Re: background vs man-made emmissions - fallout

[Bernard L Cohen <blc+@pitt.edu>]

For some perspective on long term exposures from the Hiroshima bomb, I
remember a conversation with a scientist who was among the first to enter
Hiroshima after the bombing, with the job of using survey meters to look
for radioactivity. He was finding nothing for some time until he got
excited by a substantial positive reading. On investigating it, he found
that it was a medical source. Apparently, within the limits of survey
meters at that time, there was essentially no radioactivity from fallout
in Hiroshima.

Bernard L. Cohen
Physics Dept.
University of Pittsburgh
Pittsburgh, PA 15260
Tel: (412)624-9245
Fax: (412)624-9163
e-mail: blc+@pitt.edu


On Sun, 30 Apr 2000 GlennACarlson@aol.com wrote:

> I thought the existence of fallout at Hiroshima was well established, though 
> the levels and the health impact are still debated.  Is this incorrect?  
> 
> Consider also the following:
> 
> Health Phys 1996 Sep;71(3):340-6; 137Cs concentration in soil samples from an 
> early survey of Hiroshima atomic bomb and cumulative dose estimation from the 
> fallout.  Shizuma K, Iwatani K, Hasai H, Hoshi M, Oka T, Okano M  Faculty of 
> Engineering, Hiroshima University, Japan.
> 
> Low background gamma-ray measurement has been performed to determine the  
> 137Cs content in soil samples collected in a very early survey of the 
> Hiroshima atomic bomb. These soil samples were collected just 3 d after the 
> explosion within 5 km from the hypocenter and were not exposed to the global 
> fallout from nuclear weapon tests. Out of 22 samples, 137Cs was detected for 
> 11 samples, and their radioactivities ranged from 0.16-10.6 mBq g-1 at the 
> time of the measurement. A comparison of the 137Cs deposition with the 
> rainfall area within Hiroshima city indicates that the rainfall area was 
> wider than the previously proposed one. Cumulative exposure by the fallout 
> has been estimated to be 0.31 mC kg-1 (0.12 R) in Hiroshima city except for 
> the heavy fallout area and at most 1.0 mC kg-1 (4 R) in the heavy fallout 
> area.
> 
> 
> J Radiat Res (Tokyo) 1991 Mar;32 Suppl:32-9; Studies of radioactivity 
> produced by the Hiroshima atomic bomb: 2. Measurements of fallout 
> radioactivity. Hasai H, Hoshi M, Yokoro K  Faculty of Engineering, Hiroshima 
> University, Japan.
> 
> Three studies of fallout measurements were reviewed for the discussion of 
> possible radioactivity intake from the Hiroshima atomic bomb. The first study 
> discussed correlations between enriched 234U and 137Cs specific activities 
> from the measurement of soil samples collected in the "black rain" area. The 
> second study measured 137Cs activity on the rock and roof tile samples 
> collected in the hypocenter area immediately after the explosion. Some of the 
> rock and roof tile samples collected near the hypocenter had a small but 
> detectable amount of 137Cs activity. However, it has been determined that 
> 137Cs exposure, for example, was negligible compared with DS86 dose 
> estimates, since these activity levels were low. The third study detected 
> 90Sr activity in some of the specimens of human bones exhumed on Ninoshima 
> Island. This study compared the difference in activity between the bone head 
> and shaft, with higher activities obtained in the bone head. This fact 
> suggests a short intake period for this activity, however, the levels of 90Sr 
> contamination were too low to allow a discussion of the exposure risks.
> 
> In a message dated 4/30/2000 12:37:11 PM Central Daylight Time, 
> frantaj@aecl.ca writes:
> 
> > Subj:  RE: background vs man-made emmissions - fallout
> >  Date:    4/30/2000 12:37:11 PM Central Daylight Time
> >  From:    frantaj@aecl.ca (Franta, Jaroslav)
> >  
> >  Thanks for the information Glenn....
> >  
> >  ....but I'm very dubious about its veracity.
> >  
> >  The doses absorbed by the bombing victims are estimated to have been in the
> >  range of a few hundred rem (depending on location, any shielding effects,
> >  etc. (deaths were due to CONVENTIONAL thermal burns from the light flash 
> and
> >  from building fires, and from other forms of physical trauma, NOT due to 
> ARS
> >  !! ).
> >  
> >  Even if all of this exposure were due to neutrons - which it certainly was
> >  not (there was a large gamma constituent) - it would have been very, very
> >  far from sufficient to cause "High levels of residual radiation ...on the
> >  ground...in the 
