– 8400 Bq/Kg of lead-210 was measured from sample of Yokohama (Fukushima Diary, Jan. 4, 2012):
Following up this article about soil contamination in Yokohama…
Having measured Strontium-90 from the soil of Yokohama, we suspect it may contain plutonium too.
We took 200g of the same sample and sent it to Dr C.Busby.
As a result, it was not positive for plutonium nor americium but surprisingly 8400 Bq/Kg of lead 210 (pb-210) was measured.
Honestly we are puzzled by the result and don’t know what the potential risk will be.
Dr Chris Busby comments:
The Lead 210 concentration of 8400Bq/kg is very interesting and was unexpected. Should not be more than about 20Bq/kg.
If that is a correct assignment, I believe it shows that there was a lot of Lead 210 emitted from the plant. That is a dangerous nuclide that no one has ever associated with releases from nuclear plants as far as i know, though there must be loads of it in the plant when you think about it as it is the decay product of the U-238 series and the plant runs on uranium. Lead has a very low boiling point, hence its appearance in the fallout. Ill have a look at the other samples from Fukushima.
I made a short video of me measuring the package when the sample first came.
I may put it on youtube.
It shows what can exist without anyone knowing.
On the report, he states:
The 200g soil sample was received on 5th Nov 2011. Its radioactivity was examined by Geiger and Scintillation counters, giving approximately 1.25uSv/h at the surface of the polythene packet. About 100g was removed and sent to ESG (formerly Harwell) laboratory for high resolution gamma spectrometry and determination of Plutonium 239+240. 100g was also sent to the University of Regensburg for the same high resolution gamma spectrometry. 20g was sent to Microtrace in Germany for ICPMS determination of Uranium.
Results for the ESG determinations were returned on 15th December. The gamma spectrum was analysed by ESG and also the data was set here and independently analysed by me using the FitzPeaks program.
The University of Regensburg refused to analyse the sample and discarded it.
Gamma results show moderately high levels of Caesium 134 and Caesium 137 plus some other fission product nuclides e.g. Rhodium-102, Silver 110m Also found are significant levels of Lead-210, probably from the reactor explosion since the levels are far too high for this to be a natural background.