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 build-up 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) told a news briefing. 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 US 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.