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Re: [Phys-l] Geiger counter





-----Original Message-----
From: phys-l-bounces@carnot.physics.buffalo.edu [mailto:phys-l-
bounces@carnot.physics.buffalo.edu] On Behalf Of
trappe@physics.utexas.edu
Sent: Monday, March 28, 2011 1:00 PM
To: Forum for Physics Educators
Subject: Re: [Phys-l] Geiger counter

The helicopters may be leaving to protect their navigation electronics
from radiation damage. Some bombers maintain a redundancy using old
ferrite core memory from the 60's. Supposedly this was a lesson
learned in WWII electronics.

[Bill Nettles]
Huh? The electronics get more radiation from the background from flying around every day than they would get from the reactor venting. They are leaving, I suspect, because the government is telling them to leave. Civilian radiation doses are limited to about 1/10 of that for radiation workers, and GreenPeace is STILL general population civilian, despite what they may wish.


Quoting ludwik kowalski <kowalskil@mail.montclair.edu>:

I suspect the units were mSv/hr. But the numbers could also refer
to dose densities actually received by pilots, when they were
flying. In that case mSv would be OK.

Ludwik
==============

[Bill Nettles]
The whole Greenpeace statement that Brian quoted is chock full of errors. We have NO IDEA what units would be accurate, because they give us no reliable information of how they measured anything. Their statement about the workers' limit is ridiculous or misleading or both because 250 millisieverts per hour for 48 hours would amount to 25.0 rems/hour (!yikes!) for 48 hours or 1200 rems= death. Heck, the IRCP limit is 10 rem/year! There is NO reliable info in that report. Or maybe we all die when the Mayan calendar runs out.




On Mar 28, 2011, at 12:39 PM, brian whatcott wrote:

Here's a lift of the Greenpeace para on radiation there:

"Levels above reactors reported as 4.13 "mSv" at 1000 feet and 87.7
"mSv" at 300 feet. The statements by the government and the Tepco
spokespeople seem to contradict the reported values. The helicopters
are
equipped with lead panels and crews wearing protective gear, but
were
unable to hover above the reactors to improve accuracy and had to
pull
back after only 15 minutes, yet the government-authorised emergency
dose
limit of 250 mSv/h would allow the crews to stay at 1000 feet for 48
hours, even without shielding.

"Ibaraki's
<http://www.knoxnews.com/news/2011/mar/16/battle-is-just-beginning-
says-nuclear-reactor/

(130 km south of Dalichi) radiation readings on Tuesday just before
the
monitors went "under survey" are posted online. The readings measure
at
3.4 micro-Sv/h = 30 milli-Sv per year. Current value is 0.92 micro-
Sv/h
= 8 mSv/y. In Saitama and Tochigi, close to Tokyo, readings of 1.2
and
1.3 microSv/h were measured yesterday."

Brian W