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

Archive for the ‘uranium mining’ Category

Rethinking nuclear power.

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ABC Unleashed has recently featured an article by environmentalist Geoffrey Russell; Rethinking Nuclear Power.

It’s worth reading.

I like the idea of closing down uranium mines, and using existing stocks of mined uranium efficiently.

Uranium mining is far less environmentally intensive than mining coal, of course, but it’s basically inevitable that all mining is fairly environmentally intensive, and it’s always an appealing prospect if we can mine less material (whilst still maintaining our energy supplies and our standards of living, of course.)

I have to admit, when I first saw Geoff’s claim that we could completely eliminate uranium mining, I was skeptical. So I took a more detailed look.

A nuclear reactor which is efficiently consuming uranium-238 and driving a relatively high efficiency engine (typically, a Brayton-cycle gas turbine) will require approximately one tonne of uranium input for one gigawatt-year of energy output. This high efficiency use of U-238 could be best realized something like an IFR or a liquid-chloride-salt reactor (the latter is essentially the fast-neutron uranium fueled variant of a LFTR). This figure of one tonne of input fertile fuel per gigawatt-year is also comparable for the efficient use of thorium in a LFTR.

There are about one million tonnes of already mined, refined uranium in the world, just sitting around waiting to be put to use, which is termed so-called “depleted uranium”.

According to one source, the exact worldwide inventory of depleted uranium is 1,188,273 tonnes [1].
The total electricity production across the world today is about 19.02 trillion kWh [2].

Therefore, total worldwide stocks of depleted uranium, used efficiently in fast reactors, could provide every bit of worldwide electricity production for about 550 years.

That’s not forever, but it’s a surprisingly long time. And that’s just “depleted uranium” stocks; not including the stocks of HEU and plutonium from the arsenals of the Cold War, and not including the large stockpile of uranium and plutonium that exists in the form of “used” LWR fuel.

I know some thorium proponents aren’t going to like this; but there’s a strong case to be made here that uranium-238 based nuclear energy has a clear advantage over thorium, simply became of these huge stockpiles of already-mined uranium, for which there exists no comparable thorium resource already mined. The 3,200 tonnes of thorium nitrate at NTS is tiny compared to the uranium “waste” stockpile, but they’re both really useful energy resources which can replace the need for more mining.

Any type of breeder or burner reactor utilising 238U, or 232Th, as fuel requires an initial charge of fissile material to “kindle” it; however this requirement for fissile material is quite small; and personally, I think the inventories of HEU and weapons-grade plutonium recovered from the gradual dismantlement of the arsenals of the Cold War are perfectly suited to this purpose – destroying those weapons materials, whilst putting them to a valuable use.

Then again, with the means to completely replace the use of coal and fossil fuels in a way that requires very little or no uranium mining, I really hope the rest of the world keeps buying that iron and copper and bauxite. Alternatively, we’re going to have to start developing a more technologically based economy in this country to make up the reduction in exports of these commodities – perhaps developing and selling reactor technology?

Developing uranium enrichment technology, such as SILEX, is of limited usefulness because the relatively inefficient thermal-neutron fission of 235U, and hence the need for enrichment, will not supply any large portion of world energy demand in a sustainable fashion over the long term. The small amount of 235U in nature is of limited significance, over the long term.

Alternatively, perhaps a shake up of agriculture, using extensive desalination to supply fresh water requirements, might be used to replace Australia’s income from coal and uranium. I’m not sure.

Tip ‘o the hat to Barry at Brave New Climate for pointing out this article.

[1]: http://www.wise-uranium.org/eddat.html
[2]: From the World Factbook, 2008 ed. (jokes about the integrity of CIA’s intelligence aside…)

The environmental footprints of coal and uranium mining.

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Here’s something worth thinking about.

This is a coal mine. Specifically, it’s the Blair Athol coal mine in central Queensland, Australia, but there’s no special reason why I chose this specific example of a coal mine. The mine produces 12 megatonnes of coal per year. (This is just a satellite image taken from Google Maps, which anybody can of course easily access.)

Coal has a thermal energy content of about 25 MJ/kg, and therefore 12 megatonnes of coal corresponds to a primary energy content of about 2.9 x 1017 J.

This is the Ranger uranium mine, near Jabiru in the Northern Territory of Australia. Again, nothing special about this specific uranium mine, it’s just an example.
All these satellite images are at a consistent scale factor, or zoom level/resolution.

In 2007-2008, Ranger produced 5273 tonnes of U3O8.

A conventional, relatively inefficient low-enriched uranium fuelled LWR with a thermal (primary energy) power output of about 3 GW requires approximately 200 tonnes of U3O8 to be mined to fuel it for one year, assuming that newly mined uranium is used for all its fuel.

