Environmental Science & Technology (American Chemical Society), July 11, 2014 (emphasis added): Novel Insights into Fukushima Nuclear Accident from Isotopic Evidence of Plutonium Spread along Coastal Rivers
- Our results demonstrate that Pu isotopic compositions similar to the ones found in roadside dust samples outside the 20-km exclusion zone in Iitate-Mura and Minamisoma municipalities could also be measured in fresh riverbed sediment deposits. They confirm that Pu originating from FDNPP could be transported relatively long distances from the damaged power plant and is already being supplied to coastal rivers, thereby representing a potential source of Pu to the Ocean.
- Atom ratios found in sample FNL034B which is also the most contaminated in both plutonium and radiocesium are rather surprising. This sample, collected in Nitta River headwaters, is not located within the main radioactive plume [...] more analyses should be conducted to better understand the Pu isotopic atom ratio patterns and distribution across this area.
- Transport of Pu to longer distances in Fukushima than in Chernobyl may be explained by the different accidental conditions that prevailed at both sites. In Chernobyl, the Pu bearing particles were larger because of the graphite fires, which likely explains that they deposited at a shorter distance from the power plant.
- [F]ractions of Pu from FDNPP in the analyzed materials range from ∼1% for FNS 140 and FOL 250 samples to ∼60% for FNL 034B sample. Again, this result is rather surprising as the FNL 034B sampling site is the farthest from FDNPP (∼45 km).
- Future studies should focus on analyzing Pu isotope and atom ratio values on a large set of soils from the area located to the northwest of the exclusion zone in order to better understand its spatial distribution across the area and the succession of events (burn-up, release of radionuclides, etc.) that occurred at FDNPP in March 2011 and their consequences on Pu dispersion in the environment. Furthermore, similar analyses should be conducted on a larger set of river sediment samples collected in coastal rivers draining this area as this study showed their potential delivery to the Ocean. Our results show that the high 241Pu/239Pu atom ratio of the Fukushima accident-sourced Pu may particularly provide a relevant tracer of continental-originating material from Fukushima Prefecture to the Pacific Ocean.
See also: Scientific Reports: It's "remarkable" where plutonium from Fukushima reactor is suspected to have been found -- "Even more unexpected" that it's located outside main strip of contamination -- Need to assess consequences for public of a release of plutonium-rich hot particles (PHOTO)
Published: August 4th, 2014 at 12:51 pm ET