Dear Jim,
At http://ireport.cnn.com/docs/DOC-572031?ref=feeds%2Flatest they seem to measure "Rate of space dose" in
"(nGy/h)". Could you explain the quantity, "Rate of space dose", and the unit, "(nGy/h)",
to me please?
Thanks,
Pat Naughtin
Geelong, Australia
On 2011/03/16, at 02:54 , James R. Frysinger wrote:
USMA Colleagues,
I sent this out to my family and friends last night.
Jim
Folks,
The reporters are going crazy and hyping the radiation from the failing nuclear
power plants in Japan. Meanwhile, coverage of the shortages in food, water,
fuel, shelter, and electricity and coverage of the tremendous loss of life are
being under-reported by comparison. That's because the reporters do not
understand radioactivity, nuclear reactors, radiation limits, or radiation
calculations. It's not that hard to do and I'll show you here how to do it.
There are a lot of adjectives being used in the media. Hard data is hard to
find but I heard one value stated today on TV and this site provides current
hard data.
Actual radiation levels in Japan:
http://ireport.cnn.com/docs/DOC-572031?ref=feeds%2Flatest
For your reference, the limits specified in the U.S. are listed at the bottom
of this email There are two groups presented here -- essentially for power
plant workers and for the folks on the streets. The latter is the one officials
are concerned about, but note that nuclear power plant workers are deemed safe
at about 50 times those levels!
Now you can do your own calculations. Note that 1 mSv = 1 000 µSv = 1 000 000
nSv. So, assume a conservative QF of 20 and an exposure limit of 0.02 mSv/h =
20 µSv/h. That limits you to 1 µGy/h since 20 × 1 µGy/h = 20 µSv/h. And 1 µGy/h
= 1 000 nGy/h.
From the data posted at the link above for 2011/03/15 03:20, it appears that
all the radiation levels are one-sixth or less of the U.S. limit for exposure
of members of the public to radiation from a nuclear power plant. There may
have been a brief spike near one plant today, but I do not have that figure.
Please keep these facts in mind:
1. Nuclear power plants are physically incapable of undergoing nuclear
explosion. The explosions you hear about are hydrogen explosions, rather like
natural gas explosions.
2. Radiation exists around you naturally.
3. Exposure limits are always much lower than natural radiation levels to which
you are exposed in your everyday lives.
4. Low level radiation is just that -- low level. If it's low enough, there is
nothing to be concerned about. You, the ground you walk on, the banana in your
breakfast cereal, and many other things contain low level radiation. Yes, you
yourself are a low level radiation source!
5. Reactor plants generally are designed to contain reactor cores even if the
cores melt down. I do not know for a fact, but the Japanese plants are probably
designed for events like that, too. The Russian nuclear reactor at Chernobyl
definitely was an exception to that rule, which is why nations kept after the
Russians for years not to operate plants of that design.
6. Airborne radiation is diluted as it spreads out. Our west coast is in no
grave danger!
The largest problems facing the Japanese right now do not include radiation,
despite the hyperventilating you hear or read in the news. The natural
radiation levels there seem to be much larger than those caused by the failure
of those nuclear powered plants.
Jim
10CFR20 radiation limits in the U.S.
Exposure limits for occupational workers
annual
whole body 50 mSv (5 rem)
lens 150 mSV
skin 500 mSv
Exposure limits for members of the public
annual 1 mSv
acute 0.02 mSv/h
Multiply radiation levels in grays (Gy) by the appropriate quality factor (QF)
to determine estimated dosage in sieverts (Sv).
QF exposure
1 x, gamma, or beta rays
20 fission products, alpha rays (internalized)
--
James R. Frysinger
632 Stony Point Mountain Road
Doyle, TN 38559-3030
(C) 931.212.0267
(H) 931.657.3107
(F) 931.657.3108
Pat Naughtin LCAMS
Author of the ebook, Metrication Leaders Guide, see
http://metricationmatters.com/MetricationLeadersGuideInfo.html
Hear Pat speak at: http://www.youtube.com/watch?v=_lshRAPvPZY
PO Box 305 Belmont 3216,
Geelong, Australia
Phone: 61 3 5241 2008
Metric system consultant, writer, and speaker, Pat Naughtin, has helped
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