Tokyo Electric Power Co (TEPCO) said Monday that the water temperature in the No. 2 reactor at the stricken Fukushima Daiichi nuclear power plant has risen from 45 degrees on Jan 27 to 69.2 degrees on Monday.
One of three thermometers in the reactor has shown that the temperature has risen by 20 degrees in the last four days, NTV reported. TEPCO said it is continuing to pump more water into the troubled reactor to cool it down, but so far, the utility has not been able to pinpoint the exact cause of the rising temperature.
A TEPCO official told a news conference that the replacement of a water pipe might have caused a change in the water circulation and that the temperature might be rising in areas where the water flow isn’t smooth, NTV reported. Melted fuel may also have spilled over from the containment vessel into the water, the TEPCO official said.
TEPCO said it was injecting 9.5 tons of water into the reactor, compared to the usual one ton per hour.
The latest development calls into question Prime Minister Yoshihiko Noda’s announcement last December that the Fukushima Daiichi plant had achieved a stable state of cold shutdown—which was intended to reassure the nation that significant progress had been made in the nine months since the March 11 tsunami sent three reactors into meltdowns.