One of the most challenging phases of the programme to decommission Windscale's advanced Gas-cooled Reactor - the UK's lead power reactor decommissioning exercise - has been successfully completed. Engineers have succeeded in removing, cutting and processing the 14m long stainless steel loop tubes used to test fuel as part of WAGR's research and development role.
This part of the programme presented particularly difficult circumstances because the six loop tubes were some of the most radioactive components of the plant - having been exposed to prolonged irradiation in the centre of the core.
The methodology adopted for this phase was first to fill the loop tubes with grout and then to cut them using a hydraulic shear. Cold shearing ensured avoiding the risk of spreading radioactive dust or vapour which would have resulted from sawing, grinding or hot cutting techniques.
The loop tubes were cut into approximately 1.1m lengths, their radioactive content measured and places into a plastic basket, within a specially made high-density concrete waste box.
When fully loaded the boxes were filled with high-density grout to encapsulate the contents. The boxes were completed by casting a concrete lid in place. The 43tonne boxes were then transported to the intermediate level waste store.