people, would last for about 1000 years at a rate of 0.55 KWh per person, being the output of 136 nuclear power stations. MacKay also states that this is probably an underestimate as there is no known uranium shortage.
Problems with current nuclear technology
Do you want a list? Fair enough, there are several such lists on the internet already, but here is a quick summary of why nuclear, based on current technology, isn’t going anywhere and certainly doesn’t stand up against renewables as a means of solving the world’s energy and climate change problems.
- Nuclear reactors and the waste stored on the site are vulnerable to terrorist attack and are therefore equivalent to nuclear weapons in their capacity to cause massive harm if attacked.
- Nuclear power provides material that can be used in nuclear weapons. Using such a weapon in the hope of winning a war, or even trying to deter war is insane. Wars are things that happen when politicians think they know better than the citizens they represent and have given up on talking issues through. The only wars fought these days are, arguably, fought for corporate greed for oil (Iraq being a prime example, the potential for a flare up in the South China Sea being another) or by extreme terrorist movements such as Isis (and there are other ways to deal with them given the political will. But this is another subject altogether).
- Massive amounts of carcinogenic radioactive waste with no way in which to permanently contain or neutralize it. This waste remains highly radioactive and dangerous for thousands of years.
- Chernobyl. Fukushima. Windscale. Three Mile Island. Enough said really.
- Radiation exposure increases risk of cancer. Nuclear workers and their families are regularly exposed to such exposures.
- Uranium mining inflicts sickness and genetic damage on the communities living near to where it is carried out - usually indigenous people such as the Native Americans, Aboriginal People, Traditional African and European communities etc.
- Nuclear power is the most expensive energy source ever created by industrial society once the full costs are considered, if they ever have been that is.
- Nuclear waste constantly emits penetrating radiation, therefore moving it is extremely risky, especially when it is located far from the point of generation, as is the policy in the US.
- Nuclear Power reactors regularly release radioactivity into the air and into the sea. Such releases are usually hushed up by national governments.
- That being so, reactors regularly kill sea mammals, such as the sea turtle, an endangered species. Reactors require massive amounts of water for cooling, thus there are various water-related issues to consider here.
- The immense danger created by nuclear reactors necessitate a degree of centralized control imposed by governments, such that local communities tend to find they no longer have any real decision making ability with regard to nuclear plant location.
- Nuclear power isn’t necessary, when renewable energy is far better at generating large amounts of clean energy for heating and electricity, or will be when the necessary global infrastructure is fully developed.
- A focus on nuclear means drawing vital funds away from the far more effective renewable solutions the world really needs.
This is just a small number of the reasons why current nuclear technology is dangerous, unnecessary and ineffective. A German company called Elektrizitätswerke Schöna has published even more here.
So if current nuclear technology is completely unfeasible as an energy source, what other options are there?
Fast breeder reactors using energy from the oceans
When it comes to fast breeder reactors, David MacKay states that uranium can be used 60 times more efficiently in fast breeder reactors, which burn up all the uranium, both U238 and U235. The waste produced by ‘once-through’ water cooled reactors could be used also. However, MacKay declines to comment further on fast breeder reactors.
In principle, breeder reactors can extract almost all the energy contained in uranium or thorium, which decreases the amount of fuel needed by a factor of 100 compared to conventional reactors (which use less than 1 percent of the energy in mined uranium). Those in favour of breeder reactors argue that with extraction of uranium from seawater there could be enough fuel to last 5 billion years. Another attractive feature of breeder reactors is that they can reduce waste. Almost all of the fast breeder reactors (FBRs) in existence in 2006 were cooled by liquid sodium.
The US constructed two fast breeder reactors, neither of which reached commercialisation. One of these was the Enrico Fermi Nuclear Generating Station in Michigan which was decommissioned because of engineering problems. The other was the Clinch River plant in Tennessee, construction of which was stopped in 1983 when Congress stopped its funding.
In 2010, the International Panel on Fissile Materials commented that “after six decades and the expenditure of the equivalent of tens of billions of dollars, the promise of breeder reactors remains largely unfulfilled and efforts to commercialize them have been steadily cut back in most countries.” The UK, the US and Germany have now abandoned their breeder reactor programs. One of the problems with FBRs is that the capital costs are at least 25 percent more expensive than those of water cooled reactors. Another is that there are widespread safety years with reactors using sodium coolants, which could potentially lead to sodium fires. A third problem is the proliferation risk associated with reactors producing plutonium, which can be used for nuclear weapons and also generates considerable amounts of waste that remains hazardous for at least a million years, with a billion dollar per year containment price tag.