Therefore, the annual uranium output from Ranger corresponds to about 2.5 x 1018 J of primary energy, or about 8.6 times the primary energy content supplied by the coal mine.

That is, that one uranium mine supplies the same amount of energy content as nine of the coal mines – one seemingly quite small uranium mine, which is about a third of the size of the coal mine, supplies the same amount of primary energy content as this. (I won’t embed that image in the post, since it will probably completely destroy the formatting of the page.)

Written by Luke Weston

January 9, 2009 at 7:24 am

Western Australia lifts uranium mining ban.

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Western Australia has lifted the previous Labor government’s effective ban on uranium mining, with immediate effect. The Government’s decision, which has been fully expected ever since the change of government in WA, makes way for the potential exploitation of dozens of uranium deposits across the state.

“It is now open to the mining industry in this state, if they wish to proceed with plans to develop the uranium industry,” Premier Colin Barnett said today.

“It’s significant that Australia has the largest reserves of uranium of any country in the world and is second only to Canada as the major producer and exporter.”

The move would not require legislation because Labor’s previous ban on uranium mining was only administrative, he said. “Both Geoff Gallop and Alan Carpenter talked about a ban on uranium and the like but never introduced any legislation to do it”.

“They simply put in place that administrative caveat on a mining lease; now we are removing that.

“The one practical difficulty we face is that 1475 mining leases have been issued since June 2002 which exclude uranium mining, so the department is now seeking some legal advice.”

Uranium prices have fluctuated over recent years, with a spot price of $US135.00 per pound in June 2007 to $US46 last Friday.

Australia produced and exported just 20 per cent of the world market and demand would continue to rise strongly, Mr Barnett said.

West Australian Mines and Petroleum Minister Norman Moore said he had met with uranium producers since the state election but would not say which companies had shown an interest in mining.

He said proper processes needed to be put in place first.

“The department (of minerals and energy) has met with … counterparts from South Australia and the Northern Territory and the commonwealth and we will put in place quickly the regulatory regime for the mining and transport of uranium,” Mr Moore said.

“There’s a lot of benefits to be had for Western Australia if we have a uranium industry and I’d like to see it happen sooner rather than later.”

Written by Luke Weston

November 17, 2008 at 12:24 pm

” Nuclear’s CO2 cost ‘will climb'”.

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The BBC is reporting that:

The case for nuclear power as a low carbon energy source to replace fossil fuels has been challenged in a new report by Australian academics.

It suggests greenhouse emissions from the mining of uranium – on which nuclear power relies – are on the rise.

Availability of high-grade uranium ore is set to decline with time, it says, making the fuel less environmentally friendly and more costly to extract.

A significant proportion of greenhouse emissions from nuclear power stem from the fuel supply stage, which includes uranium mining, milling, enrichment and fuel manufacturing.

Others sources of carbon include construction of the plant – including the manufacturing of steel and concrete materials – and decomissioning.

You can read the rest of the original BBC article here.

Perhaps more significantly, you can download the original academic paper in question here.

I will quote a couple of paragraphs worth:

Overall, the data clearly show the sensitivity of sustainability assessments to the ore grade of
the uranium deposit being mined and that significant gaps remain in complete sustainability reporting and accounting. This paper is a case study of the energy, water, and carbon costs of uranium mining and milling within the context of the nuclear energy chain.

In summary, the extent of economically recoverable uranium, although somewhat uncertain, is clearly linked to exploration effort, technology, and economics but is inextricably linked to environmental costs such as energy, water, and chemicals consumption, greenhouse gas emissions, and broader social issues. These crucial environmental aspects of resource extraction are only just beginning to be understood in the context of more complete life cycle analyses of the nuclear chain and other energy options. There still remains incomplete reporting however, especially in terms of data consistency among mines and site-specific data for numerous individual mines and mills, as well as the underlying factors controlling differences and variability. It is clear that there is a strong sensitivity of energy and water consumption and greenhouse gas emissions to ore grade, and that ore grades are likely to continue to decline gradually in the medium- to long-term. These issues are critical to understand in the current debate over nuclear power, greenhouse gas emissions, and climate change, especially with respect to ascribing sustainability to such activities as uranium mining and milling.

So, to summarise exactly what the paper says:

There are some inputs of energy  associated with the nuclear fuel cycle on a whole-of-life-cycle during uranium mining and milling, and in practice at present there are some carbon dioxide emissions associated with these energy inputs.

As reserves of easily recoverable high-grade uranium ore decline, assuming that the greenhouse-gas intensity of the energy inputs into the mining operations remain comparable, the whole-of-life-cycle greenhouse gas emissions intensity of nuclear energy might be expected to increase somewhat.

I think we already know that. Everyone already knows that.

