Re:LLD Need Help!

["Rodney Bauman"<rodney_bauman@wssrap-host.wssrap.com>]

If your looking for an equation to determine required count times, use an MDA
equation, not a decision level (DL) equation.  Survey instruments must be used
such that their respective MDA is capable of meeting the required release
criteria.

However, activity detected above the decision level (sometimes called the
critical level) must be considered "above background."  If you set both Type I
and Type II errors at 5% probability, your decision level is approximately 1/2
of the MDA.

For equations, try draft NUREG-1507.  It can be downloaded from the NRC's
website or I can fax you a copy if needed.

Rodney Bauman, CHP, RRPT
Weldon Spring Site
rodney_bauman@wssrap-host.wssrap.com 

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