New images from inside Fukushima reactor spark safety worry
TOKYO (AP) – Images captured by a robotic probe inside one of three melted down reactors at Japan’s devastated Fukushima power plant showed exposed steel bars in the main support structure and parts of its thick outer concrete wall missing. , causing concerns about its earthquake resistance. in the event of another major disaster.
The plant’s operator, Tokyo Electric Power Company Holdings, has been sending robotic probes inside Unit 1’s main control room since last year. The new findings released on Tuesday were from the latest investigation conducted at the end of March.
A remotely operated underwater vehicle called ROV-A2 was sent inside Unit 1’s pedestal, a support structure just below the core. He returned with images seen for the first time since an earthquake and tsunami crippled the plant 12 years ago. The area inside the pedestal is where traces of melted fuel are most likely to be found.
A roughly five-minute video — part of 39 hours of images captured by the robot — showed that the 120-centimeter (3.9-foot) outer concrete portion of the pedestal was significantly damaged near its bottom, exposing the steel reinforcement inside. .
TEPCO spokesman Keisuke Matsuo told reporters on Tuesday that the steel reinforcement is largely intact, but the company plans to further analyze data and images over the next two months to find out if and how the reactor’s earthquake resistance can be improved.
Images of exposed steel reinforcement have raised concerns about reactor safety.
About 880 tons of highly radioactive molten nuclear fuel remain inside the three reactors. Robotic probes have provided some information, but the status of the molten debris is still unknown. The amount is about 10 times greater than the damaged fuel that was removed during the cleanup of the Three Mile Island nuclear plant in the United States after the partial meltdown in 1979.
Fukushima Governor Masao Uchibori asked TEPCO to “quickly assess earthquake resistance levels and provide information in a way that the people of the prefecture can understand and ease the concerns of residents and people nationwide.”
Video taken by the robot also showed sliding equipment as well as other types of debris, possibly nuclear fuel that fell from the core and solidified, piling up to 40-50 centimeters (1.3-1.6 feet) from the bottom of the the main control room, Matsuo said. The pile is lower than mounds seen in images taken on earlier internal probes at two other reactors, suggesting the meltdown in each reactor may have progressed differently, company officials said.
Matsuo said the data gathered from the latest investigation will help experts find methods to remove debris and analyze the 2011 meltdown. TEPCO also plans to use the data to create a three-dimensional map of the details of the melted fuel and waste, which will last about a year.
Based on data collected from previous probes and simulations, experts have said that most of the molten fuel inside Unit 1 fell to the bottom of the main containment chamber, but some may have also fallen to the concrete foundation – a situation that makes it already scary The task of dismantling is extremely difficult.
Trial removal of molten debris is expected to begin at Unit 2 later this year after a nearly two-year delay. Removal of spent fuel from the Unit 1 reactor cooling pool will begin in 2027 after a 10-year delay. After all the spent fuel is removed from the pools, the focus is to return in 2031 to extracting molten waste from the reactors.
