Japan nuclear struggle focuses on cracked reactor pit - Reuters

By Yoko Kubota and Yoko Nishikawa

TOKYO | Sun Apr 3, 2011 1:12am EDT

TOKYO (Reuters) - Japanese engineers grappling on Sunday to end the world's worst nuclear crisis since Chernobyl tried to seal a crack that has been leaking radiation into the ocean from a crippled reactor.

An aide to embattled Prime Minister Naoto Kan said the government's priority was to stop the radiation leaks that are spooking Japanese, hindering work and scaring away tourists.

"We have not escaped from a crisis situation, but it is somewhat stabilized," said Goshi Hosono, a ruling party lawmaker and aide to Kan. "The Japanese people's main concern is when the leakage of radioactive substances will stop."

Plant operator Tokyo Electric Power Co (TEPCO) found a crack in a concrete pit at its No.2 reactor in the Fukushima Daiichi complex at the weekend, generating readings of 1,000 millisieverts of radiation per hour in the air inside.

The leaks did not stop after concrete was poured into the pit, and TEPCO was turning to water-absorbent polymers to prevent any more contaminated water from going out.

"We are hoping that the polymers will absorb water and fill in the pipe to prevent water from flowing," said Hidehiko Nishiyama, deputy director general of the Nuclear and Industrial Safety Agency (NISA).

He said the latest effort to staunch the flow of radioactive water into the Pacific would start on Sunday afternoon and workers would top the polymers with more concrete to block the water.

Officials believe the crack could be one source of the radiation leaks that have hobbled efforts to control the six-reactor complex and sent radiation levels in the sea soaring to 4,000 times the legal limit.

To cool damaged reactor No. 2, engineers were looking at alternatives to pumping in water, including an improvised air conditioning system, spraying the reactor fuel rods with vaporized water or using the plant's cleaning system.

PM UNDER PRESSURE

As the disaster that has left nearly 28,000 people dead or missing dragged into a fourth week, Kan toured devastated coastal towns in northern Japan on Saturday, offering refugees government support for rebuilding homes and livelihoods.

"It will be kind of a long battle, but the government will be working hard together with you until the end," Kyodo news agency quoted him as telling people in a shelter in Rikuzentakata, a fishing port flattened by the tsunami which struck on March 11 after a massive earthquake.

Unpopular and under pressure to quit or call a snap poll before the disaster, Kan has been criticized for his management of the humanitarian and nuclear crisis. Some tsunami survivors said he came to visit them too late.

Kan also entered the 20-km (12-mile) evacuation zone and visited J-village just inside the zone, a sports facility serving as the headquarters for emergency teams trying to cool the six-reactor Fukushima Daiichi plant.

Operators of the plant are no closer to regaining control of damaged reactors, as fuel rods remain overheated and high levels of radiation are flowing into the sea.