No subject

in both=20
directions. For example from April 20-22 the ratio changed from around 5
to=20
nearly 1 on Unit 4.  Does this mean more Cs-137 is being produced?  I
doubt it. =20
We are given log scales, no error bars and no discussion on measurement
or=20
sample collection quality.  The physics and chemistry of release and
migration=20
of the stew at risk are complex as stated in Bob Hearn's note.  For
credibility,=20
the expert contributor should identify him or herself and provide
further=20
information leading to the unequivocal ranking.
=20
John Ahlquist
=20
-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu
[mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of Bob Hearn
Sent: Sunday, May 01, 2011 7:55 PM
To: The International Radiation Protection (Health Physics) MailingList
Subject: Re: [ RadSafe ] Ongoing Criticalities Inside Leaking
FukushimaDaiichi Unit 2
=20
The I-131 / Cs-137 ratios or absolute concentrations are not adequate to
make any inference regarding criticality or production rate. These
radioisotopes may be released at varying rates with no criticality from
fuel
in defected cladding depending on the nature of cladding defects,
temperature, pressure, fuel burn history, etc. We do not even know for
sure
how much of the source term for these materials is the spent fuel versus
that in the reactor vessel.
=20
These is an entire area of study on radioisotope release from BWR
reactor
fuel, dating from the earlier days of GE's A/y-lambda modeling for fuel
warranty validation, and further advanced in more recent decades. These
sparse observations do not provide adequate characterization for any of
the
speculation raised in this thread.
=20
btw: How is "fresh" I-131 distinguished from any other state of I-131?
=20
Bob Hearn
pedigreed expert
=20
----- Original Message -----
From: "Randy Parker" <randy at atomicwizard.com>
To: "'The International Radiation Protection (Health Physics)
MailingList'"
<radsafe at health.phys.iit.edu>
Sent: Sunday, May 01, 2011 9:17 PM
Subject: Re: [ RadSafe ] Ongoing Criticalities Inside Leaking
FukushimaDaiichi Unit 2
=20
=20
> 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
>
>
>
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