Young Australian Skeptics

As we would probably expect, controversy surrounds the recent approval by Peter Garrett of the development of the Four Mile uranium deposit in South Australia, which will become Australia’s fifth operating uranium mine. You can read more background about this here.

Obviously Garrett will continue to cop a lot of flak for his backflipping with respect to his personal past anti uranium mining activism, and the seeming hypocrisy which goes along with that, and maybe rightly so. But obviously if Garrett was absolutely going to hold onto his past ideologies religiously and never let them change, he wouldn’t have gone into politics at all.

The Four Mile mine will have an annual production of approximately 1400 tonnes of uranium per year. Actually, that figure may represent tonnes of uranium oxide rather than tonnes of uranium equivalent; I’m not completely sure which. The difference isn’t much, in any case.

The conventional, old-​​fashioned and relatively inefficient production of nuclear energy in an existing light-​​water reactor using low-​​enriched uranium fuel with no recycling or efficient reuse of nuclear fuel and using a conventional subcritical steam Rankine-​​cycle powerplant requires an input of approximately 200 tonnes of natural uranium — before uranium enrichment and fuel fabrication — to generate one gigawatt of electrical power for one year.

Therefore, each year’s uranium production from the Four Mile mine is sufficient to generate seven gigawatt-​​years of energy, where it’s utilised really quite inefficiently and most of it isn’t actually used at all, using the old-​​fashioned ways of the established nuclear fuel cycle infrastructure.

The average energy density of typical black coal burned as fuel is approximately 24 megajoules per kilogram, on average. When coal is burned and used to drive a typical steam Rankine-​​cycle powerplant, that plant has a certain realistic degree of thermodynamic efficiency, like any such real heat engine, which is typically somewhere around 33%. Therefore, you get approximately 8 megajoules of electrical energy per kilogram of coal burned.

Therefore, the 1400 tonnes of uranium produced per year at Four Mile will be the equivalent — the alternative to — 27.6 million tonnes of coal. The Cerrejon* mine in Colombia is one of the world’s largest open-​​pit coal mines. In 2007, the black coal production from this mine was 30 million tonnes.

* There should be an accent in the name, but I’m not sure how to typeset it in this blog post.

This is rather incredible, when you think about it for a moment. One rather small uranium mine in Australia produces approximately the same output, in energy terms, as one of the world’s largest open pit coal mines, and it does so with an essentially negligible environmental impact. Furthermore, this is not a large uranium mine — the uranium production figures from Ranger and Olympic Dam are each three or four times larger, for example. This is a really, really big hole in the ground that this uranium has the capacity to replace.

At the moment, the Four Mile deposit is just a deposit. There’s no mine there. But this site is geographically very close to the existing Beverley uranium mine site in South Australia, the geology is comparable, and the in-​​situ leach extraction process to be used at Four Mile will be the same as at Beverley, so you can look at Beverley to get a sense of what the Four Mile mine will be like when it is developed. It will be essentially the same big mine anyway, since they’re right next door and they will share some infrastructure. Beverley produces about 1000 tonnes of uranium oxide per year, compared to 1400 tonnes per year at Four Mile; meaning that Four Mile will be a little bit bigger.

It’s interesting to take a look at the Cerrejon mine using Google Maps, and then take a look at the Beverley mine for comparison. At a certain given image resolution, the vast open-​​pit coal mine fills the entire screen, showing its enormous, undeniable environmental impact and blight on the landscape.

Now, look at the Beverley mine, and keep the resolution the same. There is a small airstrip, some small buildings, a road, a small evaporating lagoon, and some small plant. There’s essentially nothing there, and it’s not even recognizable as a mine at all. Yet this small mine produces two thirds of the energy output as the enormous coal mine (approximately 1000 tonnes of uranium oxide per year, which is a bit smaller than the Four Mile mine will be).
Which one do you think represents the more environmentally sound choice?

Furthermore, this all assumes that the uranium is being utilised relatively inefficiently as low-​​enriched uranium used to fuel light-​​water power reactors, where the majority of the uranium isn’t actually being utilised at all, and it remains stored, unused, in the form of “used” or “spent” irradiated fuel from light water reactors, and in the form of unused “depleted” uranium. The vast resource of uranium which is currently stored in these forms is perfectly usable as fuel — and it represents a vast energy resource which has already been mined and stockpiled. In fact, if we were serious about efficiently using these resources, we wouldn’t even need to talk about uranium mining, because we have already mined all the uranium we could possibly need to meet our energy needs — for many centuries.

