TOKYO — Japan stopped highly radioactive water leaking into the sea on Wednesday from a crippled nuclear plant, a breakthrough in the battle to contain the worst nuclear crisis since Chernobyl, but contaminated water was still being pumped into the ocean.
Analysts said the damaged reactors, whose fuel rods operator Tokyo Electric Power (TEPCO) is desperately trying to cool, were still not under control almost a month after they were hit by a massive earthquake and tsunami.
TEPCO said it had stemmed the radioactive leak using liquid glass at one of six reactors at the Fukushima Daiichi plant in northeast Japan that were damaged on March 11.
"The leaks were slowed yesterday after we injected a mixture of liquid glass and a hardening agent and it has now stopped," a TEPCO spokesman told Reuters.Video: Radiation fears seep into Japanese futures (on this page)
Engineers had been frantically struggling to stop the leaks from reactor no. 2, even using sawdust and newspapers. It was liquid glass that finally stemmed the flow of the highly-contaminated water.
Engineers are still faced with the massive problem of how to store 60,000 tonnes (60 million liters) of contaminated seawater used to cool over-heated fuel rods and are being forced to pump 11,500 tonnes of low-level radioactive water back into the sea.
Local newspapers said neighbors South Korea and China were getting concerned over the ongoing nuclear crisis and radioactive water being pumped into the sea.
"Perhaps we should have given more detailed explanations to the relevant ministries and to our neighbors. We are instructing the trade and foreign ministries to work better together so that detailed explanations are supplied especially to neighboring countries," Chief Cabinet Secretary Yukio Edano told a news conference on Wednesday.
"The situation is not under control yet," said Thomas Grieder, Asia analyst at forecasting firm IHS Global Insight.
"TEPCO's decision to displace the contaminated water into the ocean reflected the urgency of clearing the turbine buildings and trenches of radioactive water so as not to damage equipment needed for restoration of cooling systems."
Workers are struggling to restart cooling pumps -- which recycle the water -- in four damaged reactors.
Until those are fixed, they must pump in water from outside to prevent overheating and meltdowns. Radioactive iodine detected in the sea has been recorded at 4,800 times the legal limit, but has since fallen to around 600 times the limit.
Broadcaster NHK reported earlier that the leak had lessened after the company on Tuesday afternoon began pouring the sodium silicate into gravel below the concrete pit that had been the source of the leak. Images shown Tuesday on NHK's website appeared to show that a stream of water pouring from a crack had lessened.
The pit is near reactor No. 2, which was severely damaged when the core overheated because its cooling system was knocked out by the tsunami.Video: Nuclear plant dumps radioactive water into sea (on this page)
The radioactive water flowing from the plant raised concerns about the safety of seafood from the country that gave the world sushi, prompting the government to set limits for the first time on the amount of radiation permitted in fish.
Authorities insisted the radioactive water would dissipate and posed no immediate threat to sea creatures or people who might eat them. Most experts agreed.
Still, Japanese officials adopted the new standards as a precaution. And the mere suggestion that seafood from Japan could be at any risk stirred worries throughout the fishing industry.
"Even if the government says the fish is safe, people won't want to buy seafood from Fukushima," says Ichiro Yamagata, a fisherman who lived in the shadow of the Fukushima Dai-ichi plant. "We probably can't fish there for several years."
Fukushima is not a major fishing region, and no fishing is allowed in the direct vicinity of the plant. But experts estimate the coastal areas hit by the massive wave account for about a fifth of Japan's annual catch.
India announced Tuesday that it was halting food imports from Japan out of fear of radiation contamination. Few countries have gone so far, but India's three-month ban reflected the unease created by the nuclear crisis among consumers.
India said the ban would last three months or until the risk subsides. It planned to review the situation weekly.
The European Union said it will further reinforce its radiation controls on imports of food and animal feed from Japan from next week.
The announcement came the day after Japanese Prime Minister Naoto Kan asked Europe for a "calm, logical response" to the issue of Japanese food imports, and two weeks after the 27-nation bloc tightened its limits on such goods.
Yamagata, whose home is within the 12-mile-radius evacuation zone around the plant, is staying in a Tokyo soccer stadium with his wife and about 140 other refugees. He expects his fishing days are over.
After the magnitude-9.0 earthquake on March 11, he ran outside and watched the second floor of his house collapse, then fled with his family when tsunami warnings sounded.
Since then, he hasn't been allowed to return to check on the 5-ton boat he used to troll for flounder. He assumes it's gone, too. The tsunami killed up to 25,000 people and left tens of thousands homeless as it swamped about 250 miles of the northeastern coast and knocked out power to the plant.Interactive: Crisis in Japan (on this page)
The new limits on radioactivity in fish were imposed after TEPCO announced that water tested near the plant Saturday contained levels of radioactive iodine 7.5 million times the legal limit. That level had dropped to 5 million two days later.
Japan said some fish caught last week about 50 miles from the plant would have exceeded the new limits, which may change as circumstances do.
The radiation standards for fish will be the same as for vegetables. After spinach and milk exceeded safety limits following the quake, health experts said people would still have to eat enormous quantities of tainted produce or dairy before getting even the amount of radiation contained in a CT scan.Slideshow: Devastation in Japan after quake (on this page)
Japan imports far more fish than it exports, but it sent the world $2.3 billion worth of seafood last year.
Some people were undaunted. At Sushizanmai, a sushi bar just outside Tokyo's famed Tsukiji fish market, customers were still eating Japan's famed raw fish delicacies Tuesday night.
But chef Seiichiro Ogawa said the fuss over radiation could hurt business. His restaurant is trying to get more fish from the western part of Japan, which has not been affected by the nuclear crisis.
"Japanese customers are especially sensitive to this kind of thing, so I'm worried they'll stop eating sushi," said Ogawa, who has already seen his business drop 50 percent after foreigners stopped visiting the city after the quake. "We need this nuclear problem to be resolved."Map: Japan earthquake (on this page)
TEPCO said this week it is purposely dumping more than 3 million gallons of low-level radioactive water into the sea to make room in a storage tank for more highly contaminated water that it needs to remove before workers can restore important cooling systems.
That announcement angered Fukushima's federation of fisheries groups, which sent the company a letter of protest.
"Our prefecture's fisherman have lost their lives, fishing boats, piers and buildings due to the Great Eastern Japan Disaster," federation chairman Tetsu Nozaki said in the letter. "This low-level contaminated water has raised fears among fishermen that they will never be able to fish in our prefecture's waters again, and we absolutely want you to stop."
The Associated Press and Reuters contributed to this report.