[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: Skin Dose Assessment from Whole Body Contamination Meters
Anyone who wants the info related to noble gas skin dose determination through whole body
counting, just send me a note at mlantz33@cybertrails.com or mlantz@apsc.com or call at 623
393 5200. It is the favorite paper that I've ever written, so I jump at the chance for
others to read it. I just wish Emergency Planning people would ever catch on to its value:
like, determining skin dose and external deep dose too ---- like knowing that frisker alarms
on people may not be due to iodine, but more likely caused by Xe (so KI won't help). Other
ideas too, but they never ask.
I have detailed all of the EDE questions that Stewart has asked about; that part being
clarified in the ICRPs. My retention curves merely confirm the previously-determined minor
internal components. The question of whether the PCM alarn is caused by noble gases only is
one of the reasons we have so many whole body counts - i.e., looking for other
radionuclides. With Co-58 and Co-60, as Stewart has noted, being the dominant ones. We
aren't big scrub supporters because of the philosophy that some facilities utilize: that
they aren't clothing contaminations. Too long a story, but we find that >99% of our alarms
during these gas events are pure NG. But what you have said is what we do, along with a
shower. CM-7 100 cm2 friskers, PCM's, showers, whole body counts.
So bottomline, it works well. Even as a bounding condition - that they passed the
contamination monitor so they must have incurred less than 20 mrad. for example. But its
major value has been in determining doses where repressntative sampling was generally almost
impossible - gas puffs.
Mike Lantz, CHP
JSBland@aol.com wrote:
> --part1_ae.10119737.279b0c9c_boundary
> Content-Type: text/plain; charset="US-ASCII"
> Content-Transfer-Encoding: 7bit
>
> Mike, et. al.,
>
> The measurements and expanded modeling you described seems most helpful to
> the industry. And, being unable to attend Midyear, I would appreciate
> copies, as appropriate and available. For skin dose calcs, the approach you
> developed provides a great tool.
>
> One of the concerns I was looking at was how to confirm that the PCM alarm
> was solely attributable to noble gases, that was the reason for the expanded
> modeling with MCNP to examine detection capability of the BNC NaI detector.
> During our testing, we had an interesting situation where an individual
> alarmed the portal monitor. A measurement with the BNC detector (1 minute
> count with detector on chest) showed mostly Xe-133, but there was also a
> Co-58/60 component. Removal of scrubs eliminated the cobalt. Further
> examination identified the scrubs as having a very-low Co-58/60 contamination
> spot, but low enough to pass the screening done for re-use. This type
> measurement, coupled with a frisk survey to eliminate potential skin
> contamination (i.e., elevated measurement with a thin-window GM detector at a
> discrete location versus generally disperse, elevated measurements) provides
> reasonable assurance that the alarm is solely attributable to the noble gas
> retention.
>
> I was also curious about the actual EDE due to retained noble gases in the
> fat. There is also a muscle component but at a much lower level. Linking
> the Peterman model in Radiation Protection Dosimetry for determining time
> dependent body/organ contents and MCNP modeling of the standard man model,
> and application of weighting factors, an EDE could be calculated. This
> modeling can also be applied to other noble gases, such as radon and argon.
> This may have already been done, but I am not aware of it. (Help from any
> sources out there is appreciated.)
>
> Stewart Bland
> 410-266-9174
>
> --part1_ae.10119737.279b0c9c_boundary
> Content-Type: text/html; charset="US-ASCII"
> Content-Transfer-Encoding: 7bit
>
> <HTML><FONT FACE=arial,helvetica><FONT SIZE=2>Mike, et. al.,
> <BR>
> <BR>The measurements and expanded modeling you described seems most helpful to
> <BR>the industry. And, being unable to attend Midyear, I would appreciate
> <BR>copies, as appropriate and available. For skin dose calcs, the approach you
> <BR>developed provides a great tool.
> <BR>
> <BR>One of the concerns I was looking at was how to confirm that the PCM alarm
> <BR>was solely attributable to noble gases, that was the reason for the expanded
> <BR>modeling with MCNP to examine detection capability of the BNC NaI detector.
> <BR>During our testing, we had an interesting situation where an individual
> <BR>alarmed the portal monitor. A measurement with the BNC detector (1 minute
> <BR>count with detector on chest) showed mostly Xe-133, but there was also a
> <BR>Co-58/60 component. Removal of scrubs eliminated the cobalt. Further
> <BR>examination identified the scrubs as having a very-low Co-58/60 contamination
> <BR>spot, but low enough to pass the screening done for re-use. This type
> <BR>measurement, coupled with a frisk survey to eliminate potential skin
> <BR>contamination (i.e., elevated measurement with a thin-window GM detector at a
> <BR>discrete location versus generally disperse, elevated measurements) provides
> <BR>reasonable assurance that the alarm is solely attributable to the noble gas
> <BR>retention.
> <BR>
> <BR>I was also curious about the actual EDE due to retained noble gases in the
> <BR>fat. There is also a muscle component but at a much lower level. Linking
> <BR>the Peterman model in Radiation Protection Dosimetry for determining time
> <BR>dependent body/organ contents and MCNP modeling of the standard man model,
> <BR>and application of weighting factors, an EDE could be calculated. This
> <BR>modeling can also be applied to other noble gases, such as radon and argon.
> <BR>This may have already been done, but I am not aware of it. (Help from any
> <BR>sources out there is appreciated.)
> <BR>
> <BR>Stewart Bland
> <BR>410-266-9174</FONT></HTML>
>
> --part1_ae.10119737.279b0c9c_boundary--
> ************************************************************************
> The RADSAFE Frequently Asked Questions list, archives and subscription
> information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html
************************************************************************
The RADSAFE Frequently Asked Questions list, archives and subscription
information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html