The chairman of the United States Nuclear Regulatory Commission gave a far bleaker appraisal on Wednesday of the threat posed by Japan’s nuclear crisis than the Japanese government had offered. He said American officials believed that the damage to at least one crippled reactor was much more serious than Tokyo had acknowledged, and he advised Americans to stay much farther away from the plant than the perimeter established by Japanese authorities.
The announcement opened a new and ominous chapter in the five-day-long effort by Japanese engineers to bring the six side-by-side reactors under control after their cooling systems were knocked out by an earthquake and a tsunami last Friday. It also suggested a serious split between Washington and its closest Asian ally at an especially delicate moment.
The Congressional testimony by Gregory Jaczko, the chairman of the commission, was the first time the Obama administration had given its own assessment of the condition of the plant, apparently mixing information it had received from Japan with data it had collected independently.
Authorities scrambled Sunday to control an overheating reactor at the problem-prone Fukushima No. 1 nuclear power plant by injecting seawater and venting gas to reduce the pressure inside.
While acknowledging that the core of the plant’s No. 3 reactor may have overheated and deformed, Chief Cabinet Secretary Yukio Edano denied it led to a meltdown of the critical fuel rods.
At a news conference, Edano said that "a very small amount" of radioactive substances had leaked from the No. 3 reactor, dismissing concerns it posed a threat to human health.
The government’s top spokesman warned, however, that a hydrogen explosion similar to the one that blew up a building housing a separate reactor at the facility Saturday could occur again at this reactor.
Large amounts of hydrogen formed when the water injection procedure temporarily ran into trouble and may have filled the upper part of the building housing the No. 3 reactor, Edano said.
A meltdown may have occurred at at least one nuclear power reactor in Japan, the country’s chief cabinet secretary, Yukio Edano, said Sunday, adding that authorities are concerned about the possibility of another meltdown at a second reactor.
"We do believe that there is a possibility that meltdown has occurred. It is inside the reactor. We can’t see. However, we are assuming that a meltdown has occurred," he said about the No. 1 reactor at the Fukushima Daiichi nuclear facility.
"And with reactor No. 3, we are also assuming that the possibility of a meltdown as we carry out measures," Edano said.
Edano’s comments confirm an earlier report from an official with Japan’s Nuclear and Industrial Safety Agency, who said, "we see the possibility of a meltdown."
"There is a possibility, we see the possibility of a meltdown," said Toshihiro Bannai, director of the apan’s Nuclear and Industrial Safety Agency international affairs office, in a telephone interview from the agency’s headquarters in Tokyo. "At this point, we have still not confirmed that there is an actual meltdown, but there is a possibility."