A renewed attempt to survey reactor 2 at the damaged Fukushima No. 1 nuclear power plant failed Thursday when the latest robot probe became obstructed.
The robot was inserted into the primary containment vessel at around 7:50 a.m. to approach the metal grating directly underneath the pressure vessel, where a black mass has been found.
Tokyo Electric Power Company Holdings Inc. had hoped to take a closer look at what could be melted nuclear fuel, but it was forced to abandon the operation shortly after 3 p.m.
The robot didn’t reach its objective, Tepco said, and the utility eventually severed its controller cable.
Having detected an extraordinarily high radiation level —estimated at 650 sieverts per hour — in a preparatory survey, Tepco had hoped to obtain more precise readings, images and data needed to remove fuel and other debris to decommission the plant.