Thorp - the letters stand for Thermal Oxide Reprocessing Plant - is a large, expensive factory built by British Nuclear Fuels (BNFL) at its Sellafield works in Cumbria. It is not a power station; its job is to take the spent fuel that is discharged from nuclear power stations and clean it up ready for re-use.
How is this done?
After three years in the core of a reactor, nuclear fuel has to be removed, not because its uranium is used up but because there is a build-up of highly radioactive waste material known as fission products, which clog up the nuclear chain reaction and prevent the generation of power.
In a reprocessing plant, the spent fuel is stirred into a soup of hot concentrated nitric acid and other chemicals and then the various chemical components are drawn out. About 96 per cent of the original uranium is still there and after reprocessing it can be recycled. About 1 per cent has been transmuted into plutonium; the other 3 per cent is the fission products, which have no use.
How did Thorp come to be built?
In the 1970s Arab oil-producing countries held a gun to the heads of Western governments. Oil prices soared and governments feared supplies might be cut off. Many turned to nuclear power and bought up vast stocks of uranium, pushing the price to unprecedented levels. So when BNFL proposed the Thorp plant in 1977 with the promise that it could extract re-usable uranium from spent fuel, the idea was greeted with enthusiasm.
What about the plutonium?
The extra plutonium was seen as an added attraction, since it would be used in the 'fast' reactors of the future. Fast reactors were expected to be the fulfilment of the nuclear dream: not only would they make use of plutonium extracted from spent fuel, they would also 'breed' more plutonium (which in turn would be extracted at Thorp). They would be power stations which manufactured their own fuel as a by-product.
Are there customers for Thorp?
Yes. BNFL has secure orders, worth about pounds 9bn, for the first 10 years of Thorp's operational life: roughly one-third with Japan; one-third with Europe (mainly Germany); and one-third domestic (Nuclear Electric and Scottish Nuclear). The firm hopes to win orders worth pounds 3bn for the second 10 years.
So what is the problem?
The world has changed since 1977, but no one told Mrs Thatcher, the Department of Energy, or British Nuclear Fuels as it went on spending nearly pounds 2.8bn. On the one hand, since Three Mile Island and Chernobyl, public distaste for large new nuclear factories has grown, and there is a strong environmental lobby against Thorp. On the other hand, the cost of nuclear power stations rose, particularly in the US, while the price of oil and gas collapsed. As a result, there is now a glut of cheap uranium, a situation likely to persist for decades. In addition, the British fast reactor was cancelled as too complex and expensive, so there is no use for the plutonium.
Why don't the customers pull out?
Because they can't afford to. BNFL signed them up in the Seventies to contracts with heavy penalty clauses. Besides, it did not pay for Thorp itself; it got its customers to stump up pounds 1.6bn, so they're stuck.
Some of the customers are trapped in another way. The operating licence for every German nuclear power station requires its owner to demonstrate to the public that its spent nuclear fuel will be dealt with safely. For nearly 20 years the German utilities have been meeting this requirement by saying that the spent fuel would be reprocessed at Thorp. If BNFL said: 'We're not going ahead with Thorp, please come and take back the several thousand tonnes of your highly radioactive fuel that we have in storage', the German branch of Greenpeace would go to court arguing that every German nuclear power station was operating illegally.
What will happen if the Government cancels?
According to BNFL, if Thorp never operates it would potentially lose pounds 1bn in profit, about 2,000 jobs would go in West Cumbria, and overseas customers would demand their pounds 1.6bn advance payments back. Recently, the company has begun to say that it might also have to pay up to pounds 5bn compensation. The figures are disputed by opponents. The only way to know would be public examination of the contracts, but these are kept secret for reasons of commercial confidentiality.
Is there any way out?
Technically, yes. There is no reason why spent nuclear fuel needs to be reprocessed straight away. It can be safely stored for decades and then either buried in the ground or, if there is another energy crisis, reprocessed then. This option has been chosen at the Sizewell B pressurised water reactor nearing completion in Suffolk, which intends to store at least 20 years'- worth of spent fuel on site. Scottish Nuclear also reckons it can save around pounds 50m a year by building a dry store for spent fuel at its two nuclear power stations.
To cancel Thorp and do this on a larger scale, however, would offer only a technical solution; the financial, economic and legal problems would remain.
What will happen to the plutonium and uranium?
Most of it will probably be stored at Sellafield. This will not be cheap. Plutonium in particular is a highly radioactive substance which remains dangerous for tens of thousands of years. If it is to be treated as waste, the nuclear industry will probably have to build another deep underground repository of roughly the same size as the one already proposed for Sellafield (which will cost billions and require the excavation of as much rock as the Channel Tunnel). A third repository will be required to take radioactive fission products.
Any other ideas?
BNFL is now thinking about a different solution. This is to put mixed uranium-plutonium fuel, known as Mox, into ordinary reactors. But instead of the endless recycling envisaged with fast reactors, when the Mox comes out of the reactors it would just be buried. This raises the question: why separate the plutonium from spent fuel, incorporate it into Mox, use it in a reactor and then bury the spent Mox fuel, when you could have buried the original spent fuel in the first place?
How important is Thorp to the economy?
West Cumbria suffers high unemployment which is likely to get worse as the Trident submarines leave the Barrow shipyards. Building Thorp has provided a great deal of employment locally. Last week, BNFL said that about 1,700 people were being laid off as a result of delays over Thorp, but these were mainly contract staff who would have been laid off months ago if the plant had started up according to BNFL's own timetable. Friends of the Earth and Greenpeace have suggested that jobs could be created if Thorp were cancelled now and Sellafield was used to store spent fuel at the site pending its disposal. BNFL says few jobs would be created in this way.
Thorp's contribution to the national economy is more debatable. BNFL claims Thorp will make a profit of pounds 500m over the first 10 years of its operations, in which time all the capital cost will have been paid off and enough money put aside for decommissioning the plant. But the basis for these calculations is not open for public inspection, again because BNFL says its contracts are confidential. As the plant is unlikely to open before mid-November at the earliest, more than a year behind schedule, Thorp's profit potential must already be down to pounds 400m, according to the company's own estimates of pounds 2m lost for every week of delay.
Other commentators have warned that even a small increase in decommissioning costs, or further delays due to unforeseen technical problems, could turn profit into loss.
Would its cancellation doom the nuclear industry?
No. The business of the nuclear industry is to generate and sell electricity. Thorp would provide an ancillary service.
Will the Government cancel Thorp?
No. Ultimately the political cost of stopping Thorp is greater than the Government could stomach.
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