[ RadSafe ] Dose conversion in beta exposure readings at Fukushima Daiichi ?

Sun Sep 1 16:30:46 CDT 2013

A real surprise! I'll be the area in about 10 days. Bet I can find dosimeters to bring with me! :)

Regards,

Sandy
Sent from my iPhone

On Sep 1, 2013, at 1:51 PM, "Jaro Franta" <jaro_10kbq at videotron.ca> wrote:

> Thanks Sandy,
> 
> Bet you didn't know that all these leaks are causing the seas off the coast of Japan to boil !
> 
> http://voiceofrussia.com/news/2013_08_31/Fukushima-radioactive-leak-causes-the-sea-off-Japan-coast-to-boil-1867/
> 
> 
> On a less fanciful note.....
> https://www.facebook.com/photo.php?fbid=513705358709371&set=a.493867307359843.1073741828.493843777362196&type=1&relevant_count=1 
> 
> 
> Jaro
> ^^^^^^^^^^^^^^^^^^^^^^^^^
> 
> 
> 
> -----Original Message-----
> From: radsafe-bounces at health.phys.iit.edu [mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of Perle, Sandy
> Sent: September-01-13 9:59 AM
> To: The International Radiation Protection (Health Physics) Mailing List
> Subject: Re: [ RadSafe ] Dose conversion in beta exposure readings at Fukushima Daiichi ?
> 
> Jaro,
> 
> See latest article:
> http://www.cnn.com/2013/09/01/world/asia/japan-fukushima-radiation-spike/in
> dex.html?hpt=hp_t2
> 
> Quote from above article:"But TEPCO also took issue with reporting by some news outlets that the new radiation levels were high enough to cause death after several hours of exposure.
> It said the highest
> 
> levels measured were so-called beta radiation, which quickly dissipates over short distances and is easily shielded through the use of thin sheets of metal and foil.
> 
> "Since beta radiation is weak and can be blocked by a thin metal sheet such as aluminum, we think that we can control radiation exposure by using proper equipments and cloths," the company added."
> 
> Regards,
> 
> Sandy
> 
> -----------------------------------
> Sander C. Perle
> President
> Mirion Technologies
> Dosimetry Services Division
> 2652 McGaw Avenue
> Irvine, CA 92614
> 
> +1 (949) 296-2306 (Office)
> +1 (949) 296-1130 (Fax)
> 
> Mirion Technologies: http://www.mirion.com/
> 
> 
> 
> 
> 
> 
> 
> On 8/27/13 11:54 AM, "Jaro Franta" <jaro_10kbq at videotron.ca> wrote:
> 
>> The latest TEPCO handouts include the first I have seen that reports 
>> analysis results on tritium.
>> 
>> The data is NOT for the recent water leak around the H-area storage 
>> tanks, but nevertheless provides a useful indication of a typical ratio 
>> of tritium versus other nuclide activity.
>> In this case the ratio is about 39.2 relative to Cs137 (using 2000/51 
>> for “North side of Unit 1-4 water intake channel”).
>> 
>> Taking the tank water results published earlier – 100 Bq/cc of Cs137 – 
>> and including the 15.8 depletion factor from the Cs stripping process 
>> -- the tritium activity should be about 39.2 x 15.8 x 100 = 61,960 Bq/cc.
>> 
>> As noted earlier, total fission product beta based on Sb125 ratio 
>> should be 242 x 71 Bq/cc = 17,202 Bq/cc.
>> 
>> Adding 61,960 Bq/cc tritium and 17,202 Bq/cc fission product beta 
>> yields
>> 79,163 Bq/cc total beta – virtually identical to the “All ß” figure of
>> 80,000 Bq/cc originally reported for the tank water.
>> 
>> Is it just coincidence that the numbers match ? …seems unlikely.
