Physical Insights

An independent scientist’s observations on society, technology, energy, science and the environment. “Modern science has been a voyage into the unknown, with a lesson in humility waiting at every stop. Many passengers would rather have stayed home.” – Carl Sagan

Barack Obama, nuclear energy and Yucca Mountain.

Putting aside, for now, rhetoric like “OMG Obama will kill nuclear energy”, one of the only “anti-nuclear” positions that president-elect Obama has actually made overtly clear on the issue of nuclear energy is that he is opposed to the opening / licensing of the geological repository for radioactive waste disposal at Yucca Mountain.

However, it should be realized that “No Yucca Mountain facility” is not saying “No to nuclear energy”.

I really don’t think a Yucca Mountain style geological disposal facility is a prerequisite for the continuation or the expansion of nuclear energy in the United States for the foreseeable future.

Nuclear energy works just fine at present with no Yucca Mountain, and it will continue to work in future, even without Yucca Mountain going ahead.

If Obama’s position on Yucca Mountain causes the government, the nuclear energy industry, and the public to pause for a moment, step back, and ask if branding all that used fuel containing uranium, plutonium and other useful, valuable material as “waste” and sending it to geological disposal at Yucca Mountain is really a sensible proposal, then I really don’t think that’s a bad thing.

In fact, if Obama was to back efficient utilisation of these nuclear materials as the alternative to disposal at Yucca Mountain, then I wouldn’t expect to see a great deal of opposition to such a plan, from nuclear-literate parties, at all.

The used nuclear fuel removed from a conventional LEU-fueled light-water reactor is about 25 tonnes per gigawatt per year – the equivalent of less than two 15-tonne dry storage casks per reactor per year – something that is clearly not difficult to deal with.

If the uranium and plutonium comprising 97% of the nuclear fuel is recovered and re-used, and the remaining 3%* is put into dry storage casks, then just one storage cask provides enough capacity to store the material for one reactor for twenty years. Of course, of that 3% of fission product material, half the fission products aren’t even radioactive at all, or they have extremely short half-lives. Many fission products, both radioactive and not radioactive, are valuable, exotic and useful materials, with specialised, useful and interesting applications. The assumption that all such fission products would be treated as “waste” is, therefore, especially pessimistic.

* (You can account for the minor actinides (Np, Am, Cm, Cf) in either category. They constitute a very small amount of mass either way. Such actinides, like Pu and U, can be fissioned in a nuclear reactor as sources of energy, and like many fission products, they can also be used for specialised technological and scientific applications, such as the production of 238Pu from 237Np, and the use of Cf and Am:Be as neutron sources.)

Still, it seems a real shame to waste all that money that we’ve already spent on YM if it’s not going to be used. I’m not sure off the top of my head how far underground the tunnels at Yucca Mountain are, but perhaps it could be used as a deep underground laboratory, or something, just as the Waste Isolation Pilot Plant is?

Still, there are approximately 50,000 tonnes of used nuclear fuel already in the United States, the result of the last 50 years of nuclear energy. Opponents of nuclear energy are quick to point that out, but under a scenario similar to that elucidated above, with the separation of easily usable plutonium and uranium, the significantly radioactive fission product materials only constitute 1500 tonnes, or 100 DSCs worth. Until a geological repository is built, or those fission products are put to productive uses, that’s only one additional storage cask that need be stored at every power reactor in the country.

In the foreseeable future, with no Yucca Mountain, dealing with nuclear byproduct materials, storing them safely and securely on site, is not impractical, and it’s not intractable, and it’s not unsafe. There is nothing here which impedes or prevents a revival of nuclear energy generation.

Of course, under the Nuclear Waste Policy Act, the government will have to compensate nuclear utilities for the costs of this storage. No, this does not mean handing out government money to nuclear utilities – it means giving the Nuclear Waste Fund money that is supposed to go to Yucca Mountain back to the nuclear utilities in order to pay for the management of the existing 50,000 tonnes (approx.) of used fuel (and/or processing thereof), and more importantly, it ought to mean not requiring nuclear utilities to pay any more money – more correctly, not requiring nuclear electricity customers to pay any more money – for the Nuclear Waste Fund, until we know that a geological repository for radioactive waste is going ahead. Otherwise, what exactly are they paying for?

Written by Luke Weston

November 6, 2008 at 8:32 am

Bioconcentration and biomagnification of radionuclides of biochemically-significant elements.

Anti-nuclear-energy activists often talk about the potential for biomagnification of radioactive nuclides in the environment as the consequence of any, even extremely dilute, releases of such radionuclides into the environment.

Consider the following claims, typical of such views, for example:

“Tritium is also more dangerous when it becomes organically bound in molecules of food. As such it is incorporated into molecules, including DNA within bodily cells. Chronic exposure to contaminated food causes 10% of the tritium to become organically bound within the body where it has a biological half-life of 21 to 550 days meaning that it can reside in the body from one to twenty-five years.”

“When tritium is released to the environment, it is taken up by plants and trees, partially incorporating into the ecosystem. Trees constantly transpire water vapor into the air; it has been found that higher concentrations of tritium occur at night at breathing height in a forest that has incorporated tritium from a nearby reactor.”

(Extracts from Nuclear Power is Not the Answer)

So, does bioconcentration of tritium in the food chain occur?

Bioconcentration or biomagnification of tritium in the form of tritiated water in biological systems does not occur at all, although it can occur with some other radionuclides. This is due, in part, to the relatively small biological half-life for water in biological systems, and the large concentration of light water in the environment, which results in massive isotopic dilution of tritium entering the ecosphere. Tritium is simply hydrogen, and your body cannot tell one hydrogen atom from the next – whilst large volumes of water are constantly being taken into the body, and passed out of the body, the total amount of hydrogen within ones body remains essentially constant, as is also the case for the various other chemical elements which make up the human body.

Biomagnification is the buildup of certain chemical pollutants in the bodies of organisms at higher trophic levels of food webs – the bioaccumulation of a substance up the food chain by transfer of residues of the substance in smaller organisms that are food for larger organisms in the food web. It generally refers to the sequence of processes that results in higher concentrations in organisms at a higher trophic level – further “up the food chain”. Organisms at lower trophic levels accumulate small amounts. Organisms at the next higher level eat many of these lower-level organisms and hence accumulate larger amounts. These processes result in an organism having higher concentrations of a substance than is present in the organisms prey or food. Biomagnification can result in higher concentrations of the substance than would be expected if water were the only exposure mechanism. Accumulation of a substance only through contact with water is known as bioconcentration.

Bioaccumulation is a general term for the accumulation of such substances in an organism or part of an organism. The process of bioaccumulation involves the biological sequestering of substances that enter the organism through respiration, food intake and/or other routes of absorbtion of the substance. Such sequestering results in the organism having a higher concentration of the substance than the concentration in the organisms surrounding environment. The level at which a given substance is bioaccumulated depends on the rate of uptake, the route of uptake, how quickly the substance is eliminated from the organism, transformation of the substance by metabolic processes, the lipid (fat) content of the organism, the hydrophobicity of the substance, environmental factors, and other biological and physical factors. As a general rule the more hydrophobic a substance is the more likely it is to bioaccumulate in organisms, such as fish. Increasing hydrophobicity (lipophilicity) leads to an increasing propensity towards bioaccumulation.

