The nuclear crisis in Japan threatens a carefully choreographed UK Government plan to tackle the world's biggest mountain of plutonium waste stored at the Sellafield site in Cumbria.
Japanese nervousness about nuclear power following the near-meltdown at the Fukushima plant has led to a freeze in the international trade of reprocessed nuclear fuel that the Government sees as critical to solving Britain's own plutonium problem.
The Government's preferred strategy to eliminate the UK's growing plutonium stockpile centres on a technology that was developed to meet the demands of the Japanese market, yet there are now fears that Japan is about to turn its back on the enterprise.
It was hoped that Japanese contracts with Sellafield to make mixed oxide (Mox) nuclear fuel would underpin the economic and political case to tackle Britain's plutonium stockpile with a second multi-billion-pound Mox fabrication plant on the Cumbrian site.
However, Japanese power companies have told Sellafield that concerns about Fukushima have forced them to indefinitely postpone a shipment of French-made Mox nuclear fuel that would have been transported on British vessels operated from Sellafield.
The postponement is significant because the Mox shipment was not destined for the stricken reactors at Fukushima operated by Tokyo Electric, but for the unaffected Hamaoka reactors operated by Chubu Electric, the same company that was supposed to be one of the first customers of the existing Sellafield Mox Plant (SMP).
Chubu Electric and nine other Japanese power companies have also indicated that because of long-term production problems that have dogged the SMP, they will not now be taking any reprocessed fuel from Britain until at least the end of the decade – nearly 20 years after the plant was opened to serve the Japanese market.
This would mean that the existing Mox plant at Sellafield, which was designed to supply more than 1,000 tons of Mox over 10 years, is likely to produce a tiny fraction of this before it is due to be decommissioned, at enormous cost to the British taxpayer.
The setback is seen as a huge blow to the business of making and selling Mox fuel, touted by the Government as the best way of dealing with Britain's stockpile of civilian plutonium, which is itself the product of nuclear-waste reprocessing at Sellafield.
Government ministers, their officials and advisers are all privately convinced that "recycling" plutonium waste into nuclear fuel that could be "burned" in nuclear reactors represents the safest and least expensive option in dealing with the stockpile.
A Government consultation on the stockpile ends next month but ministers have already made it clear that the "Mox option" is their preferred route, even though it would require a second Mox plant at Sellafield costing £3bn at discounted prices – the actual lifetime cost of the plant is likely to be nearer £6bn.
The existing Sellafield Mox Plant, opened in 2002, has cost more than £1.3bn to date yet has produced just 13.8 tons of Mox fuel in nine years compared to an expected output of 120 tons per year. A leaked cable from the US embassy in London said Sellafield's Mox plant was a white elephant costing about £90m a year and considered, privately, by the UK Government as "[one of] the most embarrassing failures in British industrial history".
Yet, ministers have now agreed they should press on with preparing the public for an even bigger Mox plant to deal with the growing stockpile of British-owned plutonium, expected to reach 109 tons within a few years.
Independent scientists, from Sir David King, the former chief scientist, to fellows of the Royal Society, are supporting a new Mox plant and believe there is no viable alternative.
However, nuclear experts have told The Independent that the existing Sellafield Mox plant is a serious drain on the budget of the Nuclear Decommissioning Authority, which took over the Sellafield site from BNFL in 2005. They said that the authority would like to close the plant, except that to do so would be a PR disaster at a time when the Government is about to propose another one.
In January, before the nuclear crisis at Fukushima, Jonathan Marland, a junior Government minister, told the House of Lords that a new Mox plant at Sellafield would turn the world's biggest plutonium stockpile from a liability into an asset and that a decision on whether to go ahead and build it is likely later this year. Lord Marland admitted that the existing Mox plant is not fit for purpose, which is why the Nuclear Decommissioning Authority has brought in the French nuclear company Areva, which wants to build the second Mox plant based on its own Mox operation at Marcoule in the south of France.
Although the Government has not finished its consultation exercise on the plutonium stockpile, it has already made it clear that the long-term storage and disposal of plutonium would be even more expensive than building a second plant to convert it into Mox fuel.
Q: What is Britain's "plutonium mountain"?
A: It is the nation's stockpile of radioactive plutonium, kept as plutonium dioxide powder, packed into special drums stored at Sellafield in Cumbria. A further, smaller amount is stored at the Dounreay nuclear facility in Scotland, the site of the doomed nuclear fast-breeder reactor programme.
Q: Why is the plutonium stockpile so big?
A: This is civilian plutonium, not military. It is largely the result of a decision in the 1960s to extract the plutonium from spent nuclear fuel for use in fast-breeder reactors, which were never built commercially. Britain continued to accumulate civilian plutonium, currently amounting to 84 tonnes, along with foreign-owned plutonium, currently 28 tonnes. The final British-owned plutonium stockpile will be 109 tonnes, once fuel reprocessing from existing nuclear reactors has been completed.
Q: Why do we need to do anything with it?
A: Plutonium remains radioactive for many thousands of years – just how long depends on which isotope. Experts say that doing nothing with the stockpile is not an option – the current methods of storage will eventually become unsafe in decades to come. Plutonium either has to be put into long-term storage, with a view of permanent disposal at some future point in cement or glass blocks, or used in some way that makes it "safer", such as incorporating it into Mox fuel that is used in a reactor.
Q: Is converting plutonium to Mox fuel safe?
A: Plutonium is an extreme health risk if it gets inside the body – it emits alpha particles which are highly dangerous if they penetrate the skin because they damage the DNA of cells and cause cancer. It is also a security risk because of its use in nuclear weapons and "dirty" bombs. By converting it to Mox fuel, and irradiating this fuel in reactors, some experts believe that plutonium will, ironically, become safer because, being more radioactive, it will be more difficult to handle. Opponents argue that manufacturing Mox necessarily increases security risks not least because of the transport of Mox fuel rods, and even plutonium dioxide, which can be subject to terrorist attacks of accidents.
Q: Is it easy to use Mox fuel in nuclear reactors?
A: Some reactors do use Mox, but only as a small percentage (less than 30 per cent) of the total fuel. The rest of the fuel is conventional uranium oxide. Supporters of Mox suggest that the new generation of nuclear reactors to be built in Britain could burn Mox fuel and thereby be used to diminish the plutonium stockpile. However, the new reactors have been licensed to burn uranium-only fuel and none of the reactor designs being considered has been "justified" for Mox, which in any case remains far more expensive than conventional uranium fuel.