[ RadSafe ] Fwd: Pilots UV-A radiation exposure
jjshonka at shonka.com
jjshonka at shonka.com
Mon Dec 29 09:48:54 CST 2014
Hans
Thanks for the detail. Ed Bramlitt and I just published a note to the Health Physics Journal on the exposure of aircrew. I have sent a copy to your personal email in case you are not a member of the Health Physics Society. I have also sent just the email to RADSAFE.
I overstated the dose per 100 thousand frequent flyer miles, it is probably 1.25 mSv rather than the 5 that I stated earlier. If you travelled for work, should this ~25 mSv dose be considered as a part of your occupational history? The “missed” dose from your film badges (truncated at 50 mrem per month?) may be significant as well.
My interest is in radiation sources not currently accounted for in aircrew doses. The electrons and positrons from terrestrial gamma flashes are detected by satellites 550 km above because the charged particles spiral around earth’s magnetic field lines of force (for example, a 7 MeV positron or electron has an spiral radius of 34 meters in the nominal 50 uT field from earth. I think the electromagnetic cascade loses the photon component over long distances, particularly as the air thins out. Thus, the charged component of dose to aircrew from a TGF does not get reduced substantially by the inverse square law. From these crude measurements and his model, Joe Dwyer from FIU calculated that the dose can be as high as 100 mSv to an aircraft that is between the thunderstorm and the satellite. This is 200 times the NCRP recommended monthly dose of 0.5 mSv during gestation. The 1200 TGFs per day estimated from satellite measurements are for high fluence measurements alone, and we do not know how often a TGF which would deliver 0.5 mSv or more to an aircraft occurs.
So your film badge might have been blind to a nominal 50 mrem (0.5 mSv) exposure from TGF, but the OSL badges might have detected such an event. Since your flights were over 10 hours, were they transcontinental flights? If so, thunderstorm frequency over the oceans is significantly lower than continental or tropical areas. Thus, your history may not reveal much information if most of the miles you travelled and monitored via dosimetry were over oceans.
I would be interested in any information on the Concorde ion chamber, including a photograph. I understand that the instrument had an alarm set point of 10 rads per hour. This was based on the solar flare of 2/23/56 I do not know if that was de-rated for the neutron component. I also understand that the alarm never occurred on a flight during the service history of Concorde, which primarily operated on transcontinental routes because of the sonic boom.
Joe Shonka
Sent from Windows Mail
From: Ted de Castro
Sent: Sunday, December 28, 2014 10:26 PM
To: The International Radiation Protection (Health Physics) Mailing List
We did several flights - mostly in a military transport but at least two
in a U2 (of course the instruments flew the U2 - not us - not much space
in a U2!!)!
We used them many many times around the accelerators at LBL (ground
based) but once we proved the technology - by bonner sphere comparison
- we mainly used what we called the "proportional energy" counter ----
described in Pattterson and Thomas --- and a flux monitor (moderated
BF3). Then eventually we verified the high energy Andersson Braun and
deployed them all around the lab - in close and at the perimeter.
One day at the Super Hilac we compared the 3 inch 9 inch bonner sphere
method with the Proportional Energy and the extended Andersson Braun -
and of course the full bonner sphere array, in cooperation with Dale
Hankins LLNL (he did the 3 inch 9 inch). High energy AB won, then PE
and lastly 3inch/9inch.
We also did plastic scintillator activation but some one else did that
(Allen R. Smith) and so I don't have much details on that.
On 12/28/2014 7:14 PM, JPreisig at aol.com wrote:
> xrayted,
>
> Doing 7 Bonner detectors on the ground and activating a plastic
> scintillator on the ground is also a challenge. detectors = bare, Cd-covered,
> 3 inch, 5 inch, 8 inch, 10 inch, 12 inch plus plastic scintillator.
> But it can be done.
>
> Joe Preisig
>
>
>
>
> In a message dated 12/28/2014 10:08:57 P.M. Eastern Standard Time,
> tdc at xrayted.com writes:
>
> Flying a whole set of Bonner Spheres is not a trivial matter - been
> there done that! With McCaslin in fact!
>
> For just dose - an Andersson Braun detector would be easiest - although
> not light weight - especially the extended high energy version.
>
> On 12/22/2014 7:49 PM, JPreisig at aol.com wrote:
>> Joe,
>>
>> I guess there's an Ed Bramlitt. I also believe there's a
> Bramblett,
>> Ewing and Bonner --- inventors of Bonner Neutron Spectrometry. See
>> Patterson and Thomas's Accelerator Health Physics. See also Cossairt's
>> Accelerator Health Physics course notes/manual.