The lead author of the paper, Gavin Mudd, is an Australian academic with a background in geohydrological engineering. He is a nuclear energy skeptic – well, not so much a nuclear energy skeptic as someone who is skeptical of the ecological sustainability of current uranium mining practices. His main area of expertise and interest with regard to nuclear energy is uranium mining.

I use the term “nuclear energy skeptic” because it’s reasonably clear that he’s anti-nuclear-energy – but I think it’s almost uncharitable and unfair to put an academic who puts forward their arguments in terms of reasonably well constructed academic papers in peer-reviewed science journals in the same category as the likes of Wasserman, Gunter or Caldicott.

This paper does not at all say “nuclear energy is unsustainable” or “uranium mining is unsustainable” – once the journalists apply a little spin to it, however, it’s easy to see how many could try and apply this paper, and especially press articles like the above, towards evidencing such a conclusion.

Describing the fact that there are energy inputs associated with uranium – which we already know – doesn’t answer the real question at all – How does the whole-of-life-cycle greenhouse gas intensity per MWh of electricity generation actually quantitatively compare to the whole-of-life-cycle greenhouse gas intensity of other energy generation technologies?

Sure – it’s somewhat reasonable to suggest that these quantities will change over the long term, into the future. Quantitatively, how will they be expected to change?

I should add, finally, that this paper is notable for being – perhaps – the first ever nuclear-skeptical study of the energy and greenhouse gas intensity of the nuclear fuel cycle that does not invoke the work of van Leeuwen and Smith. In fact, in terms of the quality of the source material cited, this paper seems pretty good.

Expansion at Olympic Dam means increased energy inputs (of course).

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Apparently, some people out there are shocked with new projections that expanded operations, proposed to be completed around 2013, at BHP Billiton’s Olympic Dam facility will entail significant expansion of the mine’s electricity consumption – projected to be an average of 690 megawatts per year, or around 40% of South Australia’s total electricity consumption, when the expansion is complete.

Here’s the complete story, from news.com.au.

(As an aside, I’m quite pleased to note, when reading the comments on the above-linked webpage, just how much pro-nuclear-energy sentiment seems to be out there.)

Olympic Dam is a copper mine. When the expanded production reaches full capacity in 2015 or so, 450,000 tons of copper metal will be produced annually.

There is a little bit of uranium, gold, and a couple of other things mixed into the orebody which are valuable too, so they extract them as well when the copper ore is processed.

It’s a homogeneous orebody – the uranium and copper and things are all mixed together, so it is impossible to mine the copper without mining uranium, too.

For that 450,000 tons of copper metal that will be produced, only about 14,000 tons of uranium oxide will be produced. The uranium is only a byproduct.

Remember – without copper being mined out of the ground, no electricity of any kind, clean, green or not, can be generated, distributed or used. Without production of aluminium metal, a popular target of so-called environmentalists, electricity transmission over overhead cables cannot be done.

Even since the stone age or the bronze age, mining has been integral to the existence of our technological civilisation. Even as we move to clean sources of energy to power our technological civilisation, such as geothermal and nuclear energy, mining will always be essential.

Now, the expanded mine will consume 690 megawatts of electrical power, on average.

A typical nuclear power reactor generating 1 gigawatt of electricity requires an amount of uranium fuel corresponding to about 200 tons of natural uranium in the form of uranium oxide per year.

So, Olympic Dam will consume 690 megawatts of electricity – and it will produce enough uranium in one year to generate 70 gigawatts of electricity for one year –
over one hundred times the total power consumption of the mine.

Yes, you might be thinking that this ignores the other energy inputs into the nuclear fuel cycle – but it also assumes an extremely inefficient once-through fuel cycle using low-enriched uranium in current light water reactors, without recycling of fuel.

Of course, one must remember that the vast majority of the energy input at Olympic Dam goes into the extraction and smelting of copper metal – the overall “energy gain” typically associated with actual uranium mining operations are typically much higher than 100.

Another point that anti-mining and anti-nuclear-power activists love to make in Australia is that mines such as Olympic Dam use too much water.

The Olympic Dam mine consumes about 30 megalitres of water a day – 30 million litres, in total, for the township, as well as all mining operations. Is that a lot?

Olympic Dam, at present, produces about 200,000 tons of copper annually, along with a relatively small amount of uranium, about 4300 tons of U3O8.

Now, I’m not an expert on mineral extraction, hydrometallurgy, 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 600,000 litres per day, or 140 litres of water per metric ton of uranium oxide produced.

If 200 tons of natural uranium in the form of uranium oxide is sufficient to make up the fuel for a 1 GW nuclear power reactor for one year, and that reactor operates with an 90% capacity factor, then the production of Uranium at Olympic Dam then consumes 3550 litres of water per TWh of electricity that can be 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 million litres of water per TWh of electricity production.