When uranium is used efficiently and all of it is used — in a uranium-​​238 burning liquid chloride (molten salt) reactor or an Integral Fast Reactor, for example, it generates approximately 200 MeV of energy from pretty much every single uranium atom, where a single U-​​238 nucleus has a mass of about 238 atomic mass units, of course, and that thermal energy is converted into electricity in a high-​​temperature Brayton-​​cycle gas turbine powerplant, with a thermodynamic efficiency of around 50%.

Therefore, with this kind of efficient use of the uranium resource, the 1400 tonnes of uranium that will be produced each year at Four Mile gives us approximately 1800 gigawatt-​​years of electrical energy. That’s the equivalent of 7.1 billion tonnes of coal.

In 2007, total world coal production was 7.08 billion short tons, or 6.42 billion metric tonnes.

When we start using uranium properly, in an efficient way, one small uranium mine with minimal environmental impact produces more energy than the world’s entire production of coal. It has the capacity to replace all the coal extraction on Earth.

That is an incredible, astonishing, fact. But it is real, and it is awesome.

Well, you may be thinking, we don’t have Integral Fast Reactors and molten-​​salt reactors today. But that’s OK. Even if we want to take the uranium and burn off a bit of the uranium-​​235 using the established LWR plants, that’s OK.

It’s not as if we’re taking the leftover uranium and sealing it up inside a mountain where it can’t be recovered, are we now? The left over uranium is simply stored, at the moment, at our LWR sites and our enrichment sites; waiting to be used. Tomorrow, we can still go and get it and use it efficiently, getting that full value out of it.

Four Mile, like the Beverley deposit, will be mined by in-​​situ leach extraction, which works by pumping a solution underground into the uranium-​​bearing geology through a series of wells. The solution dissolves the uranium, and is then returned to the surface where the uranium is processed. Unlike conventional mining, this method is much less environmentally invasive, there is no need for massive earthmoving or big trucks, it’s much safer for mine workers compared to underground mining (which can always be dangerous, irrespective of what the mineral being mined is), and it is cheaper.

Superficially, the process is not too dissimilar to a enhanced geothermal energy plant, like the ones being developed by GeoDynamics and Petratherm, not too far from the the Olympic Dam and Beverly sites. The wells certainly aren’t as deep for uranium mining, but it’s similar plant. You drill fields of boreholes, pump pressurised solution down into the uranium bearing rock, and it comes back out to your processing plant. In the geothermal energy plant, you’re extracting thermal energy from hot rocks which are hot due to their radioactivity, in the uranium mine you’re extracting the uranium itself, and you have a chemical separation plant in place in place of the heat engine power plant. We don’t consider these geothermal energy projects to be overly environmentally intensive; and likewise ISL extraction from uranium deposits is environmentally sound, too.

The solutions used to dissolve uranium are usually either sodium carbonate and bicarbonate solutions, or dilute solutions of water and sulfuric acid. The optimum choice of the lixiviant chemistry depends on the chemistry of the uranium orebody and the surrounding rock — in the United States, for example, carbonate solutions are normally used because they are what is most compatible with the local geochemistry. Where the host aquifers contain significant quantities of carbonate minerals such as limestone, or dissolved calcium ions, the use of acid chemistry is impractical, since the acid is neutralised by these minerals, and therefore alkaline carbonate solutions are used as these give more efficient, more economical, results in this environment.

In the absence of any significant quantities of such minerals in the geological environment, sulfuric acid solutions are the usual choice of lixiviant chemistry, since this delivers the most efficient results in most geological environments, and is an economical reagent.

We’re not talking about a highly concentrated or highly acidic solution of sulfuric acid, though. In these mining operations, it’s quite a dilute solution — about 2 – 5 g/​L sulfuric acid in an aqueous solution, or about 0.02 to 0.05 mol/​L; quite dilute indeed.

These uranium deposits consist of what is basically uranium-​​bearing sand within an isolated, highly mineralised, saline aquifer. It is this isolated aquifer, and the water within it, which is utilised in the in-​​situ leach extraction process. The water surrounding the uranium is salty and slightly acidic, making an acid extraction chemistry more efficient.

According to the aforementioned article, Greens leader “Bob Brown blasted the decision, saying such a mine would not be allowed in the US because of the contamination of sub-​​ground water”. However, in-​​situ leach extraction of uranium ores started in the United States in the early 1960s. The first such uranium mine in the US was in the Shirley Basin in Wyoming, which operated between 1961 and 1970, using sulfuric acid solutions. Since 1970, all commercial-​​scale ISL mines in the US have used carbonate solutions, as they give superior results in the US geology. As of the end of 2008 there were four ISL uranium mines operating in the United States, producing 90% of the uranium mined in the US.

