BRAWM interpretation of slowly rising EPA graphs in Pac NW?

Submitted by Anonymous on Fri, 2011-10-07 13:56

Dear BRAWN team:

I've been keeping an eye on the near-real time EPA graphs in the Pacific NW, particularly Seattle, Olympia, Richland, Spokane in WA and Portland, Corvallis in Oregon and Eureka, CA. It seems like all of these graphs show an ever so slight, constant increase of most energy lines in the gamma spectrum since the end of August. Especially noticeable when looking at the bottom of the amplitudes. Some places also show significant spikes recently, including beta lines:

http://blog.alexanderhiggins.com/2011/04/12/realtime-epa-radnet-japan-nu...

Can you comment on what may cause both the slight, steady increase and the spikes, other than fluctuations or increases in Fukushima emissions reaching these places? Could it be increased radon as a result of remaining snow cover being melted in mountains and increased rainfall? It would be useful to know which energy lines correspond with radon.

Thanks so much!

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Hi BRAWN, could you take a

Submitted by Anonymous (not verified) on Wed, 2011-10-12 01:09.

Hi BRAWN, could you take a look at this? I'm NOT referring to the spikes (which you have many times explained well as likely caused by natural Radon fluctuations). I would like to know what could cause this very slow raise in most energy lines in those locations since about mid August....Thanks for any thoughts as to what may be causing this other than Fukushima emissions.

I have looked at those

Submitted by bandstra on Sun, 2011-10-16 14:19.
I have looked at those graphs and I'm not sure that I see any significant increases in the gamma rates. Was there any one city that you think shows this effect the best? Regardless, my comments about the RadNet spikes actually apply to more than just the spikes. The most relevant information is in radon prediction #3, that the radon decay products have gamma-ray lines throughout the entire spectrum and therefore all gamma-ray energy count rates should be correlated. If there is a significant increase in one gamma energy, there should also be significant increases in the other energies. On the other hand, fission product isotopes like Cesium-137 would only cause increases in one or two of the energies. Radon concentrations in the lower atmosphere can vary on different timescales for a number of reasons. The daily spiking is caused by temperature and pressure differences from the heating of the Earth by the Sun. Changes on longer timescales may be correlated to other longer-term temperature and/or pressure changes. I hope this helps. Mark [BRAWM Team Member]

Thanks very much, Mark, for

Submitted by Anonymous (not verified) on Wed, 2011-11-02 13:35.

Thanks very much, Mark, for your repeat lesson on Radon.
Digging into previous comments, I get that 1) increased Radon decays are reflected throughout all energy spectra, whereas increased decays (spikes) by Cs 134 and 137 should be visible only in energy range 5 (yellow line), I 131 in energy range 3 (blue line of EPA graphs). 2) lower air temperatures are correlated with higher Radon decays. So therefore, it is possible to conclude that the steady, slight increase in most energy ranges notable in the EPA graphs of all the above mentioned locations is due to Radon decays, which is enhanced by cooler air temps as we are heading into fall. Yes?

I would love to compare the current EPA graphs with 2010 and also data since Jan. 2011 (in graph form) to confirm that this is an annual trend. Can anyone advise how I can accomplish that with the EPA data base? I would much appreciate it. Thanks.

The decay of released

Submitted by Anonymous (not verified) on Mon, 2011-10-17 01:33.

The decay of released Fukushima fission products such as Neptunium into Radon should be elevating atmospheric background Radon levels to some degree. Despite occurring naturally at certain unpredictable levels, Radon is also a Fukushima fission product via decay pathways if not more directly. Would it then be correct to discount all Radon readings as "natural" rather than evidence of fallout, particularly if they have been increasing since March? When you mention the energy ranges we would expect coming from radioisotopes from Fukushima, do these not include Neptunium-239 (with its short half-life) or its daughter products? Thanks.

No Radon from Fukushima

Submitted by bandstra on Mon, 2011-10-31 16:48.
You have brought up a very interesting point about radon. Radon isn't produced in reactors, but only comes from natural uranium minerals. Here are more details, and answers to your other questions:

(1) Gamma energy ranges mentioned were only for I-131 (Range 3) and Cs-134/137 (Range 5). These were by far the most abundant fission products released by the Fukushima reactors, and they are the only ones that had a chance of being seen by the EPA's RadNet.

(2) We have not been able to detect any Am-241 or Np-239. These are transuranic elements produced in reactors that are gamma emitters. They are not volatile like Iodine and Cesium, so it is not surprising that we have not detected them.

(3) Radon could not have come over from Fukushima, for a few reasons. Radon is not a fission product; it is a decay product of the U-238 chain and is not made by fission. Radon (specifically Rn-222) is produced in abundance by natural uranium, which is present in all soils and rocks at roughly parts per million levels. Any purified form of uranium (e.g., reactor fuel) will not produce much Rn-222 at all because there are multiple bottlenecks in the decay chain between U-238 and Rn-222:

IsotopeHalf-life
U-234120,000 246,000 years
Th-23027,000 75,000 years
Ra-2261,260 1,600 years

It would take hundreds of thousands of years for purified uranium to decay enough to produce an appreciable quantity of radon gas. Meanwhile, the trace amounts of U-238 decay chain isotopes present in soil and rocks are already in equilibrium and produce radon gas in abundance (approximately 10 atoms of gas per second per kilogram of soil, as estimated from some of our samples). Mark [BRAWM Team Member]

Can someone out there PLEASE

Submitted by Anonymous (not verified) on Fri, 2011-10-14 18:39.

Can someone out there PLEASE take a look at these slowly rising radiation graphs across the Pacific Northwest??