Japan nuclear situation reasonably stable: IAEA

VIENNA (Reuters) - The situation at Japan's Fukushima Daiichi nuclear power plant was serious but "reasonably stable" Thursday with no major worsening since the day before, a senior U.N. nuclear watchdog official said.

"It hasn't got worse, which is positive," Graham Andrew of the International Atomic Energy Agency (IAEA) said. "The situation remains very serious but there has been no significant worsening since yesterday."

But Andrew, a senior aide to IAEA Director General Yukiya Amano, cautioned at a news conference: "It is still possible that it could get worse."

Despite the unfolding crisis in Japan, Andrew said the nuclear industry in general had a "very good safety record," even though the risks could not be reduced to zero.

"As of today I'm not aware that anyone has died from this accident. That is not to seem complacent, we're far from that."

Japanese military helicopters and fire trucks poured water on an overheating nuclear facility Thursday and the plant operator said electricity to part of the crippled complex could be restored in a desperate bid to avert catastrophe.

Andrew said the situation at the Fukushima Daiichi plant's reactors 1, 2 and 3 -- whose cores he said had suffered damage -- appeared to be relatively stable with seawater injected into all three units to cool them.

But the unit 4 reactor in particular remained a "a major safety concern, he said, adding that no information was available on the water level in the spent fuel pond.

"The water levels in the reactor pressure vessels of reactors 5 and 6 have been declining," he added.

The top U.S. nuclear regulator earlier said the cooling pool for spent fuel rods at reactor No.4 may have run dry and another was leaking and that radiation levels around the cooling pool were extremely high.

"UNFAIR" NUCLEAR CRITICISM

Workers have been trying to connect a 1-km (0.6-mile) long power cable from the main grid to restart water pumps to cool reactor No. 2, which does not house spent fuel rods considered the biggest risk of spewing radioactivity into the atmosphere.

The IAEA -- which is tasked with fostering the safe use of atomic energy -- said in a statement issued after Andrew's news conference that Japan had informed it that engineers were able to lay the power cable to the No.2 unit.

"They plan to reconnect power to unit 2 once the spraying of water on the unit 3 reactor building is completed," it said.

Andrew said the IAEA was regularly receiving radiation dose rate information from 47 Japanese cities and that there had been no significant change in levels in Tokyo since Wednesday.

"They remain well below levels that are dangerous to human health," he said.

But at some locations around 30 km from the plant the dose rates rose significantly in the last 24 hours.

Andrew also described as "unfair" accusations by a Russian nuclear accident specialist that the IAEA, as well as corporations, was ignoring lessons from the Chernobyl accident 25 years ago to protect the industry's expansion.

The IAEA official said nuclear energy had an "enviable" safety record. But "as ever you can never get the risks down to zero."

(Additional reporting by Michael Shields; editing by Janet Lawrence)