Cameras penetrate underground nuclear waste store

Two remotely-operated cameras have sent back video and photos of the intermediate-level radioactive waste stored in Dounreay’s wet silo.

The images will give the silo decommissioning team a better idea of the condition of the silo and its cargo of waste.

The silo is an underground concrete-lined, two-compartment vault where approximately 500 cubic metres of active waste was sent for storage over a period of 27 years from 1971.

The waste included metallic waste such as fuel cladding and fuel element transit cans, as well as plastic, glass, paper and filters. It was stored underwater to cool the waste and to shield operators from the radiation.

The team were the first to see inside the facility since it was partially drained and photographed in the mid-1990s.

Two 150 mm diameter holes were drilled in the 1200 mm thick concrete roof to allow access for the camera and radiation monitoring equipment.

Silo project manager Derek Richardson described what the images show.

“The photos and video recordings mean we can check the structural condition of the silo and the condition of the surface waste,” he said.

“The waste in the south compartment seems to be more degraded than in the north compartment, but that may be due to the fact that it is older and has been stored for longer.

“The images are extremely valuable to us as they will help us to plan the retrieval of the waste, develop systems for treating the waste, and the recovered cores from drilling the holes will allow us to assess the condition of the roof concrete."

Work on the scheme design for the equipment needed to retrieve the waste from the silo and the nearby shaft is expected to start later this year.