Release of using a SAM9

[June_L._Scott@FirstEnergyCorp.com]

You need to understand the characteristics of the SAM 9 cave and detectors
and how different materials affect the detection efficiency.  I suggest you
perform a series of efficiency counts with a variety of materials between
the detector and a known source, then calculate the efficiency for each.
Also vary the distance at which efficiencies were calculated from the
bottom detector ( e.g. contact, 1", 3", 6" above the detector).  This will
show you the relative attenuation.  I also graphed the efficiencies for
attenuation thickness of the same material (e.g. 1/16" wall pipe, 1/8" wall
pipe, 1/4" wall pipe, etc.).  I have done this for paper, aluminum, plastic
pipe, iron pipe, cloth, etc.  For each count perform a calculation of the
SAM 9 to source DPM ratio, from this it is easy to compare the relative
response of the SAM 9 to materials that you want to release with it.  You
will need to determine what geometry efficiency is acceptable for general
release of material and if it is appropriate for release of materials
fitting different geometries. an assessment of how conservative you desire
is necessary.  I think from review of this data the calibration geometry
for efficiency is quite evident and defensible.

Specifically, release of guages is a compound issue as the  water tends to
concentrate the isotopes.  We flush guages with DI water before release,
and if they are known to be used on a contaminated system they are counted
on a HpGe before being determined able to be released.

jlscott@FirstEnergyCorp.com
Health Physicist
Davis Besse Nuclear Power Station
419-321-8555




I am interested in hearig from facilities using the SAM-9 or SAM-11 for
free release surveys how you perform free release surveys of pressure
gauges that have come in contact with a liquid.  Is there a recommended
procedure in determining that any potential "free-standing" liquid within
the non-ventable gauge does not provide self-shielding of contaminants
which may reside inside the gauge, potentially being undetected by the
SAM-9 or SAM-11 monitor.

My e-mail address is: tarantino@vapower.com


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I am interested in hearig from facilities using the SAM-9 or SAM-11 for
free release surveys how you perform free release surveys of pressure
gauges that have come in contact with a liquid.  Is there a recommended
procedure in determining that any potential "free-standing" liquid within
the non-ventable gauge does not provide self-shielding of contaminants
which may reside inside the gauge, potentially being undetected by the
SAM-9 or SAM-11 monitor.


************************************************************************
The RADSAFE Frequently Asked Questions list, archives and subscription
information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html