It is a myth promulgated by anti-​​uranium-​​mining activists that in-​​situ leach mining using acid leachant solutions is somehow banned or prohibited in the United States. If uranium deposits with the same geochemistry as these sites in South Australia were located in the United States, they would be mined using acidic lixiviants for the same reasons that acid leaching chemistry is chosen for these Australian mining operations.

Acid leaching is generally more effective than alkaline leaching, provided that the ore is low in carbonate, as is the case at these deposits — Four Mile, as well as the Beverley and Honeymoon sites — in South Australia. In addition to a high concentration of carbonate, the requirement or mandate to return groundwater at US sites to a baseline condition approaching drinking water quality has also been a contributing factor driving the use of alkaline leachants at ISL mining operations in the USA.

This orebody and surrounding aquifer contains uranium of course, and it contains the daughter radionuclides in the uranium decay series, such as radium-​​226, which are all present in secular equlibrium within the orebody and surrounding water. At Beverley, the groundwater in the aquifer surrounding the orebody is high in salts and orders of magnitude too high in these radionuclides for any practical use for people or for the watering of livestock, without extensive processing. The quality of the water in the aquifer at the Four Mile site is comparable. There is no concievable use for the water in this isolated, uraniferous aquifer, except for serving in the extraction of the uranium. When the mining process is discontinued and the oxygen input into the aquifer is discontinued, the water chemistry will, albeit slowly, revert to its original condition over time.

ISL mining operations in the United States extract uranium from formations containing water of a much higher quality than that at the Beverley/​Four Mile site. In contrast to the Australian sites, in many instances, US projects are mining uranium by in-​​situ leach extraction from aquifers with water quality so high that it is potable water, used for domestic consumption. Additionally, disposal wells at US sites reinject any excess mining solutions into such aquifers, that are of higher water quality than the water in the uraniferous aquifer at Beverley was prior to mining.

The ISL process can certainly change the nature of the groundwater a little; slightly changing the pH, redox potential, and concentrations of dissolved mineral ions in the groundwater in the aquifer containing the uranium-​​bearing sand. But does this really have any significance if the existing water, prior to the mining, is already highly saline, high in uranium-​​series radionuclides, and unsuitable for consumption?

After the cessation of mining operations, these aquifers bearing the uranium deposits will have a slightly lower pH (4.5 — 5.0) than their natural state (pH 6.3), due to the presence of some residual sulfuric acid solution remaining within the isolated aquifer.

This is a highly radioactive, highly saline aquifer, 100 meters below the ground. Adjusting the pH of the aquifer a little will have no plausible impact on its — already non existent — value for domestic or stock watering purposes and will have no other impact on the environment.

Groundwater of a higher quality — suitable for livestock use, and in some cases human use too — is available from different aquifers that are not far from the uranium mining sites. However, the notion that uranium mining could somehow contaminate or pollute such water sources — as is often claimed by the anti-​​uranium-​​mining lobby — doesn’t seem to make all that much sense. If you’ve got one aquifer which contains high quality potable water, and a different aquifer which contains highly saline, radioactive, non-​​potable water, obviously there is no significant degree of hydraulic coupling between the two aquifers, otherwise they wouldn’t have such markedly different compositions, and there would be more of a degree of equilibrium between the two.

Obviously hydrogeological studies are an important part of the environmental impact studies which have gone into the approvals of these mining operations, and they have shown that the aquifers bearing these uraniferous formations are hydrogeologically isolated, and that they do not have any hydrological connection to any high-​​quality, potable water source.

However, as usual, some “environmentalists” retain their dogma and ideology of opposition to uranium mining and nuclear energy. You’re not allowed to question it. Why not? You’re just not. If you apply any science to the question, any open-​​minded skeptical enquiry, then you’re not “Green”, and you’re obviously a paid industry shill, on the take from the big bad industry. Well, in my experience, Big Pharma always fails to deliver those shill payments that I keep hearing about, but maybe Big Nuclear will have their shill payroll department a bit more organized? I don’t know; only time will tell.

Let’s have a look at some specific claims from the Green lobby; and how consistent they seem to be with the science elucidated above.

The Australian Conservation Foundation (ACF) has condemned the mine, saying its chemical and radioactive waste will leach into groundwater.

Greens MLC Mark Parnell said the approval of Four Mile was deeply disappointing and said the proposed in-​​situ leach method was not world’s best practice as claimed.

“The in-​​situ leaching process is highly controversial,” he said.

“Pumping acid into the soil and aquifers will leave behind acid and radioactive wastes for many years to come.”

[Source here]

Oh noes, not the scary radioactive waste!

