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Electro
Canada
10 Posts |
 Posted - 01/27/2023 : 17:33:10
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Hello I bought the GMC-500+ mainly because I love Japanese Sensha green tea and I want to test it before I drink it, just to make sure that the tea is OK.
According to a website, the following isotopes were released from the Fukushima accident:
Cesium-134: Release beta particles and Gamma radiation
Cesium-137: Release beta particles and Gamma radiation
Iodine-131: Release beta particles and small amount of Gamma radiation
Xenon-133: Release beta particles
With my device I checked the background radiation first and it gives me around 18 ~ 19 CPM over a period of 30 minutes of letting the device collecting.
Then, I took my tea which is inside of a clear plastic bag, put the device on the bag and ran the "Food Sample" setting for 10 minutes, twice. I had 21 CPMs for the first run and 19 CPM for the second run.
That batch of tea looks safe but am I doing this correctly?
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ullix
Germany
1171 Posts |
Posted - 01/28/2023 : 00:59:27
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I doubt you will ever find anything! But all is ok with the way you did it.
You also have to take the half-life of the isotopes into account: I didn't look up the other ones, but I-131 has 8 days(!) half life, so while Geiger counters are sensitive, this would be really difficult to see.
But you should also take into account that all living organism do strictly require Potassium. And it has the K-40 isotope, which is radioactive ( see my "Potty Training" article.
So when you measure long enough, you ought to be able to see a difference between background and tea. I guess you will need a minimum of 24h of background + another 24h of tea to then see a statistical difference. See my "Going Banana" article, similar challenge. Use GeigerLog for recording, or download the some 200000 records into a spreadsheet.
You might want to remove the case of the counter, to allow intimate contact between the Geiger tube (the long tube in a GMC-500+) and the tea.
Mind you I am talking of "scientifically" demonstrating that the tea has "something radioactive" in it, not that the tea is harmless. The harmlessness you have already shown.
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| Reply #2
Electro
Canada
10 Posts |
Posted - 01/28/2023 : 04:46:59
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Hello @ullix, thanks for the experiment idea, I will try removing the case to get more accurate reading and proceeding with the 24 hours background first. I'll have to learn how to download the logs also with the manual today.
I looked up the half life of the Fukushima isotopes:
Cesium-134: Release beta particles and Gamma radiation / 2 years half life
Cesium-137: Release beta particles and Gamma radiation / 30 Years half live
Iodine-131: Release beta particles and small amount of Gamma radiation / 8 Days half life
Xenon-133: Release beta particles / 5 Days of half life.
That tea is is much older then 8 days, so good news for Iodine and Xenon.
I will look at your Potty Training and going banana articles today.
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Learning with the GMC-500+ - Testing Japanese tea
