Working life of sealed industrial sources

[radgovwa@wt.com.au]

For the longer half life sealed industrial sources used in density or
level gauges, well logging, etc. (e.g. Cs 137, Am241), source
suppliers may recommend a working life of perhaps 10-15 years before
replacement even though there may be no apparent physical
deterioration of the source encapsulation when tested.

Is anyone aware of any incidents of leakage of the radioactive
material from such sources (other than that due to accident etc) which
could be attributed to corrosion or other age related failure of the
encapsulation?  

Are any regulators permitting variations to the working life
recommended by the source suppliers?

Radiation Health Section
Health Department of Western Australia
e-mail radgovwa@sage.wt.com.au