Japan Press Weekly

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2015 February 18 - 24 [SOCIAL ISSUES]

Corroded chimney at Fukushima NPP cannot be assessed due to extreme radiation

Akahata has learned that one of the exhaust stacks at the crisis-ridden Fukushima Daiichi Nuclear Power Plant may be in danger of collapse due to advancing corrosion of steel. If the chimney should collapse, radioactive substances would be dispersed.

Radiation levels are extremely high around this exhaust stack which has been kept off-limits to repair personnel since the nuclear accident in March 2011. Thus, necessary emergency countermeasures cannot be taken.

The 120-meter-tall funnel has radiation levels of up to 25,000mSv/h. If exposed, a human would die within ten minutes.

The life expectancy for the structural steel of the stack in question is four years without good film-coating effect. The four year is coming next month.

Before the March/2011 Fukushima crisis, TEPCO periodically conducted checks and recoated the structure so as to prevent steel corrosion. No one has been able to approach that area since the crisis.

The utility claims that the possibility of collapse is small, but experts warn that the stack is in a highly risky condition.

Professor emeritus of the University of Tokyo Ino Hiromitsu, a specialist on metallic materials science, pointed out that the stack is made of carbon steel which is corrosion prone. He said that it is necessary to actually check how thin the stack is now with its state of corrosion, but that it will be difficult because of high levels of radiation there. The professor told Akahata that corrosion will further advance if left untended.