- TEPCO’s do or die mission to save nuclear reactor may have caused largest radiation leaks during Fukushima disaster
The article explains that during the meltdown of Reactor #2:
"attempts to prevent explosions at the Unit 2 reactor may have in fact caused a substantially large radiation leak. They proved that hypothesis by pairing data of the recorded radiation levels which rose sharply 3 times at Fukushima Daini monitoring posts over a period of 5 hours during the night of March 14th."
Anyone who cares to remember will remember they were dumping sea water on the reactors (3 melted down and one fuel pond seems to have melted too) during the disaster. This was advertised as being done to prevent meltdown, but in fact were intended to prevent explosions, but the reactors had already melted. The report notes that:
by that time, the amount of nuclear fuel which had already melted down in the core was already leaking into the containment vessel, filling it with radioactive materials, prior to the start of seawater injection operations.
So the seawater, instead of cooling reactor rods to prevent meltdown, was actually hitting extremely hot, and in some case burning materials:
"The researchers report shows that workers were unable to get coolant water into the Unit 2 reactor"
... and that this was because the core was so hot and so in meltdown that water coming in contact with the core turned to steam. They had to vent the steam to keep the containment vessel from exploding. Even with that each injection "the pressure in the containment rose as well until it reached over two times the designed limits", which "combined with the extreme heat would threaten to crack or damage the concrete containment vessel." And the researchers theorize that "radioactive materials escaped from cracks in the concrete containment vessel, and were carried south towards the Fukushima Daini nuclear power plant." The report notes that:
"TEPCO would later hypothesize due to elevated temperatures, among other factors, that a breach roughly 10 cm wide was created in the reactor’s containment vessel 21 hours after the quake. Tepco also said it believes that parts used to ensure air tightness may have broken from overheating."
Under these conditions the cladding for the fuel rods, which is made of Zirconium alloy would have catalyzed hydrogen gas production and explosions. Also Zirconium is not particularly flammable when it is intact but as it degrades it becomes very flammable and burns like a sparkler.
For these reasons there is every reason to suspect that a good portion of the content of these reactors burned away or corroded away during the meltdown event, and that this event, if it is over, is over because the fuel is mostly gone into the atmosphere, down stream, and out to sea, by sea or in the air.
There is abundant evidence, mostly hidden in articles or the web, that the Fukushima meltdown is even much larger than TEPCO admits.