INSIDE BUILDING B33 - a drab, anonymous structure at the cutting edge of nuclear science - Janette Lount pointed lovingly at a group of strange, cage-like structures and said: "They're my babies."
It seemed an odd way to describe fuel assemblies containing deadly uranium and plutonium, but it was a measure of the pride with which she and her co-workers have pushed the frontiers of the nuclear industry to new, often misunderstood, levels.
Ms Lount is the operations manager at British Nuclear Fuels Ltd's MOX Demonstration Facility (MDF) in Sellafield, Cumbria - the place where the next generation of nuclear power has been developed. A cross between a laboratory and a shop floor, this is where plutonium waste from reprocessed fuel is again reprocessed to suck out the last drops of heat and power from the procedure of splitting the atom.
It is also the place where, according to an admission by BNFL, "irregularities" in the testing of deadly mixed-oxide (MOX) fuel pellets have been found. Worse than this is the suggestion, according to a source at the plant, that it is a place where safety records have been "falsified", allowing unchecked and potentially dangerous pellets to be packed into fuel assemblies that are destined for nuclear power stations in Japan.
It sounds complicated yet, in the words of Ms Lount, a vibrant mechanical engineering graduate from Nottingham Polytechnic, making MOX fuel is "like making cakes". In simple terms, MOX is a mixture of recycled plutonium and uranium, which is processed into powder, mixed with lubricant and cast into pellets one centimetre long and weighing six grams.
These are then "sintered" or baked at a temperature of 1600C and loaded into zirconium alloy tubes measuring about 1.25cm by 3.5m, filled with helium and welded shut. All of this takes place in a sealed assembly line, with workers using glove boxes or robot systems but, once sealed in the rods, the operation is then conducted in the open.
This is the stage where, during a recent visit by The Independent, the process appeared surprisingly low-tech. About 150 people work there, 70 of them actively involved in making the fuel rod assemblies, drawing rods into a frame through a single wooden case impregnated with resin.
"Don't touch," visitors are warned - but only to prevent blemishing of the surface of the rods. Once sealed, they give off only low levels of gamma radiation and are safe enough for workers to load into larger square assemblies ready for lowering into nuclear reactors.
Each six-gram pellet holds the equivalent energy of one tonne of coal. According to BNFL, three such pellets in a nuclear reactor can provide a family's needs for a whole year and each assembly can produce enough power for 30,000 families for a year.
"There may be waste, which is manageable, but there are no carbon dioxide emissions from nuclear power," said Ms Lount. "We are very proud of what we do here but it must be done with accuracy. We can put the rods into an assembly in half a day, yet to prepare the rods can take months."
It may be the laborious nature of the preparation of the rods that led to the "irregularities" being investigated by BNFL. Already, 40 assemblies, produced by BNFL and COGEMA in France, have been made for Japan. The consequences of defects could, therefore, be economically fatal for the industry, which sees MOX as the way to use the plutonium waste from reprocessing. Arthur Roberts, head of BNFL's MOX programme, describes the use of MOX as "completing the nuclear fuel cycle", a process which ensures that 97 per cent of nuclear waste can be recycled and sent back to customers - initially Japan. The alternative is storing it on site for at least the next 25 years.
Critics of the programme argue that transporting MOX around the world adds to the risk of nuclear proliferation because, they claim, plutonium can be extracted from it. In July, when the first MOX shipments headed for Japan, Greenpeace quoted Dr Frank Barnaby, a former Aldermaston nuclear physicist, as saying: "If a terrorist group acquired MOX fuel, it could, relatively easily, chemically separate the plutonium and fabricate a nuclear explosion." Standing next to the latest MOX assemblies in B33, Ms Lount said that Dr Barnaby's claim was rubbish.
It would, she said, be very difficult to extract plutonium - and even before you tried, you would have to get hold of the MOX, she added. And to complete that task, you would have to catch and board two fast-moving ships armed with cannon, overcome guards, neg- otiate welded hatches above the nuclear cargo, and remove the 100-tonne transportation flasks from their holds without the use of cranes, which are taken from the ships before they embark. At the time, the kidnap of her "babies" was all that the environmental groups were concerned about. However, claims of apparent wilful falsification of records by persons unknown have created concerns that had previously only haunted us in nightmares and fiction.