Re: Contamination Dispersion Cs 137

[NSSIHOU@aol.com]

Further information is needed concerning the source manufacturer and 
encapsulation to respond to your inquiry. 

You indicate an X8 or X38 capsule. I am not aware of anyone with an X8 model 
number any more. Amersham at one time had some x numbered sources. 

I also find it hard to believe that anyone would encapsulate Cs-137 in an 
Aluminum capsule. 

The early Ceramic Cs-137 sources were Cesium Chloride taken up on 
Montmorillonite clay and were not fired. Later on some were glazed and fired. 
Still later, other types of ceramics were utilized. Some were powder type 
ceramics such as microspheres. Others were pressed and fired pellets. Most of 
the ceramics disappeared about 7-10 years ago and glass became and remains 
the preferred source material.  

The use of doubly encapsulated stainless steel has been the norm for the last 
20 years. Heliarc welding has also been the norm although many of the 
microsphere sources were silver soldered.  The use of Aluminum has never been 
the norm. I am surprised that any regulatory agency would authorize 
encapsultion of  50 mCi of Cs-137 in Aluminum. 

With respect to contamination, we have recovered ceramic pellet Cs-137 
sources where the capsule has been cut in two. We were able to remove 
significant activity from the source but all of the activity was in the 
particulate of the ceramic. We did not see the activity transferring to other 
surfaces.  

The white mterial you have described may very well be Aluminum oxide or 
hydroxide from the oxidation of the Aluminum. I am unable to determine what 
type of facility the density gauge is at but, if it is a cement manufacturer, 
we have seen Aluminum components of equipment corroded away by the caustic 
nature of the cement. 

With respect to the movement of the activity, I would doubt that there was a 
pressure buildup within the source. I would believe the problem is one of 
airflow and dust. The activity, if particulate should come off the 
contaminated surfaces with a damp paper towel. If it does not, I would guess 
that the source was Cs-137 Chloride baked onto clay. 
While the use of a fume hood is not required for handling sealed sources 
normally, when handling a source holder with significant corrosion evident or 
sources encapsulated in anything other than doubly encapsulated stainless 
steel, it would be advisable. If for example, one is removing a thin window 
source of Am-241, I would recommend the use of  a glove enclosure if there is 
any possibility that source is stuck in the unit and could rupture.


ROBERT D GALLAGHER
NSSI
713 641-0391
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