I129 - What say you, BRAWM?
It's been brought to my attention that following these nuclear accidents and radiation releases, the focus is rarely (never) on Iodine-129, a low-level beta emitter, half life about 250 thousand years.
I have been told (by an industry scientist) that the (previous) presence of I131 at significant levels assures us that I129 is present. He did not understand why no one tests for I129, since, depending upon its levels, would be a factor to consider in children's exposure levels.
I asked him if we could determine the I129 level based upon a ratio to I131 based upon the Fukushima releases, and he said not anymore since the initial releases of 131 are now gone. He did say that a correlation may be possibly made to the Sr90 levels.
Mark, can you enlighten us as to the risk posed by I129 exposure, and share your educated opinion / knowledge about its levels in our environment, pre- and post-Fukushima?
Thank you, MM
The Dutch nuclear consultancy
The Dutch nuclear consultancy firm, Isotopics, answered my question about I129, relative to environmental accumulation due to NPP accidents. Here is their response:
"I-129 has a half-life of nearly 16 million years, which means its radioactivity is extremely low. Its activity in the Fukushima reactors is about 1 billion time less than I-131. Its presence in the environment is extremely difficult to determine; only a few labs world-wide can do it properly. Your contact is probably right, that the isotope will be present in the thyroid gland, but it will be in very low activities (order 1/1000 of a pCi, probably less). Other than I-131, you cannot detect it by total body counting, or placing a probe in front of the thyroid gland, or do a blood analysis. It is just below the detection limit of any technique. We do not see (any) reason for a correlation with strontium. Iodine is a halogen, strontium an alkaline earth metal. They have totally different chemical behaviour."
MM
Mm Also check out the Dartmouth study
http://now.dartmouth.edu/2012/04/dartmouth-scientists-track-radioactive-...
"The radioisotope iodine-131, a significant constituent of the fallout, is a by-product of nuclear fission, highly radioactive, acutely toxic, and presents a health risk upon its release to the environment. It does have a relatively short half-life, which is both a blessing and a curse, Landis notes. “It releases a lot of radioactivity, which makes it dangerous, but it’s gone very quickly so there is no long term exposure risk,” he says.
Its high radioactivity, however, makes it very detectable by the gamma-ray spectroscopy instruments used by the Dartmouth team in its analyses.
This is not the case with another isotope, iodine-129, released concurrently with iodine-131. It is not as radioactive, which makes it much harder to measure, but it is much longer lasting and, as it concentrates in certain areas over time, it may become more hazardous.
“Due to its long half-life and continued release from ongoing nuclear energy production, [iodine-129] is perpetually accumulating in the environment and poses a growing radiological risk,” the authors point out."
http://now.dartmouth.edu/2012/04/dartmouth-scientists-track-radioactive-...
http://www.sciencecodex.com/dartmouth_scientists_track_radioactive_iodin...
The production rate of these two isotopes in a nuclear reactor occurs at a fixed ratio of 3 parts iodine-131 to one part iodine-129. The two substances travel together, so the presence of the easily detectable isotope also signals the presence of the longer-lived one. "If you have a recent event like Fukushima, you are going to have both present. The iodine-131 is going to decay away pretty quickly over the course of weeks, but the iodine-129 is there forever, essentially," Landis says. However, he explains, "Once the iodine-131 decays, you lose your ability to track the migration of either isotope."
http://www.sciencecodex.com/dartmouth_scientists_track_radioactive_iodin...
The Dartmouth study/Surficial redistribution of fallout 131iodine in a small temperate catchment
http://www.pnas.org/content/109/11/4064.short
Ty mm and Enjoy its all very intresting . I missed the 8 day window in my soil test..tdm
http://www.evs.anl.gov/pub/do
http://www.evs.anl.gov/pub/doc/iodine.pdf
Perhaps we should be continuing to protect the thyroid with supplemental stable iodine as our exposure to radioactive iodine from this event is ongoing (as in forever), not simply the 80 days that I131 persists, not mention supplemental to/cumulative with I131/I129 releases from Chernobyl and every other event?!
I129 half life = 15.7 million years (not 250K - sorry).
Mark posted something on
Mark posted something on I-129 a while back - http://www.nuc.berkeley.edu/node/2115#comment-549
One thing I will point out to anyone is that any "protective" kelp supplements, even pre-3/11, no doubt have I-129 in them. This stuff has a very long half life.
Myself, I would like to know if we can figure out:
1) How much I-129 did Fukushima release? If we knew the I-131 to I-129 ratio from this particular event we could back out the levels of I-129 by looking at measurements we have on the I-131 (USGS, BRAWM, etc).
2) How much I-129 was released during the era of big boys doing their best to trash the planet? Even if we can't get this piece of data, if we could get the ratio of I-131 to I-129 released during an atomic detonation we could look at the known I-131 numbers and use them to calc out the I-129.
Thanks MadMama and tdm for your inputs here.
BC 5/1/12
I-129 is always present at
I-129 is always present at about the 0.1 ppm level compared to stable iodine.
It's produced in cosmic ray interactions with Xenon in the upper atmosphere.
Iodine in seawater: 50 microgm /l
Volume of the ocean: 1.3e9 km^3 = 1.3e21 liters
All of the iodine in the ocean: 50 microgm/l * 1.3e21 liters = 65e15 gm
All of the naturally occuring iodine-129 in the ocean: 65e15gm*0.1e-6 = 6.5e9gm = 6.5e6 kg or 7165 tons.
