TOKYO, April 5 (UPI) -- Radioactive water stopped flowing from Japan's damaged nuclear power plant into the Pacific Ocean Wednesday after a special material was used, the utility said.
Tokyo Electric Power Co. said it injected 1,500 liters (396 gallons) of ''water glass,'' or sodium silicate, and another agent near a seaside pit, through which the highly radioactive water had been leaking heavily, Kyodo News reported.
The Japanese news agency said the leak apparently had been seriously contaminating the ocean near the water intake of the plant's No. 2 reactor.
Meanwhile, a Japanese minister has apologized for concern over the dumping of low-level radioactive water from the quake-crippled Fukushima power plant into the ocean.
The release, which began Monday, was described as an unavoidable process to avert a much bigger problem resulting from the leakage of the highly contaminated water.
The plant's nuclear crisis was set off by the March 11 earthquake and tsunami that killed thousands of people and inflicted damage running into the hundreds of billions of dollars.
The apology Tuesday, directed especially at fishermen, came from Industry Minister Banri Kaieda as he assured the discharge of the low-level radioactive water posed no major health risk, Kyodo News reported. The nuclear safety agency is part of his ministry.
TEPCO, which operates the plant, was releasing the contaminated water as an emergency measure to provide more storage room for the water with much higher contamination in the basement of the reactor buildings.
Kaieda said currently the flooded basement of the buildings and their underground trenches at Nos. 1, 2 and 3 reactors are believed to hold about 60,000 tons of the more highly radioactive water. This water, which is also preventing workers from doing other emergency work, eventually will be removed by the company, the minister said.
As current plans stand, Tokyo Electric plans to dispose o about 11,500 tons of the less contaminated water into the seas by this weekend. The more highly radioactive water is to be stored in tanks at the reactors' nuclear waste disposal sites, the government nuclear safety agency said. Those tanks will be shipped by the end of this month, the agency said.
But before that happens, the utility must ensure there is no more radioactive water leaking from the facility.
The leakage of the radioactive water into the seas was believed to be coming from a cracked pit in the No. 2 reactor, which lost its cooling system, leading to the partial melting of the uranium fuel rods. The leaking water reportedly contains radioactive Iodine-131 at more than 10,000 times the legal limit.
Earlier efforts using concrete or water-absorbing polymers to stop the leak failed.
The utility also was considering erecting silt barriers in the sea to prevent the highly radioactive water from spreading further.
Only after the more highly radioactive water is removed can workers perform such critical tasks as restoring the cooling systems.
Currently, that effort is being accomplished by injecting huge quantities of water into the reactors to keep the spent nuclear fuel pools from boiling. However, this process can also cause more flooding in the reactor buildings.
In terms of volume, about 3 million gallons of low-level radioactive water may be dumped into the seas, Gary Was, a nuclear engineering professor at the University of Michigan told CNN.
Experts told CNN Japanese assessment that such quantities of the water into the ocean poses no health risk is a fair one as any iodine contamination should get diluted quickly.
"To put this in perspective, the Pacific Ocean holds about 300 trillion swimming pools full of water, and they are going to release about five swimming pools full," Timothy Jorgensen at the Georgetown University Medical Center told CNN.
"So hopefully the churning of the ocean and the currents will quickly disperse this so that it gets to very dilute concentrations relatively quickly."
John Till, president of the South Carolina-based Risk Assessment Corp., said he does not expect any permanent effects on the marine life, even close to the crippled nuclear plant, but urged continuing monitoring of seawater.
Radiation levels in airborne particles, however, were reported to be falling steadily in the quake-hit northeast region.
Separately, Farm Minister Michihiko Kano Tuesday announced plans to make inspections of marine products more stringent.
Chief Cabinet Secretary Yukio Edano announced the government has notified various international authorities of the radioactive leaks into the sea in compliance with the U.N. Convention on the Law of the Sea.
Also Tuesday, authorities in Fukushima prefecture began taking radiation measurements in school areas.
The three-day effort will seek to cover about 1,400 schools outside the 12.5-mile evacuation zone of the plant.
The program was initiated at the request of parents of children who began their new academic year April 1, Kyodo News reported. The parents want to know whether their children can walk to schools or play on the school premises although authorities have said there is currently no threat as long as children stay away from the designated perimeter of the plant, the report said.
In Vienna, the International Atomic Energy Agency opened its 10-day nuclear safety review meeting, attended by representatives from 72 "contracting parties" countries.
In his opening remarks IAEA Director General Yukiya Amano said while the immediate priority was to overcome the Fukushima nuclear crisis, the delegates can also begin the process of reflection and evaluation, since "the worries of millions of people throughout the world about whether nuclear energy is safe must be taken seriously."
"Rigorous adherence to the most robust international safety standards and full transparency, in good times and bad, are vital for restoring and maintaining public confidence in nuclear power," he added.
Officials of Toyota Motor said the Japanese automaker may temporarily halt all manufacturing operations at its plants in North America, its main market, this month, due to parts supply disruptions blamed on the March 11 disaster, Kyodo News reported.
The report said the automaker has already halted Saturday overtime production at those plants.
However, the report said Toyota officials said they feel even normal hour operations would be difficult as parts manufacturers in Japan have not been able to fully restore their output.
The company, however, will not lay off employees in the event of a shutdown, the report said.