Strategic Guidance on the Management of LLW and ILW / LLW ...

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LLW Repository LtdNational Waste ProgrammeNWP/REP/011Issue 2.1 – Jan 2013Page 28 of 585.2.5. Mechanical Surface Decontamination (Shot-Blasting) [Ref. 5, 14-17]UsageLLWILW/LLWSurface contaminatedVolumetricallycontaminatedActivatedAluminiumCopperMild steelMild steel (coated)Stainless steelStainless steel (coated)Description of techniqueShot-blasting is undertaken either using SLC infrastructure where available (e.g. the Metal RecyclingFacility at Sellafield) or else within the supply chain (e.g. the Studsvik UK Metal Recycling Facility atLillyhall, Cumbria). Metal is received at appropriate facility, inspected; size reduced as required and issubject to shot-blasting. Shot-blasting is a process by which the metallic waste is subjected to a stream ofhigh-pressure abrasive material; and the friction of the abrasive material removes deposits from thesurface of the item and a thin layer of the metal surface. This removes any surface contaminated layerfrom the item. It should be noted that this technique may be problematic for stainless steels, particularlywhere contamination is ingrained into the metal surface.Specific restrictions exist within the Waste Acceptance Criteria (WAC) for dose rate, surface contaminationlevels, individual item weight and acceptability of surface coated metals. Acceptability of wastes outsidethe WAC specification would require assessment and decision on a case-by-case basis (for example, thishas been successfully undertaken for waste management of the Sellafield MEBs).The Sellafield Metal Recycling Facility is currently used exclusively for the Sellafield site and processesferrous metal through shot blasting (the facility cannot accept aluminium or copper for treatment by shotblasting).The facility can accept metal at relatively low contamination levels (
LLW Repository LtdNational Waste ProgrammeNWP/REP/011Issue 2.1 – Jan 2013Page 29 of 58• For ILW / LLW:o Waste metal decontaminated to LLWstatus to enable for further processingor disposal.o Secondary wastes – mixture of blastmedia and surface wastes. This isdisposed of via disposition at LLWR ormay be returned to the customer formanagement if higher activity.• Not useful forcomplex geometriesunless size reduced.Technique used at:A company owned by UK Nuclear Waste Management LtdNOT PROTECTIVELY MARKED
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