As cleanup efforts threaten to span decades, radiation levels inside a Fukushima Daiichi reactor are at their highest since the 2011 disaster. Inside reactor number two’s containment vessel, Tokyo Electric Power (Tepco) found levels of 530 sieverts per hour. As only one sievert can cause radiation sickness, some experts described the recent reading as unimaginable.

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The previous record in the same part of the Fukushima reactor was just 73 sieverts per hour, which doesn’t sound like much compared with 530 but is still higher than a fatal level. Five sieverts would be enough to kill half of the people exposed in a month, and 10 sieverts would be fatal after just weeks. The high radiation levels recently recorded serve as a reminder there’s still a long way to go with cleanup at the damaged nuclear power station; some people say it could take as long as 40 years. Tepco says radiation is not leaking from the reactor.

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The presence of the high radiation complicates cleanup. Tepco plans to send a remote-controlled robot into the number two reactor’s containment vessel. But the robot is only designed to endure 1,000 sieverts of radiation and thus will likely break down in under two hours. The company still thinks the robot could be useful as it could move around in varying levels of radiation.

The company also said image analysis of the reactor revealed a three-foot-wide hole in a pressure vessel; melted nuclear fuel could have made the hole after the back-up cooling system failed in the tsunami’s wake. Late last year, in December, the government said they think it will cost 21.5 trillion yen, which is around $190 billion, to decommission the plant, clean up the area, store radioactive waste, and pay compensation. The hefty amount is almost double a 2013 estimate.

Via The Guardian

Images via Wikimedia Commons and IAEA Imagebank on Flickr