A related term is bioconcentration. Bioconcentration is a process that results in an organism having a higher concentration of a substance than is in its surrounding environmental media, such as stream water. Bioconcentration differs from bioaccumulation because it refers only to the uptake of substances into the organism from water alone. Bioaccumlation is the more general term because it includes all means of uptake into the organism.

Biomagnification, or bioamplification, occurs within a trophic level, and is the increase in concentration of a substance in an organisms tissues due to uptake from food and sediments in an aquatic milieu, wheras bioconcentration is defined as occurring when uptake from the environment is greater than the rate of excretion. Where bioaccumulation refers to how pollutants enter a food chain; biomagnification refers to the tendency of pollutants to concentrate as they move from one trophic level to the next, up the “food chain.” Whilst bioaccumulation refers to an increase in concentration of a pollutant from the environment to the first organism in a food chain, biomagnification refers to an increase in concentration of a pollutant from one link in the food chain to another.
We are traditionally concerned about these phenomena because together they mean that even small concentrations of toxic substances in the environment can find their way into organisms in high enough dosages to cause problems. In order for biomagnification to occur, the pollutant must be long lived, fat-soluble, mobile, and biologically active – i.e. toxic. If a pollutant is short-lived, it will be broken down before it can become dangerous. If it is not mobile, it will stay in one place and is unlikely to be taken up by organisms. If the pollutant is soluble in water it will be excreted by the organism. Pollutants that dissolve in fats, however, may be retained for a long time. Lipid soluble (lipophilic) substances cannot be excreted in urine, an aqueous solution, and so accumulate in fatty tissues of an organism if the organism lacks enzymes to degrade them. When eaten by another organism, fats are absorbed in the gut, carrying the substance, which then accumulates in the fats of the predator. Since at each trophic level of the food chain there is an energy loss, a predator must consume lots of prey, and therefore consumes significantly larger amounts of any biomagnifying lipophilic substance consumed by the prey organism.

There are two main groups of toxic substances that that are subject to biomagnification – toxic metals and persistent halogenated organic compounds. Both are lipophilic and not easily degraded. Novel organic substances are not easily degraded because organisms lack previous exposure and have thus not evolved specific detoxification and excretion mechanisms, as there has been no selection pressure from them. These substances are consequently known as persistent organic pollutants, and include the synthetic organic chlorine compounds which are today well-known for their potential for biomagnification and environmental harm, such as the insecticide DDT.

Heavy metals are chemically stable because they are chemical elements, and therefore cannot be destroyed or converted into a non-toxic form. (Except for the case of a radioactive metal, which will change into a differerent chemical element when it undergoes radioactive decay.) Organisms, particularly those subject to naturally high levels of exposure to metals, have mechanisms to sequester and excrete metals. Problems arise when organisms are exposed to higher concentrations than usual, which they cannot excrete rapidly enough to prevent damage. These metals are transferred in an organic form.

A classic example of a toxic heavy metal is mercury, which forms organic species such as methylmercury, which is lipid soluble, and can easily biomagnify in environmental systems. Other toxic transition metals – the so-called “heavy metals” – can be subject to biomagnification to some degree, too – for example, the toxic metal cadmium. Since biochemical behavior is independent of what the isotopic composition of the metal is, a radionuclide, such as the low-yield fission product $\mathrm{^{113m}Cd}$, perhaps, is subject to a potential for biomagnification just like any other cadmium. For example, though mercury is only present in small amounts in seawater, it is absorbed by algae, generally as methylmercury. It is efficiently absorbed, but only very slowly excreted by organisms. Bioaccumulation and biomagnification result in buildup in the adipose tissue of successive trophic levels: zooplankton, small nekton, larger fish etc. Anything which eats these fish also consumes the higher level of mercury the fish have accumulated. This process explains why predatory fish such as swordfish and sharks or birds like osprey and eagles have higher concentrations of mercury in their tissue than could be accounted for by direct exposure alone. For example, herring contains mercury at approximately 0.01 ppm and shark contains mercury at greater than 1 ppm.

Now, let’s talk about radionuclides. radioactive nuclides such as, say, hydrogen-3, carbon-14, iodine-131 or strontium-90, for example, can certainly be uptaken by living organisms – including, but not limited to, humans. Tritium (hydrogen-3) is almost always present in the environment in the form of water – and, of course, every living thing uptakes water from its environment, so, if there is $\mathrm{^{3}H}$ present in the water – keep in mind that all water has some naturally occurring $\mathrm{^{3}H}$ in it – then $\mathrm{^{3}H}$ will be absorbed by the organism. Now, remember – it is just hydrogen.

The biochemistry of cells does not care in the slightest what nuclide a particular atom of hydrogen or a particular element is – it is only concerned with the chemistry of the material. Therefore, the $\mathrm{^{3}H}$ will be used by the cells of the organism, and incorporated into tissues and biomolecules along with every other hydrogen atom that the organism has uptaken. Since an atom of tritium is just another hydrogen atom, of course it is exchanged into and incorporated into some hydrogen-containing biomolecules – in other words, just about any organic molecule found in a biological system. However, water is constantly being excreted from living systems as well as constantly being uptaken – a cell of Escherichia coli contains 70% water by mass, a human body 60-70%, plant tissue up to 90% and the body of an adult jellyfish is made up of 94 to 98% water. Now, the proportion of water in an organism such as these is constant – except for a small difference due to the growth of the organism, the rate of water uptake into an organism is equal to the rate of water excretion, and whilst hydrogen – which could be $\mathrm{^{1}H}$, $\mathrm{^{2}H}$ or $\mathrm{^{3}H}$, it doesn’t matter – is constantly being moved between water molecules and more complex biomolecules, and it is constantly being excreted – both in the form of water and in the form of more complex biomolecules.

However, some tritium taken up into the body could be incorporated into a biomolecule in the tissues of the body, and it could remain there for some time – but as more stable hydrogen is constantly being exchanged through the body in large quantities, the concentration of tritium within the body from any given intake will decay exponentially, just as the metabolism and excretion of, say, a drug taken into the body follows an exponential decay law – hence, we speak of the biological half-life.

The overall amount of hydrogen per unit mass of a living organism is essentially constant. If there is a constant environmental source of a radionuclide such as tritium – such as the natural cosmogenic formation of tritium – then the overall amount of tritium per unit mass of a living organism is essentially constant.

Exactly the same argument applies to radionuclides of other biologically active elements – like, say, carbon-14. $\mathrm{^{14}C}$ is constantly uptaken from the atmosphere by plants in the form of $\mathrm{^{14}CO_{2}}$, and incorporated into the organic biomolecules within the tissues of the plant as the plant grows – and when an animal eats the plant, the $\mathrm{^{14}C}$-containing biomolecules are metabolised by the animal. As with hydrogen nuclides, the $\mathrm{^{14}C}$ is constantly being turned over between living systems and the ecosphere, as organic compounds are excreted by the animals – for example in the exhalation of $\mathrm{^{14}CO_{2}}$. Again, the overall concentration of $\mathrm{^{14}C}$ within the tissues of a living system is held constant – this is how carbon-14 dating works! If the concentration of $\mathrm{^{14}C}$ within a living organism wasn’t constant, then obviously $\mathrm{^{14}C}$-dating of once-living materials would be impossible.

