[ RadSafe ] BAD INFORMATION

Sat Nov 15 17:17:25 CST 2008

Radiation Effects Research Foundation has extensive information about
Hiroshima and Nagasaki, the victims and the cities today --
http://www.rerf.or.jp/general/qa_e/index.html

>From the FAQ

12 Are Hiroshima and Nagasaki still radioactive? 

The practical answer is, "No."

People often ask, "If uranium and plutonium pose a potential hazard in
nuclear waste sites and were present at dangerous levels in the environment
following the Chernobyl nuclear accident, why aren't Hiroshima and Nagasaki
still uninhabitable?"

There are two ways residual radioactivity is produced from an atomic blast.
The first is due to fallout of the fission products or the nuclear material
itself--uranium or plutonium (uranium was used for the Hiroshima bomb
whereas plutonium was used for the Nagasaki bomb)--that contaminate the
ground. Similar ground contamination occurred as a consequence of the
Chernobyl accident, but on a much larger scale (click here for more-detailed
explanation). The second way residual radioactivity is produced is by
neutron irradiation of soil or buildings (neutron activation), causing
non-radioactive materials to become radioactive.

Fallout. The Hiroshima and Nagasaki bombs exploded at altitudes of 600
meters and 503 meters, respectively, then formed huge fireballs that rose
with the ascending air currents. About 10% of the nuclear material in the
bombs underwent fission; the remaining 90% rose in the atmosphere with the
fireball. Subsequently, the material cooled down and some of it started to
fall with rain (black rain) in the Hiroshima and Nagasaki areas, but
probably most of the remaining uranium or plutonium was dispersed widely in
the atmosphere. Because of the wind, the rain did not fall directly on the
hypocenters but rather in the northwest region (Koi, Takasu area) of
Hiroshima and the eastern region (Nishiyama area) of Nagasaki.

The maximum estimates of dose due to fallout are 0.01-0.03 Gy in Hiroshima
and 0.2-0.4 Gy in Nagasaki. The corresponding doses at the hypocenters are
believed to be only about 1/10 of these values.

Nowadays, the radioactivity is so miniscule that it is difficult to
distinguish from trace amounts (including plutonium) of radioactivity caused
by worldwide fallout from atmospheric (as opposed to underground)
atomic-bomb tests that were conducted around the world in past decades,
particularly in the 1950's and 1960's.

Neutron activation. Neutrons comprised 10% or less of the A-bomb radiation,
whereas gamma rays comprised the majority of A-bomb radiation. Neutrons
cause ordinary, non-radioactive materials to become radioactive, but gamma
rays do not. The bombs were detonated far above ground, so neutron induction
of radioactivity on the ground did not produce the degree of contamination
people associate with nuclear test sites (Nevada test site in Southwest US,
Maralinga test site in South Australia, Bikini and Mururoa Atolls, etc.).

Past investigations suggested that the maximum cumulative dose at the
hypocenter from immediately after the bombing until today is 0.8 Gy in
Hiroshima and 0.3-0.4 Gy in Nagasaki. When the distance is 0.5 km or 1.0 km
from the hypocenter, the estimates are about 1/10 and 1/100 of the value at
the hypocenter, respectively. The induced radioactivity decayed very quickly
with time. In fact, nearly 80% of the above-mentioned doses were released
within a day, about 10% between days 2 and 5, and the remaining 10% from day
6 afterward. Considering the extensive fires near the hypocenters that
prevented people from entering until the following day, it seems unlikely
that any person received over 20% of the above-mentioned dose, ie, 0.16 Gy
in Hiroshima and 0.06-0.08 Gy in Nagasaki.

As for Hiroshima and Nagasaki proper, the longest-lasting induced
radionuclide that occurred in amounts sufficient to cause concern was
cesium-134 (with a half-life of about 2 years). Most of the induced
radioactivities from various radionuclides decayed very quickly so that it
now takes considerable time and effort to measure it using highly sensitive
equipment. Despite such miniscule levels, measurements of residual
radioactivity using recently developed ultra-sensitive techniques have been
utilized to estimate neutron doses released from the bombs and have formed
part of the basis of the latest atomic-bomb dosimetry (DS02). 

Although the levels of residual radioactivity at the hypocenters in
Hiroshima and Nagasaki were initially high, they declined quickly and are
now far less than the dose received from background radiation. Hence, there
is no detectable effect of present-day residual radiation on human health.
In fact, today both Hiroshima and Nagasaki are thriving cities with large
populations.

