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Dismantling Sellafield: the epic task of shutting down a nuclear site

Nothing is produced at Sellafield anymore. But making safe what is left behind is an almost unimaginably expensive and complex task that requires us to think not on a human timescale, but a planetary one

Guardian, by Samanth Subramanian 15 Dec 22,

“……………………………………………………………………….. Laid out over six square kilometres, Sellafield is like a small town, with nearly a thousand buildings, its own roads and even a rail siding – all owned by the government, and requiring security clearance to visit………. having driven through a high-security gate, you’re surrounded by towering chimneys, pipework, chugging cooling plants, everything dressed in steampunk. The sun bounces off metal everywhere. In some spots, the air shakes with the noise of machinery. It feels like the most manmade place in the world.

Since it began operating in 1950, Sellafield has had different duties. First it manufactured plutonium for nuclear weapons. Then it generated electricity for the National Grid, until 2003. It also carried out years of fuel reprocessing: extracting uranium and plutonium from nuclear fuel rods after they’d ended their life cycles. The very day before I visited Sellafield, in mid-July, the reprocessing came to an end as well. It was a historic occasion. From an operational nuclear facility, Sellafield turned into a full-time storage depot – but an uncanny, precarious one, filled with toxic nuclear waste that has to be kept contained at any cost.

Nothing is produced at Sellafield any more. Which was just as well, because I’d gone to Sellafield not to observe how it lived but to understand how it is preparing for its end. Sellafield’s waste – spent fuel rods, scraps of metal, radioactive liquids, a miscellany of other debris – is parked in concrete silos, artificial ponds and sealed buildings. Some of these structures are growing, in the industry’s parlance, “intolerable”, atrophied by the sea air, radiation and time itself. If they degrade too much, waste will seep out of them, poisoning the Cumbrian soil and water.

To prevent that disaster, the waste must be hauled out, the silos destroyed and the ponds filled in with soil and paved over. The salvaged waste will then be transferred to more secure buildings that will be erected on site. But even that will be only a provisional arrangement, lasting a few decades. Nuclear waste has no respect for human timespans. The best way to neutralise its threat is to move it into a subterranean vault, of the kind the UK plans to build later this century.

Once interred, the waste will be left alone for tens of thousands of years, while its radioactivity cools. Dealing with all the radioactive waste left on site is a slow-motion race against time, which will last so long that even the grandchildren of those working on site will not see its end. The process will cost at least £121bn.

Compared to the longevity of nuclear waste, Sellafield has only been around for roughly the span of a single lunch break within a human life. Still, it has lasted almost the entirety of the atomic age, witnessing both its earliest follies and its continuing confusions. In 1954, Lewis Strauss, the chair of the US Atomic Energy Commission, predicted that nuclear energy would make electricity “too cheap to meter”. That forecast has aged poorly. The main reason power companies and governments aren’t keener on nuclear power is not that activists are holding them back or that uranium is difficult to find, but that producing it safely is just proving too expensive.

… The short-termism of policymaking neglected any plans that had to be made for the abominably lengthy, costly life of radioactive waste. I kept being told, at Sellafield, that science is still trying to rectify the decisions made in undue haste three-quarters of a century ago. Many of the earliest structures here, said Dan Bowman, the head of operations at one of Sellafield’s two waste storage ponds, “weren’t even built with decommissioning in mind”.

As a result, Bowman admitted, Sellafield’s scientists are having to invent, mid-marathon, the process of winding the site down – and they’re finding that they still don’t know enough about it. They don’t know exactly what they’ll find in the silos and ponds. They don’t know how much time they’ll need to mop up all the waste, or how long they’ll have to store it, or what Sellafield will look like afterwards. The decommissioning programme is laden “with assumptions and best guesses”, Bowman told me. It will be finished a century or so from now. Until then, Bowman and others will bend their ingenuity to a seemingly self-contradictory exercise: dismantling Sellafield while keeping it from falling apart along the way.

To take apart an ageing nuclear facility, you have to put a lot of other things together first. New technologies, for instance, and new buildings to replace the intolerable ones, and new reserves of money. (That £121bn price tag may swell further.) All of Sellafield is in a holding pattern, trying to keep waste safe until it can be consigned to the ultimate strongroom: the geological disposal facility (GDF), bored hundreds of metres into the Earth’s rock, a project that could cost another £53bn. Even if a GDF receives its first deposit in the 2040s, the waste has to be delivered and put away with such exacting caution that it can be filled and closed only by the middle of the 22nd century.

