The two-unit Magnox nuclear power station at Bradwell in Essex has become the first UK power plant to enter care and maintenance following approval from UK regulators.
“Bradwell’s entry into care and maintenance represents a major milestone...It marks the first time a nuclear site in the UK is placed in a dormant state, after removing the major hazards from the site," an Environment Agency spokesperson said.
During the C&M phase, the site will be monitored, maintained and inspected regularly until final site clearance begins in 65 years.
“Bradwell’s success in reaching this milestone marks a new and welcome chapter in its environmental cleanup journey, protecting the public from hazards,” said Minister for Nuclear Richard Harrington.
Bradwell, one of 17 sites owned by the UK Nuclear Decommissioning Authority (NDA), was part of the UK’s pioneering fleet of Magnox reactors. The station operated for 40 years from July 1962 until March 2002, generating nearly 60TWh of electricity. Defuelling, which removed 99% of the radiological hazard from the 20-hectare Bradwell site, started in 2002 and was completed in 2005.
In 2009 Bradwell was chosen as a ‘lead and learn’ site for the Magnox decommissioning programme, and was given a target to enter care and maintenance before 2027.
For almost a decade, teams have worked tirelessly, and by deploying a range of innovative approaches have managed to accelerate the decommissioning programme by nine years. More than ten million person-hours have been worked, with 90,000t of waste generated, much of it reused or recycled.
A site transformed
The Bradwell site has been transformed from its operational days.
Today, a 40,958 cubic metre void remains where the turbine hall once stood. The turbine hall was demolished in 2012, in a project requiring removal of some 12,000t of waste, of which 94% was sent for recycling.
The remaining pool buildings have been enclosed in weatherproof cladding and will be left for an extended period. Prior to this around 300 cubic metres of pond water was removed from the pools, the walls floors and ceilings were decontaminated and 11 buildings were demolished.
The reactor buildings have been clad with 23,600 square metres of aluminium tiles, designed to withstand the elements, seismic events and extreme conditions for 100 years. The structures were designed by Mott MacDonald and installed by Vinci Construction. It was one of the largest scaffolding jobs in Europe, using 1200t of scaffolding and requiring in excess of 800,000 hours of work.
Before the cladding was installed on the reactors, 351,000 hours had been spent deplanting the pile cap and removing the four charge machines and other plant equipment from the reactors.
Deplanting of four boiler houses, each containing three boilers, plus electrical and instrumentation equipment, cabling and pipework, was also carried out.
A portion of land contaminated by a historical leak from an active effluent discharge line, has been remediated, plus new drainage and security systems installed.
So far, 124 buildings have been taken down at Bradwell, including the administration buildings, staff canteen, and welfare block. Portacabins are now home to the 225 contractors and Magnox employees remaining onsite but are planned for removal in early 2019.
“Over the sixteen years that it has taken to achieve this major landmark significant deconstruction and demolition work has been completed with a commendable nuclear and conventional safety record," noted Mina Golshan, Deputy Chief Inspector at the Office for Nuclear Regulation (ONR). The ONR and its counterpart the Environment Agency will now continue with "proportionate regulation" of the site.
“We will tailor our regulatory activities, proportionate to the risks from site, whist ensuring the standards of protection of the public and environment are maintained," an Environment Agency spokesperson said.
Leading the way
Now in care and maintenance, four buildings will be visible on the Bradwell skyline: the two reactors, the ponds’ building and an intermediate level waste facility.
Thanks to a new waste minimisation strategy, this interim storage facility (ISF) can continue taking waste from two other Magnox sites in the southeast – a change that along with safety and environmental benefits could save UK taxpayers up to £200 million.
A novel approach to managing fuel element debris (FED) was key to accelerating the care and maintenance programme at Bradwell. Treatment in an onsite dissolution plant reduced the volume of solid waste by 90% and meant that over half of the FED at Bradwell could be re-classified as suitable for disposal as low-level waste. This work has enabled the site to enter care and maintenance nine years earlier than planned.
The equipment and techniques developed to retrieve, condition and package ILW are now being used to progress decommissioning work at other Magnox sites.
“Bradwell becoming the first of the UK’s legacy sites to enter care and maintenance is a historic moment, not just for Magnox Ltd and the NDA, but for the country,” said David Peattie, the NDA’s chief executive. He thanked all parties involved in the collaborative effort.
"Bradwell has pioneered methods for tackling the challenges we face at many of our Magnox reactor sites, and has contributed to an important body of expertise that is being shared across the NDA Group,” Peattie added.
Now in care and maintenance, the Bradwell site will be managed by Sizewell A following lengthy preparatory work.
The site will be left in a safe condition while remaining radioactivity decays naturally, and be monitored, maintained and inspected periodically until final site clearance starts (currently scheduled for 2083).
Entry to the reactors and associated buildings will only be required once year, initially, and then every five years for routine inspection and maintenance. However, Bradwell’s interim storage facility will continue to receive packaged waste from Dungeness A and Sizewell A for the next few years.
The last stage in Bradwell’s lifecycle will see the removal of reactor vessels and building demolition.
Photo: Bradwell in Care & Maintenance (Photo: Magnox)