[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: MDA vs. Critical level for DOE Free Release surveys
You have to use both concepts. Briefly:
The critical level is an after the fact decision point: Is the count due to
radioactive contamination or is it variation in background, i.e., can the
material be free released? This is usually set to provide for 5% "Type 1"
error; i.e. there's a 5% chance of a false positive.
The MDA is an a priori evaluation of your assay system. It is set so that, for
a sample which contains an MDA of contamination, the actual count will exceed
the critical level with 95% confidence, i.e., a 5% "Type 2" (false negative)
error.
I believe that Glenn Knowles's book has a good explanation of this.
The opinions expressed are strictly mine.
It's not about dose, it's about trust.
Curies forever.
Bill Lipton
liptonw@dteenergy.com
"Goff, Tom" wrote:
> > Title:
> >
> > We are discussing using a critical level for free release surveys.
> > Please provide answers to the following:
> >
> > Are you using critical value or MDA for free release surveys of
> > materials from your site?
> >
> > Does anyone have a reference/regulatory standard on whether to use
> > MDA or critical value for free release surveys?
> >
> > Given that an MDA results in a 95% confidence in detecting
> > contamination at the MDA value, what is the corresponding confidence if
> > using the critical level?
> >
> > I would welcome any other comments or thoughts on this.
> >
> > Tom Goff
> >
> > --------------------------------------------------------------------------
> > ----------------------------------------------------------------
> > Let me know if you're ok with this.
> >
> >
> >
> > Tom Goff
> > WIPP ALARA Coordinator
> > WIPP Integrated Waste Operations
> > (505) 234-8861
> > (fax) 234-8963
> > e-mail Tom.Goff@WIPP.ws
> > page (505) 234-8850 (pager 479)
> > P.O. Box 2078
> > Carlsbad, NM 88221
> > Radiological Engineering: Anticipating Problems.....providing
> > solutions!!!
> >
>
> ************************************************************************
> You are currently subscribed to the Radsafe mailing list. To
> unsubscribe, send an e-mail to Majordomo@list.vanderbilt.edu Put the
> text "unsubscribe radsafe" (no quote marks) in the body of the e-mail,
> with no subject line. You can view the Radsafe archives at
> http://www.vanderbilt.edu/radsafe/
************************************************************************
You are currently subscribed to the Radsafe mailing list. To
unsubscribe, send an e-mail to Majordomo@list.vanderbilt.edu Put the
text "unsubscribe radsafe" (no quote marks) in the body of the e-mail,
with no subject line. You can view the Radsafe archives at
http://www.vanderbilt.edu/radsafe/