The same arguments apply to, say, strontium, or iodine – whilst a radionuclide such as strontium-90 certainly can be uptaken into the human (or animal) body, and can be used in osteogenesis and incorporated into bone because of the chemical similarity between $\mathrm{Sr^{2+}}$ and $\mathrm{Ca^{2+}}$, the overall concentration of calcium – calcium and strontium combined, for that matter – within the body is maintained at a certain static level. When iodine – some of which could be contaminated with, say, radioactive iodine-131 – is uptaken by the body, iodide ions are used by the thyroid gland in the biosynthesis of the iodine-containing thyroid hormones, thyroxine and triiodothyronine. But, of course, the concentration of thyroxine and triiodothyronine in the blood is kept around a fairly homeostatic value – whilst some iodine is essential for the biosynthesis of these hormones and is thus essential for health, it does not accumulate arbitrarily in the body, either in the form of the iodine-containing hormones or as free iodide ion.

Obviously we know that such chemical elements – radionuclides or not – are uptaken extensively by biological systems; but that is not the same thing as biomagnification – do they bioaccumulate or biomagnify?

Clearly, they do not.
It has in fact been determined empirically in Perch Lake in Canada that there is a progressive decline in the concentration of cobalt-60 and strontium-90 as they are transferred to higher trophic levels. In other words, predators, such as carnivorous fish, have lower concentrations of cobalt-60 and strontium-90 per unit body weight than do forage fish, insects and plants, as a result of biological discrimination against uptake of these elements of limited biochemical usefulness. It is now generally agreed that the same principle is valid for most other radionuclides, with a few exceptions, such as tritium, soluble potassium-40 (which occurs naturally, not as a result of anthropogenic nuclear technology), and caesium-137, which is a chemical analog of potassium, which are incorporated without biodiscrimination into all living organisms. Most radionuclides are not subject to biomagnification up the food chain, thus differing them from organic pollutants such as DDT. This is of significant importance in the assessment of radioactive  releases into the environment.

Editor’s note: As you may note, I’ve just discovered WordPress’s built-in LaTeX engine. Unfortunately, it looks a little bit awkward in the above post, as you can see, with the TeX-formatted text much bigger than the surrounding text. I’ll have to see if there’s a way around that in future.

Written by Luke Weston

March 17, 2008 at 4:11 am

Kentucky senator pushing for fair consideration of nuclear energy

Atomic Insights reports that Kentucky state Senator Bob Leeper has been doing some reading and listening lately about the coming of a new wave of nuclear plant construction, and he is working to position his state as a potential site for consideration. He has recently introduced a bill that would change the language in the law to allow licensed on site storage as a means of safely handling the byproducts that remain after using fuel in a reactor for a period of time, as compared with current Kentucky law which precludes the construction of a new nuclear power plant until there is a licensed and available location for permanent disposal of used nuclear fuel or the radioactive waste which may be left following recycling of such used fuel, such as the Yucca Mountain facility under development in the United States.

Of course, some people, such as Joseph Mangano, executive director of the Radiation and Public Health Project, a name that those with their finger on the pulse of nuclear energy policy in the United States and elsewhere will have heard before, has other ideas:

“One problem with nuclear reactors is what to do with the high-level waste they produce. This waste is actually a cocktail of chemicals such as Cesium-137, Iodine-129, Strontium-90 and Plutonium-239, each radioactive and cancer-causing.”

There’s no way that it is appropriate to call these kinds of materials waste –  they are radionuclides with useful and important technological, scientific and industrial applications. Of course, if we greatly expand the use of nuclear fission as an energy source throughout the world, along with the recycling and efficient re-use of the materials contained within irradiated nuclear fuels, it is likely that the inventories of such fission products thus created will ultimately dwarf demand for some of these radioactive materials – and it could be decided that these surplus quantities might be moved to deep underground storage, either for very long term storage, or permanant disposal.

“The waste decays slowly, remaining in dangerous amounts for thousands of years, and must be kept from escaping into the air, water and food supply”

Relatively short lived fission products, such as caesium-137 and strontium-90, with half-lives of 30 years and 29 years respectively, must be isolated from the environment for around 300 years, not thousands of years.

Longer lived fission products, such as iodine-129, one of the very longest lived of the fission product nuclides, can have half-lives of millions of years – with correspondingly smaller specific activities, and in most cases, much smaller nuclear fission yields. Some such long-lived fission products, such as I-129 and technetium-99, have sufficiently large neutron capture cross sections such that destruction of the radioactive nuclide by way of nuclear transmutation in a nuclear reactor is feasable.

I get especially bothered when these people talk of plutonium-239 and “waste” in the same sentence – it is one of the most potent, most energy dense, and most useful fuels known to humankind. There is absolutely no way that it should ever be thought of as “waste”, and it should not be wasted.

“Another potential health problem is a large-scale release of radioactivity from a meltdown. Accidents have occurred at several reactors, including the 1986 total meltdown at Chernobyl and the 1979 partial meltdown at Three Mile Island. But in addition to accidents, a terrorist attack could also cause a meltdown. Safe evacuation would be impossible, and local residents would be exposed to toxic radiation, causing many thousands to suffer from radiation poisoning and cancer.”

The Chernobyl disaster was not a meltdown in the usual sense of the term – it was a disaster triggered by complete destruction of the reactor core caused by a massive, explosive power excursion and steam explosion, not a fuel damage accident caused by a loss of coolant accident.

The design, operation and physical characteristics of the RBMK power reactors at Chernobyl during the era of the Soviets have absolutely nothing  to do with the operation of the commercial nuclear power industry in the world today. The Chernobyl disaster is absolutely irrelevant, it has absolutely no relevance at all, to the use of light water reactors in the commercial nuclear power industry in the United States today.

No accident even remotely comparable to the Chernobyl accident, which, in the absence of any kind of real containment around the nuclear reactor, spewed radioactivity from the destroyed reactor core for thousands of miles, has ever occured in the commercial nuclear power industry in the Western world.

At Three Mile Island, where a loss of coolant accident and partial meltdown occurred in 1979,  was safe evacuation impossible? Were local residents exposed to “toxic radiation”? What dose of ionizing radiation did they receive? This was what is usually claimed as the most dangerous nuclear power reactor accident ever in the United States – did it cause “many thousands to suffer from radiation poisoning and cancer”? Did it harm anyone?

“Although it has never had a nuclear power reactor, Kentucky is no newcomer to nuclear plants. The Paducah Gaseous Diffusion Plant has been enriching uranium for nuclear weapons and reactors since 1952 — and contaminating the local environment for decades.”

Does the USEC Paducah plant produce HEU for nuclear weapons applications? That’s an open question to my readers – I’d like to know the answer.

