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In Focus: First Generation Magnox Storage Pond

The First Generation Magnox Storage Pond has something of a reputation on the Sellafield site.

Anyone working here, and indeed many who don’t, will know its nickname (which we can’t print here for security reasons around revealing building numbers). But in nuclear folklore it’s seen as a big, dirty, problematic radioactive beast that encapsulates the challenge we have in dealing with the legacy of its past.

It’s a reputation which has been hard earned. Primarily a storage pond and ‘decanning’ facility to strip the cladding from used fuel rods so the fuel inside could be reprocessed, the pond has seen some action. As well as receiving spent fuel from all of the UK’s nine Magnox nuclear power stations, the facility has been used to process fuel from Italy and Japan.

“It’s a bit of a battleship,” said the Head of the First Generation Magnox Storage Pond Programme, Dorothy Gradden. “It was out there helping to keep the lights on in Britain during national coal strikes in the 1970s. It was a stalwart of operations on the site and has definitely got its scars from those days. Around half of the Magnox fuel that has ever come to Sellafield has been through here – and that includes the fuel going to the facilities which replaced it.”

The year it opened (1962) was the same year the last trolley buses ran in London and Britain opened its first legal casino. It’s been around for exactly the same time as James Bond has been on screen – but as much as possible has been neither shaken nor stirred in that time.

First Generation Magnox Storage Pond

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    From the archives: the First Generation Magnox Storage Pond in 1965
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    The pond under construction in 1958
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    The construction of a store for sludge from the pond
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The opening of the modern, enclosed Fuel Handling Plant in 1985 meant that for the last 30 years, the pond has been largely redundant in terms of operations and the focus has been on care, control and surveillance. But the pressing need to decommission this ageing asset with its significant inventory of irradiated solid nuclear fuel, mobile uranic sludge and miscellaneous beta gamma waste, together with the contaminated pond water, has long been our high priority (along with decommissioning the three other main legacy facilities in the Pile Fuel Storage Pond, Pile Fuel Cladding Silo and Magnox Swarf Storage Silo).

Emptying such hazardous material from a building that was not built with emptying in mind has taken years of planning, research, design and engineering. While that work was going on, the pond programme has had two main priorities: Keep It Safe and Keep it Standing. Achieving these has involved significant refurbishment of the facility to strengthen its structure – including replacing all degraded steelwork – as well as overhauling, fixing and replacing its operational equipment, such as the huge skip handler crane which slides over the top of the pond area to lift and move the skips below.

It was out there helping to keep the lights on in Britain during national coal strikes in the 1970s.

Author's image
Dorothy Gradden
Head of the First Generation Magnox Storage Pond Programme

This strengthening work has also been vital to underpin the programme’s third key priority: get the waste out. Installing the new equipment needed for waste retrievals has been like fitting a new engine in a vintage car – nuclear engineers have to be sure that the old parts of the ‘vehicle’ will run safely and effectively alongside the new ones.

The good news is that the car is now on the road. In March 2016 , the first ever ‘bulk’ sludge export took place from the pond, starting a gradual transferral of the pond’s main radioactive sludge content, which will take until 2022 to remove. Sludge had already been transferred from the pond via a pipebridge to the specially-built £240m Sludge Packaging Plant over the preceding 12 months, but this was via a lower volume ‘Plan B’ floating platform sludge removal system which was primarily designed to check that the main system worked and allow the active commissioning of the packaging plant.

The other key recent development showing historic progress in this crucial mission was the removal of the first skip of fuel in April 2016 – billed as officially starting a new era of hazard and risk reduction at the Sellafield site. By taking a skip of fuel out of the pond and exporting it to the Fuel Handling Plant (the same facility which replaced it as the main recipient pond for Magnox fuel in 1985), we proved that we had all the equipment, all the know-how and all the capability to gradually begin emptying the plant of bulk stocks of sludge and fuel.

It’s a mission expected to take until 2022, at which point the risk and hazard at the facility will have been massively reduced.

  • In its 26 years of full operations, the First Generation Magnox Storage Pond processed around 27,000 tonnes of nuclear fuel – that’s nearly 2.5 million fuel rods. 
  • The water in the pond is kept at an alkaline level of 11.4 to minimise the corrosion of material in the pond.
  • The pond is classed as the second highest hazard at Sellafield (Magnox Swarf Storage Silo is the highest hazard).

It is part of a mission expected to take until 2022, at which point the risk and hazard at the facility will have been massively reduced as the main stocks of its most radioactive contents will be stored in a far safer place. But even then there will still be a significant radioactive inventory in the pond and the decommissioning work will stretch on for more than 25 years, according to the current programme schedule.

The step change into waste retrieval operations has required a completely new mindset from the people running the programme. As Dorothy Gradden has already been on this journey when she was in charge of the Pile Fuel Storage Pond’s shift into retrieval operations (that pond completed its bulk fuel exports in early 2016), the facility is in good hands.

“I’m working with great people who have got incredible expertise. As you go into operations, the pulse rate of the whole place changes,” said Dorothy. She compares the step up to a  football team, which can spend hours on the training pitch and planning in front of videos or blackboards, but when they’re on the pitch, decisions have to be taken instantaneously. “Things really do have to come together and everyone knows their jobs and what they’re accountable for. The heartbeat at the start of waste retrieval operations will be slow as we understand the equipment and the material. But then it will quicken up as we really get going.”

Of course, safety will remain the overriding priority throughout. “The First Generation Magnox Storage Pond is a completely different challenge from Pile Fuel Storage Pond. There’s far more radioactive waste inside it and the building itself requires a more sensitive approach in terms of maintaining its structural integrity while introducing new equipment.

“It isn’t a trite comment with a facility like this that nuclear safety has to come first. If something went wrong here, it would affect the whole of the site, the whole of west Cumbria and the whole nuclear industry,” said Dorothy.

There is an understanding and acceptance among all of our stakeholders that in order to achieve long-term risk and hazard reduction by emptying the legacy ponds and silos, there has to be a period of elevated risk as we stir these sleeping giants back into action. Radioactive material that has sat undisturbed for decades starts to be moved again. It is our job to manage that risk and have fail-safe procedures in place which allows the job to get done.

Inventory Estimates

  • 14,000m³ of water – the equivalent volume of nearly six Olympic-sized swimming pools.
  • 1,500m³ of radioactive sludge – this varies in depth around the facility. Around two-thirds of the sludge is in the pond and the other third in the ‘wet bays’ which were originally used for decanning fuel rods, but then became waste storage areas.
  • 500 tonnes of solid nuclear fuel.
  • Waste contents consist of sludge, fuel, miscellaneous intermediate level waste and low level waste.

First Generation Magnox Storage Pond Timeline

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Looking Ahead

Current programme estimates – these are subject to change:
2018 – Begin exports of waste in self-shielded boxes to the Interim Storage Facility.
2019 – Start sludge retrievals from D Bay.
2022 – Complete bulk fuel and sludge exports.
2033 – Complete all solid waste retrievals. Start dewatering
2038 – Dewatering complete.