Tag Archives: Cs 137

Radio-isotopic Analysis of Post-Fukushima Accident Japanese Soil Samples

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The full document can be read here
All supporting data can be accessed here
Radioactive fallout from the triple reactor disaster at the Fukushima Daiichi Nuclear Power Station, following a magnitude 9.0 earthquake and subsequent tsunami, is readily observed in soil samples collected from Japan, well beyond the exclusion zone. Samples from three regions, approximately 210 km, 550 km, and 1060 km from the Fukushima Daiichi Nuclear Power Station, were tested for gross gamma activity and radio-isotopic composition. The primary isotopes of focus were the most commonly detected radio-isotopes of Cesium, 134 Cs and 137 Cs.

Note: Another individual should be listed as a co-contributor, given their important role in providing material from Japan for testing, but their name has been left out for purposes of anonymity. To that person, go my deepest thanks.

Documents and data used in the report. This data will allow anyone to view and come to their own conclusions. Data transparency is important.

Please remember that this document is Open For Comment until March 11.

Japanese Soil Tests – First Results

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Soil Sample J-A From Kashiwa City, Chiba Prefecture (26km NE from Tokyo)

Soil Sample J-A From Kashiwa City, Chiba Prefecture (26km NE from Tokyo)

[NOTE: This is not my official results, but a merely my first test of the materials. Much more to come]

I have just received a set of samples from a friend in Japan. The samples are from various locations around the country and ready to be tested in my gamma spectrometer. I will be publishing a full set of tests very soon, but until that time I thought I might provide a small glimpse of the preliminary results. This is a gamma spectrum from a sample, J-A_3600s, which was tested for one full hour using gamma spectroscopy. The sample shown came in a small 1” x 2” canister and contained soil from just under a water rain spout in residential housing area (back yard), of a person living in Kashiwa City, Chiba Prefecture (26km NE from Tokyo).

The sample measured about 306 CPM at contact using a 2” pancake Geiger Muller probe. During the hour of testing, clear photo-peaks for Cesium 134 and 137 were easily detected from the sample. Other features included several very small deformations in the spectrum which were either inconsequential, i.e. x-ray interference, or unidentifiable due to extremely low activity.

The extreme amounts of background “noise” found in the spectrum is consistent with a powerful beta emitter. Gamma spectroscopy cannot directly detect Strontium 90, but given the release amounts of Cs 137 and the typical matching of Cs137 and Sr90 isotopes following a nuclear release, like that of Fukushima, it is plausible to consider that Sr90, and by decay association Y90 and Y90m, are also present.