Endoscope looks inside marred nuclear reactor

Workers inserted a remote-controlled endoscope inside a damaged Japanese nuclear reactor Jan. 19, hoping the first look inside since the tsunami disaster helps them better assess conditions and make repairs.

The operator, Tokyo Electric Power Co., said the probe _ an industrial version of the kind of endoscope doctors use -- was inserted through a hole in the beaker-shaped containment vessel at the Fukushima Dai-ichi plant's No. 2 reactor to take photos and collect measurements.

That will help workers know how best to plug holes and cracks in the containment vessel -- a protective chamber outside the core -- to contain radiation leaks and gradually work toward dismantling the reactors.

Three of six reactors at the Fukushima plant melted down after the March 11 earthquake and tsunami knocked out the plant's cooling systems and set off the world's worst nuclear accident since Chernobyl.

TEPCO and nuclear officials have said that melted fuel probably fell to the bottom of the core in each unit, most likely breaching the bottom of the core and falling into the primary containment vessel, some dropping to its concrete floor.

Experts have said those are simulation results and that exact location and condition of the fuel could not be known until they have a first-hand observation inside.

Getting temperatures from inside the core could also confirm whether the unit has really reached a ``cold shutdown state,'' the stable condition that the government had declared in December despite skepticism from experts.

The government has said that it would take 40 years until the Fukushima plant is fully decommissioned.

The initial outcome from the probe was not immediately available, TEPCO spokesman Chie Hosoda said. She said that officials are still trying to analyze the data collected from the 70-minute operation.

TEPCO also plans to use the endoscope to look inside the two other reactors that had meltdowns.