Thank you very much for your replies.
Just as a matter of curiosity, you were right, i'm not writing from the US. I'm writing from Colombia!. i've had some trouble figuring out what MDA's, MDC's MACs, RCRA SW, LASS system, MDA, etc. mean...
Beleive it or not, colombian regulation concerning radiological protection dates from 2002, and its application on practice remains "folcloric". So thats part of our present task, to seek if becomes more rigourous in the labs at the National University.
i'll be posting soon with more questions...