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Nuclear Power Dossier - Uranium Mining and Milling

Jon Hughes

1st June 2006

Remote, unregulated and...running out. Why the business of fuelling nuclear power can't give us energy sovereignty

Once construction is under way, the business of sourcing uranium to fuel the reactor starts. The problem is that uranium doesn’t sit neatly in the ground in ready-to-use packages, it has to be mined and milled – both environmentally destructive processes. While the element is found everywhere on earth, geological surveys show that most deposits of uranium are found in concentrations of about 0.02-0.01 per cent (200-100g per tonne of rock).

This means that round 9,800 tonnes of rock has to be mined and milled to give up one tonne of uranium. A standard 100mw/eh nuclear reactor requires in the region of 160 tonnes of uranium fuel – processed from around 16 million tonnes of rock – each year. At these levels of concentration, mining and milling uranium is uneconomic and uses more energy to recover than it will ultimately produce.

Uranium is taken from the earth like any other raw material: blasted and dug from open pits, causing thousands of tonnes of radioactive rock to be disturbed, the dust of which finds its way into water, plants, animals, fish and humans for hundreds of miles around. Sometimes these pits can be 250 metres deep. When they are, polluted surface water has to be pumped away from the mine to keep it operational, further contaminating local water supplies.

Worse is to come at the mill, which is a chemical plant by another name. Here, huge diesel-powered machines crush the rock into a more manageable size ready for leaching. In most cases, sulphuric acid is used as the primary leaching agent. As this not only extracts uranium from the ore, but also several other constituents like molybdenum, vanadium, selenium, iron, lead and arsenic, the uranium must be separated out of the leaching solution. The final product from the mill, commonly referred to as ‘yellowcake’, is packed in casks ready to be shipped to the purchaser.

The leaching process only ever extracts around 90 per cent of the uranium, the rest remains in the waste rock, which is known as tailings. Sometimes leaching takes place ‘in situ’. This involves pumping hundreds of tonnes of sulphuric acid, nitric acid, ammonia and other chemicals into the rock strata and then pumping it up again after some 5 to 25 years. In situ leaching is fast becoming the industry’s preferred method because it is cheaper. But it is also wasteful, yielding only about a quarter of the uranium from the treated rocks. The end result is the same – vast amounts of radioactive and toxic metals are dumped into the local environment and aquifers.

Dumping the waste

The uranium mill tailings are normally dumped as a sludge in special ponds or piles, where they are abandoned. The largest such piles in the US and Canada contain up to 30 million tonnes of solid material. In Saxony, Germany, the Helmsdorf pile near Zwickau contains 50 million tonnes, and in Thuringia, the Culmitzsch pile near Seelingstädt has 86 million tonnes.

The amount of sludge produced is nearly the same as that of the ore milled; at a grade of 0.1 per cent uranium, 99.9 per cent of the mined rock is left over. This contains all the constituents of the ore and 85 per cent of its initial radioactivity, as long-lived decay products such as thorium-230 and radium-226 are not removed, and up to 10 per cent of the uranium is never captured. In addition, the sludge contains heavy metals and other contaminants, such as arsenic, and residual chemical agents used during the milling process.

Mining and milling removes hazardous constituents in the ore from their relatively safe underground location and converts them to a fine sand, making the hazardous materials more susceptible to dispersion in the environment.

By rights this waste should be treated: the acids should be neutralised with limestone and made insoluble with phosphates; the mine floor should be sealed with clay before the treated tailings are put back into it; the overburden should be replaced and the area should be replanted with indigenous vegetation. In practice, all this is rarely done. It is expensive, and according to Ceedata, a renowned environmental consultancy, it also requires approximately four times the amount of energy that was needed to extract the ore in the first place.

The cavalier regulation of mines has been cruelly exposed. In the 1980s in America, highly radioactive tailings were used in building homes, dramatically increasing the cancer rate amongst the inhabitants. Similar abuses have taken place in Eastern Siberia in the 1990s. As mines are often found in remote locations, so they are almost impossible to police and regulate. And just as unscrupulous builders can use the tailings, so, too, could the potentially lethal yellowcake fall into the wrong hands.

The Navajo legacy

Having experienced the mining and milling process first hand, the Navajo nation has said, ‘Never again’. They know from experience what a poisonous business it is. In the 1950s, uranium mines were opened across the Navajo nation, leaving a legacy the current tribal president Joe Shirley Jr describes as ‘genocide’. Dozens of premature deaths of Navajo miners and passed-on genetic defects have been attributed to uranium exposure from that time.