According to Professor Adrian Simper of the UK Nuclear Decommissioning Authority, FBRs require the conversion of plutonium into a metal alloy, with uranium and zirconium, thereby generating a sizeable amount of industrial activity to achieve this along with the potential for a large amount of plutonium-contaminated salt waste. Simper is also worried that the plutonium would be even more vulnerable to theft by terrorists for making nuclear weapons, a view shared by the Union of Concerned Scientists in the US.
FBRs also share the problem experienced by nuclear plants generally with regard to late delivery and being wildly over budget. An FBR in Finland has experienced huge cost and time overruns, such that it is the only FBR operating in the country.
As Swaminathan S A Aiyar pointed out in an article for India’s Economic Times, the liquid sodium used as a coolant by FBRs is extremely dangerous as it reacts with both air and water. Even a tiny leak of the stuff can therefore cause a fire and the use of water to try and put such a fire out would be impossible because the sodium coolant would react explosively. Furthermore, two Indian scientists, MV Ramanna and Ashwin Kumar, have pointed out that the Indian FBRs are dangerous for other reasons, specifically that the containment dome is not as strong as in other reactors and furthermore they have a positive coolant void coefficient presenting the risk of a positive feedback loop leading to an accelerated melting of the core during an accident. Such a positive coolant void coefficient, not involving sodium, contributed to the runaway reaction increase at Chernobyl in 1986.
A study by India’s Department of Atomic Energy (DAE) argued that the worst case scenario for a core disruptive accident would be an explosive release of about 100 megajoules. However, this has been questioned, with an estimate of such an incident occurring in a smaller German reactor producing an explosion of 370 megajoules. Other studies of FBRs around the world have drawn similarly high conclusions. Experiments conducted by Britain’s Atomic Energy Authority have suggested up to 4 percent of the thermal energy could be converted into mechanical energy and given that the phenomena occurring inside the reactor core could be very complex, a reliable experiment to ascertain the full impacts is impractical.
The International Panel on Fissile Materials has reported that many of the world’s liquid-sodium cooled reactors have been shut down for long periods because of sodium fires, with a particularly huge fire breaking out at Russia’s BN-350 FBR. The BN-600 that replaced it experienced 27 sodium leaks, 14 of which caused sodium fires. The Japanese Monju plant has also experienced a sodium fire, which again led to its being shut down.
In general, experience all over the world shows that these types of reactor aren’t yet ready for commercial use. An example is the French Superphénix reactor which was inoperative for most of its 11-year lifetime before shut down in 1996.
Extracting uranium from sea water (google search mass extraction of uranium from the oceans)
According to Ugo Bardi, writing for The Oil Drum in 2008, extracting any low concentration mineral from the oceans is a hugely expensive and complex task. That means the nuclear industry has a rather large problem, given that uranium from other sources, i.e. mining, is a finite resource. Mining, at present, can only deliver about 60 percent of the uranium needed for reactors currently operating (which generate about 16 percent of global electricity). The rest is supplied from stockpiled reserves, partly from dismantling old nuclear warheads. There is a continuing debate going on around the world about whether uranium is peaking, after which we’ll run out, but certainly the idea cannot be discounted.
Extracting uranium from seawater is regularly discussed among nuclear supporters, but it’s very much only a theoretical idea. The amount potentially available in the oceans would be more than sufficient to blow all worries about energy out of the water, excuse the pun, for a very long time. The idea was first presented in the 1960’s (see Nebbia 2007). A major step forward was the development of a membrane which could recover uranium from seawater (Vernon and Shah 1983). It led to a series of experiments in the 1990’s conducted by the Japanese Atomic Energy Agency (JAEA), but these tests only recovered a few grams of uranium oxide (see Seko, 2003). Another experiment in 2006 focused on braided fiber as an adsorbent (JAEA, 2006).
However, JAEA has now stopped all research in this area. There are no more reports coming out of Japan on this, no demonstration plants, no plans to run up scale-up tests. So basically the whole thing has, to use a colloquial term, ‘gone belly up’.
