Caithness Map :: Links to Site Map Great value Unlimited Broadband from an award winning provider  

 

57,000 Tonnes Of Hazardous Materials Finally Dealt With At Dounreay

6th April 2012

Dounreay today completed the destruction of one of the most hazardous legacies of Britain's earliest atomic research.
A purpose-built chemical plant processed the last of 57,000 litres of liquid metal lifted from the primary cooling circuit of the experimental fast breeder reactor.

The coolant - an alloy of sodium and potassium (NaK) - was a major chemical and radiological hazard. An estimated 1000 trillion becquerels of caesium-137 was removed from the coolant during the chemical process that turned the 57 tonnes of liquid metal into 20,000 tonnes of salty water and took four years to complete.

Scotland's Cabinet Secretary for the Environment Richard Lochhead saw the last batches being processed.
He said: "This is a tremendous achievement and another example of how the highly skilled Dounreay workforce is delivering a world-class clean-up operation at one of the most complex nuclear sites in Europe.

"The Scottish Government welcomes today's announcement that Dounreay have successfully destroyed 57,000 litres of highly radioactive liquid metal from the Dounreay Fast Reactor."

The Nuclear Decommissioning Authority said it was "extremely pleased" the liquid metal no longer posed a hazard.
"This was very high on the list of hazards we wanted reduced across our whole estate," said Nigel Lowe, head of the NDA's Dounreay programme. "It's a significant achievement for Dounreay and joins a long list of examples whereby the site has delivered on key objectives and technical challenges."

The reactor - built in the 1950s - was one of only two ever built in Britain to run on liquid metal. Two cooling circuits connected by heat exchangers were filled with more than 161,000 litres of liquid metal.

More than 100,000 litres of NaK from the secondary circuit was destroyed when the reactor shut down in 1977.
Work on the primary circuit - a labyrinth of pipes 9 kilometres in length - stopped in the early 1980s when higher levels of radioactive contamination were detected.

The primary circuit contained 57,000 litres of NaK that flowed over the fuel pins in the reactor core.
The "open vent" design of the fuel cladding allowed the liquid metal to come into direct contact with the fuel, contaminating the primary coolant with huge levels of soluble radioactive caesium. Radiation measurements of the primary coolant showed the presence of 1000 trillion becquerels of caesium-137.

The high level of radioactive contamination added to the chemical hazard of alkali metal that reacts in contact with air or water. Its destruction remained on hold until a decade ago when work started on the construction of a purpose-built clean-up plant. The plant was designed to lift the liquid metal in small batches, neutralise the alkalinity with acid and extract the caesium via ion exchange.

In September 2007, the first of a total of 354 batches was lifted from the reactor. Each batch underwent chemical neutralisation to convert the alkali metal to a salty water before being passed through ion exchange columns that trapped the caesium. Designers thought the plant would decontaminate the effluent by a factor of 1000. Decontamination rates of up to 4 million were achieved during the operation, reducing levels of radioactivity in the effluent to below the limit of detection.

The resin columns used to trap the caesium will now be cemented up and managed as higher-activity waste.
"It's been a fantastic achievement by the whole team to deliver this milestone a year ahead of schedule and to higher environmental standards than anyone thought possible at the design stage," said Andy Swan, the engineer in charge of the reactor decommissioning.

"This stuff was highly volatile and highly radioactive. The chemical and radiological hazards combined to make this a real danger to the workers involved, so we needed to be certain they were protected at every step of the process until the hazard was destroyed. Their safety record throughout this operation was excellent."

Destruction of the liquid metal was among the strategic national priorities of the Department of Energy and Climate Change, which sponsors the Nuclear Decommissioning Authority.

With the reactor vessel empty of liquid metal, attention now turns to cleansing the residual traces from the primary circuit pipework and destroying small pockets in other vessels. When complete, a robotic arm will reach into the reactor vessel and begin removing the burst fuel pin and almost 1000 breeder elements still positioned around the core.

