Tokyo Electric Power Co. said it found the highest radiation levels inside one of the crippled reactors at its Fukushima Dai-Ichi nuclear plant since the disaster in March last year.
Radiation levels inside the No. 2 reactor containment vessel were between 31.1 and 72.9 sieverts per hour, Naohiro Omura, a spokesman for the utility, said by phone. The high levels indicate the presence of radioactive substances from melted fuel inside the containment chamber, said Omura.
The findings came more than three months after Tepco and the government declared they succeeded in bringing the crippled reactors into a safe state known as cold shutdown. Tepco will need to conduct further studies to see whether the high radiation levels would affect its plan to decommission the reactors within 30 to 40 years, Omura said.
“We still believe melted fuel is being cooled” as the water temperature was between 48.5 and 50 degrees Celsius (119.3 and 122 degrees Fahrenheit) even as the water level inside the containment was lower than expected, Omura said. The water level was 60 centimeters from the bottom of the containment vessel, compared with as much as 4.5 meters estimated by the utility before the investigation, he said.
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