Geiger counters and Rainwater

Submitted by bandstra on Fri, 2011-07-22 23:11

Berkeley Radiological Air and Water Monitoring Forum

I recently mentioned that I was able to reproduce the "radioactive rain" measurements that some have done. Since that topic seems to keep coming up, I thought I would write up what I did to show what is going on. I was able to show that the radioactivity is consistent with the decay products of radon gas, which is naturally occurring and everywhere.

You can see my measurements here.

The world we live in is naturally radioactive, and these measurements are a perfect demonstration of that fact. In North America the fallout from Fukushima is so tiny that very specialized detectors are needed to see it above the intense natural background. Handheld detectors will not do the job.

Mark [BRAWM Team Member]

Mark and all- Thinking more

Submitted by BC (not verified) on Sun, 2011-07-31 09:38.

Mark and all-

Thinking more on the radon daughters and such found in rainwater and air filters...could one also expect to see such materials concentrated/deposited by a dry-deposition wind storm? We frequently have nasty windstorms here and I have on several occasions wiped down the car window with a wet paper towel and then took a count with my lil' toot geiger counter. While I have never had a result above the error bars, the counts have typically been higher than background.

I know it is impossible to say for sure, but do you suppose the static and what-not created by a windstorm could cause some radon etc to stick exposed objects?

One of the professors in our

Submitted by tjaucott on Sun, 2011-07-31 13:44.

One of the professors in our department has been studying radon and its daughters for some time now, and he confirmed that the radioactive daughters will strongly accumulate on surfaces, even without the rain -- likely because the decay daughters are initially charged particles. The windstorm could contribute even more.

Tim [BRAWM Team Member]

Thanks Tim. I live not far

Submitted by BC (not verified) on Sun, 2011-07-31 15:17.

Thanks Tim.

I live not far from the Black Rock Desert and we had an incredible dust storm last night - enough dust in town to see tire tracks on the streets. But the cars got the worst of it, may have to do with sheet metal. It has occurred to me that the dust no doubt has some minute amount of Fukushima in it.

As for static and wind, I know that explosive professionals will often call it quits for the day if the wind kicks up, due to the static electricity the wind can generate.

Again, thanks for the response. Interesting stuff.

Mark- Very interesting. I

Submitted by BC (not verified) on Sun, 2011-07-24 08:23.

Mark-

Very interesting. I wish that the guys running around with geiger counters measuring rain would take a damned sample and test it the next day and show their viewers the big fat goose-egg above background (or if there is a difference, let's be truthful about that too)..

BC, I agree with you. I live

Submitted by Anonymous (not verified) on Wed, 2011-07-27 09:46.

BC, I agree with you. I live in Edmonton, Alberta. This is one of the places that the person from Youtube has posted a reading of 1.14 microseiverts per hour from a single rainfall. I read what Mark has posted and it makes sense. I just wish the guy travelling around taking readings would also measure the air and take some measurements at ground level and like you said, take measurements of the same spot on his truck the next day. I also think he may be getting a cummulative reading from what has already been deposited on his truck. He is driving across the country and it is not like he is starting with a perfectly clean truck when he takes the measurements.

I have young kids so it would be nice to know what we are dealing with here as my kids go for outings with thier daycare to the park and play in the sand etc.

Thanks Mark, that is very

Submitted by Anonymous (not verified) on Fri, 2011-07-22 23:48.

Thanks Mark, that is very informative. Unfortunately our World is also artificially radioactive too, from weapons testing fallout (the people who did that were so stupid), nuclear accidents, leaks, etc. etc.. Do you know of any studies that compare the background radiation now to what it was likely to have been say 500 years ago?

Nuclear testing and plants have added very little

Submitted by bandstra on Tue, 2011-07-26 09:25.

Those numbers have been looked at. It turns out that exposure from weapons testing, leaks, and Chernobyl are very tiny. The UNSCEAR 2008 Report, Vol. I, Table 1 gives a breakdown of the average dose per person due to different sources. Here is a summary of Table 1:

SourceAverage annual dose (mSv)Notes

Inhalation (radon gas)	1.26
External terrestrial	0.48
Ingestion	0.29
Cosmic radiation	0.39

Total natural	2.4
Medical diagnosis	0.6	Individual doses depend on specific examinations.
Atmospheric nuclear testing	0.005	The average has fallen from a peak of 0.11 mSv in 1963
Occupational exposure	0.005
Chernobyl accident	0.002	The average in the northern hemisphere has decreased from a maximum of 0.04 in 1986.
Nuclear fuel cycle	0.00002
Total artificial	0.6

Weapons testing, Chernobyl, and the nuclear fuel cycle currently contribute a very tiny amount to the total dose the average person on earth receives each year.