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24 September 2014

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You are in: Cumbria > Places > Features > So what the heck is this Sellafield thing all about?

Inside Sellafield

Inside Sellafield

So what the heck is this Sellafield thing all about?

The Sellafield site is one of the largest nuclear engineering centres in the world. For over 30 years, BNFL has owned, managed and operated the plants on Sellafield site. Today the main focus is on decommissioning.

Reprocessing - the basics

Nuclear Fuel has a life span of about 5 years. After this it has to be removed from a nuclear reactor. 

It can then be reprocessed in Thorp, a process which recovers its component parts; Uranium, Plutonium and a cocktail of highly radioactive waste.

The Uranium and Plutonium recovered from the spent fuel can then be recycled into new fuel.

The cocktail of radioactive waste is the dangerous part - this is the High Level Waste. This cocktail goes through a process called Vitrification -  turning a dangerous liquid into a stable solid so it can be stored easily.

Vitrification is done by heating the cocktail of waste, after evaporation, what's left is a powdery substance which looks like instant coffee.  This is then mixed with liquid glass, poured into a stainless steel container, sealed, and then left to cool for 24 hours. It's then placed inside several shielded containers, and moved to the storage chamber inside the Vitrified Product Store where it is stores pending its return to its country of origin.


High Level Waste

UK high level waste is stored in the Vitrification plant for 50 years - so far the storage chamber is about 50 percent full and it's not yet been decided where the waste will go after the 50 years.

Foreign high level waste is "cooled" pending its return to its country of origin.  (The natural radiation decay generates heat which is ventilated out of the store to keep the high level waste cool).

Buildings that you may hear about.

B30 or Dirty 30

All buildings at Sellafield are numbered B something - B30 was the original storage pond for Magnox fuel at Sellafield.  This building is the NDA's biggest concern and prime goal for decommissioning - not just for Sellafield, but for all civil nuclear sites in the country.

So far this year 70 million pounds alone has been spent on the plant. This money has been spent bringing the building up to safety standards so that it can be decommissioned.

It's expected that it'll cost 1/2 a billion pounds worth of tax payers money to bring it down to the foundations. This is what the NDA wants.  Expected decommissioned date - 2054.

Why dirty 30?

Radiation levels in parts of this building are so high, it's not possible for people to spend more than a couple of minute inside. This is why it's such a difficult building to decommission - hence its nickname dirty 30. In the past workers were told not to touch rails or walls because of the fear of contamination.

Today that is not the case.  Because the building was running while the nuclear industry was still in its infancy mistakes were made. If something broke inside the plant  there was nowhere to send it - so they dumped it inside the storage ponds. These ponds are now packed with radioactive broken parts which are extremely difficult to remove.


Thorp is a reprocessing plant. It reprocesses nuclear fuel, separating out plutonium, uranium and high level waste in the process. 

The building first removes nuclear fuel from the containers it travels in from abroad or other UK sites. The fuel's then stored in the pond before the uranium and plutonium from the high level waste stream goes to the vitrification plant.

You may have seen a large swimming pool like structure on tv - that's the pond in Thorp. Water is nature's shield to radiation.

Windscale reactors

There were two of these - one famously had a fire in 1957 - this one still has its stack. When you look at Sellafield from a map  the reactor is underneath what looks like a massive air traffic control tower. That's the stack, known onsite as the chimney. It's one of the tallest buildings on the plant.

Each reactor had a stack, one has been decommissioned and removed. Work started to decommission the other stack (the one where the fire was) but there was a fatality two years ago (2003) which has halted the process. 

Calder Hall

The country's first commercial nuclear power station. Can be picked out by the cooling towers. It has four reactors and the world's largest Asbestos removal operation is currently ongoing to removing asbestos from these buildings. Closed March 2003.

The Sphere

Perhaps the most identifiable building on the plant - the big ball like building - it was an experimental Advanced Gas Cooled Reator (AGR) which was designed to generate electricity.  It is now 70 percent decommissioned.  


HIGH LEVEL WASTE - the cocktail acids - extremely dangerous - you wouldn't live long if you stood next to it.

INTERMEDIATE LEVEL WASTE – is mainly comprised of fuel cladding (outer casing) which is mixed with a cement mixture and stored in drums in an engineered store.

LOW LEVEL WASTE - is mainly comprised of paper and protective clothing which has very low levels of radioactive contamination.  This waste is ‘compacted’ on the Sellafield site and sent to the Low Level Waste Repository near Drigg.  The LLWR also receives low level waste from industry, hospitals, universities and research establishments.

last updated: 28/04/2008 at 14:47
created: 12/12/2005

You are in: Cumbria > Places > Features > So what the heck is this Sellafield thing all about?

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