Latest probe of reactor 2 fails after Fukushima robot blocked by obstacles

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A robot shown in this photo by the International Research Institute for Nuclear Decommissioning was put inside reactor 2 at the Fukushima No. 1 nuclear plant on Thursday

Robot stops working in Fukushima reactor

The operator of the crippled Fukushima Daiichi nuclear power plant says it suspended a survey by a robot at one of its reactors after the device stopped working.
Tokyo Electric Power Company, or TEPCO, sent the scorpion-shaped robot into the containment vessel of the plant’s No. 2 reactor on Thursday.
The company believes fuel in the reactor melted through its core during the 2011 accident and accumulated at the bottom of the facility’s containment vessel.
The survey was aimed at getting a close look at what could be fuel debris — a mixture of nuclear fuel and melted parts of the reactor.
The robot was also expected to measure radiation and temperatures there to gather data for scrapping the reactor.
TEPCO officials say the device was advancing on a metal rail leading to a central area below the reactor’s core, but stopped moving before it could reach the center.
The officials say they decided to give up the robot and cut its remote-control cable.
TEPCO plans to analyze data collected by the robot and figure out how to carry out future probes.

https://www3.nhk.or.jp/nhkworld/en/news/20170216_34/

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Robot survey of crippled Fukushima reactor ends in failure

The operator of the crisis-hit Fukushima Daiichi nuclear power plant said Thursday its attempt to take a close look at the crippled No. 2 reactor using a scorpion-shaped robot ended in failure due to a technical flaw.

A track glitch meant the self-propelled robot was unable to climb over obstacles, Tokyo Electric Power Company Holdings Inc. said. It gave up on retrieving the robot by cutting its remote control cables.

TEPCO, however, said, “We have received new important information about the radiation level and temperature inside the (reactor) containment vessel,” emphasizing it did not view Thursday’s survey as a failure.

http://english.kyodonews.jp/news/2017/02/459048.html

Latest probe of reactor 2 fails after Fukushima robot blocked by obstacles

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.

In previous surveys, the utility found deposits on the grating believed to be nuclear debris and a 1-sq.-meter hole believed to have been created by molten fuel escaping from the pressure vessel.

Challenges dogged the latest attempt from the start. There was little clear surface for the robot to move around, and the radiation could kill the unit as with the preliminary surveys.

Next month, Tepco plans to survey the No. 1 reactor.

http://www.japantimes.co.jp/news/2017/02/16/national/latest-probe-reactor-2-fails-fukushima-robot-blocked-obstacles/#.WKWoEPLraM9

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