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.
The International Research Institute for Nuclear Decommissioning (IRID) carried out the experiments using a 20-meter wide, 12-meter high model of the No. 2 reactor's suppression chamber and torus room -- areas located below the reactor's containment vessel. IRID was established in 2013 by nuclear plant makers, power firms and government organizations to develop technology needed for the decommissioning of the Fukushima plant, which was damaged by the March 3, 2011 earthquake and tsunami. After the disaster, three of the plant's reactors suffered meltdowns in the world's most severe nuclear crisis since the 1986 Chernobyl disaster. The model is located at the Naraha Remote Technology Development Center, near the crippled Fukushima No. 1 plant. "We would like to continue testing until next summer, approximately, and use (the outcomes) in deciding methods to retrieve fuel debris," Atsufumi Yoshizawa, IRID executive director, said.
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.
Tokyo Electric Power Co. Holdings Inc. has said that the water levels in the containment vessels for the No. 1 and No. 3 reactors at its disaster-crippled Fukushima No. 1 nuclear power plant have fallen by tens of centimeters. The water levels are continuing to drop by several centimeters each day, Tepco said Friday. The event has had no radiation impact outside of the plant's premises, the company said, noting that the injection of water into the reactors, as well as operations to cool melted nuclear fuel debris at the bottom of the containment vessels, are continuing. The plant was heavily damaged in the powerful March 2011 earthquake and tsunami. On Feb. 13, an earthquake measuring a strong 6 -- the second-highest level on the Japanese seismic intensity scale -- rocked the Tohoku region, which includes Fukushima Prefecture.