Fukushima: how it happened

The Worst Disaster That You’ll Never Hear Anything About, Criticl, 2 Aug 15 The Fukushima Daiichi nuclear disaster embodies one of the worst man-made calamities in human history that day-by-day receives a dearth of coverage. Three nuclear reactors melting down on March 11th, 2011 ushered in the beginning of one of the most effective and insidious works of misinformation and obfuscation of reality that has been seen in recent memory.

The impetus for the disaster arose from the 2011 Tohoku earthquake, which was estimated to be the most powerful earthquake to ever hit the island in recorded history. The magnitude of the 869 Jogan Sanriku quake (the previous record holder) is only an approximation due to the lack of seismograph technology, nonetheless the Tohoku earthquake was more powerful than the plant was designed to withstand.

Nuclear reactors are designed to shutdown at the slightest event, quickly reducing the amount of heat produced; yet any heat inside the reactor (comprised of the radioactive decay of short lived fission products) is still a magnanimous amount. Backup diesel generators were quickly ushered into action at Fukushima after outside power was destroyed by the quake in order to keep the reactors cool to prevent a meltdown.

However, standard operation procedures for the plant flew out the window when tsunami waves of 14-20 meters struck the Fukushima prefecture shortly after the earthquake, rendering the 5.7-meter seawall beyond useless and knocking out the generators. Interestingly enough, the nearby Onagawa plant was saved by a 14.8-meter seawall despite being struck by a more powerful wave. Yanosuki Hirai fought bureaucracy for years that clamored for the same 5.7-meter seawall at Onagawa, and got his higher wall, remarking, “Corporate ethics is different from compliance, just being ‘not guilty’ is not enough.” The wall was remarkably effective to the point that local residents sought shelter in the plant’s gymnasium after their homes were destroyed by the wave.

The resulting influx of water into the Fukushima reactor led to a station blackout, meaning the operators lost all monitors and the ability to remotely control the reactor. Isolation condensers can cool the reactor with no electricity as long as the condenser is filled with water. Regrettably, operators had no idea that the reactor was quickly running out of water and that the valves opening the condensers were not working, rendering the first line of defence against a potential meltdown useless.

Authorities decided next to depressurize the reactors and inject water from fire engines to flood the reactors, yet unseen diversions to steam condensers via small bypasses meant injected water was not sufficient to prevent an overheating of the core. Reactor 1 saw a hydrogen explosion resulting from molten fuel cladding three hours after the tsunami. Vents and piping intended to filter hydrogen were either severely damaged by the earthquake or unable to operate due to a lack of power.

Unit 2 and the Unit 3 Reactor Core had steam-powered turbines that would circulate cooling water, but suffered a hydrogen explosion due to the pressure in the reactor becoming too low for the turbines to operate. Operators were too inexperienced to properly inject water via the fire engines, which again resulted in a meltdown of both reactors. Leading the cleanup efforts several days later, Japanese authorities quickly created a temporary cover over Unit 1 and begin to filter out contaminated water and repair the other components of the reactors, while devising a plan to contain exposed radioactive material from the damaged reactors……………. Like what you see? https://thefirsttruth.wordpress.com/



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