* Govt warns of radiation leak, says situation not yet
* U.S. Air Force delivers coolant to nuclear plant
* Thousands of residents evacuated as precautionary measure
(Repeats to fix formatting)
By Osamu Tsukimori and Kiyoshi Takenaka
TOKYO, March 12 Japan warned there could be a
small radiation leak from a nuclear reactor whose cooling system
was knocked by Friday's massive earthquake, but thousands of
residents in the area had been moved out of harm's way.
Underscoring grave concerns about the Fukushima plant some
240 km (150 miles) north of Tokyo, U.S. Secretary of State
Hillary Clinton said the U.S. air force had delivered coolant to
avert a rise in the temperature of the facility's nuclear rods.
Pressure building in the plant was set to be released soon,
a move that could result in a radiation leak, officials said.
Some 3,000 people who live within a 3 km radius of the plant
had been evacuated, Kyodo news agency said.
"It's possible that radioactive material in the reactor
vessel could leak outside but the amount is expected to be small
and the wind blowing towards the sea will be considered," Chief
Cabinet Yukio Edano told a news conference.
"Residents are safe after those within a 3 km radius were
evacuated and those within a 10 km radius are staying indoors,
so we want people to be calm," he added.
Prime Minister Naoto Kan was set to visit the plant on
Saturday morning and also fly over the quake-hit area.
Tokyo Electric Power Co said pressure had built up
inside a reactor at the Fukushima-Daiichi plant after the
cooling system was knocked out by the earthquake, the largest on
record in Japan.
Pressure had risen to 1.5 times the designed capacity, the
Japan Nuclear Safety agency said. Media also said the radiation
level was rising in the turbine building.
The cooling problems at the Japanese plant raised fears of a
repeat of 1979's Three Mile Island accident, the most serious in
the history of the U.S. nuclear power industry. Experts,
however, said the situation was, so far, less serious.
Equipment malfunctions, design problems and human error led
to a partial meltdown of the reactor core at the Three Mile
Island plant, but only minute amounts of dangerous radioactive
gases were released.
"The situation is still several stages away from Three Mile
Island when the reactor container ceased to function as it
should," said Tomoko Murakami, leader of the nuclear energy
group at Japan's Institute of Energy Economics.
Toshiaki Sakai, director of the Japan Atomic Industrial
Forum International Cooperation Center, said global nuclear
power companies around the globe have since the U.S. accident
implemented over 53 safety improvements to avert a repeat.
Reactors shut down due to the earthquake account for 18
percent of Japan's nuclear power generating capacity.
Nuclear power produces about 30 percent of the country's
electricity. Many reactors are located in earthquake-prone zones
such as Fukushima and Fukui on the coast.
The International Atomic Energy Agency (IAEA) estimates that
around 20 percent of nuclear reactors around the world are
currently operating in areas of significant seismic activity.
The IAEA said the sector began putting more emphasis on
external hazards after an earthquake hit TEPCO's
Kashiwazaki-Kariwa plant in July 2007, until then the largest to
ever affect a nuclear facility.
When the earthquake hit the Kashiwazaki-Kariwa nuclear power
plant four reactors shut down automatically. Water containing
radioactive material was released into the sea, but without an
adverse effect on human health or the environment, it said.
TEPCO had been operating three out of six reactors at the
Fukushima Daiichi nuclear plant at the time of the quake, all of
which shut down.
The spokesman added that there were no concerns of a water
leak for the remaining three reactors at the plant, which had
been shut for planned maintenance.
(Additional reporting by Risa Maeda, Chisa Fujioka and Chikako
Mogi in Tokyo and Fredrik Dahl in Vienna; Writing by Edwina
Gibbs; Editing by Edmund Klamann and Miral Fahmy)