AW: [ RadSafe ] Gamma measurements in planes

Tue Dec 19 05:23:38 CST 2006

Kim,

you are absolutely right. 

However, the relative contributions of the dominant sources, i.e. neutrons, gammas, electrons, protons, vary more or less in parallel in the given altitude and latitude range (see attached graph for the requested data) so that the ratio of the effective dose would closely reflect the ratio of e.g. the quoted gamma doses.

My point simply was that altitude/latitude variability might explain the reported differences without the need to invoke radioactive sources. 

Best regards, Rainer 

Dr. Rainer Facius
German Aerospace Center
Institute of Aerospace Medicine
Linder Hoehe
51147 Koeln
GERMANY
Voice: +49 2203 601 3147 or 3150
FAX:   +49 2203 61970

-----Ursprüngliche Nachricht-----
Von: McMahan, Kimberly L. [mailto:mcmahankl at ornl.gov] 
Gesendet: Montag, 18. Dezember 2006 19:06
An: Facius, Rainer; Charles.Ellars at qsa-global.com; mso at forsmark.vattenfall.se; radsafe at radlab.nl
Betreff: RE: [ RadSafe ] Gamma measurements in planes

Dr. Facius,

I suspect the dose equivalent rates you mention are totals for all radiation types. If a concise summary of dose rate by incident radiation type is available, I would be interested to see it. I don't know what detectors are built into these small portable devices, but if they are G-Ms then they would be pretty transparent to neutrons bouncing off fuel, and therefore miss a significant fraction of the total dose equivalent. A quick browsing of the papers in the RPD issue mentioned earlier by John Johnson finds the neutron dose rates at typical flight altitudes are generally 100 - 150% of the gamma dose rates. Adding that estimated neutron component to the gamma measurement, there is reasonably good agreement between all of the values mentioned.

Another study on this subject is, "The NIOSH/FAA Working Women's Health Study: Evaluation of the Cosmic Radiation Exposures of Flight Attendants," published in the Health Physics Journal, Vol. 79, No. 5, November 2000. Unfortunately, the authors did not report gamma/charged particle/neutron doses separately.

Kim McMAHAN    ORNL External Dosimetry 

-----Original Message-----
From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] On Behalf Of Rainer.Facius at dlr.de
Sent: Monday, December 18, 2006 11:51 AM
To: Charles.Ellars at qsa-global.com; mso at forsmark.vattenfall.se; radsafe at radlab.nl
Subject: AW: [ RadSafe ] Gamma measurements in planes

Charles:

	Between Boston (42.35 degree N ) and Florida (Orlando? 29 degree N ) the present (quiet sun) effective dose rate at 35 kft would vary between 7.4 and 5.1 microSv/h. Unless you took care to take your readings at the same geographical latitude (aside from the altitude), the variation could easily be accounted for. Furthermore, depending on the distance of your seat from the fuel tanks and their fuel content you can observe substantial variations due to the high energy 'albedo' radiation from the fuel. So probably you need neither DU nor Tritium or any other radioactive material to explain your observed variation.

Regards, Rainer

Dr. Rainer Facius
German Aerospace Center
Institute of Aerospace Medicine
Linder Hoehe
51147 Koeln
GERMANY
Voice: +49 2203 601 3147 or 3150
FAX:   +49 2203 61970

-----Ursprüngliche Nachricht-----
Von: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] Im Auftrag von Ellars, Charles
Gesendet: Montag, 18. Dezember 2006 16:24
An: Olsson Mattias :MSO; radsafe at radlab.nl
Betreff: RE: [ RadSafe ] Gamma measurements in planes

On a recent trip to FL from Boston, my RadEyeG measured 0.01 mr/hr on the ground and 0.40 mr/hr at 35Kft during the day.  On the return flight the next night it measured 0.01 on the ground and 0.30 mr/hr.  These are completely unscientific since I probably changed locations relative to DU ballast if any.  Also, I don't know what energies were involved and therefore can't correlate the response of the RadEyeG.  Still it was interesting.

-----Original Message-----
From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] On Behalf Of Olsson Mattias :MSO
Sent: Saturday, December 16, 2006 1:14 PM
To: radsafe at radlab.nl
Subject: [ RadSafe ] Gamma measurements in planes

There has been some writing about dose rate measurements in planes. I seem to recall that DU can be used as ballast in planes. Even though not exceptionally active, I suppose that could affect measurements somewhat inside a plane!

Mattias Olsson
PhD, Nuclear chemistry
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