A rough translation of the NHK article tells something almost unbelievable to see admitted by the state news agency.
“It is a result, in addition to the radioactive cesium, zirconium material of the fuel rods and uranium, and iron of the material of the pressure vessel, material that matches the structure of the nuclear reactor and nuclear fuel has been detected.”
NHK has been one of the less critical news sources in Japan, frequently downplaying or omitting what other news sources have told about the disaster. This has been blamed on the state ties and funding with NHK, something akin to a state media service but more so than what many in the west see in their national broadcasters.
NHK’s new admission comes from this study published by the American Chemical Society, conducted by the University of Tokyo.
The samples were taken March 14-15 of 2011 at the Meteorological Research Institute in Tsukuba using an air filter, 172km south west of the plant. The amount of micro particles pulled is estimated to have been about 10 micro particles per square meter. The micro-particles were found to have a number of isotopes and included uranium and what could be identified as metals from the reactors.
” These results strongly suggest that the FDNPP was damaged to emit U fuel and fission products outside the containment vessel as aerosol particles.”
The analysis goes on to confirm that these micro particles had about 1 becquerel each of cesium 134 and 137 at the time of release. They also found iron, zirconium, uranium and cesium 137 and 134 in the proper ratio to confirm it is from Fukushima Daiichi. The uranium (and zirconium) finding further confirms that this was more than released cesiums and includes reactor fuel components.
” Because of the lack of the access to the damaged reactors, we do not have direct evidences to identify the source of these elements. However, we conclude that U fuel,
FPs, and components of the reactors are very likely the sources of the elements identified within the three radioactive microparticles, although further investigation will be needed to confirm their sources. We assume that, because these elements could originate from different sources, they were melted together during the accident and eventually formed spherical microparticles.”
This matches with conclusions from a previous study by the same authors and also a series of studies done by Marco Kaltofan at Worcester Polytechnic Institute. These studies found that these tiny particles were fused bits of all of these elements and materials from inside the reactors at Fukushima Daiichi. We would add that the size of these particles make them small enough to potentially inhale.
These substances now analyzed properly were being reported all over north east Japan soon after the disaster. They were being found as what was described as highly radioactive black sand. They have been found in the exclusion zone, north of the exclusion zone including Minamisoma and as far south as Tokyo. Our ongoing reporting of this can be found here. There was also what is confirmed to be a fuel fragment from Fukushima Daiichi found in a vacuum bag in Nagoya, 460km south west of Fukushima Daiichi. Tsukuba is on the edge of the Tokyo metro area. These fuel particles then did make it at least to the outskirts of Tokyo, and probably further if the Nagoya particle was transported by air. As seen on this radiation map of Japan, the area of Tsukuba is marked as being fairly low in radiation yet fuel particles are found in that area.
The new study confirming Fukushima reactor fuel in the environment came out on the heels of TEPCO’s new admission about unit 3. They admitted unit 3 had a total melt through, where all the fuel melted and left the reactor vessel to end up in the containment structure. It was also admitted this took place about 5 hours earlier. This puts the melted fuel in the containment structure before the massive blast took place. There has been considerable evidence that part of unit 3′s massive explosion was an ex vessel steam explosion. This is where a massive steam buildup happens rapidly causing a powerful ejection from the containment structure. The dark mushroom cloud seen in unit 3′s explosion is considered to likely be that steam explosion that took place seconds after the initial blast. TEPCO has also admitted within the last year that unit 3′s containment cap at the top of the reactor structure failed and is a leak path from containment. There is a known phenomenon where the containment cap can lift up due to high heat and pressure during a meltdown. In our research we also found that the gasket materials used have a failure point lower than the temperatures seen in the meltdowns at Fukushima Daiichi. TEPCO’s admissions and independent research show the mechanism for these fuel particles to potentially be released. There is also speculation that some of the efforts to vent the reactors could have released such materials.
These particles being found around Japan could be the missing link between the official reports declaring the disaster to have a minimal impact and the large number of described and documented health problems people have had. The monitoring done on people to date also may miss such things as inhaled hot particles. Some of these materials found in the micro particles are alpha emitters, known to be more damaging than gamma emitters if taken internally. Plutonium is one such alpha emitter that can have devastating effects on the lungs. Plutonium can lodge in the lungs and stay there rather than being expelled from the body, giving the person an ongoing internal radiation exposure the rest of their life. It is not known how one of these micro particles of fuel might behave if inhaled.
These micro particles could also help explain some of the extremely high small hot spots that have been found around the evacuation zone and to a lesser extent further away from the disaster zone.