Ugo Bardi, attempts to explain why this happened using the ‘energy return on energy invested’ concept (EROEI). Using information from a table that Bardi presents in his article (see image), Bardi explains that 2E+13 tons of water would need to be processed every year in order to produce enough fuel for the world’s current fleet of nuclear reactors. Given that the present worldwide generation of nuclear energy is about 2.5E+3TWh per year (WNA 2007), the ‘energy density’ of seawater exploitable by present nuclear technology is about 1E-1 kWh/ton (one tenth of a kWh per ton). This is much larger than the kinetic energy produced by the same mass of water moved by ocean currents.
Elements theoretically extractable from seawater [Image source: Table 2, Bardi and Pagani, 2007, via Bardi (2008) The Oil Drum]
In order to extract the uranium, seawater could be pumped through the membrane, or it could be dropped into the sea. However, energy is needed for both these operations: pumping, infrastructure building, moving the membranes, manufacturing them, and so on. Darcy’s Law, which says that the energy required is inversely proportional to a parameter called "permeability", comes into play here. Taking an "order of magnitude" estimate of 1 kWh/ton the blunt truth is that it can't be done, or at least that’s Bardi’s argument, based on comparisons with the reverse osmosis membranes used by the global water treatment industry for desalination. He states that if the amount of uranium recovered from seawater is about 1E-1 kWh, “it makes no sense to spend 1kWh/ton for the extraction, even if we could do that at 100% efficiency.” Others, such as Schwochau (1984) draw the same conclusion. In other words, the energy expense of pumping water through membranes is such that it can’t be taken seriously as a method for uranium extraction.
What about simply dropping the membrane into the sea?
For a start off, it is a far less efficient method of using the membrane. That in turn means that more membranes would have to be used, as well as a larger infrastructure and some method of moving the membranes in and out of the sea. All that, again, entails energy costs. Dittmar (2007) has looked at this and concluded that it is a huge task. 2E+13 tons of water per year plus a relatively shallow body of water. The North Sea would work, as it is a shallow sea with an average depth of less than 100 meters containing 5E+13 tons of water. Assuming a recovery efficiency of 50 percent, which Bardi considers to be optimistic, this means that the entire North Sea would have to be used in order to recover enough uranium for just 16 percent of current global electricity generation. Extend that to generating power for the entire world, and the equivalent of at least 6 North Sea’s would be needed.
There is another problem. The North Sea is unlikely to have sufficiently strong currents for long-term uranium extraction. So what next?
Herman Sorgel in the 1920s considered damming the Strait of Gibraltar with his ‘Atlantropa’ dam. This was supposed to generate about 50 GW of hydroelectric power, representing about 10 percent, if that, of the power presently generated by the global nuclear industry currently. Naturally the idea is completely ridiculous. If someone even attempted it, they would need around 10 Straits of Gibraltar just to satisfy current global requirements.
Seko et al (2003) concluded that about 300 kg of membrane would be needed per kg of uranium extracted per year. Recovering the uranium would additionally require at least 3 tons of membranes per year, ten times the weight of the total catch of the modern fishing industry.
In other words, the EROEI of any attempt to recover uranium from seawater is far too low to be interesting to anybody except nuclear fantasists. Bardi does explain, in answer to a comment on his article, that with an efficient fast breeder reactor, this method could be possible. However, the reasons why there will probably never be such a thing have already been explained, which Bardi himself acknowledges.
Thorium is 3 times as abundant in the earth’s crust and in seawater as uranium. However, it couldn’t be extracted from seawater as it is even less soluble than uranium (see mdsolar’s comment on Bardi’s article). Perhaps thorium from the crust could be used? Not according to another commentator (drillo) on Bardi’s article, who says that there have been several attempts to burn thorium in pilot plants, all of them unsuccessful. Another commentator raises the point that India has abandoned thorium because they haven’t been able to develop the technology.
This is just a very tiny summary of the arguments raging below Bardi’s article and to investigate this in detail would require an article about 2-3 times the size of this one. However, it seems quite clear that the title of this article is fairly convincing.
Nuclear isn’t actually going anywhere, apart from, eventually (and the sooner, the better), into the history books.
Written by Robin Whitlock