 

Related Businesses

 

Related Articles

Contract For World's Deepest Nuclear Clean-up Awarded At DounreayThumbnail for article : Contract For World's Deepest Nuclear Clean-up Awarded At Dounreay
Dounreay has awarded a major contract as the world's deepest nuclear clean-up job gets underway.   Dounreay Site Restoration Ltd (DSRL), on behalf of the Nuclear Decommissioning Authority, awarded the £7.5 million contract for "advanced transition works" at the 65 metre deep shaft and silo to Nuvia and its partner Graham Construction, through the site's decommissioning framework following a competitive tendering process.  
NDA Launches Leadership Partnership To Inspire Young Nuclear ProfessionalsThumbnail for article : NDA Launches Leadership Partnership To Inspire Young Nuclear Professionals
The Nuclear Decommissioning Authority (NDA) has today launched a year-long partnership aimed at inspiring and supporting young people in the nuclear industry.   Chief Executive David Peattie announced the NDA's partnership with the Nuclear Institute's Young Generation Network (YGN) today at a special webinar for young professionals.  
NDA Calls For People To Have Their Say On Its StrategyThumbnail for article : NDA Calls For People To Have Their Say On Its Strategy
The Nuclear Decommissioning Authority has today published its fourth Draft Strategy and begun a 12-week public consultation.   The NDA regularly reviews its Strategy to ensure it has the right approach to decommissioning its 17 nuclear sites and benefits from the latest learning, best practice and can continue to deliver value for the taxpayer.  
Radioactive particles in the environment around Dounreay - Updates 17 AugustThumbnail for article : Radioactive particles in the environment around Dounreay - Updates 17 August
The updates for 2020 include - 17 August 2020 Attachment updated - Sandside beach near Dounreay particle finds 17 April 2020 Attachments updated: Dounreay foreshore particle finds Sandside near Dounreay particle finds 18 March 2020 Dounreay Foreshore particle finds document updated.   7 February 2020 Attachment updates - Dounreay foreshore particles finds and Sandside beach near Dounreay particles finds.  
Dounreay Explores Decommissioning With Robotics ExpertsThumbnail for article : Dounreay Explores Decommissioning With Robotics Experts
Dounreay is exploring ways of decommissioning with the help of robotics experts.   The nuclear site at Dounreay, which was the centre of the UK's research into fast reactor technology in the last century, is being cleaned up and taken apart.  
Nuclear Decommissioning Agency To Take Over Dounreay Site With No Job LossesThumbnail for article : Nuclear Decommissioning Agency To Take Over Dounreay Site With No Job Losses
DSRL and LLWR to become NDA subsidiaries.   The Nuclear Decommissioning Authority (NDA) has announced that Dounreay Site Restoration Ltd (DSRL) and LLW Repository Ltd (LLWR) will become wholly owned subsidiaries of the NDA next year.  
Two Dounreay officers recognised and rewarded by Chief ConstableThumbnail for article : Two Dounreay officers recognised and rewarded by Chief Constable
Two officers based at Dounreay received prestigious awards from Chief Constable Simon Chesterman this week in recognition of their long service and good conduct.   Supt Andy Peden, who is Operational Unit Commander (OUC) at Dounreay, received a Certificate of Service, having joined us in 1980.  
Dounreay Cash Reaches Groups In Need During Coronavirus LockdownThumbnail for article : Dounreay Cash Reaches Groups In Need During Coronavirus Lockdown
More than 30 community groups received help from a fund supported by Dounreay and the Nuclear Decommissioning Authority during the COVID-19 crisis.   In March 2020, Dounreay Site Restoration Ltd anticipated an upsurge in demand from community organisations for small-scale financial assistance.  
Dounreay helps motorbike charity support NHS in CaithnessThumbnail for article : Dounreay helps motorbike charity support NHS in Caithness
A charity which delivers vital medical supplies for the NHS is set to receive £10,000 from Dounreay Site Restoration Ltd (DSRL).   The cash will enable Highland and Islands Blood Bikes to establish a permanent presence in Caithness.  
Dounreay Accommodation Units Support Coronavirus ResponseThumbnail for article : Dounreay Accommodation Units Support Coronavirus Response
Around 80 portable accommodation units deemed surplus to requirements are being removed from the site and transported to England to be used as isolation cubicles in the prison service.   Known as Bunkabins, the demountable cabins have been located at the site for the last five years.