[ RadSafe ] Ongoing Criticalities Inside Leaking Fukushima Daiichi Unit 2

Sun May 1 20:17:40 CDT 2011

Greetings!

Viewing the graphical data for the samples from the six units, I see:

Unit 1 has I-131 in the range of 50 to 500 Bq/cc, decreasing relative to
Cs-137 by a (very approximate) factor of 20 in 20 days.

Unit 2 has I-131 in the range of 50 to 800 Bq/cc, not decreasing relative to
Cs-137 until 4/22/2011, then decreasing relative to Cs-137 by a (very
approximate) factor of 5 in 6 days.

Unit 3 has I-131 in the range of 2 to 20 Bq/cc, decreasing relative to
Cs-137 by a (very approximate) factor of 3 in 12 days until 4/18/2011, then
increasing relative to Cs-137 by a (very approximate) factor of 10 in 8
days.

Unit 4 has I-131 in the range of 0.06 to 20 Bq/cc, decreasing relative to
Cs-137 by a (very approximate) factor of 20 in 20 days. 

Unit 5 has I-131 in the range of 0.05 to 1.1 Bq/cc, decreasing relative to
Cs-137 by a factor of 2 (or less) in 20 days. 

Unit 6 has I-131 in the range of 0.08 to 0.9 Bq/cc, maintaining a roughly
constant level relative to Cs-137.

If any of these 6 reactors is presumed to be making new I-131, why not pick
Unit 3?

The only conclusion I can derive from these graphs is "insufficient data".
The data that I need are those that would give a production RATE of the
fission isotopes.  These results are for water concentration, but they
provide no clue about total quantities without some way to measure the total
volume of the water represented by each sample.  Since they are water
samples, they give no clue as to the amount of I-131 potentially released by
gaseous pathways.  Also, I'm certain there would be other fission products
present such as I-133 which (with a shorter half-life) would more clearly
indicate an on-going fission process.  Since I don't know why these are not
plotted, I can draw no conclusion from such information.

If I were to speculate on the information I actually have, I would speculate
that the author of the article prefers speculation...

Not a pedigreed "expert", but my opinion -
Randy Parker

-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu
[mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of Doug Huffman
Sent: Sunday, May 01, 2011 10:10 AM
To: The International Radiation Protection (Health Physics) Mailing List
Subject: Re: [ RadSafe ] Ongoing Criticalities Inside Leaking Fukushima
Daiichi Unit 2

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A definition of criticality, a practical one that I used to determine
criticality, was "a constant positive change in neutron population (Start Up
Rate) with no reactivity addition."  Subcritical multiplication and
spontaneous fission might explain "fresh" I-131 but the whole spectrum of
fission fragmants should be present and as detectable.

On 5/1/2011 07:20, Ahmad Al-Ani wrote:
> TEPCO Data Shows Ongoing Criticalities Inside Leaking Fukushima 
> Daiichi Unit 2 April 28, 2011 Analysis by: GLG Expert Contributor
> 
> Data released on April 28, 2011 by TEPCO is now unequivocal in showing
ongoing criticalities at Unit 2, with a peak on April 13. TEPCO graphs of
radioactivity-versus-time in water under each of the six reactors show an
ongoing nuclear chain reaction creating high levels of "fresh" I-131 in Unit
2, the same reactor pressure vessel (RPV) with a leak path to reactor floor,
aux building, and outdoor trenches, that is uncontrollably leaking high
levels of I-131, Cs-134, Cs-137 into the Pacific Ocean.
> 
> Source:
> http://tinyurl.com/663j24z
> 
> TEPCO Data:
> http://tinyurl.com/5sz375o
> 
> Can the experts on the RADSAFE list comment on this analysis, please.
> 
> Ahmad Al-Ani
> Radiation Physicist
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