Management of Disused Sealed Radioactive Sources

Management of Disused Sealed Radioactive Sources

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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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