What evidence, is there, that Paducah has been “contaminating the local environment for decades“? Is there any evidence of health or ecological effects on the surrounding community?

Local residents have breathed, drunk or eaten these contaminants, and they may have suffered. In the past quarter century, the death rate in the four closest counties (Ballard and McCracken in Kentucky, Massac and Pulaski in Illinois) is about 9 percent above the U.S. rate for both whites and blacks. This amounts to nearly 3,000 “excess” deaths in a population of only 95,000. The four counties have no obvious health risk, like language barriers, lack of education or extreme poverty, so Paducah must be considered as a potential factor in these high rates.

Kentucky already has the highest cancer death rate of any state in the nation. There is no need to increase cancer risk by introducing a hazardous means of producing electricity.

Has any scientific, peer-reviewed, epidemiological study of  health, death and disease, and the aetiology of any such abnormalities, in these counties ever been performed?

Is there any evidence, peer-reviewed scientific evidence of any kind, that nuclear energy is a “hazardous means of producing electricity” which “increases cancer risk”?

Written by Luke Weston

March 13, 2008 at 9:10 am

Climate of Hope – an anti-nuclear look at nuclear energy, energy systems and climate change.

This is a documentary video produced by the Anti-Nuclear Alliance of Western Australia – whilst they clearly make some statements that I contend, for the most part, the video is well produced, and the graphics and so forth are very well made.

This video starts off looking promising serves as a good factual primer on the science of the nuclear fuel cycle, energy generation, and the issue of fossil fuels and artificial forcing of the greenhouse effect. One starts to think, upon watching the first 5-10 minutes, that this is a good unbiased piece, with the film focussed on statistics and factual scientific and historical discussion, with none of the emotionally manipulative rubbish that anti-nuclear-power groups often produce.

It’s worth watching, anyway.

Now, a rebuttal of the parts I think deserve a rebuttal. Suffice to say, there’s a lot, and once I get ranting, it can be difficult to stop.

I’m sure you’ve all heard all this before – this is preaching to the converted. But I needed to get it off my chest – again.

200 tons of U3O8 is about the appropriate amount of Uranium required to fuel a nuclear power reactor for one GW-year. Assuming 0.15% U3O8 in the ore, then 133,200 tons of ore must be processed to support one GW-year of reactor operation, so, these numbers are OK.

It is claimed that the Olympic Dam mine in South Australia consumes 33 megalitres of water a day. I don’t have a reference for this data in front of me, so I’ll take their word for it.

However, since we’re talking about the nuclear fuel cycle, it must be remembered that Olympic Dam is predominantly a copper mining operation, producing about 220,000 tons of copper annually, along with a relatively minor amount of uranium, about 4500 tons of U3O8.

The other elements present in the orebody at Olympic Dam – uranium, silver and gold – are combined together in the orebody, with the uranium extracted during the processing of copper ore – essentially, a byproduct of copper production. Silver and gold, along with selenium and tellurium in small quantities, are extracted from the “anode slime” produced in the electrolytic refining of copper. Thus, even if the Uranium was not being extracted and marketed, the same amount of ore is still being mined out of the ground.

Now, I’m not an expert on mineral extraction and mining operations, but I will make the rough assumption that the production of one ton of copper metal consumes the same amount of water as the production of one ton of Uranium oxide. Therefore, we infer that Uranium production at Olympic Dam consumes 2% of the total amount of water, or 660,000 litres per day, or 53.5 kilolitres of water per metric ton of uranium oxide produced.

If 200 tons of Uranium Oxide is fuel for a 1 GW nuclear power reactor for one year, and that reactor operates with an 80% capacity factor, then the mining and milling of Uranium at Olympic Dam, then, consumes 1.53 megalitres of water per TWh of electricity produced from that uranium.

For comparison, the mining of coal consumes about 200 litres of fresh water per ton of coal produced. Given that a typical coal-fired power station consumes about 0.5 metric tons of coal to produce 1 MWh of electricity, the mining of coal for electricity generation consumes 100 megalitres of water per TWh of electricity production.

Considering ore with a uranium oxide concentration of 0.15%, as above, 133,200 tons of ore needs to be mined to operate a typical, current technology, 1 GW LWR for one year. A 1 GW reactor operating for one year with a capacity factor of 80% produces 7 TWh of electrical energy – hence, 19 tons of ore mined per GWh. For comparison, again, 500 metric tons of coal needs to be mined and burned to generate the same amount of electricity.

Given that once used nuclear fuel is removed from a typical current reactor, a full 96% of the fuel material, by mass, is Uranium, completely unchanged from when it went into the reactor, and a further 1% of the fuel is good nuclear fuel in the form of plutonium, strictly speaking, if this uranium is recycled and used efficiently, then only 3% of current uranium fuel consumption is needed – 570 metric tons of uranium ore mined per TWh, as contrasted with 500,000 metric tons of coal per TWh.

Of these 17 radionuclides, only five have significantly long half-lives – U-234, Th-230, Ra-226, Pb-210 and Po-210. The remainder have half-lives of between 24 days for Th-234, down to 1.5 seconds for At-218, and 164 microseconds, for Po-214.

Must the tailings from Uranium mining be isolated from the environment for “tens of thousands of years”? Well, the half-life of U-234 is 245,500 years, and the half-life of Th-230 is 75,380 years. However, these half-lives are dwarfed by the half-life of Uranium-238 itself, with a half-life of 4.47 billion years, created in supernovae, billions of years ago.

There is no nuclear transformation of these tailings during uranium extraction – all these daughter products are produced in exactly the same quantities that they were all originally present in, in the original uranium bearing rock.

As such, these radioactive minerals can simply be put back in the original mine, and sealed up with the rock that was originally extracted in the mining operation. Since this is where all these radioactive minerals came from in the first place, the same nuclides, in the same quantities, it is hard to believe that such practice is somehow unsafe or ineffective.

Now, we have the claim that uranium enrichment is a key technology for nuclear proliferation. Uranium must be enriched up to a very high concentration of U-235 for use in a nuclear weapon, and uranium enrichment plants, especially those capable of producing weapons grade material, are very large scale industrial facilities, taking up great volumes of space and consuming a significant amount of energy themselves – they are not easy to hide. The great difficulty involved in the enrichment of uranium, especially to very high levels, is the main reason why plutonium is greatly preferred as the basis for nuclear explosives. Uranium enrichment plants employed in the civilian nuclear fuel cycle can be subject to inspection by the International Atomic Energy Agency, where the nations using them are signatories to the NPT, and international schemes such as the Global Nuclear Energy Partnership can allow nations access to nuclear fuel technology whilst controlling the widespread employment of potentially proliferation-sensitive technologies.

Now, we have the big scary looking list of radionuclides, and accompanying half-lives.

Let’s see – Selenium-79, Zirconium-93, Strontium-90 and so forth. OK, these are reasonably long lived fission products – they comprise the 3% by mass of the used fuel that is not usable as recycled fuel. Some of these materials are valuable, and have potentially important and economical industrial applications, however, it is unlikely that world production of such materials in nuclear reactors will all be consumed, meaning that a significant portion constitutes radioactive waste which needs to be disposed of – most likely, in a deep geological repository.

