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In Focus: The Thermal Oxide Reprocessing Plant

It has generated billions of pounds for the UK economy by recycling nuclear fuel that generated low carbon electricity and kept lights across the world burning bright.

The Thermal Oxide Reprocessing Plant – or Thorp, as it is better known – is set for some big changes in the next couple of years. Our teams in the plant are working hard to ensure that their mission is finished safely and with pride whilst also planning for transitioning their own careers and planning for life beyond reprocessing.

• Thorp cost £1.87 billion to build
• It had 34 customers in nine different countries
• Earned £billions for the UK
• Employed almost 5,000 people during construction
• Supported 10,000 further jobs in the supply chain
• Reprocessing ends in November 2018
• Thorp is one third of a mile long
• The storage pond is 73m long, 23m wide and 8m deep – that’s enough water to fill 20 Olympic swimming pools
• Thorp has now reprocessed over 8,500 tonnes of spent fuel
• There are less than 850 tonnes of fuel to be reprocessed before completing in 2018
• Thorp will have reprocessed approximately 9,350 tonnes of fuel when its mission completes

Thorp – how it began

Our ability to reprocess used nuclear fuel is as old as the Sellafield site. It is how we extracted plutonium for the atomic weapons programme. It is how we managed used nuclear fuel from the Magnox fleet of reactors, such as Calder Hall. These missions relied on the availability of support plants across the site; storage ponds where the fuel could cool, reprocessing buildings that could chemically separate the fuel into plutonium, uranium and waste products, waste and effluent plants and stores for the special nuclear materials.

In the mid-1970s there was a new fleet of nuclear reactors around the world that used a new type of nuclear fuel; Oxide fuel.

In 1978 the UK government approved the construction of a new building at Sellafield that brought as many of the facilities needed to reprocess nuclear fuel under one roof.

The result was the Thermal Oxide Reprocessing Plant, or Thorp as it is better known. Construction got under way in 1981 with the project dominating the Sellafield site and bringing thousands of contractors to West Cumbria. The construction project was one of the largest of its time in Europe, beaten in size only by the Channel Tunnel and Disneyland Paris.

It took more than 5,000 people on site, supported by a further 10,000 jobs in the supply chain, to make Thorp a reality. What they created was a building that stretches for a third of a mile across Sellafield and one that can receive and store used nuclear fuel, reprocess it and then deal with the resulting nuclear products.

To give you a sense of the scale of the building, Thorp’s storage pond where fuel is cooled before undergoing reprocessing is 73m long, 23m wide and 8m deep meaning it holds enough water to fill 20 Olympic swimming pools.

But Thorp wasn’t just a feat of civil and nuclear engineering; it was also a big earner for the UK. It received used nuclear fuel from the UK’s Advanced Gas-cooled Reactors and from Light Water Reactors in the UK and overseas, making billions of pounds for UK plc.

The Thermal Oxide Reprocessing Plant

  • IN FOCUS: The Thermal Oxide Reprocessing Plant
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The different areas of Thorp

Receipt and storage – here the fuel arrives in a transport flask, it is removed and placed into the storage pond to allow the fuel to cool and the radioactivity to decay.

Head end – The fuel is sheared and dissolved in hot nitric acid, the fuel inside the metal casings dissolves and the liquid is transferred to the chemical separation plant.

Chemical separation – using a solvent then goes through a chemical separation process to separate out the uranium, plutonium and fission products (waste).

Finishing lines – The uranium and plutonium are processed here and dried into powder which is placed into containers and safely and securely stored. Thousands of tonnes of recovered uranium has already been export on behalf of customer to be remade back into new fuel-completing part of the fuel cycle and enabling continued low carbon electricity generation. Further thousands of tonnes remain to be exported.

The Thermal Oxide Reprocessing Plant

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The end of an era

By the end of next year Thorp will have honoured all of its contracts and this chapter of our reprocessing mission will be finished. Our teams will then start the process of cleaning up the parts of the building that chemically separated the nuclear fuel. This will take a few years to complete.

Thorp’s receipt and storage ponds and facilities will continue to operate beyond 2018, and will continue to receive used fuel from EDF Energy’s Advanced Gas-cooled Reactors. Instead of being reprocessed this fuel will be stored in the ponds pending a final disposition decision.

With less than two years until the end of reprocessing in Thorp, preparations and planning are already well under way, not only for how the plant will be cleaned out but also in preparing the workforce for their future.

Colin Savage the post operational clean out facility lead in Thorp explains: “We have huge changes ahead of us, this is not only due to the fact that we won’t be reprocessing anymore and the tasks we carry out will be different as we move into the post operational clean out phase, but culturally for the people who work in Thorp. Some of our people have been here since the beginning so adjusting from a mind-set of working to production targets to one of cleaning out the plant will be a challenge.

“We are used to reprocessing, that is what we do and what we will continue doing until November 2018 but also we are planning for the future at the same time. We are working with the workforce to see where they see themselves after reprocessing. After 2018 fewer people will be required so the business is working through the options available.

“We will still need a large number of the workforce to carry out the post operational clean out of the plant and also for surveillance and maintenance but we can’t hide from the fact that there are a number of roles that will no longer exist and so we are working now to address this, this may involve some training and reskilling so doing it two years in advance is the right thing to do.”

IN FOCUS: The Thermal Oxide Reprocessing Plant

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