A South Korean passenger at a Seoul rail station watches TV news showing… (Park Ji Hwan, AFP/Getty…)
Reporting from Tokyo and Beijing — — A day after responding to one of the worst earthquakes on record and a massive tsunami, the Japanese government sought to allay fears of a radioactive disaster at a nuclear power plant on the country's battered northeastern coast.
The outer walls of the Fukushima power plant's No. 1 reactor were blown off by a hydrogen explosion Saturday, leaving only a skeletal frame. Officials said four workers at the site received non-life-threatening injuries.
The inner container holding the reactor's fuel rods is not believed to be damaged, said Japan's Chief Cabinet Secretary Yukio Edano, and workers were cooling the facilities with seawater.
Photos: Scenes from the earthquake
In a press conference shortly after the explosion, which left the facility shrouded in plumes of gray smoke, Edano explained that the reactor is contained within a steel chamber, which in turn is surrounded by a concrete and steel building. Although the explosion destroyed the building, it did not occur in the chamber.
"The escape of hydrogen mixed with the air between the chamber and the concrete-and-steel building and led to the explosion," Edano said.
"Tokyo Electric Power Co. has confirmed that the inner reactor is undamaged," he added. "There was no massive release of radiation."
Videos of the earthquake
Still, the reactor was already showing signs of a partial meltdown after Friday's magnitude 8.9 earthquake had prevented the plant 150 miles north of Tokyo from fully powering its water cooling system. Without it, the facility could overheat and explode, spewing radiation into the air.
Edano said experts were still determining what caused the blast.
"We are doing everything to ensure the safety of residents living nearby," said Edano, the government's chief spokesman. "I'm sure residents [living nearby] are feeling unease."
People were reportedly fleeing the surrounding area and Japanese television was urging people to cover their faces with wet towels and not to expose any skin to the potentially contaminated air. An evacuation zone was doubled to a 12-mile radius around the plant by Saturday evening.
"By taking all these appropriate measures, we would like to avoid any situation where any people's health is damaged," said Japanese Prime Minister Naoto Kan at a press conference. "This is an unprecedented disaster we're suffering."
Earlier in the day, workers had been racing to prevent the No. 1 reactor from over-heating by releasing accumulated vapor.
Officials of Japan's Nuclear and Industrial Safety Agency had insisted that the "slightly radioactive" emissions release posed no risk to people or the environment. Radiation levels inside the overheated reactor housing were 1,000 times normal, the agency said, but only eight times normal background at the plant's main gate. Experts explained that the steam carries low-level radiation that rapidly dissipates.
Japan relies on nuclear power for a third of its electricity and is said to require exacting safety standards for its plants.
The radiation scare comes on a day most of Japan was still trying to dig-out from an earthquake that's believed to have killed 1,700 people so far with countless still missing under rubble and muddy debris.
Japanese self-defense forces reportedly found 400 bodies in the seaside town of Rikuzentakata in Iwate prefecture. Television showed a rising tide rolling into the community, first filling the gaps between buildings before finally swallowing the city past its rooftops.
The force of the magnitude of Friday's quake, which seismologists said released 1,000 times the energy of the January 2010 earthquake in Haiti, broke the foundations under homes and buildings and opened chasms in fields and pavement, swallowing cars and shearing off sidewalks and driveways.
More than 100 aftershocks have jolted Japan since Friday's 2:46 p.m. temblor, including at least a dozen of magnitude 6 or higher, said Dave Applegate, a senior advisor at the U.S. Geological Survey.
The earthquake, centered just off the northeastern coastal city of Sendai, was the most powerful since a December 2004 quake and ensuing tsunami killed 230,000 people in Indian Ocean nations.
The havoc unleashed on Japan just ahead of Friday rush hour has left the nation mired in fear, suffering and hardship. Millions of people are without power, utility officials said, and they warned that outages would continue through the weekend, with rolling blackouts persisting for weeks.
Four trains carrying passengers along the coast at the time of the quake remain unaccounted for, East Japan Railway Co. reported. Television footage showed two passenger train carriages half submerged under water by the coast.
Only half of the hundreds of people reported trapped in elevators were rescued overnight, according to the Ministry of Land, Infrastructure, Transport and Tourism.