the lead up to and design of the necsa shars mobile ... - eventsm.co.za
the lead up to and design of the necsa shars mobile ... - eventsm.co.za
the lead up to and design of the necsa shars mobile ... - eventsm.co.za
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THE LEAD UP TO AND DESIGN<br />
OF THE NECSA SHARS<br />
MOBILE HOT CELL<br />
SARPA-SAAPMB CONGRESS:<br />
Radiation Protection: A new challenge<br />
By:<br />
Harry Swart<br />
Manager: De<strong>co</strong>mmissioning <strong>and</strong> waste management (LD)<br />
September 2011
Contents<br />
•<br />
•<br />
•<br />
•<br />
•<br />
What is SHARS<br />
The origin<br />
NLM’s involvement<br />
Development<br />
Design & SA
What is “SHARS”
• Before 2003<br />
• Orphaned sources<br />
• Mobile hot cell idea<br />
• From late 2003<br />
Project origin<br />
• USA NNSA: RTR<br />
• IAEA: Idea <strong>of</strong> <strong>mobile</strong> hot cell<br />
• Contracts for individuals <strong>and</strong> NLM
Project his<strong>to</strong>ry<br />
• NLM<br />
• Development<br />
• Design requirements: 10 kCi, <strong>mobile</strong>, easy<br />
usable, ss capsule, LTSS, cell <strong>to</strong> next<br />
<strong>co</strong>untry,<br />
• Design<br />
• Pier reviews
Initial <strong>design</strong>
Final <strong>design</strong>
Training<br />
• Local manipula<strong>to</strong>r <strong>co</strong>mpetency<br />
• International (USA):<br />
• Manipula<strong>to</strong>r <strong>co</strong>mpetency<br />
• Irradia<strong>to</strong>r heads
Training at SWRI (Texas)
Preliminary safety assessment<br />
• Prepared: AJ Ramlakan, Dr W Truter<br />
• Assessing operational doses (Dr GP de<br />
Beer)<br />
• Accident <strong>co</strong>nditions<br />
• Skyshine (Dr GP de Beer)<br />
• FMEA<br />
• Fire protection<br />
• Fire severity<br />
• Certain <strong>design</strong> suggestions
IAEA expert <strong>co</strong>nsultancies<br />
• November 2004: IAEA-005<br />
• November 2005: Note <strong>of</strong> meeting<br />
• Finalisation <strong>of</strong> Operational Safety<br />
Assessment
Operational safety assessment<br />
• Annual dose limits<br />
• Facility description<br />
• Operation<br />
• Radiation protection<br />
• FMEA<br />
• Fire protection
Annual dose limits<br />
• From BSS 115<br />
• Occ<strong>up</strong>ational exposure limits<br />
–20 mSv/a averaged over 5 years<br />
–50 mSv in single year<br />
–150 mSv lens <strong>of</strong> eye<br />
–500 mSv extremities
Facility description<br />
• Source term<br />
–Typically Co-60, Cs-137<br />
–1000 Ci (37 000 GBq)<br />
–Co-60: Shielding<br />
–Cs-137: Airborne
Facility description<br />
• Facility <strong>design</strong><br />
–Mobile hot cell<br />
–Biological shield with window<br />
–Manipula<strong>to</strong>rs<br />
–Cranes<br />
–Exhaust ventilation<br />
–LTSS
Facility description<br />
• Conditioning team<br />
– Team <strong>lead</strong>er<br />
– Technical expert<br />
– RPO<br />
– Technicians (2)<br />
– Counter part<br />
– IAEA technical <strong>of</strong>ficer<br />
– Labour<br />
• Pre-mission<br />
– Admin<br />
– Leak checks
Operations<br />
• Operational times estimated<br />
• Limiting <strong>co</strong>nditions<br />
– < 1000 Ci<br />
– < 0,4 Bq/cm 2<br />
– Extraction operational<br />
– QC: Equipment, assembly<br />
– Public distance<br />
– Opera<strong>to</strong>rs radiation workers<br />
– Pre-mission: Source not leaking
Radiation protection<br />
• 4 – 5 operations/a<br />
• Radiological ha<strong>za</strong>rds (external & internal)<br />
• Modelling s<strong>of</strong>tware<br />
• MicroShield<br />
• MicroSkyshine<br />
• McSky
Position<br />
MicroShield<br />
(μSv/h)<br />
McSky<br />
(μSv/h)<br />
Against shield 125 32<br />
0,5 m from<br />
shield<br />
77 30<br />
Against window 85<br />
0,5 m from<br />
window<br />
54<br />
Public 12 14<br />
S<strong>of</strong>tware results
Total dose expected<br />
• Duration: 545 minutes<br />
• Opera<strong>to</strong>r dose: 221 μSv<br />
• Public dose: 22 μSv
Thank You!!!
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