CHERNOBYL ECHOES

Two of the plant's six reactors are now seen as safe but the other four are volatile, sometimes emitting steam and smoke.

TEPCO officials indicated the contaminated water is probably coming from inside the reactors rather than from pools of spent fuel rods outside.

Experts are anxious to find out whether the reactor cores are broken and leaking, as that could lead to a meltdown.

One long-term solution may be to entomb the Fukushima reactors in sand and concrete as happened at Chernobyl, Ukraine, after the 1986 disaster that was the world's worst.

The Japan crisis has prompted a reassessment of nuclear power across the world. It had its most direct political impact yet in foreign politics in Germany at the weekend.

Chancellor Angela Merkel's Christian Democrats lost control of Germany's most prosperous state, Baden-Wuerttemberg, as anti-nuclear sentiment benefited her opponents in a regional vote.

Japanese Prime Minister Naoto Kan has kept a low profile during the crisis, but may face awkward questions after Kyodo news agency said his visit to the region the day after the disaster delayed TEPCO'S response to the unfolding situation.

"The process to release the steam was delayed due to the premier's visit," because the power company feared Kan could be exposed to radiation, it quoted an unnamed government source as saying.

The nuclear crisis has compounded Japan's agony after the magnitude 9.0 quake and massive tsunami devastated its north east coast, turning whole towns into apocalyptic-looking landscapes of mud and debris.

The latest death toll was 10,804 people, with 16,244 still missing 17 days after the disaster. About a quarter of a million people are living in shelters.

Damage could top $300 billion, making it the world's costliest natural disaster.