RE: Atmospheric deposition -Reply

[Franz Schoenhofer <schoenho@via.at>]

At 10:32 30.07.1998 -0500, you wrote:
>I was in high school when Chernobyl happened.  I don't even remember
>hearing about it.  I guess I had other things on my mind.
>
>But people involved in env. monitoring in Europe as well as the US were
>detecting that something happened.  Remeber it took days before the
>event was actually reported by the former Soviet Union.
>
>Historical #'s from our REMP show nicely the increase in cesium and in
>some cases the identification of iodine from that event.
>
>Matt Williamson
>Indian Point Unit 3
>williamson.m@nypa.gov
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Peter and Matt,

Sorry, you are confusing things a little. The task of CTBT-equipment is to
identify extremely low activity concentrations - preferably of xenon,
because from underground explosions you will hardly be able to detect any
fission products like Cs-137. There is only a small chance that volatile
radionuclides like iodine and rare gases will be released to the surface -
if at all. Therefore - if at all - only extremely low activity
concentrations will be in the air and therefore the development of special
stations was necessary to have a chance to detect these traces. If I
remember correctly 80 stations will be distributed over the whole world and
will also be located in very remote places. They will have to work
automatically and will have to transmit results also on xenon in real time,
so that data can be linked as soon as possible to data obtained from other
surveillance methods.

This task cannot be compared with the impact of Chernobyl, where a nuclear
reactor exploded and the graphite in it burnt for 10 days, emitting a large
percentages of the core inventory, especially volatile radionuclides.  

Regarding the Chinese tests I remember that we were "expecting" radioactive
clouds, because the information leaked through or probably there were other
sources for data suspecting an atmospheric test. In 1980 when we had
information that a Chinese atmospheric nuclear test had been performed we
put a special high volume sampler into operation - and after a few days we
saw the first traces of fission products. We were proud than, that we were
able to detect so small amounts by high resolution gamma-spectrometry. I
think it therefore unlikely that such traces could have interfered with
other surveillance operations. 

All over Europe traces of I-131 have been observed once, when obviously a
Sovjet underground test site leaked. The observations were in quite good
agreement with seismic data and meteorological calculations. But these
observations were done, using high volume air sampling. I can assure you
that we never detected any traces from other underground tests.

Franz


Franz Schoenhofer
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Tel.: +43-1-495 53 08
Fax.: same number
mobile phone: +43-664-338 0 333
e-mail: schoenho@via.at

Office:
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