>> 
>> http://www.tepco.co.jp/en/nu/fukushima-np/f1/smp/2013/images/2tb-east_1
>> 308
>> 2601-e.pdf
>> 
>> 
>> Jaro
>> ^^^^^^^^^^^^^^^^^^^^^^^^^
>> 
>> 
>> 
>> 
>> 
>> 
>> -----Original Message-----
>> From: radsafe-bounces at health.phys.iit.edu
>> [mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of Jaro Franta
>> Sent: August-26-13 10:34 AM
>> To: 'The International Radiation Protection (Health Physics) Mailing List'
>> Subject: Re: [ RadSafe ] Dose conversion in beta exposure readings at 
>> Fukushima Daiichi ?
>> 
>> Thanks Jim,
>> 
>> I am not familiar with conversion factors for deriving skin dose 
>> expressed as dose equivalent.
>> 
>> Is there a decent on-line reference somewhere, please ? (PS. I’m not an 
>> HP, but judging by the number of responses to my question, that doesn’t 
>> seem to make much difference…)
>> 
>> Also, is it normal practice to leave people guessing about what sort of 
>> interpretation is the correct one, rather than simply spelling out what 
>> it is that’s being published ?
>> 
>> 
>> Jaro
>> 
>> ^^^^^^^^^^^^^^^^^^^^^^^^^
>> 
>> 
>> 
>> 
>> From: Jim Hardeman [mailto:jim.hardeman at gmail.com]
>> Sent: August-26-13 10:13 AM
>> To: jaro_10kbq at videotron.ca
>> Subject: Re: [ RadSafe ] Dose conversion in beta exposure readings at 
>> Fukushima Daiichi ?
>> 
>> 
>> 
>> Jaro --
>> 
>> 
>> 
>> Yeah, I was thinking that Sr-90 and Pu-241 might make a significant 
>> contribution.
>> 
>> 
>> 
>> Looks as if the Japanese were PERHAPS a bit more rigorous in performing 
>> their dose estimates than I originally thought. I'm interpreting 
>> TEPCO's latest as being (shallow) skin dose expressed as dose 
>> equivalent as opposed to organ dose to the skin. Is that your interpretation as well?
>> 
>> 
>> 
>> Jim
>> 
>> 
>> 
>> On Mon, Aug 26, 2013 at 9:08 AM, Jaro Franta <jaro_10kbq at videotron.ca>
>> wrote:
>> 
>> Additional instrument info posted by Tepco today:
>> 
>> "Measurement device: Shallow ionization chamber survey meter (AE-133B)"
>> 
>> Also, the same four high dose rate numbers listed previously as "γ+β ray"
>> are now listed as "Dose equivalent rate measured from 70μm (β ray)"
>> 
>> http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2013/images/handouts
>> _13
>> 08
>> <http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2013/images/handout
>> s_1
>> 30823_05-e.pdf>
>> 23_05-e.pdf
>> 
>> 
>> 
>> Jaro
>> ^^^^^^^^^^^^^^^^^^^^^^^^^
>> 
>> 
>> 
>> 
>> -----Original Message-----
>> From: radsafe-bounces at health.phys.iit.edu
>> [mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of Jaro Franta
>> 
>> Sent: August-23-13 7:53 PM
>> To: 'The International Radiation Protection (Health Physics) Mailing List'
>> Subject: Re: [ RadSafe ] Dose conversion in beta exposure readings at 
>> Fukushima Daiichi ?
>> 
>> Jim, I will save you the time:
>> 
>> Here are the results of SNF decay after 2.49y, obtained using the 
>> SpentFuelExplorer java tool, by K. Sorensen.
