WRAPUP 2-Japan focuses on hydrogen buildup after nuclear leak

* Nuclear crisis far from under control

* China says finds radioactive iodine in some spinach

* U.S. nuclear agency doubts meltdown in reactor No. 2

* Fisherman angry over radiation water pumped into sea
(Adds comment from U.S. nuclear agency official, paragraph
18)

By Chizu Nomiyama and Shinichi Saoshiro

TOKYO, April 7 (Reuters) – Japan began pumping nitrogen gas
into a crippled nuclear reactor, refocusing the fight against
the world’s worst nuclear disaster in 25 years on preventing an
explosive buildup of hydrogen gas at Fukushima Daiichi power
plant.

Workers started injecting nitrogen into the containment
vessel of reactor No. 1 on Wednesday night, following a morning
breakthrough in stopping highly radioactive water leaking into
the sea at another reactor in the six-reactor complex.

“It is necessary to inject nitrogen gas into the
containment vessel and eliminate the potential for a hydrogen
explosion,” an official of plant operator Tokyo Electric Power
(TEPCO) (9501.T: Quote, Profile, Research) told a news briefing.

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The possibility of another hydrogen explosion like those
that ripped through reactors 1 and 3 early in the crisis,
spreading high levels of radiation into the air, was “extremely
low,” he said.

But TEPCO suspected that the outside casing of the reactor
vessel was damaged, said the official.

“Under these conditions, if we continue cooling the
reactors with water, the hydrogen leaking from the reactor
vessel to the containment vessel could accumulate and could
reach a point where it could explode,” he added.

Although engineers succeeded after days of desperate
efforts to plug the leak at reactor No. 2, they still need to
pump 11.5 million litres (11,500 tonnes) (3.04 million U.S.
gallons) of contaminated water back into the ocean because they
have run out of storage space at the facility. The water was
used to cool overheated fuel rods.

Nuclear experts said the damaged reactors were far from
being under control almost a month after they were hit by a
massive earthquake and tsunami on March 11.

The growing concerns of nearby South Korea and China about
radioactive fallout from Japan were underscored when China’s
health ministry reported trace amounts of radioactive iodine in
spinach in three Chinese provinces.

The two western neighbours of Japan have reportedly
complained they have not been fully informed about TEPCO’s
plans to release radioactive water into the Pacific Ocean.

“We are instructing the trade and foreign ministries to
work better together so that detailed explanations are supplied
especially to neighbouring countries,” Chief Cabinet Secretary
Yukio Edano told a news conference on Wednesday.

Experts insisted the low-level radioactive water to be
pumped into the ocean posed no health hazard to people.

“The original amount of radioactivity is very low, and when
you dilute this with a huge body of water, the final levels
will be even lower than legal limits,” said Pradip Deb, senior
lecturer in Medical Radiations at the School of Medical
Sciences, Royal Melbourne Institute of Technology University.

The government is preparing to revise guidelines for legal
radiation levels, designed for brief exposure to high levels of
radiation in emergencies and not cumulative absorption, for
people living near the damaged plant.

Workers are struggling to restart cooling pumps — which
recycle the water — in four damaged reactors.

Until those are fixed, they must pump in water to prevent
overheating and meltdowns, but have run out of storage capacity
for the seawater when it becomes contaminated.

Radioactive iodine detected in the sea has been recorded at
4,800 times the legal limit, but has since fallen to about 600
times the limit. The water remaining in the reactors has
radiation five million times legal limits.

Martin Virgilio, a top official for the U.S. Nuclear
Regulatory Commission, said at a House of Representatives
hearing that the NRC did not believe that the core of
Fukushima’s reactor No. 2 had melted down. Earlier, Democratic
congressman Edward Markey had said the NRC informed him that
the core had become so hot it had probably melted through the
reactor pressure vessel.

COOLING REACTORS KEY

Japan is facing its worst crisis since World War Two after
the 9.0 magnitude earthquake and tsunami left nearly 28,000
people dead or missing and thousands homeless, and rocked the
world’s third-largest economy.

It will likely take months to finally cool down the
reactors and years to dismantle those that have been damaged.
TEPCO has said it will decommission four of the six reactors.

Two Fukushima plants together provide 4 percent of Japan’s
electric power and local politicians warn that reopening them
will be politically difficult. [ID:nTKB007431]

The key to bringing the reactors under control is the
extent of damage to the plant’s cooling system, said analysts.

In a sign the cooling systems may be severely damaged, the
Sankei newspaper reported that the government and TEPCO were
considering building new cooling systems for three reactors to
operate from outside the reactor buildings.

Japan’s fishermen, who are part of the politically powerful
agricultural lobby, made it clear they were not assuaged by
assurances that ocean radioactivity levels were low and safe.

“From now on, our fishermen will never cooperate with or
accept nuclear power generation. I would like them to stop even
those reactors that are now in operation right away,” Ikuhiro
Hattori, chairman of the Japan Fisheries Cooperatives, told NHK
state television.

In Ibaraki, a prefecture south of Fukushima where prices
for flounder and sea bream have plummeted, 53-year-old
fisherman Yutaka Iijima told Reuters he worried about his
future.

“The fact that we cannot work, that will have a big impact
on us, and there is no end in sight to this.”
($1=84 Japanese yen)
(Additional reporting by Kiyoshi Takenaka in Tokyo, Sui-lee
Wee in Beijing, Scott DiSavino in New York and Tan Ee Lyn in
Singapore; Writing by Paul Eckert; Editing by Jeremy Laurence
and Eric Walsh)

WRAPUP 2-Japan focuses on hydrogen buildup after nuclear leak