The situation in Fukushima is bad enough that a Major Japanese News Outfit, the Asahi Shimbun reports that excessive radiation is killing Robots seeking to inspect the Fukushima Reactor #1. In an article titled "Nuke watchdog critical as robot failures mount at Fukushima plant" THE ASAHI SHIMBUN March 24, 2017, they report:
"These regulators are increasingly calling for a new survey methodology after recent investigations utilizing robots controlled remotely generated few findings and were quickly terminated." [http://www.asahi.com/ajw/articles/AJ201703240064.html]
The problem is not with the Robots, but with the regulators. They don't like what they are finding.
"The lower part of the reactor’s containment vessel is submerged in water where deposits of fuel debris are believed to reside below the surface after melting through in the 2011 nuclear disaster, triggered by the Great East Japan Earthquake and tsunami."
They essentially admit that all that is left is debris, that any corium left long melted through the containment and are located in water beneath it.
"At one location, the robot succeeded in placing a camera, which is combined with a dosimeter, to a depth 0.3 meter from the containment vessel floor."
But they are unable to proceed far.
"The probe measured underwater radiation levels from 3.0 to 11 sieverts per hour during the five-day survey. But it was unable to take images of the debris in the water.
A Gift that Keeps Giving
Apparently the Robots cannot get past the debris or withstand the radiation, and are dying before they are able to see any corium. Apparently these ruins are stil incredibly dangerous, still leaking large amounts of radiation, and still are a hazard to people around the world, but especially around the Pacific basin.
Read more at Asahi Shimbun: http://www.asahi.com/ajw/articles/AJ201703240064.html