Rubidium-87 has an extremely long half-life – 49 billion years – meaning that, like Uranium-238 and U-235, it is abundant on Earth, as a cosmogenic nuclide created in supernovae, and comprising 28% of all Rubidium occurring in nature. Similarly, Potassium-40 is a naturally abundant, cosmogenic, primordial radionuclide, which is not created artificially in reactors.

Krypton-83, with a half-life of 10 years… and Calcium-42, claimed to have a half-life of 14,000 years… now just wait one minute. These nuclides are stable – non-radioactive. Whilst I can see how it might be possible to get Kr-83 confused with Kr-85 – a fission product with a half-life of 10.78 years – there are no radioactive nuclides of calcium with a half-life of anything close to that figure. Anyway, Ca-42 is not a fission product. Yttrium-90 is the decay product of Sr-90, with a half-life of only 64 hours.
We see Cobalt-60, Iron-55 and Nickel-63 and Nickel-59 – whilst these themselves are not fission products, they are produced as neutron activation products in the steel and metal structures of the intra-reactor assemblies and reactor vessel – only becoming significant in the form of the intermediate-level waste stream produced during decommissioning of the power reactor. Whilst small amounts of Carbon-14 and Tritium are produced in the cooling water and similar during reactor operation, Beryllium-10 is quite uncommon.

Whilst it is claimed that used nuclear fuel needs to be isolated from people and the environment for hundreds of thousands of years, the radioactive fission products that make up the waste component of the used nuclear fuel – only 3% by mass, remember – will remain significantly radioactive for only 300-500 years.

The film claims that in time, the waste “will escape” even the best engineered containment, and that it is not clear if deep geological disposal of radioactive waste will be possible in practice – however, the process of radioactive decay is absolutely immutable, and the waste only needs to be isolated from the environment for perhaps 500 years, until it is no more radioactive from the uranium ore whence it came – assuming the actinides present are consumed via sensible recycling of the fuel.

Observation of the two-billion year old natural nuclear fission reactors at Oklo provides conclusive empirical evidence that a geological repository is capable of isolating these radioactive waste products from the environment over timescales up to billions of years – amply sufficient for even the longest lived nuclides to completely decay. When the operation of the sixteen nuclear reactors at Oklo was over, nature showed that it could effectively contain the radioactive wastes created by the reactions. It is clear, from this observation of the physical characteristics of nature, that it is possible to isolate such radioactive materials from the environment over the time scale required.

Sweden’s SKB – amongst other such efforts around the world -is engineering a permanent, deep underground, repository for radioactive waste, that requires no monitoring by future generations.The spent nuclear fuel will not be reprocessed, but the used fuel assemblies will be encapsulated in copper. The copper canisters will then be deposited in the bedrock, embedded in bentonite clay, at a depth of 500 metres.

The KBS-3 method used by SKB calls for the spent nuclear fuel to be encapsulated in copper. The copper canisters will then be deposited in the bedrock, embedded in clay, at a depth of about 500 metres. When deposition is finished the tunnels and rock caverns will be sealed.

SKB has chosen to build the repository using materials that are present naturally in the earth’s crust. By studying nature we can find out how copper, bentonite clay, rock and uranium dioxide behave both under different conditions and over different periods of time. By studying the radioactive byproducts of nuclear fission at Oklo, ancient natural cement in Jordan, natural copper in southern England, bentonite clay in Italy, concentrated Uranium deposits in Canada, and so forth, scientists understand the properties of these materials and phenomena that can occur over geologically long spans of time – longer than completely manmade experiments can cover. Analogues are often used to test models, which are in turn used to calculate the solubility of radionuclides in the groundwater.

The fuel will be placed in leaktight copper canisters with a cast iron insert. The canisters will then be transported down to a deep repository consisting of a system of horizontal tunnels at a depth of 400–700 metres in the bedrock.

The tunnels will be about 250 metres long and spaced at a distance of about 40 metres from each other. On the floor of the tunnels, deposition holes will be spaced at intervals of about 6 metres. The copper canisters will be deposited in the deposition holes and surrounded by a buffer of bentonite. When deposition is finished, the tunnels and shafts will be filled with a mixture of crushed rock and bentonite.

The leaktight copper canister will keep the spent fuel completely contained. The buffer of bentonite clay will protect the canister against corrosion attack and rock movements. If a crack should form in one of the canisters, the buffer and intact parts of the canister will prevent water from entering the canister. The buffer will also prevent radionuclides from leaving the canister. The rock will provide an environment where the function of the engineered barriers is preserved for very long periods of time. The rock and the great depth of the repository will keep the spent fuel isolated from man and the environment.

The copper canister that will surround the spent nuclear fuel is nearly five metres long and has a diameter of just over one metre. It weighs between 25 and 27 tonnes when filled with fuel. The outer shell consists of thick copper, and inside is an insert of nodular iron (a kind of cast iron) to provide sufficiently high mechanical strength.

As long as the canister is intact, no radionuclides can escape into the environment. Corrosion and mechanical forces due to movements in the rock are events that could lead to the breach of a canister. The canister is therefore made of materials that are designed to withstand such events. The canister is also designed to withstand major earthquakes following a future ice age.

Before the buffer is lowered into the deposition hole, the hole will be lined with blocks and rings so that a layer is formed between the inner walls of the hole and the canister. This layer is called the buffer, since its purpose is to dampen both mechanical and chemical changes in the rock.

The buffer consists of bentonite clay. It has three functions in the repository: to prevent corrosive substances from reaching the canister, to protect the canister from minor movements and to retard any radionuclides that might escape from a leaking canister.

The purpose of the rock is to isolate the waste. It is also supposed to provide a stable chemical environment for the canister and the buffer and protect them from whatever happens on the ground surface.

The groundwater moves in different ways in the rock’s fracture system. If radionuclides are dissolved in the water, they will accompany the movements of the water. The flow rate of the water varies both between different fractures and within a fracture, but is generally very low.

Virtually all radionuclides in the spent nuclear fuel can adhere to fracture surfaces, fracture minerals and the micropores inside the rock. Only iodine-129 and carbon-14 are somewhat mobile.

Reprocessing plants are not operated with the primary goal of separating plutonium from nuclear fuel – in a specifically plutonium-oriented fuel cycle, this may be the case; however, at present, the worthiness of reprocessing of used nuclear fuel comes primarily from recycling the uranium which makes up 96% of the fuel.

Even if no plutonium is extracted or recycled, recovering this uranium alone makes a vast difference to the long-term sustainability of the nuclear fuel cycle.

It is claimed that no commercially successful plutonium “breeder” reactor has ever been built – however:

* The BN-600 fast breeder reactor in Russia generates 600 MW of electricity, and has been in operation since 1980.

* The BN-350 in Kazakhstan first generated electricity in 1973, producing 150 MW, as well as 120 million litres of fresh water per day via desalination using the reactor’s heat. Whilst the project lifetime of the reactor officially finished in 1993, it continued to operate at reduced capacity until 1999 – a lifetime of 26 years.

