Over a quarter of the laboratories in Dounreay’s Fuel Cycle Area, which provided support to the whole of the site, have now been taken apart.
Lab 75 is the largest of the heavily-shielded laboratories to be cleaned up. It housed eight interconnected gloveboxes, or cells, heavily shielded by concrete, lead and mild steel slabs.
The gloveboxes were heavily contaminated, and a team of decommissioning experts from UKAEA Dounreay, NDSL and Doosan Babcock cleaned them out as far as practicable, with the waste being removed in shielded flasks. This allowed them to remove the external services and the heavy shielding around the gloveboxes.
A massive 73 tonnes of metal, lead and concrete shielding was removed. Much of the concrete and steel shielding was consigned as clean or exempt waste.
Some of the steel plates used as shielding were 55mm thick. Their size reduction was complicated by the cramped working environment which prevented use of the more usual heavy cutting methods.
Workers in protective air-fed suits dismantled the gloveboxes with hand-held power tools. Localised shielding was used to minimise the radiation dose to the workers.
The project was successfully completed on time and with an excellent safety and environmental performance.