At Trawsfynydd, we are the main management and operations contractor on site, responsible for effectively and safely managing the decommissioning programme of the former Magnox nuclear power station on behalf of the Nuclear Decommissioning Authority.

Decommissioning challenge

Trawsfynydd comprises twin Magnox reactors, a cooling pond building and a multitude of ancillary buildings. Defuelling of the reactors was completed in 21 months in 1995 – four months ahead of schedule and under budget.

The challenges being embraced by Magnox North fall into two main categories. The first is to reduce the radiological hazard, and the second centres around the safe dismantling of non-radioactive parts of the plant and managing hazards whilst getting the best value from materials that can be recycled and re-used.

In addition, the management on site face two further unique challenges. Because it is an inland site, effluent is treated to a higher specification than coastal power stations. And because of its location in the Snowdonia National Park, a bespoke strategy is required for entry of the site into the Care and Maintenance phase.

Preparations for the care & maintenance phase began in 1993 and work is well underway to streamline the site by removing facilities, reducing remaining site hazards and processing legacy wastes. This will leave only three buildings for the care and maintenance phase – Reactors 1 and 2, height reduced and cladded to become Safestore buildings and the new ILW safe storage building. They will remain in a quiescent state for a prolonged period, continuously monitored and routinely inspected until such time that they are removed, the site de-licensed and the land is clear for re-use.


 

Delivering value

The decommissioning programme at Trawsfynydd - which now comprises non-operational and defuelled twin Magnox reactors, a cooling pond and ancillary buildings - is at an advanced stage and is now in its fourteenth year.

Key achievements

• All fuel elements despatched to Sellafield – defuelling completed in 1995, four months ahead of schedule and under budget
• All scheduled work on deplanting completed ahead of schedule and within budget
• Turbine hall demolished and area landscaped following the removal of asbestos insulation, the cutting up and removal of all generating equipment and steam pipework including four 126-tonnes turbine alternators, which were removed in one piece
• Cooling water pumphouse successfully removed and landscaped following the successful removal of all equipment including overhead travelling cranes, large valves, pipework and electric motors. Once removed all equipment was sent off site as scrap material. Sealing off the pumphouse from the lake using divers was a key challenge which was successfully achieved
• Operational legacy waste is being safely recovered and packaged. These wastes are made up of Fuel Element Debris, Miscellaneous Active Components, Resins, Scabbled Pond Lanes materials and Sludges.