* The Dounreay Fast Reactor in Scotland came online in November, 1959, producing an electrical output of 14 MW. The reactor was taken offline for decommissioning in 1977.

* The 233 MWe Phénix fast breeder reactor in France first supplied electricity to the grid in 1973 – it continues to operate to this day, with decommissioning expected possibly in around 2014.

* The 1242 MWe Superphénix fast breeder reactor, a full-scale nuclear power plant, completed construction in 1981 and was closed as a commercial plant in 1996.

* The Monju nuclear power plant in Japan, a sodium-cooled, MOX-fuelled fast breeder reactor, first acheived criticality in April 1994, and generates 280 MW of electricity. Whilst it was closed down for maintenance in 1995 following a sodium leak from the secondary coolant circuit, it is expected to be re-opened next year, and Japan has plans to construct more fast breeder reactors in the future.

It is claimed that major expansion of civilian nuclear energy will greatly increase the amount of nuclear material in circulation in the world – as though the “nuclear material” associated with nuclear power and nuclear weapons is the same thing!

The plutonium produced in power reactors is not weapons grade plutonium, and using such plutonium in a nuclear weapon is very difficult, and requires significant experience and knowledge in nuclear weapons physics – such technology is significantly harder to master than the already very difficult task of designing a nuclear weapon using plutonium.

It is claimed that he cleanup bill for a number of civilian and military nuclear facilities in the United Kingdom is estimated at more than 90 billion pounds – the nuclear weapons programs of the world’s nuclear weapons states, the Manhattan Project, and the Cold War arms race between the United States and the Soviet Union left a very significant legacy of radioactive wastes that were created and stockpiled, with little long-term attention to their safe disposal. Many of these wastes are not in forms which are easily managed, and cleaning them up will take much time and money.

But this is nothing to do with nuclear power – who estimates this cleanup bill, and how much of this cost is the nuclear energy industry responsible for? In the United States, and in other nations using nuclear power, the cost of final decommissioning and waste disposal is factored into the cost of marketed nuclear electricity.

It is claimed that “every stage in the nuclear fuel chain produces radioactive materials” – this is far from correct. It is only the operation of the nuclear reactor itself that “produces radioactive materials” – the radioactivity associated with uranium fuel production, uranium mining and mine tailings is all radioactivity that was originally, naturally present in the ground, and the radioactivity associated with used nuclear fuel and reprocessing wastes is radioactivity that was created in the reactor, along with the radioactivity of naturally occurring uranium.

Yes, exposure to high doses of ionising radiation can cause cancer, teratogenesis, and other deleterious effects on health. This is recognised by everybody – but these high doses of ionising radiation are not relevant to the context of the operation of nuclear power plants.

It is claimed that plant operators at Three Mile Island “fought to keep the reactor core from exploding” – this is simply ridiculous. A reactor core can not, does not, and will not explode – by what physical mechanism can it explode?

The small hydrogen explosion and hydrogen burn that occured within the reactor containment building had no significant engineering consequences – and there was never any danger of the overpressure from such a phenomenon breaching the containment vessel.

It is claimed that “operators released several hundred tons of radioactive gas” into the air, in order to prevent such explosion of the reactor.

It is estimated that a maximum of 13 million curies (480 petabecquerels) of radioactive noble gases were released in the course of the Three Mile Island event.

The noble gas – Krypton and Xenon – nuclides which are produced as fission products with any significantly large yield and which are radioactive, with a half-life so long as to be significant are Kr-85 (approx. 10 years), Kr-88 (2.8 hours), Xe-133 (5.24 days) and Xe-135 (9 hours).

If we assume the entire quantity of radioactive gas vented at TMI was the least radioactive of all the above, Kr-85, then the 13 MCi of radioactivity released corresponds to only 31 kilograms. So, not quite several hundred tons.

The average radiation dose to people living within ten miles of the plant was eight millirem, and no more than 100 millirem to any single individual. Eight millirem is about equal to a chest X-ray, and 100 millirem is about a third of the average background level of radiation received by US residents in a year.

Not a single person was injured, made ill or killed as a result of the Three Mile Island accident – and this is usually regarded as the worst nuclear reactor accident in history, outside the Soviet Union during the Cold War.

The Chernobyl No. 4 reactor experienced a massive power excursion, resulting
in a steam explosion, exposure of the reactor core and ensuing oxidation in
the extremely hot graphite moderator – nuclear grade graphite does not ignite
and burn per se, contrary to popular belief – resulting in a massive release of
radioactive material into the air. The reactor did not experience a “meltdown”.

Quantifying the effects of this event has proven to be difficult due to both
the widespread geographical influence of the radioactive contamination and the long time-scales involved in observing the potential long-term epidemiological consequences of exposure to high doses of ionising radiation.

The reactor was of a fundamentally flawed and unsafe design, and had had all safety systems shut off during a dangerous and unauthorized experiment.

On April 25, 1986, Chernobyl Reactor 4 was scheduled to be shut down for
maintenance. It had been decided to use this occasion as an opportunity to
test the ability of the reactor’s turbine generator to generate sufficient electricity to power the reactor’s water pumps, essential for safety systems, in the event of a loss of connectivity external electric power grid. The RBMK (Reaktor Bolshoy Moshchnosti Kanalniy) reactor requires water to be continuously circulated through the core, as long as the nuclear fuel is present.

A pair of diesel generators are normally used as a source of standby power, but these do not activate instantaneously. The reactor was, therefore, to be used to spin up the turbine, at which point the turbine would be disconnected from the reactor and allowed to spin under its own angular momentum, and the aim of the test was to determine whether the turbines running down could power the pumps while the generators were starting up.

The test was successfully carried out previously on another unit (with all safety provisions active) with negative results: the turbines did not generate sufficient power, but additional improvements were made to the turbines, prompting the need for a second test. As conditions to run this test were prepared, and the reactor electricity output had been gradually reduced to 50%, a regional power station unexpectedly went offline, meaning that the reduction in energy output needed to be postponed in order to supply demand on the electricity grid. The safety test was then left to be run by the night shift crew who would be working Reactor 4 that night. The power output of Reactor 4 was to be reduced from its nominal 3.2 GW thermal to 0.7 − 1.0GWth in order to conduct the test at the prescribed lower level of
power. However, the new crew were unaware of the prior postponement of the reactor slowdown, and followed the original test protocol.

The 135-Xe buildup in the reactor core makes it dangerous to attempt to operate the reactor a few hours after it has been shut down, without great care and understanding of reactor operation. Starting a reactor in a high-Xe condition requires pulling the control rods out of the core much farther than normal, to compensate for the nuclear ‘poisoning’ by 135-Xe. But if the reactor does achieve criticality, then the neutron flux in the core will become quite high and the 135Xe will be rapidly consumed by neutron-induced transmutation – this has the same effect as very rapidly removing a great quantity of reactivity control from the core, and can cause the reaction to grow too rapidly, with the potential to achieve prompt criticality. For this to be attempted in any reactor is a massive lapse in judgment on the part of the operators, and is indicative of extremely bad operator training, lack of safety culture and awareness, and a lack of design features which should make such a procedure impossible, or mitigate its risks.

