DECOMMISSIONING | TRANSPORTING THE HUNTERSTON A LEGACY WASTE waste bunker retrieval
After a lifetime of electricity generation the two-unit Hunterston A nuclear power plant presented some unique decommissioning challenges and one of the UK’s largest inventories of solid high-level waste. Recovering and transporting this material for encapsulation fell under the SAWBR project.
By Stuart Blair, Hunterston A Site Waste Manager, Nuclear Restoration Services. Hunterston A solid
Above: The two- unit Hunterston A nuclear power plant presented some unique decommissioning and transport challenges
Above right: The final box of solid waste being sealed at Hunterston A ready for transport
HUNTERSTON A WAS SCOTLAND’S first civil nuclear power station. At the time of opening in 1964 it was the largest nuclear station in the world. After generating a total of 73 TWh of electricity it ceased operations in 1989. Unusually, Hunterston A’s two reactors were constructed in an elevated position at a height of more than 10 metres, which enabled access from underneath. Gravity assisted removal of spent nuclear fuel, and refuelling could be carried out without the need for lifting machinery above the active core. The nuclear fuel elements were also unique, incorporating an outer graphite sleeve and fuel support member which provided structural support to the fuel element under higher reactor temperatures and additional moderation in the reactor.
Hunterston A’s radioactive legacy waste Hunterston A holds one of the largest inventories of solid higher active waste (HAW) across the 13 Nuclear Restoration Services (NRS) reactor and research sites. NRS is responsible for safely decommissioning the first
generation nuclear and research sites across the UK as a wholly-owned subsidiary of the Nuclear Decommissioning Authority. The Hunterston A inventory consists of radioactive metallic components, debris removed from the
24 | July 2025 |
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irradiated fuel elements during discharge from the reactors and 30,000 graphite sleeves. It was transported from the reactors via underground tunnels and stored in five above-ground reinforced concrete bunkers constructed in the 1960s and 1980s. Hunterston A entered its decommissioning phase in 1995 when spent nuclear fuel defueling was completed. One of the requirements of the decommissioning strategy was the early retrieval and on-site storage of solid post-operational HAW from the existing solid active waste building (SAWB) which led to the conception of the solid active waste bunkers retrieval (SAWBR) project.
The SAWBR project The purpose of the SAWBR project was to safely retrieve, package and export 2,300 tonnes of HAW from five large overground bunkers by breaking through the gable end of bunker 5 to form part of the new SAWBR waste package export facility (PEF) that would be remotely operated from an external control room. As bunker 5 contained less waste than the other four bunkers, it was selected for the active commissioning phase of the SAWBR project. Costain was awarded the contract to manage the design,
procurement, engineering, construction and inactive commissioning of this facility using a number of specialist subcontractors. Construction commenced in 2008 before moving into equipment install, integrated testing and completion of the inactive commissioning phase in 2014. Bunker breakthrough was achieved in May 2014 using core drills and wire saws to remove an 800mm deep
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