Decommissioning
Once a nuclear facility has completed its operational life it then undergoes decommissioning. Decommissioning involves the safe, cost-effective reduction of the radiological hazards. It includes the removal of nuclear materials, plants and buildings in a multi-stage, controlled manner with due regards for the environment.
Legacy nuclear reactors, plants and buildings were not built with decommissioning in mind, therefore skills and techniques have had to be developed to safely remove Sellafield’s historic facilities, some of which date back to the 1950s. Decommissioning at Sellafield started in earnest in the 1980s, however it was only with the formation of the Nuclear Decommissioning Authority in 2005 that decommissioning of historic high hazard facilities became a priority.
The safe decommissioning of redundant nuclear facilities is an essential aspect of the UK's civil nuclear programme. At Sellafield, we can demonstrate the successful decommissioning of legacy nuclear facilities, which underpins confidence in new nuclear build and the management of future nuclear spent fuel and wastes. New plants are designed and built using our decommissioning knowledge to ensure that when they require decommissioning it should be a straightforward process.
For the moment however, decommissioning of highly radioactive facilities can be a complicated and technically challenging process. Firstly, the wastes are characterised in order to define the types of materials that are present, the appropriate disposal route is chosen, and then the methods selected for the dismantling and demolition phases. Depending upon radiation and contamination levels, decommissioning and dismantling involves either manual or robotic removal of all process plant and equipment and the radiological decontamination of the structure as far as possible.
Standard industry demolition techniques are then used wherever possible and can either be mechanical or, if the structure and location allows, explosive. The land is then remediated for whatever future use is determined for the site.
Facts and figures:
- 55 buildings have been safely demolished at Sellafield
- 2,110 Sellafield Ltd employees are working on decommissioning
- 108 decommissioning projects are currently underway at Sellafield today
Recent Achievements:
- Over 200m3 of legacy radioactive liquid waste from the 50-year-old Magnox Swarf Storage Silo has been transferred to a treatment plant as part of the process to bring radioactivity levels in the building down.
- In the First Generation Magnox Storage Pond dating back to the 1950s, a new pond purge system has been commissioned to reduce radioactivity levels in the pond water and the pond crane and steelwork refurbished in preparation for retrieval of legacy fuel from the pond.
- The original Pile Fuel Storage Pond used to store fuel from the Windscale Reactors is now being emptied. Twenty two redundant fuel skips have been exported out of the pond and radioactive sludge is being retrieved from the pond floor and from inside skips.
- An 11 storey, 61 metre high process cell in the Primary Separation Plant has been stabilised using a special light-weight foaming to grout as part of decommissioning the facility.
- Construction of the new Separation Area Ventilation (SAV) stack concrete windshield has been completed and it stands at 122m high. Completion of this project will mean aerial discharges from historic stacks can be re-routed to SAV, so allowing the decommissioning of redundant facilities.
Images
Decommissioning Updates
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Decommissioning the world’s largest open air nuclear fuel storage pond continues
One of Sellafield’s historic fuel storage ponds is benefiting from the development of a new sludge retrieval machine to help safely decommission what is a 60 year old facility. The sludge retrieval project has taken nine years of work requiring significant engineering on the plant, as well as the design of bespoke equipment to operate in an underwater, radioactive environment.