All these factors were present at Chernobyl.

Nuclear physicists and engineers – most notably Edward Teller – discovered such safety concerns in the context of the early graphite-moderated reactors built at the Hanford site in the US for plutonium production for the Manhattan project, some 40 years before the Chernobyl accident. The early scaled-up graphite moderated nuclear piles at Hanford were arguably the closest the Western world has ever come to building a Chernobyl RBMK style reactor.
Nuclear poisoning due to 135Xe was first discovered in these first such reactors. Teller and his colleagues quickly discovered and pointed out the potential safety concerns associated with graphite-moderated water-cooled reactors having a positive void coefficient. As a result of his team’s persistent voicing of safety concerns over such reactor designs, Teller, most infamous for his tireless advocacy of a strong nuclear arms program and continued argument testing and development of nuclear weapons, in fact became known as “the reactor opposer” around this era, and the graphite-moderated design was never used again in the United States, aside from the nine original military reactors at the Hanford site.

It is exactly this situation which played a large part in the Chernobyl accident: about eight hours after the scheduled maintenance shutdown, workers tried to
bring the reactor to a zero power critical condition to carry out the turbine test, but because the core was loaded with 135Xe from the previous day’s operation, the reactor power output could not be increased above 30 MWt, approximately 5% of what was expected. The operators believed that the rapid fall in output was due to malfunctioning of one of the automatic power regulators, not because of fission poisoning.

In order to increase the reactivity of the reactor, automatic control rods were pulled out of the reactor beyond what is allowed under safety regulations.

Despite this breach, the reactor’s power only increased to 200MW, still less than a third of the minimum required for the experiment. Despite this, the reactor crew’s insufficiently trained and inexperienced management chose to continue the experiment. As part of the experiment, the water pumps that were to be driven by the turbine generator were turned on; increasing the water flow beyond what is specified by safety regulations. Since water absorbs neutrons, this further increase in the water flow necessitated the removal of the manual control rods, producing a very precarious operating situation where coolant water and nuclear poisons were substituting the role of most of the control rods of the reactor.

The unstable state of the reactor was not reflected in any way on the control panel, and it did not appear that anyone in the reactor crew was fully aware of any danger. Electricity to the water pumps was shut off and, as the momentum of the turbine generator drove them, the water flow rate decreased, decreasing the absorption of neutrons by the coolant. The turbine was disconnected from the reactor, increasing the level of steam in the reactor core. As the coolant heated, pockets of steam formed voids in the coolant lines.

The operators were careless and violated plant procedures, partly due to their
lack of knowledge of the reactor’s design, and lack of experience and training.
Several procedural irregularities also contributed to cause the accident. One
was insufficient communication between the safety officers and the operators in
charge of an experiment being run that night. The operators switched off many
of the safety systems, which was generally prohibited by the plant’s published
technical guidelines.

To reduce costs, and because of its large size, the reactor had been constructed
with no containment vessel, and only a large concrete biological shield atop the
reactor, primarily designed for radiation protection for plant personnel whilst
working atop the reactor. This allowed the radioactive contaminants to escape
unchecked into the atmosphere after the steam explosion burst the primary
pressure vessel, and the graphite core started to “burn” – not catching fire, but
oxidising as it was heated to great temperatures, facilitating the dispersal of

The Chernobyl disaster has absolutely no relevance what so ever to the question
of how much radioactivity could conceivably escape from the reactor, reactor
vessel and containment structure into the environment in the event of a
nuclear accident involving today’s civilian light water reactors, since the Chernobyl
RBMK reactor didn’t have a containment structure at all, amongst many
reasons.
Given that the factors that contributed to the Chernobyl disaster have absolutely
no relevance whatsoever to the issue of nuclear energy, today, in the
Western world, by rights, on a rational, factual basis, the disastrous medical
consequences of the disaster have no bearing on the nuclear energy industry in
the United States or elsewhere.

Now, we have the claim that the Forsmark Nuclear Power Plant in Sweden “came within half an hour of a meltdown” in 2006.

On 25 July 2006, one reactor was shut down after an electrical fault. According to the Swedish Nuclear Power Inspection authority, SKI, the incident was rated 2 on the International Nuclear Event Scale.

According to Lars-Olov Höglund, a former construction chief at Vattenfall, it is the most serious nuclear incident in the world since the Chernobyl disaster and it was pure luck that prevented a meltdown.

Both SKI and the safety chief of Forsmark power plant disagree with that opinion and state that the incident was serious but the description provided by Höglund was incorrect and there was no risk of a meltdown.

The media hype in Sweden started with the “independent nuclear expert” Lars Olov Hoeglund stating that this was the “most dangerous event since Chernobyl” and “only luck saved Forsmark from a total meltdown”.

Originally titled “former construction manager” in media reports, Hoeglund has been promoted to “plant manager” and “CEO” of Forsmark in American and English media, and even head of the Swedish Nuclear Inspectorate in German media reports.

In reality, he was never employed by Forsmark. He was “construction manager” for some years at a Vattenfall mechanical engineering department.

He did spend some years at the Forsmark site as a constractor, but only at the waste storage and disposal facility, unconnected with the nuclear power plant.

Maybe more importantly, he has for years been locked in legal conflict with Forsmark (as well as Ringhals NPP), regarding some jobs that his consultancy tendered on but did not get selected for. Apart from this, he has, through legal appeals in environmental courts, delayed a number of projects at both Ringhals and Forsmark.

His claims regarding the shutdown at Forsmark in 2006 have never been substantiated by any credible source.

Regarding the “near miss” at Davis-Besse in the US in 2002, a breach in the Davis-Besse reactor’s corroded pressure vessel head would have
contaminated the reactor’s containment building with reactor coolant from the primary loop. All the radioactivity in such coolant would be contained within
the containment vessel. Emergency procedures would have protected the reactor from core damage, as with any Loss of Coolant Accident. Even the worst
possible situation in this case, a loss of reactor coolant, is far from being a “major catastrophe”, although it is a serious reactor incident. Since the carbon
steel reactor vessel is lined on the inside with a further inch of stainless steel, the corrosion of the outer carbon steel part of the reactor head, caused by a small,
persistent leak of boric acid, could not have completely breached the integrity of the pressure vessel, as stainless steel could not be corroded at all in such a way.

If the vessel was breached, in such a near-impossible manner, then the plant would be shut down, and would be offline for some time. The reactor may have even been, in the worst-case scenario, written off. But no radioactivity would possibly be released into the environment, thanks to the containment vessel.

It is claimed that under the Global Nuclear Energy Partnership, Australia is being promoted as the site for disposal of the world’s nuclear waste, and that sites are being selected for such.

There is simply no credible evidence what so ever that this is a widely promoted ideology, and especially not that it is widely accepted.

It would be kind of like thinking that Saudi Arabia has some kind of obligation to take the world’s production of carbon dioxide, for geosequestration, because they’re one of the leading producers of oil, wouldn’t it?

