Magnox, on behalf of Hinkley Point ‘A’, engaged with Steve Vick International (SVI) to ask them to design and supply an effective method for sealing and decommissioning radioactive pipework.
Magnox were looking to decommission 1.2km of pipework housed in an Active Drains Trench (ADT). Access and spaces around the pipes were very restricted.
SVI’s FOAMBAG™ system offered the ideal solution whereby contamination in the pipes could be immobilised using expanding Polyurethane (PU)Foam, allowing the pipes to be cut safely. SVI’s solution overcame the issue of access and space as the PU foam can be deployed from a remote location. Using SVI’s technique, the project was completed with just 50 injection points and took just 20 days to complete.
Mike Gladwyn, Project Engineer at Magnox commented:
“When I first spoke to SVI, I was very impressed by the work they’d already undertaken in the gas industry, using their expanding foam techniques. It was also reassuring to see that they’d already carried out work in the nuclear decommissioning sector, specifically at Harwell, Chapelcross, Sellafield and Hunterston. Given their history within the industry I felt confident I’d come to the right place. Rich Ditte, SVI’s Nuclear Project Manager was extremely knowledgeable and together, the solution we devised offered benefits that far outweighed the other options we’d explored. SVI’s FOAMBAG™ system helped to improve safety by encapsulating contamination prior to cutting but also significantly reduced the timescale of the project and therefore helped to reduce our overall costs.”
SVI’s Hot-tapping and Foam Technology
Part of the overall technique chosen by SVI for the project was their bespoke hot-tapping system which allows for a fully contained insertion of their FOAMBAG™. The FOAMBAG™ creates a
permanent plug inside the pipe without the loss of pipe integrity. The semi porous FOAMBAG™ uses an expanding PU resin foam, comprising of a resin base and hardener which is mixed prior to application and then injected into the bag via an injection tube. The expanding foam fills the bag and at full expansion, a measured volume of foam seeps through the FOAMBAG™ material to adhere to the pipe wall.
Once the FOAMBAG™ has cured the void between two Foambags can then be filled with foam. The foam encapsulates loose debris and contamination as it expands and cures. Once cured hard, it is then possible to section the pipe into 800mm lengths for disposal without contamination becoming airborne.
The SVI products can be introduced from a remote location allowing application in contaminated or hard to reach places and are suitable for all pipe materials including steel, asbestos, concrete and plastic.
FOAMBAG™ was developed by Steve Vick International as a safe and effective method of sealing off gas mains for abandonment and has become a gas industry standard technique. The same method has been further developed to meet the needs of nuclear decommissioning and emergency repair engineers.
Graham Steer, project manager, noted that this technology has not only reduced the programme and cost, it has also resulted in significant safety improvements.
SVI Technicians were trained by Magnox to enable them to work on site and SVI Technicians in turn trained Magnox Technicians in the installation of Foambags and pipe drilling operations. The collaboration between the two companies and their respective staff was excellent and a strong working relationship was formed. This working relationship was invaluable during the final project with problem solving and collaborative working being key to the project’s ultimate success.