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

Tue Mar 30 21:50:22 CDT 2010

Jerry,

Good point. Consider that a large lightning strike may appear to resemble a line source contrasted to a point source, and the inverse square might not be pertinent. However, let's assume your calculation at 50' is correct and there would be an exposure of 1.3 mR. Also consider that there exists the probability that lightning strikes can be much closer than 50', and this would be true on an aircraft or other vehicle or fixed location where a dosimeter may be located, then the exposure would be higher. Dosimeters can accurately detect exposure down to 1 mR (DIS, Copper Doped TLD, OSL). Film would not accurately detect and report exposure down to 1 mR. There are numerous shipments and the probability exists where there can be this scenario, yet I and others have never observed these anomalous irradiations, that cannot be explained based on other exposures, such as dosimeters stored near a medical or industrial source.

All of the above is hypothetical, but interesting dialogue.

Regards,

Sandy
____________________
Sander C. Perle
President
Mirion Technologies
Dosimetry Services Division
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On Mar 30, 2010, at 7:35 PM, <gelsg at aol.com> wrote:

> 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
> report dose at 10 mrem (0.10 mSv). If a film, dosimetry or otherwise, is exposed
> to doses in the rem range, you can definitely expect an issue! If you let your
> camera film go through a carry-on x-ray unit, the exposure is in the tenths of
> mrem. Checked baggage could be irradiated to between 150 and 300 mrem each time
> it goes through a unit. This will damage the film, no doubt. As stated, I don't
> buy the premise of lightning causing this level of ionizing radiation, period.
>
> Regards,
>
> Sandy
>
> ____________________
> Sander C. Perle
> President
> Mirion Technologies
> Dosimetry Services Division
> 2652 McGaw Avenue
> Irvine, CA 92614
>
> +1 (949) 296-2306 (Office)
> +1 (949) 296-1144 (Fax)
>
> Mirion Technologies:
> http://www.mirion.com/
>
>
>
>
>
> On 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
> camera and usually had fairly sensitive color film.)  Has anybody had experience
> with film fogging after a lightning strike on an airplane?  Not as good as a
> badge, but it would support, or challenge the notion of significant x-rays.
> Otherwise, has anybody had an environmental dosimeter register a surprise high
> dose rate (assuming a lightning strike nearby).
> >
> > just looking for something that would register the xrays, or support the fact
> that they aren't significant.
> >
> >  - -jmr
> >
> > John Rich
> > 312-269-3768
>
>
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