TOKYO – Russia has repeated an offer first made two years ago to help Japan clean up its accident-ravaged Fukushima nuclear station, welcoming Tokyo Electric Power Co.'s decision to seek outside help.

As Tokyo Electric pumps thousands of metric tons of water through the wrecked Fukushima station to cool its melted cores, the tainted runoff was found to be leaking into groundwater and the ocean. The approach to cooling and decommissioning the station will need to change and include technologies developed outside of Japan if the cleanup is to succeed, said Vladimir Asmolov, first deputy director general of Rosenergoatom, the state-owned Russian nuclear utility.

"In our globalized nuclear industry we don't have national accidents, they are all international," Asmolov said. "We need to cooperate to prevent future accidents because it's in everyone's interest."

Since Japan's new government took over in December, talks on cooperating between the two countries on the Fukushima clean up have turned "positive" and Russia is ready to offer its assistance, he said by phone from Moscow.

'The last to realize'

After 29 months of trying to contain radiation from Fukushima's molten atomic cores, Tokyo Electric said this week it will reach out for international expertise in handling the crisis. The water leaks alone have so far sent more than 100 times the annual norms of radioactive elements into the ocean, raising concern it will enter the food chain through fish.

The latest leak of 300 metric tons of irradiated water prompted Japan's nuclear regulator to label the incident "serious" and question Tokyo Electric's ability to deal with the crisis, echoing comments made by Prime Minister Shinzo Abe earlier this month. Zengo Aizawa, a vice president at TEPCO, as the Tokyo-based utility is known, made the call for help at a briefing on Aug. 21.

"It was clear for a long time that TEPCO was not adequately coping with the situation," Asmolov said. "It looks like TEPCO management were the last to realize this. Japan has the technologies to do this, but they lacked a system to deal with this kind of situation."

'A failure of management'

The Fukushima accident of March 2011 is the world's biggest nuclear disaster since the Soviet Union faced the explosion at Chernobyl in 1986.

So far, Tokyo's solution to cooling melted nuclear rods at Fukushima that otherwise could overheat into criticality, or a self-sustained nuclear chain reaction, has been to pour water over them. The result is more than 330,000 tons of irradiated water in storage tanks at the site, which is growing every day. The water is treated to remove some of the cesium particles in it, which in turn leaves behind contaminated filters.

The sheer quantity of water used is the most at a nuclear accident since the 1972 London convention banned the dumping of waste and radioactive water into the sea, said Peter Burns, formerly Australia's representative on the U.N. scientific committee on the effects of atomic radiation.

"Until they figure out how to deal with such vast volumes of water, how to manage it, the problem" will persist, Burns, a retired radiation physicist, said from Melbourne.

Retaining thousands of tons of radioactive water in tanks was the wrong strategy from the start and TEPCO's handling of the task is a "textbook picture of a failure of management," Michael Friedlander, who has 13 years of experience running nuclear stations in the United States, said in an interview with Bloomberg TV in Hong Kong.

The idea of pumping water for cooling was never going to be anything but a "machine for generating radioactive water," Asmolov said.

Russia's nuclear company, Rosatom, of which Rosenergoatom is a unit, sent Japan a sample of an absorbent that could be used at Fukushima almost three years ago, Asmolov said. It also formed working groups ready to help Japan on health effect assessment, decontamination, and fuel management, among others, Asmolov said. The assistance was never used, he said.

"Since the arrival of the new Japanese government, the attitude's changed," he said. "So far the talks have been on a diplomatic level, but they are much more positive."