An activity where types of waste or material (radioactive or exempt) are separated or are kept separate on the basis of radiological, chemical and/or physical properties, to facilitate waste management.
At some of our sites, early practices involved storing different types of waste together in vaults and other storage facilities. Now that treatment and conditioning processes have improved, there can be significant advantages in sorting and segregating waste in order to ensure it is managed in the safest and most effective manner. Mixing together radioactive wastes that have different properties and different methods of future management can be therefore avoided.
Sorting and segregation of waste is most effectively carried out during the early steps of radioactive waste management, and is completed in order to provide ease in the subsequent steps of the lifecycle. Waste is segregated using characterisation data including their physical, chemical, radiological and biological properties. The objectives are to remove non-radioactive waste, separate radioactive waste into appropriate categories or classifications, and recover materials for reuse and recycle. Segregation should be completed using the origin of the waste, radiological components involved and other characteristic properties.
Size reduction is a form of pre-treatment of radioactive waste to minimise the volume going into treatment/conditioning, storage or disposal. Size reduction can occur through incineration, shredding, cutting operations and compaction; this usually occurs at treatment facilities however, it can be advantageous to start at the source when possible. Pre-treatment is usually performed as preparation for further treatment steps.
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Case study
Hinkley Point A – foam and away (November 2021)
Polyurethane foam has been used at NRS Hinkley Point A to help contain and immobilise contamination while undertaking size-reduction activities.
Already in use across the gas utility industry, the reverse engineering innovation has been successfully demonstrated on a project to remove 1.2km of contaminated pipework, allowing not only significant time and cost savings but also increased safety benefits for personnel and the environment.
The original baseline strategy for the work in an active drains trench was to drill holes and inject shaving foam at cutting locations along the length of the pipework – this would have involved 1,500 positions for drilling and foaming and taken around 70 days to complete, with the prospect of potential contamination events.
Project engineers worked with the supply chain to adapt their technologies to meet the needs of nuclear decommissioning. For this application, a FOAMBAG™ system was used to create permanent blocks within the pipe to define the boundaries of the pipe to be injected with polyurethane foam. This immobilised residue debris and contamination within the pipe, without the loss of the pipe’s integrity, whilst the foam expands and cures.
Once cured, it is then possible to section the pipe into suitable lengths for disposal without contamination becoming airborne. Importantly the technology can be introduced from a remote location allowing application in contaminated or hard to reach places and is suitable for all pipe materials.
The technology meant that this aspect of the work was completed with just 50 injection points, from an original estimate of 1,500 bringing the schedule down to just 20 days from an original programme of 70 days.
Project managers noted that this technology has not only reduced the programme and cost, it has also resulted in significant safety improvements.
The images show colleagues working to cut away sections of pipe filled with polyurethane foam, wearing respirators because of the asbestos hazard, and a cut through of some of the pipes filled with the foam technology.