Hi Bob,
Here in the states, it is pretty uncommon to find a source attached to a meter--for the reasons you stated and the extra expense of buying and maintaining all those sources. But we have far fewer exit points from our RCA's than you folks do.
Normally, we keep one source and use it daily to check each meter. Every meter has a sticker on the side for us to record the daily check (usually by initialling or marking off the date). But, as I stated above, we don't have hundreds of them all over the station. There are few enough that one RP tech can check them all in a few hours or less. We are a little more strict about checking them too. Instead of just verifying a response, we use the same source every day, with a calculated count rate. Each meter has to register a rate within the acceptable range--just like the dose rate meters.
Since you have so many meters and so many peope qualified to use them, perhaps you could wall mount some sources in central locations like you do with the other check sources.
