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Home > Stakeholders and Community > Insight - Stakeholder Newsletter > A closer look at pond life  

Insight Stakeholder Newsletter

A closer look at pond life

12 November 2012

Empty pond BradwellEmpty pond BradwellEmpty pond BradwellWork continues at pace to decommission cooling ponds across a number of the Magnox sites. The aim of the £300 million programme is to reduce the hazards of the highly radioactive facilities, and associated plant, in ways that are safe, cost-effective and comply with regulatory requirements. 

Magnox is taking a 'lead and learn' approach across all its work programmes. The Ponds Programme team was fundamental in pioneering this strategy, initially starting with a team at Hinkley who moved on to Bradwell, bringing the learning, innovation and best practice with them to inform the next set of challenges. 

Steve Walters, Magnox Ponds Programme Director, said:

"Dealing with the ponds legacy is particularly important in realising the benefits from the Magnox Optimised Decommissioning Programme. The programme is active on five sites and the team continuously share learning across these sites to ensure safe, innovative and cost-efficient solutions." 

Fact File

Concrete-lined ponds store irradiated fuel as it is removed from the reactors.

The fuel is stored in skips.

Water cools the fuel and acts as a barrier to radiation.

Spent fuel can be stored in ponds for long periods, sometimes years.

Ponds also contain various kinds of debris and sludge.

During 2011, 3,000 cubic metres of pond water were drained from Magnox ponds.

More than 20,000 cubic metres remain to be drained – the equivalent of more than 50 standard swimming pools.

By the end of 2015, just over 7,800 cubic metres will remain.

 Hazard will be completely removed by 2020.

The programme team are currently working at Bradwell, Chapelcross, Hinkley Point, Hunterston A and Trawsfynydd sites.

The optimised 'lead and learn' approach will save approximately £45 million from the original estimate.

The ponds task isn't a small one: the team will tackle eight Magnox sites (Berkeley's ponds were decommissioned in the 1990's and Wylfa uses a dry store), applying a consistent approach where the ponds are first drained of liquor and then decontaminated to a level that will enable entry to the Care and Maintenance (C&M) phase - facilities remaining on a site are made safe and left passively until final dismantling decades later. 

Innovation is vital to overcome challenges, with a focus on adapting technologies and off-the-shelf equipment from outside the nuclear arena rather than developing expensive bespoke solutions. 

Examples include:

  • Replacing the electrical drive system of a mini-digger with water-powered hydraulics, enabling underwater operations to recover, for example, bulk sludge.
  • A floating 'pontoon' system (as used in marinas) which forms a working platform on the pond surface, dropping lower as the liquor drains down.
  • A freeze-dredge system traditionally used for clearing silt from water channels, but now for retrieving mixed wastes from the Bradwell pond centre bay. 

The pontoons were first introduced at Hunterston - which has the largest Magnox pond at around the size of an Olympic swimming pool – for workers using ultra high pressure jets to remove contamination from the pond walls. 

At Bradwell and Chapelcross, individual ponds have been completely drained and stabilised, while the draining of Hinkley Point ponds has recently started. Although the steps are the same at all sites, some bring greater challenges, such as Trawsfynydd, where the ponds walls are being scabbled to remove contaminated surface concrete.