>> 
>> One is in pie chart form, the other a table:
>> 
>> https://dl.dropboxusercontent.com/u/11686324/SNF_2%2C49y_old.JPG
>> 
>> https://dl.dropboxusercontent.com/u/11686324/SNF_2%2C49y_old_table.JPG
>> 
>> Cheers,
>> 
>> Jaro
>> ^^^^^^^^^^^^^^^^^^^^^^^^^
>> 
>> 
>> 
>> From: Jim Hardeman [mailto:jim.hardeman at gmail.com]
>> Sent: August-23-13 9:02 AM
>> To: jaro_10kbq at videotron.ca
>> Subject: Re: [ RadSafe ] Dose conversion in beta exposure readings at 
>> Fukushima Daiichi ?
>> 
>> Jaro --
>> 
>> It's unclear to me that what TEPCO calls "all Beta" is tritium -- I 
>> think it's more likely to be a gross beta measurement, which would 
>> include both
>> Cs-134 and Cs-137 and any other non-volatile beta-emitters in the water.
>> This long after the incident, I'd have to do some decay calculations to 
>> see what I would "expect" to be in the water, but the Cs isotopes, 
>> while certainly the most prominent, aren't the only ones.
>> 
>> Jim
>> 
>> On Fri, Aug 23, 2013 at 8:07 AM, Jaro Franta <jaro_10kbq at videotron.ca>
>> wrote:
>> Tepco's latest analysis results:
>> 
>> Aug 23, 2013 - Sampling Results Regarding the Water Leak at a Tank in 
>> the
>> H4
>> area in Fukushima Daiichi Nuclear Power Station
>> 
>> http://www.tepco.co.jp/en/nu/fukushima-np/f1/smp/2013/images/south_disc
>> har
>> ge
>> <http://www.tepco.co.jp/en/nu/fukushima-np/f1/smp/2013/images/south_dis
>> cha
>> rge_130823-1e.pdf>
>> _130823-1e.pdf
>> 
>> ....where the "All beta" numbers are much closer to the Cs numbers - 
>> suggesting but not confirming that the 80kBq/cc in the leaked water 
>> from tank no.5 is largely tritium (these latest results sample nearby 
>> "drainage channel B", not the water from the tank..)
>> 
>> 
>> Jaro
>> ^^^^^^^^^^^^^^^^^^^^^^^^^
>> 
>> 
>> 
>> -----Original Message-----
>> From: radsafe-bounces at health.phys.iit.edu
>> [mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of Jaro Franta
>> Sent: August-22-13 9:41 AM
>> To: 'The International Radiation Protection (Health Physics) Mailing List'
>> Subject: Re: [ RadSafe ] Dose conversion in beta exposure readings at 
>> Fukushima Daiichi ?
>> 
>> A search on Tepco's web site turned up this reference document:
>> 
>> Radiation Monitoring at the site - measuring method  (November 19, 
>> 2011) 
>> http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_111119_04-e.p
>> df
>> 
>> Some of the more interesting slides:
>> 
>> Slide 7:  Estimation of Sv/h from Bq/cm2
>> 
>> Quote: "In the case of Cs-137 contamination radius (40cm), Distance (1m):
>> 13,000cpm = approx. 0.04 Sv/h"
>> 
>> ..presumably this conversion applies only to gamma ?
>> (...yet in their table published this week, they report beta + gamma 
>> dose rates of ~100 mSv/h, with only a tiny fraction of that being 
>> gamma)
>> 
>> 
>> Slide 9: Radiation Meter for contamination measurement (GM Survey 
>> Meter) Slide 11: External exposure evaluation measure Slide 15: Beta 
>> nuclide measurement (Tritium)
>> 
>> 
>> Tepco report slide:
>> http://db.tt/UfPU1FpJ
>> 
>> 
>> Jaro
>> ^^^^^^^^^^^^^^^^^^^^^^^^^
>> 
>> 
>> 
>> -----Original Message-----
>> From: radsafe-bounces at health.phys.iit.edu
>> [mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of Jaro Franta
>> Sent: August-21-13 2:57 PM
>> To: 'The International Radiation Protection (Health Physics) Mailing List'
>> Subject: Re: [ RadSafe ] Dose conversion in beta exposure readings at 
>> Fukushima Daiichi ?
