Fukushima Plant's Nos. 2, 3 Reactors Also Suffered Meltdown: TEPCO

JapanToday.com - May 24, 2011

TOKYO —

The operator of the troubled Fukushima Daiichi nuclear power complex said Tuesday that meltdowns are assumed to have occurred in the cores of the Nos. 2 and 3 reactors in addition to the meltdown already confirmed at the No. 1 reactor, but stressed that it believes the melted fuel is being kept cool at the bottom of the pressure vessels.

Tokyo Electric Power Co also maintained its view that it was only after the giant tsunami hit after the devastating March 11 earthquake that the plant lost all its power sources, eventually leading to the loss of the reactors’ key cooling functions.

The announcement came as the utility is proceeding with work to assess data taken shortly after the nuclear accident occurred. Industry minister Banri Kaieda said the government agreed at a cabinet meeting Tuesday to set up a third-party panel to look into the causes of the country’s worst ever nuclear crisis.

The government has tapped Yotaro Hatamura, a 70-year-old professor emeritus at the University of Tokyo, as head of the special panel, Deputy Chief Cabinet Secretary Yoshito Sengoku said in a press conference.

Yotaro Hatamura, a veteran researcher on human errors, will head the panel which has power to access accident-related documents and question people concerned including officials of the plant operator, Cabinet members and bureaucrats, Deputy Chief Cabinet Secretary Yoshito Sengoku told a news conference.

Hatamura, 70, an emeritus professor at the University of Tokyo, and the other members, mostly academics, plan to compile a mid-term report on the matters in December and a final report will be due by summer 2012, government officials said.

The panel is also designed to make recommendations to ease the impact of the nuclear accident on residents who were forced to evacuate from their homes near the plant following the nuclear emergency.

In its assessment, Tokyo Electric estimated that the pressure vessels of the Nos. 2 and 3 reactors containing the fuel rods may have been damaged if it turns out that the levels of the water inside the vessels are lower than data now shown by measuring gauges.

If the water levels are lower, then it can be assumed a large part of the fuel in the No. 2 reactor dropped to the bottom of the vessel about 101 hours after the reactor automatically shut down following the quake, while the same must have happened at the No. 3 reactor in about 60 hours, TEPCO said.

TEPCO said that the current temperatures around the pressure vessels suggest that the melted fuel has settled at the bottom of the vessels and is being kept stably cool with water injected into the reactor cores from outside as an emergency measure.

TEPCO said in mid-May that it believes that the No. 1 reactor suffered a meltdown about 16 hours after the 2:46 p.m. quake, based on data taken after workers earlier in the month adjusted water gauges to accurately measure the water level inside the pressure vessel.

The gauges had indicted before the adjustment that the No. 1 reactor fuel was half covered by water, but revealed afterward that the fuel had been fully exposed.

As for the Nos. 2 and 3 reactors, the accurate water levels are still unknown as adjustment work for the gauges has not yet finished.

The company submitted a report on its assessment about the reactors to the government’s Nuclear and Industrial Safety Agency on Tuesday.

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