Article discussing 241Am ingrowth and Pu isotope ratios in Japan

Sorry to be a downer here, but it concerns me highly that governments around the world consist of many people with low scientific aptitudes. More than ever, society needs leaders who are scientifically literate, able to process and comprehend complex data of various types and perform analysis based on information inputs.

More and more it seems like society is rewarding those who “innovate” in scamming more than in creating.

I was reading an article today about research on Plutonium from the Fukushima Daiichi Nuclear Power Plant accidents and there were some interesting points relating to the danger of Plutonium in the environment.

From the article “Isotopic evidence of plutonium release into the environment from the Fukushima DNPP accident“: http://www.nature.com/srep/2012/120308/srep00304/full/srep00304.html

Analysis of Plutonium isotope ratios and concentrations in exclusion zone areas around Fukushima DNPP indicate higher than normal amounts of Plutonium 241, attributable to the nuclear accident.  The amounts of Plutonium are lower than Chernobyl, which also had fuel containing Plutonium, and are consistent with distribution of bits of Plutonium being distributed as fragments of fuel cores which got blown up when the #3 reactor exploded. Plutonium 241 is a beta emitter.  Its half-life is 14.4 years.  It decays into Americium 241, which is an alpha and gamma emitter.  Both of these are serious concerns, particularly if they are inhaled or otherwise ingested into the body.

Based on analysis Plutonium and Americium in soil near Nagasaki where a bomb with a Plutonium core was detonated over the city in 1945, there has been “no significant difference regarding their downward migration behavior” (through the soil) in the past 60 years. The concentration of Americium increased and reached a peak in 2008 after which it will continue to decrease gradually. In other words, it sticks around for a long time and over time as it turns into Americium it actually transfers more easily into plants.

From the Plutonium that has been scattered across the Earth from all the atomic weapons tests, the amount of Americium 241 is expected to peak in 2042.  From the Fukushima DNPP accident it is expected to peak in 2081.  In other words there will be significant issues related to the radiation release from the Fukushima DNPP disaster for many decades to come in exclusion zone areas.

Some other info from the article:

MEXT has estimated the 239+240Pu dose of external exposure and inhalation from resuspension as 0.12 mSv for a person living for 50 years in the contaminated area8. On the other hand, the 241Pu/239+240Pu activity ratio of the Fukushima-derived Pu was found to be higher than 100. The additional dose contribution from 241Pu has to be estimated. As an example, assuming a similar contamination of 241Pu in the surface soil as that in the litter layer and using the method of IAEA-TECDOC-95524, we estimated the 241Pu dose for a person living for 50 years in the vicinity of S2 site to be 0.44 mSv, about 4 times the 239+240Pu dose.

We noted that in the surface soil (0–1 cm) under the litter layer at sites S3 and S2, no 241Pu was determined and 240Pu/239Pu atom ratios were 0.144 and 0.177, respectively, close to the global fallout value of 0.180. This phenomenon indicated that the released Pu deposited in the litter layer, had not reached the underlying surface soil by May 2011 when the samples were collected. We considered that the atom ratios of 240Pu/239Pu and 241Pu/239Pu found in the litter layer reflected the isotopic composition of the released Pu from the Fukushima DNPP accident.

It was found that although the inventories of Pu isotopes in the reactors in the Fukushima DNPP were ca. 3.5 times those in the Chernobyl No. 4 reactor23, the percentages of core inventory released for both 239+240Pu and 241Pu were about 5 orders of magnitude lower than those of the Chernobyl accident. These results suggested that for the Fukushima DNPP accident, the plutonium emitted into the environment was mainly due to the release of Pu associated with fuel fragments as a consequence of the hydrogen explosions, as suggested by Kirchner et al.22.