By Editors of Power Engineering
A new inspection at the Fukushima Daiichi nuclear power plant found previously-undetected deadly radiation, and a leak of melted fuel is the likely cause.
Tokyo Electric Power Co. inspected the inside of the No. 2 reactor’s containment vessel using a camera on a pole, and discovered a hole the size of a square meter melted into a steel-grating walkway directly underneath the reactor pressure vessel, the Nikkei Asian Review reported.
“Noise” on the images indicates one area of the vessel was emitting radiation at 530 sieverts per hour, which is enough to kill a human under a minute. Previously, emissions at the reactor after it was crippled by the March 2011 tsunami only reached 73 SV/hour.
TEPCO previously believed most of the nuclear fuel had been contained, but the company now says it’s highly possible melted fuel leaked through. A press release from the company indicated further examination is necessary to verify the leak.
For example, black chunks found in pictures released by TEPCO could either be fuel debris or missing paint. The company also noted the control rod drive housing, position indication probe cable and CRD exchanger haven’t changed position from normal.
The imaging work was originally taken to ensure a clear path for a Scorpion robot to enter the vessel and take readings on temperature and radioactivity.