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Tepco probe to directly touch melted fuel debris at Fukushima plant

The Japan Times

The operator of the crippled Fukushima No. 1 nuclear plant is planning to survey melted fuel debris at the No. 2 reactor by the end of March -- using a special device -- in an operation it hopes will help it determine the best method for its removal, sources said Wednesday. It will be the first survey by Tokyo Electric Power Company Holdings Inc. involving direct contact with the debris at the Nos. 1 to 3 units, which suffered core meltdowns triggered by the March 2011 earthquake and tsunami. Tepco is considering extracting debris -- the most difficult part of the decommissioning process -- first from the No. 2 unit. Gravel-like fuel material was confirmed at the bottom of its containment vessel in a January survey using a telescopic arm. The utility aims to collect information in the survey to help determine how to extract the debris and develop a container in which to keep it.

TEPCO completes physical examination by probe of melted reactor fuel

The Japan Times

The operator of the disaster-hit Fukushima No. 1 nuclear power plant said Wednesday it has completed its first attempt to use a remote-controlled probe to manipulate melted fuel accumulating at the bottom of one of the crippled reactors. During the nearly eight-hour operation, Tokyo Electric Power Company Holdings Inc. inserted the probe that is equipped with a camera, radiation meter and tong-like grips into the primary containment vessel of the No. 2 reactor. Of the six locations that were surveyed, the probe, which is 30 centimeters tall and 10 cm wide, successfully lifted several centimeters of deposits at five locations, a TEPCO official said at a news conference. But in the remaining area that resembled clay, the probe could not pick up any of the deposited material, indicating it was relatively solid. The findings from the operation will provide important information to help in the decommissioning of the Nos. 1 to 3 reactors at the plant that suffered core meltdowns in the nuclear crisis that began in March 2011, according to Tepco.

Tepco to send robot into Fukushima reactor 1 in bid to find melted fuel, collect samples

The Japan Times

The operator of the disaster-struck Fukushima No. 1 nuclear power plant said Thursday it will attempt to examine the inside of reactor 1 next Tuesday using a remote-controlled robot. The move follows a botched attempt by another self-propelled robot to take a look inside reactor 2, which had also sustained a meltdown after the March 11, 2011, Great East Japan Earthquake and tsunami. That robot became unable to move when it encountered debris and eventually could not be retrieved. These are the first attempts by Tokyo Electric Power Co. Holdings Inc. to examine the insides of the wrecked reactors since the nuclear disaster started. For the reactor 1 inspection, Tepco said the new robot will carry out a four-day probe inside the containment vessel.

Group mulls Fukushima No. 1 melted fuel debris extraction without filling containment vessels with water

The Japan Times

A state-backed entity is expected to soon compile a plan for decommissioning the crisis-hit Fukushima nuclear power plant, unveiling how to extract fuel debris from three reactors for the first time, sources said Tuesday. The Nuclear Damage Compensation and Decommissioning Facilitation Corp., tasked with providing technical support for decommissioning the complex, may propose a method to remove nuclear debris without fully filling their reactor containment structures with water, the sources said. It means the debris inside reactors 1, 2 and 3 at the crippled Fukushima No. 1 complex is likely to be shaved off gradually with a drill or laser equipment, while pouring a water shower under a remotely controlled operation, the sources said. A method to fulfill reactor containers with water first is effective in blocking radiation from spreading but the entity decided not to adopt the approach as the three reactor containers are believed to have been damaged and water would probably leak out. Under the method the entity currently envisions, some debris would remain in the air during the operation so a major challenge facing the debris extraction work is how to shield from radiation and prevent debris from flying off.

In big step forward, Tepco finds melted fuel at bottom of reactor 3 in Fukushima

The Japan Times

More than six years after the core meltdowns triggered by March 2011 mega-quake and tsunami, Tokyo Electric said Saturday that the robot probing reactor 3 at the defunct Fukushima No. 1 power plant had likely spotted fuel debris for the first time at the bottom of its primary containment vessel. Some of the debris looks like rocks and sand, and was accompanied by scaffolding and other objects from the reactor that had formed a pile about a meter high. On Friday, Tokyo Electric Power Company Holdings Inc. announced that the same robot had found what appeared to be melted fuel at the bottom of the pressure vessel, which holds the core. On Saturday, images released by the utility showed black, lava-like objects discovered by the so-called mini sunfish robot. "It's natural to assume that the debris melted and dropped," said a Tepco official who briefed reporters.