>> 
>> Thanks Jim,
>> 
>> Its important to get to the bottom of this bizarre dose rate reporting.
>> 
>> Here's why: According to Reuters,
>> 
>> "Water in the latest leak is so contaminated that a person standing 
>> close to it for an hour would receive five times the annual recommended 
>> limit for nuclear workers."
>> 
>> http://www.reuters.com/article/2013/08/21/us-japan-fukushima-severity-i
>> dUS
>> BR
>> <http://www.reuters.com/article/2013/08/21/us-japan-fukushima-severity-
>> idU
>> SBRE97K02B20130821>
>> E97K02B20130821
>> 
>> ......how on earth does one get "five times the annual recommended 
>> limit for nuclear workers" from an external beta dose ?
>> ......and how does one even calculate a dose rate in mSv/h from an 
>> instrument reading of beta radiation in the environment ?
>> 
>> Jaro in Wonderland
>> 
>> 
>> 
>> 
>> 
>> From: Jim Hardeman [mailto:jim.hardeman at gmail.com]
>> Sent: August-21-13 10:49 AM
>> To: jaro_10kbq at videotron.ca
>> Subject: Re: [ RadSafe ] Dose conversion in beta exposure readings at 
>> Fukushima Daiichi ?
>> 
>> Jaro --
>> 
>> My GUESS is that what TEPCO is talking about isn't an actually dose 
>> rate MEASUREMENT, but a dose rate ESTIMATE performed with some sort of 
>> GM tube / counter with a removable beta shield -- something like the 
>> old HP-270 "hot dog probe". Seems to me that they're simply reporting 
>> open window readings as "beta + gamma" and closed window readings as 
>> "gamma". I doubt they're doing much in the way of making beta dose rate 
>> conversions.
>> 
>> My $0.02 (US -- don't know what that is these days in Canadian)
>> 
>> Jim Hardeman
>> jim.hardeman at gmail.com
>> 
>> 
>> 
>> 
>> 
>> On Wed, Aug 21, 2013 at 10:35 AM, Jaro Franta <jaro_10kbq at videotron.ca>
>> wrote:
>> Here's a question about exposure/dose rate numbers reported by Tepco at 
>> the FD contaminated water storage tank farm earlier this week.
>> 
>> A picture from Tepco's pdf document is linked below.
>> 
>> Of interest are the sample analysis results for "Leakage water" in the 
>> table at bottom left, reported in Bq/cm3:  Note especially the "All 
>> beta" figure of 8.0E+4 figure.
>> 
>> The curious part is the table at right, which lists dose rates at 
>> various points around the site in mSv/h - for either "beta + gamma" or 
>> gamma
>> alone:
>> the highest number being ">100 mSv/h" for "beta + gamma" at point #1, 
>> and similar values for points 10, 11, and 12.
>> 
>> My question is how does one apply dose conversion factors to instrument 
>> readings, to derive "beta + gamma" dose rates in mSv/h ? ..which look 
>> to be mostly beta, if one deducts the gamma-only number in the right 
>> column.
>> 
>> This is clearly not a case of committed dose due to radionuclides 
>> absorbed in the body. So what is it ? ..if its simply a conversion of 
>> instrument beta particle count rate, what sort of conversion factor 
>> would one apply to betas from tritium, to get mSv/h ?
>> 
>> And although its not explicitly stated, the activity numbers in the 
>> lower table suggest that much of the 8.0E+4 Bq/cm3 activity is tritium, 
>> with very low beta energy (this water was used for cooling the damaged 
>> reactors, and circulated in a closed loop through filters that remove 
>> much of the fission products, but not the tritium..)
>> 
>> 
>> Tepco report slide:
>> http://db.tt/UfPU1FpJ
>> 
>> Thanks
>> 
>> Jaro
>> ^^^^^^^^^^^^^^^^^^^^^^^^^^^
>> 
>> 
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