Dohn,
Thanks for the link.
Bob Sorber
From: [email protected] [mailto:[email protected]] On Behalf Of
LITTLE, DOHN V
Sent: Friday, January 20, 2012 1:36 PM
To: '[email protected]'
Subject: Powernet: RE: Beta Correction Factor for Handheld Ion Chamber
Instruments
This may be the report mentioned
http://www.pnl.gov/main/publications/external/technical_reports/PNNL-13603.pdf
Thanks,
Dohn
Dohn Little
Radiation Health Specialist - Dosimetry
[email protected] - (402) 533-7162
Admin Building FC 2-1
OPPD - Fort Calhoun Station
9610 Power Lane
Blair, Ne. 68008
From: [email protected] [mailto:[email protected]] On Behalf Of
BREHM, DAVID M
Sent: Thursday, January 05, 2012 6:37 AM
To: [email protected]
Subject: Powernet: RE: Beta Correction Factor for Handheld Ion Chamber
Instruments
Battelle PNNL did a study a number of years ago to determine correction factors
for measurements made with an ion-chamber with the source close to the chamber.
Several geometries were used (e.g., disks, cylinders, etc.). The range of
correction factors was quite large (over 100 in some cases), particularly for
small disks in close proximity to the chamber window. The initial study was
for the RO-3, but was re-done in the late 90's for the RO-20.
I probably have a copy of the studies, or at least the results, somewhere in my
archives, but it would be best to get it from them. That should be possible as
it was done on the taxpayer's dime.
David Brehm
Fort Calhoun Nuclear Station
Supervisor - Radiological Equipment & Dosimetry
Office: 402.533.7582
Cellular: 402.214.0107
Pager: 402.561.3310
From: [email protected]<mailto:[email protected]>
[mailto:[email protected]]<mailto:[mailto:[email protected]]> On
Behalf Of Williams, Dane R. (INPO)
Sent: Thursday, January 05, 2012 6:21 AM
To: [email protected]<mailto:[email protected]>
Subject: Powernet: RE: Beta Correction Factor for Handheld Ion Chamber
Instruments
What about smear geometry? I seem to remember a correction factor of 8 (was
with an RO-2).
Dane R. Williams, CHP
Team Leader
Institute of Nuclear Power Operations
[email protected]<mailto:[email protected]>
770.644.8882
From: [email protected]<mailto:[email protected]>
[mailto:[email protected]]<mailto:[mailto:[email protected]]> On
Behalf Of Sorber, Bob
Sent: Wednesday, January 04, 2012 1:02 PM
To: [email protected]<mailto:[email protected]>
Subject: Powernet: RE: Beta Correction Factor for Handheld Ion Chamber
Instruments
Gordon,
Duke Energy uses the following beta correction factors for the RO-20:
* 4 for bare instrument.
* 5 for single bagged instrument.
* 6 for double bagged instrument.
* 7 for a single bagged instrument measuring a noble gas atmosphere.
These factors were developed using slab sources of Tc-99, Tl-204 and U-238 at
contact. The sources were wider than the instrument beta window. Note that
geometry is important. We measured significantly lower correction factors
using on axis point sources. The beta correction factor for a bare instrument
changes only slightly with changes in beta half value layer (energy) because
the window thickness approximately equals the 7 mg/cm^2 depth at which skin
dose is defined.
Inspection of the detector geometry explains the measured bare instrument
correction factor of 4. The anode blocks the rear half of the detector chamber
making it insensitive to all but high energy beta radiation. This accounts for
a correction factor of 2. Partial shielding of the space around the side walls
of the chamber for radiation entering off axis brings the bare instrument
correction factor to 4.
We do not perform a beta calibration on each instrument since once the
instrument's overall gamma response is accurately calibrated, the correction
for beta is fixed since the beta correction factor depends only on the geometry
of the chamber, the thickness of the anode and the thickness of the window. We
do confirm the beta response of individual instruments.
Bob Sorber
704-382-7259
_____________________________________________
From: [email protected]<mailto:[email protected]>
[mailto:[email protected]] On Behalf Of
[email protected]<mailto:[email protected]>
Sent: Wednesday, January 04, 2012 10:44 AM
To: [email protected]<mailto:[email protected]>
Subject: Powernet: Beta Correction Factor for Handheld Ion Chamber Instruments
Palo Verde requests the following information:
What beta source is used to establish beta correction factors for handheld ion
chambers (RO-20, RO-2/2A, RSO-50E) at your facility?
Is a generic beta correction factor is assigned (such as 4 or 5) or is the
specific value established during calibration assigned (such as 3.8)?
Thanks
Gordon Nelson
Radiological Engineering
Palo Verde Nuclear Generating Station
Phone (623) 393-5200
Cell (623) 238-0542
Pager (877) 466-7534
[email protected]<mailto:[email protected]>
________________________________
.DISCLAIMER:
This e-mail and any of its attachments may contain proprietary INPO or WANO
information that is privileged, confidential, or protected by copyright
belonging to INPO or WANO. This e-mail is intended solely for the use of the
individual or entity for which it is intended. If you are not the intended
recipient of this e-mail, any dissemination, distribution, copying, or action
taken in relation to the contents of and attachments to this e-mail is contrary
to the rights of INPO or WANO and is prohibited. If you are not the intended
recipient of this e-mail, please notify the sender immediately by return e-mail
and permanently delete the original and any copy or printout of this e-mail and
any attachments.
Thank you.
________________________________
This e-mail contains Omaha Public Power District's confidential and proprietary
information and is for use only by the intended recipient. Unless explicitly
stated otherwise, this e-mail is not a contract offer, amendment, or
acceptance. If you are not the intended recipient you are notified that
disclosing, copying, distributing or taking any action in reliance on the
contents of this information is strictly prohibited.
