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. A special device will be attached to a pipe with a camera to check whether the fuel material can be moved. Samples may also be collected for analysis, the sources said.
In the road map compiled by Tepco and the government for scrapping the damaged reactors, the two are to decide on the method for debris extraction and from which unit they will start removing debris. In an underwater robot probe conducted last July at the No. 3 unit, Tepco found what was believed to be debris, but extracting that will be much harder than in the No. 2 unit because the company will need to lower the water level inside the containment vessel.
The location of the material in the No. 1 unit remains unknown.