Re: Working life of sealed industrial sources

[Roger Gelder <74167.2472@CompuServe.COM>]

We had the same problem in the UK but the microspheres crushed - readily,
worse still some one put an anti-static gauge (Po-210) through the paper
guillotine
resulting in 40' of product line being vigorously contaminated and scrapped -too
costly to decontaminate.

Other sources:
A	I used to do leakage tests on sugar mills (sugar beat processing) which
required lime, freshly made in kilns loaded with limestone and coke via
automatic
hoppers and --- level gauges with Cs-137. At some 10 to 15 years of age these
sources
started to show genuine leakage in a small fraction of cases.
B	A pneumatically driven Co-60 radiography source (single encapsulation)
released 
mCi quantities, contaminating several other items of equipment, since
alternative sources 
were used on the pneumatic system before the problem was detected.
C	Thickness gauges (Sr-90 with a silver foil cover) were used on a rubber
tyre
plant. Rubber contained sulphur - a simple wipe test of what was thought to be a
dirty
source face wiped off half the source. My contamination monitor behaved much as
I suspect
the first survey meter at Chernobyl  must have done. Sources retired, and a gold
foil replaced 
the silver.

	These are old stories (>15 y) but may be relevant. Other events exist.
	Probe first + Presence of mind + Absence of body.

	Roger Gelder