Lava-like rocks believed to be melted nuclear fuel have been spotted inside Japan's stricken Fukushima reactor by an underwater robot, the plant's operator said at the end of a three-day inspection. TEPCO representatives added that fuel rod assemblies found in that vessel had "melted into a puddle" after the 2011 tsunami, before burning through the bottom. Part of the damaged reactors are still highly contaminated with radiation, and robots play a crucial role in cleaning them up.
Cameras mounted on the robot showed extensive damage caused by the core meltdown, with fuel debris mixed with broken reactor parts, suggesting the hard challenges ahead in the decades-long decommissioning of the destroyed plant. Kimoto noted it would take time to confirm whether this debris contains melted fuel.
TEPCO said this week it is working on a plan to remove the melted fuel from the facility's reactors. "The recent investigation results are significant early signs of progress on the long road ahead".
If true, the discovery could mark a watershed moment for the complex and costly cleanup of the Fukushima plant - an effort that could cost more than $70 billion and up to 40 years to complete, the Japan Times reported.
Dismantling reactor No. 3 has been complicated by the extreme levels of radioactivity inside it.
"There is a high possibility that the solidified objects are mixtures of melted metal and fuel that fell from the vessel", a TEPCO spokesman said, adding that the company was planning further analysis of the images. The company hopes to begin the removal process in 2021.
The plant was destroyed by a massive quake and tsunami in March 2011.
Similar to the latest findings in the No. 3 reactor, Tepco took photographs in January of what appeared to be black residue covering a grate under the Fukushima Dai-Ichi No. 2 reactor, which was speculated to have been melted fuel.