Radiation Danger Rises as Crisis at Crippled Japan Nuclear Plant Worsens

Japan’s Prime Minister said the danger of further radiation leaks from a crippled nuclear power station is rising after three explosions and a fire at the site 135 miles north of Tokyo.

Naoto Kan appealed for calm in a televised address, saying his government was doing its utmost to contain the radioactive leakage at Tokyo Electric Power Co.’s Fukushima Dai-Ichi plant following last week’s earthquake and tsunami. Blasts have occurred at three of the station’s six reactors since March 12 and a fire was discovered in a fourth unit’s building today.

Citizens living within a 30-kilometer (19 miles) radius of the plant should stay indoors, Kan said.

Chief Cabinet Secretary Yukio Edano said the vessel containing the radioactive core of the plant’s No. 2 reactor was damaged in a blast today and radiation levels could harm public health. Sea water is being pumped to cool the three reactors and the fire at a fourth unit wasn’t due to any internal problem at that reactor, Edano said.

Asia’s biggest utility said the containment chamber of the No 2 reactor may be damaged after the blast and radiation leakage is possible. The explosion occurred around 6:14 a.m. local time near a suppression chamber that controls pressure in the reactor core, and its cause is being investigated, Tokyo Electric said.

Radiation Level

As of 10.22 a.m. local time, 400 millisieverts of radiation were detected at the No. 2 and No. 3 reactors, Edano said. That’s 20 times the annual limit for nuclear industry employees and uranium miners, according to the World Nuclear Association. A radiation dose of 100 millisieverts a year is the lowest level at which any increase in cancer is evident, the London-based WNA said on its website.

The level of radiation at the plant rose above the legal limit after the latest explosion, Kyodo News reported. The utility will continue to pump water into the unit, a company spokesman said in a briefing broadcast on NHK television.

Today’s blast follows one at the No. 3 reactor yesterday after a buildup of hydrogen gas and a similar explosion at the No. 1 reactor on March 12.

As workers battled to head off the risk of a potential meltdown at the Fukushima plant, millions of people remained without electricity or water following the earthquake, which may have killed 10,000. Japan sought aid from the United Nations atomic agency, and the U.S. pledged any help needed.

The March 11 temblor -- updated yesterday to a magnitude of 9, from 8.9, by the U.S. Geological Survey -- and subsequent tsunami have led to what Kan called the country’s worst crisis since World War II. There have been 405 aftershocks since then. Stocks plunged and the Bank of Japan poured record funds into the economy.

More than 2,000 people are confirmed dead since the March 11 earthquake and tsunami hit the northeastern part of Japan, Shikata said.

To contact the reporters on this story: Tsuyoshi Inajima in Tokyo at tinajima@bloomberg.net; Michio Nakayama in Tokyo at mnakayama4@bloomberg.net; Shigeru Sato in Tokyo at ssato10@bloomberg.net

To contact the editor responsible for this story: Amit Prakash at aprakash1@bloomberg.net