Post-quake explosion at Japanese nuke plant

TOKYO, March 12 (UPI) -- Thousands of Japanese were told to evacuate Saturday after an explosion at an earthquake-damaged nuclear power plant, officials said.

Iodine was distributed to people in the affected area to counter any radiation exposure.

Yukio Edano, the government's top press officer, said an explosion at the Fukushima No. 1 plant occurred in the building housing the reactor's container but did not damage the container itself, Kyodo News reported. No increase in radiation levels around the reactor was detected immediately after the blast.

The explosion was caused by a mixture of hydrogen gas with oxygen, and was not nuclear in nature, The New York Times reported.

At an evening news conference, Edano said radioactive gas was being vented from the No. 1 and No. 3 reactors, though he said there was no danger to human health and radiation levels appeared to be decreasing.

"As of 8:33 p.m. we see that the figure is going down and we are continuing to see a decrease in the readings, therefore we believe that it is not a harmful level to human health," Edano said, NHK reported.

"Venting is continuing. Reactor No. 1 of course we are continuing to inject seawater, but the venting activity from reactor No. 1 is continuing, and the air coming out does include some radioactive substances. And also we are doing the same operation with reactor No. 3."

Tokyo Electric Power Co. flooded the reactor with seawater to cool it down in an emergency action that could damage the facility beyond repair, Nikkei reported.

The company operates other power plants in the heavily populated area. Those living within 7 miles of the plant had already been ordered to evacuate, and that radius was doubled after the explosion as a precaution, Edano said.

Four employees in the building were injured.

Officials said the reactors shut down automatically after the quake.

RIA Novosti reported iodine would be handed out to help shield residents from radiation exposure. The United States and France are sending supplies of the chemical.

Prime Minister Naoto Kan declared a state of emergency in the area, the BBC said.

Friday's earthquake also triggered a tsunami that reached as far as California.

Japanese officials say more than 600 people were killed, but that number was expected to reach 1,800 as rescuers searched for hundreds of missing people.