-----Original Message-----
From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] On Behalf
Of Franz Schönhofer
Sent: Saturday, November 15, 2008 10:01 AM
To: 'George Stanford'; 'Peterson, Ken'
Cc: radsafe at radlab.nl
Subject: AW: [ RadSafe ] BAD INFORMATION

George,

Having been interested in nuclear bomb topics since many years I find your
comment unacceptable, sloppy and simply unbelievable, that somebody who
obviously regards himself as a member of the community of radiation
protection professionals distributes something like this on the RADSAFE
list. Following your reasoning it must have been really funny to have been a
victim of the Hiroshima bombing! Fission products can still be measured in
Hiroshima as well as those from fallout. Could you give some sources for
your unbelievable comment? There are more than enough who show facts
contrary to your caimed ones. Interesting to read, that there is no local
fallout - again please give sources for this nonsensicle claim? I have been
the leader of the terrestrial working group of the International Mururoa
Project on the Nuclear Tests of France in the South Pacific - what a
surprise we found quite a lot of fission products on the atolls of Mururoa
and Fangataufa. How can you dare to say, that there is no local fallout in a
nuclear bomb explosion? (They were all of the type you call "air burst" and
even more they were not above ground but above the lagoon. No "local
fallout"? You are kidding!!!! - which is true for your claim that one need
not worry, if one is not wounded. Neither Hiroshima nor Nagasaki were ground
level bursts - don't you know that?

I would really recommend that  y o u  get the facts straight. Read about the
hundreds of thousands victims of both the Hiroshima and Nagasaki bombings
and then stop distributing the nonsense you did. With my disdain for your
unbelievable opinions

Franz 

Franz Schoenhofer, PhD
MinRat i.R.
Habicherg. 31/7
A-1160 Wien/Vienna
AUSTRIA

-----Ursprüngliche Nachricht-----
Von: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] Im Auftrag
von George Stanford
Gesendet: Freitag, 14. November 2008 23:01
An: Peterson, Ken
Cc: radsafe at radlab.nl
Betreff: Re: [ RadSafe ] BAD INFORMATION

Ken:

         The problem is somewhat more subtle.  The old brochures you 
link to clearly are bald-faced attempts to make the public think 
nuclear war is like a romp in the park.  However, while the sheets 
are simplistic in the extreme, and seriously misleading, all the 
statements are, in a literal sense, accurate.

- "By the time the debris stops falling, there is no radiation 
hazard."  The statement is true. It is made in the context of a 
Hiroshima-type "air burst" (one in which the fireball does not touch 
the ground).  In such a case, all the radioactive fission products 
are carried upward -- there is no local fallout.  There is a small 
amount of radioactivity induced by neutrons near ground zero, but 
it's too low to be of concern, especially in a wartime context.

-  "In most cases, if you are not wounded or burned, you need not 
worry about radiation."  This also is true, for the same reason.

- "Or radiation exposure from airbursts can be avoided by maneuvering 
your ship or vehicle."  Certainly false, as you phrase it -- but the 
pamphlet doesn't say that.  If you read the footnote more carefully, 
you will see that the context is the aftermath of a ground-level 
burst -- so the footnote, while it might not be relevant, is 
literally accurate -- under the unlikely assumption, that is, that 
you know where the fallout has landed (covering perhaps many square 
miles) so that you can drive around it (good luck!).

         Being from the late 40s or early 50s, presumably, those 
simplistic propaganda sheets assumed relatively small, Hiroshima-size 
(~15 kiloton) bombs.  They would be even more misleading (although 
still literally true) in these days of much larger, even more 
destructive, weapons.

         Nuclear weapons are nasty, but we still need to get our 
facts straight.

         Cheers,

         George Stanford
         Reactor physicist, retired

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

At 11:21 AM 11/14/2008, Peterson, Ken wrote:
It is interesting to note how the US Government publishes erroneous
information in the 1950's, and it STILL impacts the military and public
today.  It would be funny if it weren't so serious.  Note that: "By the
time the debris stops falling, there is no radiation hazard.", "In most
cases, if you are not wounded or burned, you need not worry about
radiation."  Or radiation exposure from airbursts can be avoided by
maneuvering your ship or vehicle.....

http://www.safetycenter.navy.mil/photo/index.asp

http://www.safetycenter.navy.mil/photo/images/images-301-350/photo313-1_high
-res.jpg

http://www.safetycenter.navy.mil/photo/images/images-301-350/photo313-2.jpg

Ken Peterson

************************************************************