[ RadSafe ] 10 rem from lightning?? (UNCLASSIFIED)

[gelsg at aol.com]

Sandy et al:

Have we forgotten the inverse square law?  I have not read the original paper, but let me speculate that the 10 rem was measured at, say, 2 mm from the point where the "lightening" struck some object (unlikely to be tungsten on an airplane).  In any case, let's also say that the dosimeter is 50 feet away from that point.  If you assume that all x-rays are produced at the point of the strike, then at a distance of 50 ft, you will see about 1.3 mrem.  And this does not assume any intervening shielding materials.

You can jiggle those assumption numbers around and get different results, but if the 10 rem number was the result of a measurement very close to the point of origin of the x-rays, you will probably get a number well below the rem range.  Right?

Jerry Gels






-----Original Message-----
From: Perle, Sandy <SPerle at mirion.com>
To: <JOHN.RICH at sargentlundy.com> <JOHN.RICH at sargentlundy.com>
Cc: radsafe at health.phys.iit.edu <radsafe at health.phys.iit.edu>
Sent: Tue, Mar 30, 2010 6:49 pm
Subject: Re: [ RadSafe ] 10 rem from lightning?? (UNCLASSIFIED)


John,
I'd expect some optical density since film dosimetry can accurately detect and 
eport dose at 10 mrem (0.10 mSv). If a film, dosimetry or otherwise, is exposed 
o doses in the rem range, you can definitely expect an issue! If you let your 
amera film go through a carry-on x-ray unit, the exposure is in the tenths of 
rem. Checked baggage could be irradiated to between 150 and 300 mrem each time 
t goes through a unit. This will damage the film, no doubt. As stated, I don't 
uy the premise of lightning causing this level of ionizing radiation, period.
Regards,
Sandy
____________________
ander C. Perle
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irion Technologies
osimetry Services Division
652 McGaw Avenue
rvine, CA 92614
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n Mar 30, 2010, at 3:12 PM, <JOHN.RICH at sargentlundy.com> wrote:
>
 Just a quick thought.  Would a few rem fog camera film?  (used to carry a film 
amera and usually had fairly sensitive color film.)  Has anybody had experience 
ith film fogging after a lightning strike on an airplane?  Not as good as a 
adge, but it would support, or challenge the notion of significant x-rays.  
therwise, has anybody had an environmental dosimeter register a surprise high 
ose rate (assuming a lightning strike nearby).

 just looking for something that would register the xrays, or support the fact 
hat they aren't significant.

  - -jmr

 John Rich
 312-269-3768

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