The news comes only a day before a last-ditch attempt in the High Court by Greenpeace and Lancashire County Council to stop the controversial pounds 2.85bn thermal oxide reprocessing plant from going ahead.
BNFL completed Thorp, intended to recycle spent fuel from nuclear power stations, in March 1992, but intense public opposition has led to nearly two years of delay. Although the Government finally gave the company permission to start the plant on 15 December, in the High Court tomorrow Greenpeace and Lancashire will seek a judicial review of the decision.
A company spokeswoman confirmed that engineering design work for a new reprocessing plant was now being carried out 'as part of our continuing business practice to look at cheaper and smaller alternatives, post-Thorp.' If realised, the company's plans could lead to Sellafield being the site of four reprocessing plants, in various stages of use.
Last week the Independent on Sunday exclusively revealed that the radioactive waste from these and other plants could produce an uncontrollable nuclear reactor beneath the Cumbrian countryside - according to a former Sellafield scientist - if the nuclear industry goes ahead with its plan to bury it in a deep underground repository.
Although Thorp has not yet operated, its design was drawn up in the Seventies and would use old technology. The company's design engineers think they can now employ new technologies in planning a smaller, successor plant. The company said it would be premature to suggest who might be the new plant's customers.
One nuclear industry source, from outside BNFL, said that the projected lifetime of Thorp was about 20 years 'and that's not long'. It took the company nearly 15 years to build Thorp so, allowing time for design work to be completed and for planning permission to be granted, the company is almost compelled to start planning the plant now.
A possible customer could be Nuclear Electric's new pressurised water reactor at Sizewell in Suffolk, which is due to come on-line later this year. Sizewell will store spent fuel on-site for at least 25 years, so that its fuel would have to be reprocessed in a 'son of Thorp' plant, if it is reprocessed at all.
There are three reprocessing plants on the Sellafield site, but only one of them is fully operational. The 30-year-old Magnox reprocessing plant, known as building B205, takes fuel from the first generation of Britain's civil nuclear reactors and also from the military reactors operated by BNFL at Calder Hall, adjacent to Sellafield, and at Chapelcross in southern Scotland.
Next to the Magnox plant stands B204, which was originally built to extract plutonium for military use. In the Seventies, this plant suffered an internal explosion resulting in widespread internal contamination after BNFL had used this plant for experiments in reprocessing more advanced fuels than the Magnox type.
Pending the outcome of the court case this week, no fuel has yet been put through the Thorp plant.
However, the reprocessing plants represent only a small part of the nuclear fuel cycle operations now being conducted on the Sellafield site.
Last month, the company started a new plant to manufacture fresh fuel containing a mixture of plutonium and uranium. The pounds 26m mixed-oxide fuel fabrication plant at Sellafield is a pilot-scale operation, making fuel for a Swiss pressurised water reactor.
The demonstration plant has a capacity of eight tonnes of fuel a year and the company said that 60 per cent of its capacity for the first ten years has either been contracted or reserved.
For reasons of commercial confidentiality, BNFL would not name any of the interested parties other than its confirmed customer, the Swiss utility NOK.
Later this month, the company hopes to get the go-ahead from the local planning authority, Copeland Council, to start building a full-scale mixed-oxide fuel fabrication plant at Sellafield.
Although the Swiss utility is the company's only existing customer for plutonium-uranium fuel, it has sufficient confidence that others will be forthcoming to invest pounds 300m over the next four years in building the new plant to make 120 tons of fuel a year.
Nuclear Electric confirmed yesterday that it had asked BNFL to look at the 'indicative costs' of providing mixed oxide fuel for the Sizewell-B pressurised water reactor, in Suffolk, which is due to start generating electricity later this year.
(Photograph omitted)Reuse content