Self Shielded Irradiators

["Kent N. Lambert" <lambert@auhs.edu>]

Group,

Those that are familiar with self shielded irradiators are aware of 
the inherent safety of the devices under normal use.  I was asked 
about radiological considerations in a disaster.  

My initial impression is that because the shielding is made of lead, 
and lead has a low melting point, that one obvious concern is a loss 
of shielding in a fire.  Presumably the lead is encased in steel such 
that this is unlikely to occur.  But at what temperature would the 
structure fail?  Is this temperature likely to be achieved in a 
serious building fire?  Is the device more suseptible to structural 
damage at these elevated temperatures?

Also are there other disasters which might create a major problem - 
explosions (don't laugh, I'm sure that we are not the only one that 
has seen the bomb squad at their facility), earthquakes (structural 
damage to building causing the device to fall tens of feet onto a 
hard, solid object), tornadoes, thermal shock (e.g., fire followed by 
water from fire suppression system),  others?  

So, what sort of disaster could affect the integrity of the shielding 
or the sources?  Are there written standards that these devices must 
meet?  Are actual tests performed on prototypes?  I would appreciate 
references if possible.

Kent N. Lambert, M.S., CHP
lambert@auhs.edu
Allegheny University of the Health Sciences
Hahnemann Division
Radiation Physics and Safety, MS 106
Broad and Vine Streets
Philadelphia, PA  19102-1192

215-762-8768 (voice)
215-762-7683 (fax)