We at SimplyInfo.org have reported extensively on the highly radioactive “black stuff” being found around eastern Japan, as far away as Tokyo. Citizens initially found the substance, usually concentrated in gutters and low spots. Some superficial analysis had been done on the substance, again by citizens. The government has refused to acknowledge the issue or publicly acknowledge testing of the substance.
Marco Kalofan, an environmental engineer in the US was able to obtain a sample for detailed analysis. What was found was quite unusual. The substance isn’t a sand but an aggregate of radioactive substances, metals and rare earth materials. The materials for some reason clumped together into an aggregate rather than dispersing as tiny particles.
What the detailed analysis showed was that the material may have come from inside failed fuel assemblies from the damaged reactors. The high level of uranium daughter isotopes like radium 226 are seen as an indicator of amounts of unburned uranium fuel. The sample also has a mix of other substances like cesium 134 & 137 and cobalt 60 that are reactor emissions as they do not exist in nature. The specific combination of substances found and the aggregate nature of the pieces confirm it is not organic in nature. The sample also contains a number of things expected to be found in used nuclear fuel.
Nuclear reactors tend to produce both heavy (atomic weight 125 to 155) and light (atomic weight 80 to 110) byproducts. These include light radioactive isotopes of the elements yttrium and silver, plus the heavier isotopes tin, antimony, cesium, cerium, neodymium, and lanthanum. All of these were detected in this dust sample by SEM/EDS, in the form of tiny particles on the order of 10 microns in size.
These particles as they are currently, do not pose an inhalation hazard. If they were to un-clump they could then pose an inhalation hazard as some of the individual particles are small enough to be inhaled. In the current clumped size they pose more of an ingestion hazard if someone were to get them in their mouths.
This one sample from Namie, about 20km from the damaged reactors may not be completely representative of the radioactive black substances being found in other locations in eastern Japan. It does show the need to fully test more samples to determine if they are the same or differ from the one found in Namie.
In recent weeks pieces of highly radioactive debris were found in Nahara in an area the government reopened to residents to move back. The pieces included a piece of a branch and a small piece of what looks like flat metal. NaharaDebris_handouts_130708_07-j The items are suspected to have been from the explosions at Fukushima Daiichi. TEPCO would not confirm or deny this.
These findings raise many questions about how widespread in Japan these potential fuel particles may be and how much radioactive reactor debris may still be distributed around the evacuation zone.
The entire paper by Marco Kaltofan on the Namie sample can be found here.