> >  > form of induced radioactivity produced secondarily as a result of the
> >  > nuclear reaction of neutrons."
> >  > 
> >  Trust me, its BS. 
> >  We have the recent example of the Tokaimura criticality accident, where the
> >  absorbed doses were about ten times higher than those in Japan (actual
> >  deaths from ARS), yet even there the levels of neutron-induced 
> radioactivity
> >  inside the building were negligible ( escaped airborne radioactivity was 
> due
> >  to vapours issuing from the precipitation tank containing the critical
> >  solution of 20% U235 & FPs ).
> >  
> >  Radioactive fallout rain in Japan reportedly occurred, but far outside the
> >  cities, after much dilution.
> >  Any fallout soot from "intense firestorms" would NOT have been radioactive,
> >  for the reasons given above.
> >   
> >  Glenn, the quotations you provide look to me like the same sort of
> >  self-delusion that is practiced in the Ukraine and Belarus on account of 
> the
> >  Chernobyl disaster. Its amazing how many people believe THAT nonsence (tens
> >  of thousands dead as a result, etc.). I take it you're NOT one of them ?
> >  
> >  Thanks again,
> >  
> >  Jaro
> >  frantaj@aecl.ca
> >  
> >  > ----------
> >  > From:  GlennACarlson@aol.com[SMTP:GlennACarlson@aol.com]
> >  > Reply To:  radsafe@romulus.ehs.uiuc.edu
> >  > Sent:  Sunday April 30, 2000 12:01 PM
> >  > To:    Multiple recipients of list
> >  > Subject:   Re: background vs man-made emmissions - fallout
> >  > 
> >  > _From http://www.city.hiroshima.jp/C/City/ABombDamage/07.html
> >  > 
> >  > "7.2 Residual Radiation 
> >  > 
> >  > High levels of residual radiation were present on the ground for a 
> certain
> >  > 
> >  > period of
> >  > time starting one minute after the explosion.  Residual radiation came in
> >  > the 
> >  > form of
> >  > induced radioactivity produced secondarily as a result of the nuclear 
> >  > reaction of
> >  > neutrons when initial radiation collided with the soil and building 
> >  > materials, and it
> >  > also came from nuclear fission products and unfissioned uranium scattered
> >  > by 
> >  > the
> >  > bomb. 
> >  > 
> >  > It is quite likely that anyone entering the area within 1 km of the 
> >  > hypocenter within
> >  > 100 hours after the explosion to search for people or help with relief 
> >  > efforts was
> >  > affected by radiation coming from the soil and other such places due to 
> >  > induced 
> >  > radioactivity. In addition, soot and dust saturated with induced 
> radiation
> >  > 
> >  > from nuclear fission products and unfissioned uranium scattered at the
> >  > time 
> >  > of the bombing were carried high into the atmosphere and later fell to 
> the
> >  > 
> >  > ground as radioactive fallout, giving rise to further possibilities for 
> >  > contamination. 
> >  > 
> >  > 7.3 Black Rain
> >  > 
> >  > As the downtown area erupted in huge fires after the explosion, intense 
> >  > firestorms
> >  > and whirlwinds developed. After 20-30 minutes, black rain began to fall 
> in
> >  > a 
> >  > wide area
> >  > stretching from downtown to the northwest.
> >  > 
> >  > Large amounts of fallout, referred to as "Ashes of Death" were contained
> >  > in 
> >  > the rain
> >  > in the form of radioactive soot and dust and caused contamination even 
> in 
> >  > areas
> >  > remote from the hypocenter.
> >  > 
> >  > According to a study after the bombing, heavy rain fell in a 19km x 11 
> km 
> >  > area and
> >  > light rain fell in a 29km x 15km area, but there have been testimonies
> >  > that 
> >  > black rain
> >  > fell in places outside these areas as well."
> >  > 
> >  > Glenn A. Carlson, P.E.
> >  > glennacarlson@aol.com
> >  > 
> >  > > Subj:  RE: background vs man-made emmissions - fallout
> >  > >  Date:    4/30/2000 7:18:00 AM Central Daylight Time  
> >  > >  >  
> >  > >  > Regarding your comment, what about exposure from fallout?
> >  > >  > 
> >  > >  > Glenn A. Carlson, P.E.
> >  > >  > glennacarlson@aol.com
> >  > >  >
> >  > ************************************************************************
> >  > >  > 
> >  > >  Reply :  as far as I know, there wasn't any, since in both cases it 
> was
> >  > a
> >  > >  high-altitude explosion. This was confirmed by radiation surveyors on
> >  > the
> >  > >  ground there soon after the explosions.
> >  > >  
> >  > >  Jaro
> >  > >  frantaj@aecl.ca
> >  > >  *************************************
> >  
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