>>
>> Joe Preisig
>>
>> PS Badges are OK in airplanes....but one really needs a Neutron
>> Spectrometer (for thermal neutron to 20 MeV energies) and a plastic
> scintillator
>> (n,2n reaction) for 20 MeV to 400 MeV neutrons. Scintillator see the
> back end
>> of Patterson and Thomas's Accelerator Health Physics book (McCaslins's
>> plastic scintillator lab exercise).
>>
>>
>>
>> a message dated 12/21/2014 2:36:32 P.M. Eastern Standard Time,
>> jjshonka at shonka.com writes:
>>
>> Hans
>>
>>
>> I am quite interested in your badge results, and what would be a
>> significant radiation exposure. You have an unusually high number of
> frequent flyer
>> miles. If we assume total neutron plus gamma of 500 mrem (5 mSv) per
>> 100,000 frequent flyer miles or per year, and 15 rem over a 3 million
> mile or
>> 30 year career, I have the following questions: (1) were your badges
>> neutron sensitive (80% of GCR dose is due to neutrons)?; (2) how often
> were
>> they read out (quarterly, monthly?); (3) were many of your miles extra
> credits
>> rather than actual miles flown (e.g. first class gets 2X miles)?; (4)
> were
>> your miles collected evenly or did you travel more extensively during
> some
>> fraction of your career?; (5) what would you say the reporting limit or
>> detection limit of the badges was (e.g any reading less than 10 mrem
> (0.1
>> mSv) reported as 0)?; (6) were your badges used for work and did they
> have
>> measureable exposure from sources other than background plus your
> flight time?
>>
>> Ed Bramlitt and I have a note in the January, 2015 issue of Health
> Physics
>> that discusses intermittent sources of exposure to aircrew, including
>> solar proton, neutron and gamma events and terrestrial gamma flashes.
> About 1%
>> of the 1200 Terrestrial gamma flashes that are large enough to be
> detected
>> by satellites that occur each day (world-wide) approach estimated doses
> in
>> aircraft of up to 30 to 100 mSv, for example. Although rare, these
> likely
>> would have been observed on your badge. The more numerous dose of 10
> mSv
>> or greater (my estimate of the lower limit of detection for the GBM
>> detectors on board FERMI) might also be detectable, however, presumably
> even more
>> numerous but undetectable lower dose TGFs (below 10 mSv) might not be
>> detected. I am interested in how large one of those events could have
> been
>> without your noticing an unusual reading.
>>
>>
>> I assume the background control badges were at your place of
> employment.
>> Finally, (7) For example, if you typically had 12 flights per quarter,
> and
>> one of those flights encountered a source that provided 1,000 mrem (10
> mSv)
>> 80 % of which was neutron and only 200 mrem (2 mSv) was gamma, would you
>> have noticed it as an unusual badge reading?
>>
>>
>> Joe Shonka
>>
>>
>>
>>
>>
>>
>> Sent from Windows Mail
>>
>>
>>
>>
>>
>> From: Hans J Wiegert
>> Sent: Saturday, December 20, 2014 7:18 PM
>> To: The International Radiation Protection (Health Physics) Mailing List
>>
>>
>>
>>
>>
>> For what it's worth.
>>
>> I am not so sure about this. During my career I traveled almost 3
> million
>> miles on various airlines with my seating preference being a window
> seat.
>> Never noticed anything like this. As a side note, on almost all of those
>> trips I carried a film badge on me and in recent years the Landauer
> Luxel
>> OSL badge. The badges never showed any significant radiation exposure.
>>
>> Best Regards,
>>
>> Hans
>>
>> *Retirement is, when the only day you have to set your alarm clock is
>> Sunday - so you are not late for church!*
>>
>> On Thu, Dec 18, 2014 at 2:19 PM, Chris Alston <achris1999 at gmail.com>
> wrote:
>>> This is easy to believe. I, as a passenger, have gotten a pretty good
>>> tan, mostly on one side of my face, on just one trip from Seattle to
>>> San Diego. Fortunately, I had a window seat on the other side of the
>>> aircraft (DC-9 family, for whatever it is worth) on the northward
>>> return flight, to "touch up" the other side of my face, else I would
>>> have looked like that arch-criminal in the Batman comics.
>>>
>>> Cheers
>>> cja
>>>
>>> On Wed, Dec 17, 2014 at 8:36 PM, ROY HERREN <royherren2005 at yahoo.com>
>>> wrote:
>>>> Hopefully the following isn't too "off topic", given that the article
>> is
>>> dealing with UV-A radiation.
>>>
>>
> http://media.jamanetwork.com/news-item/airline-pilots-can-be-exposed-to-cockpit-radiation-similar-to-tanning-beds/
>>> > Airline Pilots Can Be Exposed to Cockpit Radiation Similar to
> Tanning
>>> Beds
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