ENRICHMENT | FUEL & FUEL CYCLE
Above: As centrifuges have got much bigger and faster they deliver significantly more performance than they did 50 years ago Source: Urenco
A reassessment dated 1 January 2024 added five years to
the expected lifetime of some centrifuges. Peers explains, “Our centrifuges are incredibly reliable. Whatever end date we expect to achieve they outperform it, so we do have to reassess [regularly] what ‘end of life’ might mean.” Peers says that like any mechanical system, centrifuges typically have a ‘bathtub curve’, with failures more likely at the start of life and rising towards the end, and very few over most of their lifetime. Peers says, “we see almost no failures, or very low failures – so low as to suggest we are not at the end of life for our centrifuges – certainly not for the newer models. It gives a bit of confidence to increase our expected lifetimes to the machines”. Looking back to that first generation of machines, he
says: “We see a similar level of excellent performance in our newer machines and that’s what gives us the confidence to say we can extend their lifetimes by conservative amounts, by five years.” When it comes to maintaining that performance “there is no substitute for experience,” says Peers. The working assumption is that the machines run at full capacity and there will be no outages. “After 50 years we have experience of how to operate them in a smooth and reliable manner so we get the best out of them.”
End-of-life considerations Even the most long-lived centrifuges reach the end of their lives eventually. With thousands in operation, there is a balance to be made to optimise efficiency. “The individual machine will fail, and we can leave that machine and the plant carries on, until there are lots of machines in the same scenario,” says Peers, adding; “eventually you have enough that replacing them will be beneficial. That’s what starts to make the case for doing some refurbishment – swapping out failed machines and replacing them with new ones to restore us to full capacity”. Of course, he says, “you still have to look after the other
components and the auxiliary systems that support the centrifuges. Uranium take-off systems all need a level of maintenance and from time-to-time refurbishment, especially in the older plants, so we do targeted refurbs as well.” He adds that after the first batch of centrifuges were finally retired: “That plant from 1982 is still running: we shut down the oldest centrifuges in 2016 but we completed a
significant outage in 2024 to make some upgrades to the auxiliary systems and some safety upgrades and it is now back online”. As in all nuclear installations, the end-of-life phase for equipment and buildings implies a very different regime from their operating life. In its annual report Urenco said; “work on centrifuge
decommissioning will be a critical enabler to the success of the capacity programme and will involve dismantling, declassifying and decontaminating all centrifuge types”. That process is directed by James MacLeod, Urenco Nuclear Stewardship’s Managing Director. As Peers has described, over time there will be steady trickle of centrifuges that have to be stripped out and replaced, with occasional larger volumes as a result of a refurbishment. MacLeod explains that all waste – not just radiological waste – has to be handled through a set process. Waste prevention and minimisation are the first considerations and MacLeod says “creating as little waste as possible,” is key. This fits with UK and EU guidance on ‘waste hierarchy’ used by many industries, which gives top priority to waste prevention, followed by re-use, recycling and recovery, before disposing of residual waste. In accordance with this process, the company is looking at options to re-use centrifuges parts where appropriate. “Our R&D department is in discussions with ETC, our centrifuge technology joint venture, on agreeing decontamination techniques and limits to allow the outer casings of the centrifuges (called the recipients) to be returned to ETC in such a state that they would be able to refurbish them and we would be able to reinstall and reuse them,” says MacLeod, adding “It is difficult, because you need dismantling lines capable to carefully remove the internals and decontaminate to a level that is sufficient for re-use.”.
That development work is ongoing. To prepare for the
process, all the sites will need additional storage facilities in the first instance to store the centrifuges followed by dismantling lines and enhanced waste treatment facilities to manage the resulting waste. “They have to have a centrifuge dismantling line and that will be a number of cells that will take the centrifuge apart and decontaminate it”, explains MacLeod. In that process, he says, “We work to separate and decontaminate component parts of the
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