[ RadSafe ] Lethal Amount of Po-210 - any gamma?

[Jim Hardeman]

Kai --

Just a guess, but take a look at http://www.sec.noaa.gov/ftpmenu/plots/proton.html ... looks like the flux of high-energy solar protons has been elevated by several orders of magnitude since sometime on 12/5 and is just now coming back down to normal. For example, the flux of 100+ Mev protons (as measured by the GOES 11 satellite) normally runs around  0.1 protons per square centimeter-second-steradian ... where over the past few days the peak flux was around 20 protons per square centimeter-second-steradian. Similarly, the flux of 50+ MeV protons went from 0.3 up to around 100 ... and the flux of 10+ MeV protons went from around 0.5 up to around 2,000 (same units as above). 

I noticed a similar phenomenon with my GammaWatch a few years back ... I was sitting in my office when I heard the alarm going off (it was set at 100 uR/hr) ... I looked at it, and it was measuring 250 - 350 uR/hr ... stayed at that level for about 30 minutes ... every other radiation detection instrument we had in the office was measuring normal background (10-15 uR/hr). One of my staff looked at the website above, and to the best we could determine, the increase was due to an increase in solar proton flux. Why the little GM in this watch would respond to these protons so well, when no other instruments in the office (other GM instruments, NaI-based micro-R meters, etc.) does I don't know.

Of course, the other possibility is that you were seeing shine from one or more radioactive packages in the cargo hold. Airlines don't like to admit it, but it's by no means uncommon for radioactive packages to be transported aboard passenger aircraft. 

My $0.02 worth for the day ...

Jim Hardeman
Jim_Hardeman at dnr.state.ga.us

>>> Kai Kaletsch <eic at shaw.ca> 12/12/06 6:11 PM >>>
Dear Franz,

To answer your question: Yes, I have heard about cosmic rays.

However, I am not sure how your question of "Ever heard about cosmic 
rays???????!!!!!!!" relates to either a lethal dose of Po-210, or to 
elevated radiation readings on a plane BEFORE take-off and AFTER landing. 
(The plane is not that tall.) I'm also not sure how it relates to seeing a 
noticeable increase ABOVE normal cosmic ray dose rate for that route DURING 
the flight.

Best Regards,
Kai

----- Original Message ----- 
From: "Franz Schönhofer" <franz.schoenhofer at chello.at>
To: "'Kai Kaletsch'" <eic at shaw.ca>; <radsafe at radlab.nl>
Sent: Tuesday, December 12, 2006 2:16 PM
Subject: AW: [ RadSafe ] Lethal Amount of Po-210 - any gamma?


Ever heard about cosmic rays???????!!!!!!!

Franz Schoenhofer
PhD, MR iR
Habicherg. 31/7
A-1160 Vienna
AUSTRIA
phone -43-0699-1168-1319


> -----Ursprüngliche Nachricht-----
> Von: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] Im
> Auftrag von Kai Kaletsch
> Gesendet: Montag, 11. Dezember 2006 16:13
> An: radsafe at radlab.nl
> Betreff: [ RadSafe ] Lethal Amount of Po-210 - any gamma?
>
> Po-210 emits a gamma ray, but at a very low branching ratio. I did a quick
> calculation and concluded that you would not be able to see a gamma field
> above background, even a very small distance away from a lethal dose of
> Po-210, or even a few tens of lethal doses of Po-210 (it doesn't seem like
> those guys were particularly stingy with the stuff).
>
> I would appreciate it if anyone in radsafe land could tell me if this
> conclusion is correct.
>
> History:
>
> I was on a plane yesterday and noticed elevated gamma readings on my
> radiation detecting watch. (5 to 20 times normal BG before take-off and
> after landing and noticeably higher than what I am used to during flight.)
> Was told afterward that there were medical isotopes in cargo. But, you
> have
> a lot of time to consider possible scenarios during a 4 hour flight.
>
> BTW, it's a pretty strange experience trying to tell an airline that their
> plane is radioactive. You don't know who to talk to and you are not sure
> if
> they are going to stick you in a straight jacket. Especially, at a time
> when
> all you hear on the news is ted. The first few people you talk to do not know
> that there is radioactive material in cargo.
>
> Kai
>
>
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