Recently I came across this article from Hideo Watanabe, a Japanese blogger, which I find very interesting. It has the merit to raise some questions about the real quantity of Plutonium released in March 2011 during the Fukushima Daiichi nuclear plant catastrophe.
The claim of Hideo Watanabe that there was plutonium stocked in reactor 4 and plumed from it seems highly unlikely, as Bellona were in there and they would have picked up on high readings in the number 4 building if the reactor seals had been damaged like the others. That is why I have left that part out in this blog article.
However, his article has the merit to point out the contradictions between the two studies and that August 2015 IAEA report, report which itself has contradictions in its text, regarding the quantity of plutonium released from Fukushima Daiichi reactors in March 2011.
The issue of Pu release from the other reactors and spent fuel pools is a bigger issue as well as the water contamination issues. The measurements earlier on were in Beta and Alpha and little was mentioned on Pu and Uranium isotopes.. Some info came out about Pu but the data was sparse.. There has been no mention of Uranium isotopes but I think Uranium was likely spread around to some degree,
Anyway the discussion on the missing isotopes is valid and worth reminding people about. The general observations are that Fukushima Daiichi has low amounts of Sr 90 compared to Chernobyl and less Pu on average.. There may be Pu hotspots around but they would be hard to find.
The IAEA would like us to believe that the March 2011 Plutonium release from Fukushima Daiichi reactors was very minimal, though their own August 2015 report shows contradictions. Furthermore two independent studies say otherwise.
Inside 200km zone, 240PU/239PU atoms ratios 0.216 – 0.255
Significantly higher than that of global fallout.
figure 1. (a) Results of 239+240 Pu and 241 Pu activities and 240 Pu/239 Pu atom ratios in surface soil and litter samples collected in the evacuation-prepared area (J-Village) and the deliberate evacuation area (S1, Katsurao Village; S2, Namie Town; and S3, Iitate Village). Data are cited from ref 27. (b) Map showing the locations of marine sediment and seawater sampling sites. Results of 239+240 Pu activity (Bq/kg) and 240Pu/239 Pu atom ratio are shown. Data of sediment samples are cited from ref 37, and seawater samples (FSK1 and FSK 2) are cited from ref 65.
By Hideo Watanabe
Here is the Nature report :
Isotopic evidence of plutonium release into the environment from the Fukushima DNPP accident
The IAEA, published a comprehensive report of Fukushima in August 2015, the Fukushima Daiichi accident technical volume 1: description and context of the accident
Still, in that IAEA’s report there are some contradictions and weaknesses.
In the 2014 study, some researchers are saying the same thing as the Nature report.
Source: Hideo Watanabe’s blog