Years of investment have made Urenco one of the world's leading suppliers of nuclear fuelessionAn eerie tick-tock greets you as you enter E23, a plain industrial building on Urenco's sprawling campus at Capenhurst, near Chester, central England. The noise, like an amplified grandfather clock, is everywhere in the cavernous building, crackling out of tannoys perched above the banks of machines. The noise should never stop. It signifies that the building's radiation monitoring system is working properly. It gives a clue to what goes on in E23 - the uranium-enrichment process that provides fuel for nuclear power stations and is one of Britain's best-kept secrets. The 72-hectare site has housed Britain's efforts to turn mined uranium into something suitable for use as a nuclear fuel since the 1950s. Now, in E23 and two other similar buildings, thousands of centrifuges - the exact number is not disclosed - spin night and day, separating the useful uranium atoms from the ordinary ones. Urenco, which is owned by the British and Dutch governments and the German utility groups Eon and RWE, is reaping the rewards of 40 years of taxpayer-funded investment in centrifuge technology. "It's a classic case of their having made a much better mousetrap than anyone else," said one nuclear industry executive. In recent years the trinational group has enjoyed a boom, its turnover rising from euros 700m (pounds 600m) in 2004 to euros 1.1 billion last year as it grabbed market share from its international rivals. It now makes about a quarter of all the enriched uranium used in civil nuclear plants around the world and has an order book that extends beyond 2025. More than three-quarters of Capenhurst's production is exported, with American power plants among its big customers. Urenco is also profitable in a way that most businesses can only dream of, turning that euros 1billion of sales into an operating profit of euros 460m. Last year, in the depth of the credit crisis, it was able to raise nearly euros 700m (euros 500m from a bond issue, euros 196m in a loan from an insurance group) to help pay for a large expansion programme, including the construction of a facility in America. The good times, however, could soon get even better thanks to what promises to be a bonanza for uranium enrichers. All around the world governments are pressing ahead with big reactor programmes, with China alone planning to have dozens in operation or under construction in the next 20 years. In Britain, up to 10 reactors could be built or started over the same period. Even this renaissance could be just the tip of the iceberg. Many energy experts think that to address climate change, we will have drastically to curtail the burning of fossil fuels to generate electricity. This could bring an even faster rate of construction. Malcolm Wicks, a former energy minister, said in a report published recently that Britain should plan to double the proportion of its energy generated from nuclear power, from 20 per cent to 40 per cent. Helmut Engelbrecht, Urenco's chief executive, is optimistic about the prospects but warns that the company's competitors will catch up. "Our competitors are in the process of changing their enrichment methods to centrifuge technology. This will enable them to supply customers under comparable conditions to Urenco. While we expect to continue to grow our share of an expanding market, that growth may be moderate in the future. The overall demand for nuclear fuel will definitely increase when the new reactor construction programmes are realised and that will create additional demand for our services," he said. Much of the technology in use at Capenhurst remains closely guarded, and not just for commercial reasons. Enriched uranium is also used in the construction of atomic weapons, and international worries about nuclear proliferation led to the 1970 treaty that created Urenco. At first a marketing organisation for state nuclear bodies such as BNFL, it took over the manufacturing operations in 1993. Uranium arrives at Capenhurst in crystals that look a bit like sugar. This is uranium hexafluoride, the end result of the chemical processing of mined uranium ore. At the plant the crystals are heated and uranium hexafluoride gas is piped into the centrifuges. Natural uranium has a tiny percentage of slightly lighter atoms in it, called Uranium 235. These are the ones that are useful for atomic power plants. The centrifuges spin the gas at high speed, with the lighter atoms moving to the edge of the drum, increasing the amount of 235 atoms. This stream of gas is siphoned off and sent to the next centrifuge, where it is enriched again. The Capenhurst machines typically increase the proportion of 235 atoms from 0.7 per cent - the natural rate of occurrence - to about 4 per cent. Although the tick-tocks in the factories are a reminder that it handles radioactive substances, the main safety threat is not radiation but the uranium hexafluoride itself, which is extremely corrosive and toxic. Urenco's stellar financial record means that it has frequently been mentioned as a potential candidate for privatisation, although the trinational ownership structure makes a sell-off unlikely in the near term. Senior investment-banking sources say, however, that a fundraising through the sale of shares - perhaps to fund an acquisition in America - cannot be ruled out. Engelbrecht said he is confident of having sufficient funds to invest in whatever expansion will be required when the nuclear power boom arrives. "We invest only when customer commitments require an expansion of capacity," he said. "Our strategy of growth through investment is mainly based on our own earnings. Fifty percent of all our profits are spent on growing our business. In addition to that, we use the capital markets to fund our growth. We are confident that, based on our conservative business model, we will be able to secure our future financial needs."