management of disused sealed radioactive sources
TRANSCRIPT
Management of Disused Sealed Radioactive Sources
Date
By:Alan Carolissen
Senior Manager: NLM
Background
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• Proper management of disused sealed radioactive sources a priority– Developing countries: Poor accounting systems and/or lack of
expertise/funds– Developed countries: Large quantities - Difficult to control.
• Disused High Activity Radioactive Sources (SHARS) especially problematic
• No standard procedures or suitable technologies available• Disused sources, including SHARS, kept in working
shields in storage facilities or places of earlier use – not always under very secure or safe conditions
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• Responsible radioactive waste and spent/disused sources in South Africa.
• Initial work outside SA was on the smaller/lower activity sources
• 1998 performed first IAEA radium source conditioning operation in Ghana
• Since then about 15 countries done, mostly in Africa.
NLM experience
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Continues…
• Repair of SHARS units.• SHARS source removal and
transfer for storage• SHARS unit removal at
facilities and safeguarding done in various countries
NLM experience
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SHARS mobile hot cell development• Identified the need for technology to handle SHARS• In 2003 – concept of a mobile hot cell evaluated by international
team of experts (Canada, USA, UK, Belgium, South Africa)• Necsa (South Africa) - 2003 - develop basic design for a mobile
conditioning unit (“hot cell”) • Detail design and manufacturing from 2005• Every phase evaluated by peer review team• Funding provided by IAEA - additional support from US NNSA
through the IAEA Nuclear Security Fund.• Demonstrated in 2007 – field operations since 2009
• Sudan, Tanzania, Uruguay
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Design of Mobile Hot Cell
• Cell Components:– Cell walls – Double cavity wall 1,55 m thick - filled with river
sand with density of 1,6 - Mild steel “shuttering” plates – Working volume 1,6 m x 2,5 m x 3 m high– Roof – 3 x 0,23 m thick concrete slabs– Window – oval shaped steel container with polycarbonate
ends - filled with 50% ZnBr2– Telescopic master-slave manipulators with 20 kg lifting
capacity
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Design of Mobile Hot Cell• Auxiliary Equipment
– Jib crane on inside– Exhaust ventilation unit– 3600 camera coverage on inside– Table with tools, welding and leak testing equipment– Lighting
• Long Term Storage Shield – designed by RWE Nukem (UK) and design modified in 2011 for licensing as transport container (LANL Areva) – 4 drawers with 10kCi capacity.
• A-frame crane over unit • Transported in 2 x 20ft shipping containers
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Management Approach• Removal of heads from working unit • Transport all units to conditioning site (centralized store)• Transport unit into country – assemble and prepare for operation• Removal of SHARS from working shields and transfer into long term
storage shield – Partial dismantling of head/irradiator outside cell– Placement inside cell and further dismantling– Removal of SHARS – Segregation of sources in terms of origin (country)– Encapsulate in stainless steel capsules – welding and leak testing– Placement into LTSS or Transport Container– Stored safely and securely or repatriated
• Dismantle unit and return to SA
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Logistics
• Equipment shipped to country in 2 x 20 ft ISO shipping containers
• Total operation – 1 week to assemble and 1 week to disassemble and work in-between depending on number of sources to recover
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26WM Training Course, Botswana 2008
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Conclusion
• 3 Operations successfully completed– Sudan– Tanzania– Uruguay
• Mobile Hot Cell proved itself as a very useful tool for recovery of high activity sources – proved itself under various conditions
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Thank You!!!
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