As the DOE themselves put it, The Global Nuclear Energy Partnership has four main goals. First, reduce America’s dependence on foreign sources of fossil fuels and encourage economic growth. Second, recycle nuclear fuel using new proliferation-resistant technologies to recover more energy and reduce waste. Third, encourage prosperity growth and clean development around the world. And fourth, utilize the latest technologies to reduce the risk of nuclear proliferation worldwide.

Through GNEP, the United States will work with other nations possessing advanced nuclear technologies to develop new proliferation-resistant recycling technologies in order to produce more energy, reduce waste and minimize proliferation concerns. Additionally, the partner nations will develop a fuel services program to provide nuclear fuel to developing nations allowing them to enjoy the benefits of abundant sources of clean, safe nuclear energy in a cost effective manner in exchange for their commitment to forgo enrichment and reprocessing activities, also alleviating proliferation concerns.

The nuclear fuel cycle is not heavily dependant on cheap fossil fuels – certainly not any more dependant on fossil fuels than the production of fossil fuels themselves, or the use of solar, wind, or other energy systems, and the life-cycles associated with them.

The idea that whole-of-life-cycle analysis can demonstrate that nuclear energy
is unsustainable, both on an energy intensity basis and a greenhouse gas intensity
basis, is based on a very limited set of highly dubious science, which has
been widely rebutted, and found to be irreconcilable with the body of scientific
literature established relating to the energy and greenhouse gas intensities of
the nuclear fuel cycle. This will be discussed in greater detail in a later section.
It should not be unreasonable to believe that one day, we can as a society dispense
with fossil fuels entirely, and use clean wind, nuclear and solar-generated
electricity to supply the energy inputs associated with mining and processing
raw materials such as Uranium, Aluminum or Silicon, and the construction of
energy infrastructure, with electricity, and advanced thermochemical processes
used to generate Hydrogen, as transport fuels, thus leading to solar, nuclear or
wind-based energy generation which truly does not produce any greenhouse gas
emissions at all.

The Rossing Mine in Namibia has a Uranium concentration in the ore of about
350 ppm, and produced 3037 tonnes of Uranium in 2004, which is sufficient
for about 15 GW-Yr of electricity with current fuel cycle and power reactor
technology. The energy used to mine and mill this Uranium is about 30 MW-yr,
thus corresponding to an energy gain of about 500.

Extrapolating this, for a Uranium mine to produce no net energy gain, it would
be required to have a Uranium concentration in the ore of no more than about
0.7 ppm. Given that the average concentration of Uranium in the Earth’s crust
is 1-3 ppm, one can expect that the majority of exploitable Uranium reserves
can reasonably be expected to produce a non-trivial energy gain, even utilizing current reactor technologies and current, inefficient 235U based nuclear fuel
cycles.

As I mentioned above, the energy inputs that go into the nuclear fuel cycle don’t
implicitly need to come from polluting, unsustainable fossil fuels. As the rest
of society moves away from fossil fuels to an energy mix of solar, wind, nuclear,
hydroelectric and other sustainable energy sources, so will the mining industry.
In fact, Australian hot fractured rock geothermal energy company PetraTherm
recently signed a memorandum of understanding to supply geothermal electricity
to South Australia’s Beverley Uranium mine by late 2009.

The EURODIF Uranium enrichment plant in Pierrelatte, France receives its entire energy supply from the nearby large Tricastin Nuclear Power Plant, on the same site – no indirect greenhouse gas emissions here, either.

To consider another example, the United States Enrichment Corporation’s Uranium
enrichment plant near Paducah, Kentucky operates using electricity – a
significant amount, about 3 GW at peak operation capacity – generated by the
Tennessee Valley Authority, and supplied via the normal electricity grid. The
TVA supplies energy to the electricity grid using a diverse mix of energy sources
– 11 fossil-fuel plants, six combustion turbine plants, five nuclear reactors and
twenty-nine hydroelectric dams. In 2006, 35% of TVA’s generation capacity –
which we can assume corresponds to 35% of the energy supplied to the Paducah
enrichment plant – was provided by these non-greenhouse intensive hydroelectric
and nuclear generation technologies.

There are a number of publications by Storm van Leeuwen and Smith (hereafter,
SLS) that have received considerable attention because of these authors critical
attitude regarding nuclear power.

There have been scientific counter arguments and rebuttals to their work published
by the World Nuclear Association, with a rebuttal by SLS, and by physicists
from the University of Melbourne, with a rebuttal by SLS, a response by
the authors; a second rebuttal, and a second response. The ISA report mentioned
above is also particularly critical of the work of van Leeuwen and Smith.
The arguments put forward in some of these exchanges are nothing new.

The study of Storm van Leeuwen and Smith neither states energy nor greenhouse
gas intensities, but instead presents temporal profiles showing break-even points
with gas-fired power plants. ISA, therefore, have therefore extracted all energy
coefficients from the study and applied them to a hypothetical nuclear fuel cycle
in Australia. For ores of 0.15% grade, they obtain energy and greenhouse gas
intensities of 0.66 kWhth/kWhe and 212 g CO2e/kWhe, respectively. If such
rich ores are assumed, the construction and decommissioning of the power plant
are the main contributions to energy and greenhouse gas emissions.

If lean ores are assumed (0.01% U), the situation changes drastically: Mining,
milling, and the clean-up of the mine site become the main components of the
total energy and greenhouse gas intensities. The energy and greenhouse gas
intensities are 1.63 kWhth/kWhe and 527 g CO2e/kWhe, respectively.
From a review of the literature concerning the energy intensity, sustainability
and greenhouse gas emissions intensity of nuclear energy over the whole of life
cycle, one notes that there is considerable agreement between numerous different
bodies of work, such as Vattenfall’s environmental product declarations, the
work of the University of Sydney ISA group, the World Nuclear Association,
and independent physicists from the University of Melbourne, just to name a
few, and they all demonstrate findings which are for the most part completely
inconsistent with the work of van Leeuwen and Smith.

Although the greenhouse gas emissions from the nuclear fuel cycle, even with low-grade Uranium ores, remain in the same order of magnitude as other sustainable non-fossil energy sources, this still ignores the point, as previously made, that the nuclear fuel cycle does not implicitly require fossil fuel generated energy to supply these energy inputs – although at present the nuclear fuel cycle
generates a comparatively tiny amount of greenhouse gases, just as does wind,
solar or hydroelectric energy – as clean non-fossil energy sources are developed
further in the future, this will change, and all energy generation will potentially be one hundred percent GHG emission free.

Sure, geothermal and hydro are baseload sources of electrical generation – hydroelectricity, along with nuclear, is one of the largest sources of clean electricity in the world. But if you don’t have the right geology in the right places, if you don’t have the rivers and water resources to play with, then hydro and geothermal are of limited use. Cogeneration – combined heat and power – is usually realised using natural gas, and whilst it realises an increase in the overall efficiency of energy conversion, you’re still burning a greenhouse intensive fossil fuel!

Written by Luke Weston

November 26, 2007 at 5:05 pm