[ RadSafe ] Ongoing Criticalities InsideLeaking FukushimaDaiichi Unit 2

Tue May 3 09:10:54 CDT 2011

A third method is a Xe-131(n,p)I-131.  Xe-131 is a naturally occurring isotope of Xe.  I believe this technique is being used at McMaster University to produce I-131 for medical use.

Phil Simpson
Asst. Reactor Manager (Ret.)
University of Michigan
Ford Nuclear Reactor

On May 3, 2011, at 12:51 AM, Edmond Baratta wrote:

> There is another method.  It is neutron bombardment of Tellurium (Te).  A company in South Africa produces Iodine-131 by this method.
> 
> Ed Baratta
> Consultant - Radioactivity
> edmond0033 at comcast.net
> 
> -----Original Message----- From: Jim Darrough
> Sent: Monday, May 02, 2011 8:21 AM
> To: 'The International Radiation Protection (Health Physics) Mailing List'
> Subject: Re: [ RadSafe ] Ongoing Criticalities InsideLeaking FukushimaDaiichi Unit 2
> 
> Pardon my ignorance, Bob. Are you saying that I-131 can be created in some
> manner other that fissioning? I was always led to believe that I-131 is
> strictly a fission byproduct/fragment. Looking at an old copy of Nclides and
> Isotopes Chart of the Nuclides, (16th edition) it seems to me that I-131
> would not be readily created by neutron absorption.
> 
> Cesium 137 on the other hand has a long half life, relatively speaking so
> any release from broken or leaking fuel rods (such as those in the pools)
> could release plenty.
> 
> In short, I do not think there is enough spontaneous fission going on in the
> reactor(s), especially with Boron injections, to produce I-131 in any
> meaningful amount.
> 
> 
> Am I wrong about this?
> 
> 
> Regards, Jim Darrough
> 
> 
> -----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
> 
> 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.
> 
> 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.
> 
> btw: How is "fresh" I-131 distinguished from any other state of I-131?
> 
> Bob Hearn
> pedigreed expert
> 
> ----- 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
> 
> 
>> 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
>> 
>> -----BEGIN PGP SIGNED MESSAGE-----
>> Hash: SHA1
>> 
>> 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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