‘You look around the reservation and see so many elderly people who are crippled and can barely breathe,’ said Robert Stewart Sr, a Navajo who worked for five years in a mine in the mid- to late 1950s. ‘This pretty much devastated much of a generation.’

Navajo chiefs have understandably outlawed a return of mining to their reservation, which covers 27,000 square miles across parts of Arizona, New Mexico and Utah.

Hydro Resources Inc, however, is expected to fight the ban. The mining company says there are nearly 50,000 tonnes of uranium reserves on the reservation, which they want to mine using the in-situ leaching method.

Around the world there is a backlash against uranium mining. Australia has the largest deposits of uranium ore in the world, with 40 per cent of an identified 3.5 million tonnes – enough, the industry say, to fuel current world nuclear capacity for another 45-50 years.

Opposition to this environmentally destructive business has restricted companies in Australia to mining just 10 per cent of the reserves and the Australian government has just awarded the Aboriginal owners and Kakadu national park the right to veto mining there, setting a precedent for the Northern Territories where most of the country’s reserves of ore are.

There is, however, a more pressing problem for industry. Uranium is a finite fuel and it is running out. Nuclear power currently generates 2.5 per cent of the world’s electricity supply. In industrialized countries, such as the UK, US and Japan, nuclear generates in the region of 17-20 per cent of electricity. All these countries are talking about increasing their nuclear capacity. The government’s chief scientist Sir David King has talked about doubling capacity in the UK, to around 30 per cent. Japan envisages building another 30 reactors, the US around 10-15. If nuclear capacity doubles in size, then the ore is going to run out in 20 years.

Under such circumstances there is no guaranteed price stability. The spot market price has risen 600 per cent in the past four years amid talk that nuclear capacity is to double in size.

In turn there will be no security of supply. Outside of Australia the other 60 per cent of the world’s reserves of ore are, in order of size, divided between Kazakhstan, Canada, South Africa, Namibia, Brazil, the Russian Federation, America, and Uzbekistan. As a uranium shortage looms, it is unlikely that nuclear nations such as America, Russia and Canada will sell their uranium, which means the UK will be reliant on supplies from less stable sources. Having made such a capital investment in nuclear, we would be a hostage to fortune. Creating an electricity supply around a fuel that is known to be running out gives us no greater energy sovereignty than we would get from relying on the Middle East for oil or Russia for gas.

Understandably, the nuclear industry is seeking to assure its potential markets that any uranium shortage will be addressed. To that end it has been looking at alternative sources: notably, extracting uranium from granite and seawater. Both are fantastical.

Granite has an average uranium content of four grams per tonne. Ceedata say the process would use 30 times more energy to extract the uranium than it would eventually produce.

Seawater is promoted as another option. This involves using nets in the ocean to fish for uranium, and a five stage chemical process to clean, separate and prepare it for use. The process is so complicated that it would take three times as much energy to source as it would eventually produce and involve the use of highly-polluting chemicals.

The other hope is that fast-breed reactors will come on stream. These are reactors that create their own fuel while they generate electricity. It was the promise of this technology that led to the claim 50 years ago that nuclear power would generate electricity ‘too cheap to meter’. The problem is that fast-breed reactors have never worked.

‘Breeding’ involves three complex operations working in conjunction: breeding, reprocessing and fuel fabrication, which has never been achieved. The process causes waste that clogs and corrodes the equipment undertaking it. There are three fast-breed reactors in the world: Beloyarsk-3 in Russia, Monju in Japan and Phenix in France. Monju and Phenix have long been out of operation; Beloyarsk is still operating, but it has never bred.

Nevertheless, the nuclear industry still believes fast breed technology holds the answer to future electricity supply, using thorium as a fuel. Ceedata estimates this technology, which relies on uranium and plutonium as a start-up fuel, could theoretically double in size every 40 years. So if we use uranium and plutonium to fire up two thorium reactors today, in 40 years they would have made enough fuel to start another two. This accepts the technology is ready, which it is not. The most optimistic forecast is that this technology might be ready in 20 years.

All the while, greenhouse gas emissions will be being released into the atmosphere. A 1998 study for the Canadian nuclear industry found that for every unit of usable uranium recovered, 20 units of C02 are released into the atmosphere. This figure is generous to the industry, as it is based on extracting particularly high grades of uranium, of around one per cent.

As most deposits of uranium in the world are found in concentrations of about 0.02 per cent or less, the true picture is far more corrosive. According to Ceedata, as soon as it becomes necessary to mine ores of below 100g per tonne, more C02 is emitted into the atmosphere than any emissions savings a nuclear power station could make over a 24-year generating life.

To read the full Nuclear Power Dossier click here

This article first appeared in the Ecologist June 2006

 

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