Anywhere else, this state of temporariness might induce a mood of lax detachment, like a transit lounge to a frequent flyer. But at Sellafield, with all its caches of radioactivity, the thought of catastrophe is so ever-present that you feel your surroundings with a heightened keenness. At one point, when we were walking through the site, a member of the Sellafield team pointed out three different waste storage facilities within a 500-metre radius. The spot where we stood on the road, he said, “is probably the most hazardous place in Europe”.

Sellafield’s waste comes in different forms and potencies. Spent fuel rods and radioactive pieces of metal rest in skips, which in turn are submerged in open, rectangular ponds, where water cools them and absorbs their radiation. The skips have held radioactive material for so long that they themselves count as waste. The pond beds are layered with nuclear sludge: degraded metal wisps, radioactive dust and debris. Discarded cladding, peeled off fuel rods like banana-skins, fills a cluster of 16-metre-deep concrete silos partially sunk into the earth.

More dangerous still are the 20 tonnes of melted fuel inside a reactor that caught fire in 1957 and has been sealed off and left alone ever since. Somewhere on the premises, Sellafield has also stored the 140 tonnes of plutonium it has purified over the decades. It’s the largest such hoard of plutonium in the world, but it, too, is a kind of waste, simply because nobody wants it for weapons any more, or knows what else to do with it.

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………………………………… I only ever saw a dummy of a spent fuel rod; the real thing would have been a metre long, weighed 10-12kg, and, when it emerged from a reactor, run to temperatures of 2,800C, half as hot as the surface of the sun. In a reactor, hundreds of rods of fresh uranium fuel slide into a pile of graphite blocks. Then a stream of neutrons, usually emitted by an even more radioactive metal such as californium, is directed into the pile. Those neutrons generate more neutrons out of uranium atoms, which generate still more neutrons out of other uranium atoms, and so on, the whole process begetting vast quantities of heat that can turn water into steam and drive turbines.

During this process, some of the uranium atoms, randomly but very usefully, absorb darting neutrons, yielding heavier atoms of plutonium: the stuff of nuclear weapons. The UK’s earliest reactors – a type called Magnox – were set up to harvest plutonium for bombs; the electricity was a happy byproduct. The government built 26 such reactors across the country. They’re all being decommissioned now, or awaiting demolition. It turned out that if you weren’t looking to make plutonium nukes to blow up cities, Magnox was a pretty inefficient way to light up homes and power factories.

For most of the latter half of the 20th century, one of Sellafield’s chief tasks was reprocessing. Once uranium and plutonium were extracted from used fuel rods, it was thought, they could be stored safely – and perhaps eventually resold, to make money on the side. Beginning in 1956, spent rods came to Cumbria from plants across the UK, but also by sea from customers in Italy and Japan. Sellafield has taken in nearly 60,000 tonnes of spent fuel, more than half of all such fuel reprocessed anywhere in the world. The rods arrived at Sellafield by train, stored in cuboid “flasks” with corrugated sides, each weighing about 50 tonnes and standing 1.5 metres tall.

………….. at last, the reprocessing plant will be placed on “fire watch”, visited periodically to ensure nothing in the building is going up in flames, but otherwise left alone for decades for its radioactivity to dwindle, particle by particle.

ike malign glitter, radioactivity gets everywhere, turning much of what it touches into nuclear waste. The humblest items – a paper towel or a shoe cover used for just a second in a nuclear environment – can absorb radioactivity, but this stuff is graded as low-level waste; it can be encased in a block of cement and left outdoors. (Cement is an excellent shield against radiation. A popular phrase in the nuclear waste industry goes: “When in doubt, grout.”) Even the paper towel needs a couple of hundred years to shed its radioactivity and become safe, though. A moment of use, centuries of quarantine: radiation tends to twist time all out of proportion.

On the other hand, high-level waste – the byproduct of reprocessing – is so radioactive that its containers will give off heat for thousands of years. …………………………….

Waste can travel incognito, to fatal effect: radioactive atoms carried by the wind or water, entering living bodies, riddling them with cancer, ruining them inside out. During the 1957 reactor fire at Sellafield, a radioactive plume of particles poured from the top of a 400-foot chimney. A few days later, some of these particles were detected as far away as Germany and Norway. Near Sellafield, radioactive iodine found its way into the grass of the meadows where dairy cows grazed, so that samples of milk taken in the weeks after the fire showed 10 times the permissible level. The government had to buy up milk from farmers living in 500 sq km around Sellafield and dump it in the Irish Sea.