Fuel load of an average reactor: 100 tons of Uranium. If all of the uranium fissioned (it doesn't but that's conservative) you would produce 1 ton of I-129. If four reactors dumped all of their fuel load in the ocean it would add at most 4 tons to the 7165 tons that are already there.
Negligible, compared to what's already there.
No need to relocate to South America just yet.
Even lower...
You can cut that estimate even lower.
Yes - there are 100 tons of Uranium in a reactor core - but it is at an enrichment of 3% to 4%. That means there are only 3 tons to 4 tons of the isotope U-235 in the reactor, and it is the U-235 that is the true fuel.
So we can divide your number by at least 25 - so that 4 tons = 8,000 pounds becomes only 320 pounds.
So let's continue. The human
So let's continue.
The human body has about 50 milligrams of iodine in it of which 60% is in the thyroid.
I-129 in the thyroid: 50 mg * 0.1ppm * 60% = 3e-9 gm
Decay rate I-129: 1.8e-4 Curie/gm = 540e-15 Curie = 20e-3 Becquerels (about one disintegration every 50 seconds.
Energy deposition: 0.064 MeV/disintegration = 1.27e-3 MeV/s = 2.0e-16 Joules/s
Mass of thyroid: 30 gm max
dose: 2.0e-16 Joules/s/0.03kg = 6.6e-15 Joules/kg/s or 6.6e-15 Sv / s or 210e-6 mSV / year.
Normal background dose to the thyroid: about 3.5 mSv/year
Component from I-129 in the environment: 0.00021 mSv/year
If 7,000,000 fukushima type reactors dumped all their fuel in the ocean it would increase the concentration of I-129 in the environment by a factor of 1000.
That would increase the thyroid radiation dose to 2.1 mSv/year or roughly where you would start to be mildly concerned about the increased radiation dose.
Keeping I-129 in perspective...
In Mark's post referenced above, Mark states:
So then the I-129 activity should be smaller than the I-131 activity by a factor of at least one million
We can get an idea of how much the average person's exposure due to all fallout from now discontinued atmospheric nuclear testing by looking at the entry for "Fallout" in the following table, courtesy of the Health Physics Society chapter at the University of Michigan:
http://www.umich.edu/~radinfo/introduction/radrus.htm
which states that the dose due to "Fallout" is < 0.03% of our normal background exposure which is mostly due to Mother Nature.
Very outdated source
The information that is provided in the link you cite is based on the National Council on Radiation Protection and Measurement report no. 93, 1987. This report was replaced by report no. 160,
Ionizing Radiation Exposure of the Population of the United States, 2006. The new updated report is much more relevant. The most notable difference is that an increased exposure over the past quarter century puts the cumulative national medical exposures on a level with natural background radiation exposure.
===============================
http://radiology.rsna.org/content/253/2/293.full.pdf
Source is still current!!
More irrelevant flotsam added to confuse people.
Evidently you didn't notice that the comparison was NOT to total background; but to NATURAL background. The natural background hasn't changed even though the medical exposure has gone up.
The comparison is that the exposure due to fallout is <0.03% of the natural radiation due to Mother Nature; the increased use of radiation for medical purposes, notwithstanding.
WRONG, WRONG,WRONG
Do you really think that the objective of the updated report was to provide "More irrelevant flotsam... to confuse people"?
If you took the time to read the new report you would clearly see that the natural background is on the increase since the 1980's.
No where in the report is an estimate given for "exposure due to fallout" as you have cited.
It is highly relevant that the exposure from medical procedures is reaching parity with natural background.
We can count on you to provide data that is severely outdated.
WRONG!!!! WRONG!!! WRONG!!!
NO - the natural background isn't going up.
As you report, it's the medical use that is going up.
That's NOT part of what Mother Nature is exposing us to. Medical uses are considered part of our "Man-made" exposure, NOT our "natural" exposure.
The natural exposure is due to radon, cosmic rays, K-40,....
THAT'S what I was comparing to; NOT including man-made.
There isn't a reference to the fallout in the most recent reports because it isn't changing much. ( The decay is dominated by the 28 / 30 year half-lives of Sr-90 and Cs-137. )
So the NCRP assumes that you know to look in the previous report which included the fallout.
I guess they assumed wrong.
Half life life of iodine 129 Is 15 . 7 million years weak emiter
http://www.epa.gov/rpdweb00/radionuclides/iodine.html#properties
Where do iodine-129 and iodine-131 come from?
Both iodine-129 and iodine-131 are produced by the fission of uranium atoms during operation of nuclear reactors and by plutonium (or uranium) in the detonation of nuclear weapons.
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How do iodine-129 and iodine-131 change in the environment?
Radioactive iodine can disperse rapidly in air and water, under the right conditions. However, it combines easily with organic materials in soil. This is known as ‘organic fixation' and slows iodine's movement in the environment. Some soil minerals also attach to, or adsorb, iodine, which also slows its movement.
The long half-life of iodine-129, 15.7 million years, means that it remains in the environment. However, iodine-131's short half-life of 8 days means that it will decay away completely in the environment in a matter of months. Both decay with the emission of a beta particle, accompanied by weak gamma radiation.
http://www.epa.gov/rpdweb00/radionuclides/
Is there a medical test to determine exposure to iodine-129 and iodine-131?
Since iodine is concentrated in the thyroid gland, a radioassay of the thyroid can determine the level of exposure to many of its isotopes. However, I-129 has very low activity and emits extremely low energy beta particles, making a radioassay much more difficult. Tests for I-131 in the body should be available through most major medical centers.