May 16 (Bloomberg) — Tokyo Electric Power Co. said fuel in other reactors at its damaged nuclear plant may have melted, after confirming rods in the No. 1 unit had fallen from their assembly, potentially delaying plans to resolve the crisis.
“The findings at the No. 1 reactor indicate the likelihood that the water level readings in the other reactors aren’t accurate,” Junichi Matsumoto, a general manager at the utility known as Tepco, said today. “It could be that a meltdown similar to that in the No. 1 reactor has occurred.”
Moody’s Japan K.K. cut Tepco’s credit ratings and put it on review for further possible downgrade after today’s news. Tepco has been struggling to cool reactors and stop radiation leaks to end the worst nuclear crisis since Chernobyl in 1986. The discovery that fuels rods melted within 16 hours of power being knocked out means it’s unlikely Tepco can meet its timetable for containing the leaks, a nuclear engineering professor said.
“Tepco didn’t clearly indicate how much uncertainty and potential negative scenarios were factored into the road map,” said Hironobu Unesaki at Kyoto University. “I don’t think they gathered enough data before coming up with the plan.”
Tepco fell 7.3 percent today to 420 yen in Tokyo. The shares are down about 80 percent since the March 11 quake and tsunami struck, leaving more than 24,000 people dead or missing.
Moody’s cut senior secured rating by one step to Baa2 from Baa1 and long-term issuer rating to Baa3 from Baa1, saying that damage at the plant appears worse than previously indicated. The agency cut its short-term rating for commercial paper to Not Prime from Prime-2. It was the third downgrade since the disaster.
Standard & Poor’s cut Tepco’s credit rating for a third time on May 13, to BBB from BBB+. Tepco has 6.99 trillion yen ($86.5 billion) of debt, making it the nation’s second-largest corporate borrower among members of the Nikkei 225 Stock Average, behind Mitsubishi UFJ Financial Group Inc., Bloomberg data show.
The operator of the Fukushima Dai-Ichi plant said earlier it believes 35 percent of the rods of reactor No. 2 melted after cooling systems failed and 30 percent of those in the No. 3 unit. An announcement on the status of the two reactors will be made later, Matsumoto said, without giving a time frame.
The fuel in the No. 1 reactor started melting about 4 1/2 hours after the magnitude-9 earthquake hit on March 11 when the water level in the reactor core vessel fell below the base of the assembly, Tepco said yesterday.
The temperatures in the core rose to about 2,800 degrees Celsius (5,072 degrees Fahrenheit), the melting point of fuel rods, after emergency cooling was knocked out by the tsunami that hit the plant about 45 minutes after the quake, the company said.
By 6:50 a.m. on March 12, “most of the core” had melted and fallen to the base of the vessel, Tepco said.
Engineers established the extent of the damage after fixing gauges in the reactor No. 1 building last week. The building was damaged by a hydrogen explosion on March 12. Tepco said water from the reactor has leaked out through the outer chamber and has filled the building’s basement to a depth of 4.2 meters (14 feet).
The melted fuel has cooled because enough water has accumulated in the bottom of the inner vessel after being pumped in, Tepco said. A “large-scale release of radioactive materials is unlikely,” the statement said.
Fukushima’s No. 1 reactor may have been damaged in the earthquake before the tsunami hit, Kyodo News reported yesterday. Japan’s nuclear safety commission has said the damage that caused the meltdown was done by the tsunami, according to Kyodo.
“We currently haven’t been able to confirm this,” Matsumoto said today when asked about the report. “In a few days, when the data is in, we’ll know more.”
The company tomorrow plans to provide an update on its progress and revisions to the plan for bringing the damaged reactors and spent fuel pools at Fukushima into a stable state.
Japanese Prime Minister Naoto Kan said there’s no need to change Tepco’s timetable.
“In terms of achieving cold-shutdown status within six to nine months, I believe we should be able to proceed without changing the timeframe,” Kan said today in parliament. The government will also provide a schedule for ending the crisis, Kan said.
Tepco on April 17 set out a so-called road map to end the crisis in six to nine months. The utility said it expects to achieve a sustained drop in radiation levels at the plant within three months, followed by a cold shutdown, where core reactor temperatures fall below 100 degrees Celsius.
The company expects to meet its timetable, President Masataka Shimizu said in parliament today. He said the risks of more hydrogen explosions and leaks of contaminated water remain at the plant. Shimizu was responding to a question on what risks are incorporated in the road map.
The utility has made initial payments of 1 million yen to 10,000 households, Shimizu told lawmakers. The company has received claims from 50,000 households forced to evacuate areas around the nuclear plant that is about 220 kilometers (137 miles) north of Tokyo.
“We plan to begin provisional compensation payments for those who run agricultural, forestry and fishery businesses by the end of May,” Shimizu said. “We’d like to start discussions with related organizations immediately.”
By Michio Nakayama and Yuji Okada – May 16, 2011 2:18 PM GMT+0200