: LUDWIK KOWALSKI <KOWALSKIL@alpha.montclair.edu>
wrote:
"A piece of trivial information. The estimated dose from normally operating
reactors of the world is 400,000 man*Sv (1 Sv=100 rems). These 340 reactors
produced about 2000 gigawatt-years of electric energy so far. The dose can
be compared with abnormal situations. "Accidents at Windscale, TMI and
Chernobyl have added 2000, 40 and 600,000 man Sv, respectively."
I have no reason to doubt the numbers but some readers may become alarmed
by comparing the the cumulative dose to the world population from nuclear
power to the cumulative dose from the Chernobyl accident. A more realistic
comparison would be to compare the dose from nuclear power to the
cumulative dose from background radiation. Background varies considerably
around the world. In the US the accepted background dose rate is 3 mSv/y.
The annual cumulative dose to the US population is about 750,000 person-Sv,
if my arithmatic is correct. That is, annual radiation from nuclear power
plants is trivial compared to that from annual background radiation.
A related piece of trivia is that the power produced by all the
natural radioactivity in the earth is about 2.7 x 10^12 W. Roughly equal
to the electrical power from 2700 nuclear power plants! The role of this
energy in geological phenomena (earth quakes, volcanoes, continental drift,
etc. ) is seldom mentioned.
There is no evidence that radiation is a health risk at low doses.
(See Sohei Kondo - Health Effects of Low-Level Radiation (1993) ) In fact,
there is good evidence (but not proof) that low level radiation is
beneficial to the health. For example, the A-bomb survivors had about 400
additional cancer deaths induced by radiation in the last 50 years.
However, survivors with low to moderate doses (<200 mSv) had a lower death
rate from all causes than unexposed Japanese. The net result is that the
A-bomb survivors are living longer on the average than the unexposed
control populations.
In the US the seven western states with the highest background
radiation levels have a cancer death rate about 15% lower than the average
for the country. A study of radon levels Vs lung cancer death rate in
1600 US counties found that the counties with the highest radon levels (5
pCi/l) had a 40% lower lung cancer death rate than the counties with the
lowest radon levels (<0.05 pCi/l) (References available on request.)
If you demonstrate natural radiation with a GM counter don't forget
to mention that the typical adult contains about 9 kBq of natural
radiation. This gives about a half million disintegrations per second.
This is my first contribution to this list server. I was originally
a nuclear physicist (1952-58) since then I have been in medical physics. If
I can provide information about radiation to any readers, please feel free
to contact me directly. Best wishes for 1998! John Cameron
John R. Cameron, we are at our winter home at 2678 SW 14th Dr.,
Gainesville, FL 32608 phones : 352/371-9865; Fax 352/371-9866 until about
May 15, 1998 We then revert back to our summer home:
2571 Porter Rd., P.O. Box 405, Lone Rock, WI 53556-0405 Phones:
608/583-2160; Fax: 608/583-2269