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An e-newsletter from the Nuclear Decommissioning Authority

"Pigs" might clean pipes

15 July 2009

An innovative pipe-cleaning technique could save money and time as well as minimise waste. 

The NDA commissioned Bristol University to investigate using ice to clean pipes on nuclear sites. Sellafield Ltd and Magnox North Ltd also contributed to the work with funding and support of the practical work on sites.

Other industries use 'pigging' to clean pipe walls by pushing a solid plug-like object (known as a "pig") through a pipe.

What is novel about this new approach to pigging is the innovative use of crushed ice in water, known as "Ice Pigging" and patented by Bristol University. Crushed ice "pigs" can negotiate bends or minor changes in pipe work.

Once a quantity of ice has been pushed into the pipe to form a "pig", water pressure then pushes it through the pipeline. As the pig is pushed through the pipeline, it doesn't lose its shape, allowing it to clean the entire pipe surface. This results in a highly fast and efficient system, improving on conventional methods, not just by cleaning the pipes and reducing time taken, but also dramatically reducing the cost per metre.

Ice pigging has the potential to accelerate work already identified in Site Licence Company Lifetime Plans, while protecting the health and safety of workers and significantly reducing the amount of radioactive effluent that might have been generated by previous pipe-cleaning techniques. It does not require special purpose-built launch or receive stations, and unlike a fixed size, solid pig it will not get stuck if the pipe is partially obstructed.

Professor Joe Quarini, Professor of Process Engineering at Bristol University, said:

"I am particularly pleased that the ice pigging technique can be applied to nuclear decommissioning with such environmental benefits."

Dr Melanie Brownridge, NDA Head of Research and Development, said:

"We are always looking at the ways in which other industries use innovative technologies and how these techniques might be transferred to the challenges we face in nuclear decommissioning.

"Bristol University presented us with a technical solution to a common decommissioning challenge. As a result we can share this technique across the Site Licence Companies to accelerate decommissioning and achieve cost savings, where possible, whilst also benefiting from a reduction in production of radioactive waste."