[ RadSafe ] Feds puzzled by gamma radiation higher than normalnear wildfire -Cs-137, K-40 data

Tue Jul 17 09:24:50 CDT 2007

Hi all,

I've mentioned aspects of the woodash survey I conducted back in the  1990s 
on radsafe before. Based on actual measurements, from this survey of Cs-137 
in woodash, the typical K-40 content of woodash is about 120,000 picoCuries 
per kg of ash.  Woodash is 10 to 15% potassium by weight --thus it's use as 
a feedstock to the early US potash industry in colonial times.

Ash samples from burning mature hardwoods in the East in my survey had 
Cs-137 as high as 20,000 [in many parts of New England] to 25,000 picoCuries 
kg of ash [in oak ash from FL].

At these latter levels, the  Cs-137 peak dwarfed the K-40 peak due to gamma 
abundance in K-40 being relatively low vs. Cs-137 and Cs-137 efficiency in 
gamma counting being much higher than K-40. Thus total counts from Cs-137 at 
say 20,000 pCi/kg ash showed a peak on a gamma spec that was much, much 
higher than that from K-40 at 120,000 pCi/kg ash. Every other peak in the U 
and Th decay series in woodash faded to the baseline vs. the K-40 and Cs-137 
peak heights.

I received  data in this survey on Cs-137 in wood ash from Idaho which was 
about 1,000 pCi/kg in pine ash. Wood ash samples from trees in CA showed 
Cs-137 at only about 300 pCi/kg ash. Cs-137 content in woodash varies by 
factors of up to 100 despite relatively even Cs-137 areal deposition from 
airborne nuclear bomb testing, due to soil factors:  stable Cs in soil 
[higher stable Cs leads to higher Cs-137 in biomass per unit deposition], 
stable potassium levels in soil [inverse relationship  --more stable K, 
lower Cs-137 per unit deposition], and more.

A wild fire can throw up  2 to 3% or more of the mass of biomass burned as 
airborne ash particulates which might contribute to elevated activity 
measured on filters due to K-40 and Cs-137 [residual from generalized 
weapon's test fallout].

Stewart Farber, MS Public Health
Consulting Scientist
Farber Technical Services
1285 Wood Ave.
Bridgeport, CT 06604
[203] 441-8433 [office]
[203] 522-2817 [cell]
email: radproject at sbcglobal.net

==========================

----- Original Message ----- 
From: "Dan McCarn" <hotgreenchile at gmail.com>
To: "Michael McNaughton" <mcnaught at lanl.gov>; "Emer,Dudley" 
<EMERDF at nv.doe.gov>; <HotGreenChile at gmail.com>
Cc: <radsafe at radlab.nl>
Sent: Monday, July 16, 2007 3:13 PM
Subject: Re: [ RadSafe ] Feds puzzled by gamma radiation higher than 
normalnear wildfire

Hi Michael:

As you probably already know, Bi-214 is the most significant gamma
emitter of the Ra-226 daughters (dominantly the 609 KeV gamma photopeak),
but the early part of the chain has quite short half-lives.  Perhaps the
"gamma" detectors *during* the fire were seeing the gamma from the Bi-214
which decayed to the three radionuclides - Pb-210, Bi-210, and Po-210.

If the 'ingrowth" chain is broken during the fire, then perhaps the only
R/Ns to survive on an air filter would begin with Pb-210 and the ingrowth
daughters Bi-210 and Po-210.  After only a few hours (4.46 hours), the
Pb-214 would have decayed (10 half lifes) to 1/1024 of the original value
and may be undetectable along with the Bi-214.

Another gamma emitter that would certainly be lofted during the fire would
be K-40, which accumulates in soils and wood as a macronutrient in plants.
SInce the soils "burn" in forest fires as well as the trees (similar caloric
value), the K-40 could easily be lofted with the ash from the forest floor.
The name "potash" comes from the use of wood ash from the firepalace as a
fertilizer, since it is significantly enriched in potassium.

Rn-222 3.8235 d
Po-218 164.3 µS
Pb-214 26.8 m
Bi-214 19.9 m
Po-214 164.3 µS
Pb-210 22.20 y
Bi-210 5.012 d
Po-210 138.376 d

Best regards!

Dan ii

Dan W McCarn, Geologist
Houston & Albuquerque

On 7/16/07, Michael McNaughton <mcnaught at lanl.gov> wrote:
>
> Following the Cerro-Grande fire at Los Alamos, I and my colleagues
> investigated the increased airborne radiation measured during the fire.
> Almost all the increased radioactivity we detected is from the long-lived
> radon decay product, lead-210, and its progeny: bismuth-210 and
> polonium-210. However, I am puzzled by the word "gamma" that appears
> several times in the article below. Pb-210, Bi-210, and Po-210 emit few
> gammas, mostly of low energy. Does anyone on this list have more
> information?
>
> mike
>
> At 01:35 PM 07/13/2007, Sandy Perle wrote:
> >Feds puzzled by gamma radiation higher than normal near wildfire
> >
> >The Salt Lake Tribune, Jul 13 -  A puzzle has sprung from the flames
> >of the Milford Flat Fire: What's pumping radiation into the air? The
> >National Nuclear Security Administration said Thursday its radiation
> >monitors in the area are showing gamma radiation spikes seven times
> >higher than the normal background. But before anyone runs to the
> >doctor, it's worth pointing out that even those spikes, if someone
> >breathed them for seven hours straight, produce less than one-2,000th
> >of the radiation dose a Utahn normally gets in a year. "You're
> >talking about a very small dose," said NNSA spokesman Darwin Morgan.
> >The agency, which had proposed a massive, non-nuclear explosion
> >experiment at the Nevada Test Site last year, monitors the air for
> >radiation at 29 monitoring stations in Utah, California and Nevada.
> >The agency canceled the so-called Divine Strake test after hearing
> >from thousands of Utahns who complained that the explosion would send
> >radiation-tainted debris into their air and onto their landscape. "We
> >heard loud and clear from the people of Utah they are concerned about
> >radiation," said Morgan, explaining his agency's reasons for
> >publicizing the radiation-meter findings. Morgan said filters from
> >the Milford monitoring station are being analyzed at a laboratory.
> >The agency thinks that naturally occurring radon is being released
> >from the ground, but only study of the material captured on the air
> >filters will tell them for sure. Dane Finerfrock, director of the
> >Utah Division of Radiation Control, said the fact that radiation is
> >released during combustion is no secret. "There's a radioactivity in
> >that forest and brush," he said, "and some of it stays in the ash and
> >some of it goes into the atmosphere." Morgan said there is no data
> >about the radiation from the Neola North Fire in eastern Utah. The
> >agency does not have monitors in that part of the state.
> >----------------------
>
> Mike McNaughton
> Los Alamos National Lab.
> email: mcnaught at LANL.gov or mcnaughton at LANL.gov
> phone: 505-667-6130; page: 505-664-7733
>
>
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-- 
Dan W McCarn
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