When you mine uranium, you start off with a deposit of uranium ore, which contains uranium. The uranium is radioactive, but only very, very weakly radioactive. It’s a pretty stable radionuclide — uranium-​​238 has a half-​​life of approximately 4.5 billion years; about as long as the age of the Earth. (According to Ray Comfort, of course, god set it up 6000 years ago to trick us.)

This relatively high stability is the reason there is so much uranium in the Earth in our time — if it was less stable, it would all have decayed away long ago, just as the less stable nuclides, like plutonium, which don’t occur naturally on Earth in significant quantities any more, did.

In the uranium-​​bearing ore, you’ve also got the decay products, including things like radium, radon and polonium, which are a much more significant body of radioactivity than the actual uranium itself. So, you’ve got these radioactive materials — but they all occur completely naturally in the rock inside the Earth. Obviously uranium mining does not “create” any of this radioactivity — it’s all a part of nature. Uranium mining doesn’t involve any kind of nuclear transmutation. All the radioactivity you could possibly be dealing with is all what is naturally present in the orebody.

The chemical composition of the leaching water is set up so that uranium is kept in solution and bought to the surface; the other radionuclides, the daughter products of uranium such as radium, are not dissolved into the solution to a significant degree beyond the extent to which they’re naturally dissolved in the groundwater in the aquifer.

If any radium or what-​​have-​​you is bought to the surface in the pregnant solution, it can just be returned to the wells and put back into the orebody from which it came. The uranium is extracted, it’s bought to the surface, and it’s used. The extraction chemistry is set up so that minimal quantities of radium and other daughter nuclides are extracted and bought to the surface, but for those small amounts that are, why is it a big deal?

Those materials can simply be returned down hole to the aquifer, right back where they naturally came from. You might be left with very small trace quantities of natural uranium that are left over, for example as residues on the plant that handles and packages the natural uranium product, but so what? It’s just uranium; it’s actually less radioactive than the naturally occurring uranium ore, since the highly radioactive components of the uranium ore, like radium, have been separated from the weakly radioactive uranium. Just take those trace residues of uranium, and re-​​inject it into the deposit.
What’s the problem?

Some of the radioactivity in the orebody, that contribution from the uranium itself, is removed from the orebody, since the uranium is being extracted. The remaining radioactivity due to the naturally occuring uranium daughter nuclides is simply left alone where it was originally.

You can see why the notion of “radioactive waste” associated with a uranium mine is a bit of a mendacious one. You simply take what you want — the uranium — out of the deposit, and anything that you don’t want can simply be put back in the ground, where it naturally exists.

Next up in the ring, we have some drama from the Australian Conservation Foundation: [source here]

Contrary to government and mining industry assurances, the newly-​​approved uranium mine at Four Mile in South Australia will harm the environment.

The Australian Conservation Foundation has described the Federal Government approval of the new uranium operation as out of step with community opinion and inconsistent with Labor’s commitment to best practice industry standards.

“Canberra has given a secretive American uranium company the green light to conduct activities it would not be permitted to conduct in the USA,” said ACF nuclear free campaigner David Noonan.

The operation has been granted approval to use the contested acid in-​​situ leach (ISL) technique to extract the uranium. This method involves injecting chemicals into aquifers, contaminating groundwater and poisoning the underground environment.

In 2003 a detailed Senate examination of the Beverley mine recommended that “mines utilising the ISL technique should be subject to strict regulation, including prohibition of discharge of radioactive liquid mine waste to groundwater”.

“General Atomics and its subsidiary Heathgate Resources will be directly dumping increased volumes of liquid radioactive and heavy metal wastes to the groundwater with no requirement for rehabilitation,” David Noonan said.

“This is a long way from best practice; it is a quick and dirty way to get hold of a long-​​lasting and dangerous mineral.”

ACF and other environment and Indigenous organisations have been critical of the operations of the existing Beverley mine and the safety culture of Heathgate Resources following multiple sub and surface spills at the mine.

We’ve examined above how these “activities it would not be permitted to conduct in the USA” claims are mendacious and out of step with impartial, skeptical, science-​​based enquiry. I fail to see how either Alliance Resources, Quasar Resources or Heathgate Resources — those with interests in the development of the mine — are “a secretive American uranium company”. The only American company of relevance is San Diego-​​based General Atomics, the parent company of Heathgate Resources; and they don’t seem particularly secretive to me. We’ve also discussed how the “discharge of radioactive liquid mine waste to groundwater” is a bit of a misleading and mendacious statement — these “liquid radioactive and heavy metal wastes” are the same minerals you originally started with in the deposit; that’s where they come from.

Are there any claims from the Green lobby in relation to mining development at this site which actually do make sense? I’d like to see them.

This entry was posted on Monday, July 27th, 2009 at 4:00 pm and is filed under Luke Weston, Politics, Science. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.