Decommissioning of the Plutonium Purification and Residues Recovery Plant

Conference · Sat Jul 01 04:00:00 EDT 2006

OSTI ID:21208681

Hunt, J G ^[1]

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1. British Nuclear Group Sellafield Ltd, Sellafield, Seascale, Cumbria, England, CA20 1PG (United Kingdom)

British Nuclear Group is continuing to build on BNFL's successful record of decommissioning redundant nuclear facilities. Challenging radiological conditions and complex technical problems have been overcome to reduce the hazard associated with the UK's nuclear legacy. The former Plutonium Purification and Residues Recovery Plant at Sellafield operated from 1954 through to 1987. This is the only plant to have experienced an uncontrolled criticality incident in the UK, in August 1970 during operations. The plant comprised of two mirror image cells approximately 6.5 m x 13.5 m x 16 m, constructed of bare brick. The cell structure provided secondary containment, the process vessels and pipes within the cell providing primary containment. The plant utilized a solvent extraction process to purify the plutonium stream. Surrounding the two process cells to the north, east and south is an annulus area that housed the operational control panels, feed and sample glove-boxes, and ancillary equipment. The building was ventilated by an unfiltered extract on the process cells and a filtered extract from the vessels and glove-boxes. During the long operational lifetime of the plant, the primary containment deteriorated to such an extent that the process cells eventually became the main containment, with levels of radioactive contamination in excess of 14,256 pCi alpha. This led to significant aerial effluent discharges towards the end of the plant's operational life and onerous working conditions during decommissioning. Implementation of a phased decommissioning strategy from 1991 has led to: - A reduction of approximately 60% in the Sellafield site's aerial alpha discharges following installation of a new ventilation system, - Removal of 12 plutonium contaminated glove-boxes and sample cabinets from the building, - Disposal of the approximately 500 m{sup 2} of asbestos building cladding, - Removal of over 90% of the active pipes and vessels from the highly contaminated process cells, despite challenging criticality and radiological hazards. With Phase 2 decommissioning nearing completion, work has commenced on Phase 3 to define and deliver the final phases of work that will lead to the complete remediation of this highly contaminated building. This work will include the development of fit for purpose engineering solutions linked to reliable and innovative safety cases to enable accelerated: - Removal of the highly contaminated redundant ventilation system, - Removal of the process cell structure which consists of contaminated brick, concrete and steel, - Remediation of the Low Active drain trench, - Demolition or recovery of the building structure. (authors)

• Research Organization: WM Symposia, Inc., PO Box 13023, Tucson, AZ, 85732-3023 (United States)
• OSTI ID: 21208681
• Report Number(s): INIS-US--09-WM-06210
• Country of Publication: United States
• Language: English

Related Subjects

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
BNFL
CONTAINMENT
DECOMMISSIONING
DEMOLITION
GLOVEBOXES
PLUTONIUM
RADIOACTIVE WASTE DISPOSAL
REMEDIAL ACTION
SELLAFIELD REPROCESSING PLANT
SOLVENT EXTRACTION
UNITED KINGDOM
VENTILATION SYSTEMS
WORKING CONDITIONS