From the outset, authorities hedged and fibbed. For three days, no one living in the area was told about the gravity of the accident, or even advised to stay indoors and shut their windows. Workers at Sellafield, reporting their alarming radiation exposure to their managers, were persuaded that they’d “walk [it] off on the way home”, the Daily Mirror reported at the time. A government inquiry was then held, but its report was not released in full until 1988. For nearly 30 years, few people knew that the fire dispersed not just radioactive iodine but also polonium, far more deadly. The estimated toll of cancer deaths has been revised upwards continuously, from 33 to 200 to 240. Sellafield took its present name only in 1981, in part to erase the old name, Windscale, and the associated memories of the fire.

The invisibility of radiation and the opacity of governments make for a bad combination. Sellafield hasn’t suffered an accident of equivalent scale since the 1957 fire, but the niggling fear that some radioactivity is leaking out of the facility in some fashion has never entirely vanished. In 1983, a Sellafield pipeline discharged half a tonne of radioactive solvent into the sea. British Nuclear Fuels Limited, the government firm then running Sellafield, was fined £10,000. Around the same time, a documentary crew found higher incidences than expected of leukaemia among children in some surrounding areas. A government study concluded that radiation from Sellafield wasn’t to blame. Perhaps, the study suggested, the leukaemia had an undetected, infectious cause.

It was no secret that Sellafield kept on site huge stashes of spent fuel rods, waiting to be reprocessed. This was lucrative work. An older reprocessing plant on site earned £9bn over its lifetime, half of it from customers overseas. But the pursuit of commercial reprocessing turned Sellafield and a similar French site into “de facto waste dumps”, the journalist Stephanie Cooke found in her book In Mortal Hands. Sellafield now requires £2bn a year to maintain. What looked like a smart line of business back in the 1950s has now turned out to be anything but. With every passing year, maintaining the world’s costliest rubbish dump becomes more and more commercially calamitous.

The expenditure rises because structures age, growing more rickety, more prone to mishap. In 2005, in an older reprocessing plant at Sellafield, 83,000 litres of radioactive acid – enough to fill a few hundred bathtubs – dripped out of a ruptured pipe. The plant had to be shut down for two years; the cleanup cost at least £300m. …………………………………………………………………………….

Waste disposal is a completely solved problem,” Edward Teller, the father of the hydrogen bomb, declared in 1979. He was right, but only in theory. The nuclear industry certainly knew about the utility of water, steel and concrete as shields against radioactivity, and by the 1970s, the US government had begun considering burying reactor waste in a GDF. But Teller was glossing over the details, namely: the expense of keeping waste safe, the duration over which it has to be maintained, the accidents that could befall it, the fallout of those accidents. Four decades on, not a single GDF has begun to operate anywhere in the world. Teller’s complete solution is still a hypothesis.

Instead, there have been only interim solutions, although to a layperson, even these seem to have been conceived in some scientist’s intricate delirium. High-level waste, like the syrupy liquor formed during reprocessing, has to be cooled first, in giant tanks. Then it is vitrified: mixed with three parts glass beads and a little sugar, until it turns into a hot block of dirty-brown glass. (The sugar reduces the waste’s volatility. “We like to get ours from Tate & Lyle,” Eva Watson-Graham, a Sellafield information officer, said.) Since 1991, stainless steel containers full of vitrified waste, each as tall as a human, have been stacked 10-high in a warehouse. If you stand on the floor above them, Watson-Graham said, you can still sense a murmuring warmth on the soles of your shoes.

Even this elaborate vitrification is insufficient in the long, long, long run. Fire or flood could destroy Sellafield’s infrastructure. Terrorists could try to get at the nuclear material. Governments change, companies fold, money runs out. Nations dissolve. Glass degrades. The ground sinks and rises, so that land becomes sea and sea becomes land. The contingency planning that scientists do today – the kind that wasn’t done when the industry was in its infancy – contends with yawning stretches of time. Hence the GDF: a terrestrial cavity to hold waste until its dangers have dried up and it becomes as benign as the surrounding rock.

A glimpse of such an endeavour is available already, beneath Finland. From Helsinki, if you drive 250km west, then head another half-km down, you will come to a warren of tunnels called Onkalo…………. If Onkalo begins operating on schedule, in 2025, it will be the world’s first GDF for spent fuel and high-level reactor waste – 6,500 tonnes of the stuff, all from Finnish nuclear stations. It will cost €5.5bn and is designed to be safe for a million years. The species that is building it, Homo sapiens, has only been around for a third of that time.

………. In the 2120s, once it has been filled, Onkalo will be sealed and turned over to the state. Other countries also plan to banish their nuclear waste into GDFs…. more https://www.theguardian.com/environment/2022/dec/15/dismantling-sellafield-epic-task-shutting-down-decomissioned-nuclear-site

December 14, 2022 Posted by Christina Macpherson | - plutonium, decommission reactor, technology | Leave a comment