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Nuclear fuel debris hangs like icicles in Fukushima reactor No 3

Fukushima robot finds potential fuel debris hanging like icicles in reactor 3 http://www.japantimes.co.jp/news/2017/07/21/national/fukushima-robot-finds-potential-fuel-debris-hanging-like-icicles-reactor-3/#.WXJyHRWGPGg, BY KAZUAKI NAGATA, STAFF WRITER, JUL 21, 2017 Tokyo Electric said Friday that a remotely controlled robot investigating the interior of reactor 3 at the Fukushima No. 1 power plant has finally spotted objects that could potentially be fuel debris.

The objects look like icicles hanging around a control rod drive attached to the bottom of the pressure vessel, which holds the core, Tokyo Electric Power Company Holdings Inc. said at an evening news conference.

 Enclosed by the huge primary containment vessel, the pressure vessel originally contained the fuel rod assemblies. But the rods melted into a puddle and pierced the bottom of the pressure vessel once the plant lost power after being swamped by the monstrous tsunami of March 11, 2011.

The robot also captured images of lumps of material that appear to have melted and resolidified near the wall of the pedestal, a concrete structure that supports the pressure vessel.

“From the pictures taken today, it is obvious that some melted objects came out of the reactor. This means something of high temperature melted some structural objects and came out. So it is natural to think that melted fuel rods are mixed with them,” said Takahiro Kimoto, a Tepco spokesman.

“In that sense, it is possible that the melted objects found this time are melted fuel debris or probably around it,” he said, saying the utility will think about how they can be analyzed to determine if they are the former fuel rods.

This is the first time Tepco has found something likely to be melted fuel. When the utility sent a different robot into reactor 2 in January, it found black lumps sticking to the grating in the primary containment vessel but said they were difficult to identify.

The utility began probing reactor 3 on Wednesday. Since the PCV has 6 meters of water in it, which is higher than in reactors 1 and 2, the 30-cm robot will have to go deep under water.

The robot has two cameras — one on the front that can pivot 180 degrees vertically, and another on its back.

Tepco will continue the probe on Saturday.

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July 22, 2017 - Posted by | Fukushima continuing

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