Japan on Sunday pushed on with its desperate efforts to contain a nuclear crisis triggered by last week's devastating earthquake and tsunami.

Water Injected Into Troubled Reactor Units

Japan's Defense Ministry said Sunday it succeeded in putting water into the No. 4 reactor at the troubled Fukushima No. 1 nuclear power plant.

About 80 tons of water was believed to have been shot into the reactor's spent fuel pool in a 70-minute mission which ended at 9: 30 a.m. local time (0030 GMT).

In a separate move, the Tokyo Fire Department shot over 2,000 tons of water into a spent fuel pool of the No. 3 reactor in an overnight mission that lasted more than 13 hours until 3:40 a.m. local time Sunday.

However, nuclear safety agency official Hidehiko Nishiyama said efforts to put water in the No. 3 reactor might not have been working.

He said the plant operator will release some radioactive gas from the reactor into the environment and that this may slow down work on restoring power and cooling systems to the unit.

That meant radiation levels around the plant would rise again, he said.

The cooling system was reactivated at the No. 6 reactor, thanks to restoration of electricity supply, and the temperature of its overheated spent fuel pool has dropped to around 40 degrees Celsius, according to the operator Tokyo Electric Power Co.

The company is trying to restore electricity to the No. 1 and 2 reactors later Sunday to restart the cooling system.

Engineers had hoped to reconnect power to the two reactors on Saturday but the work is taking longer than expected, partly because of water-spraying operations.

The power plant, about 220 km northeast of Tokyo, was stricken by the catastrophic March 11 earthquake and ensuing tsunami, which triggered a series of explosions and fires at four of its six reactors following failure of their cooling function due to the damaged power supplies.

A magnitude-9.0 earthquake struck offshore Japan on March 11, creating a tsunami that swept over low-lying areas, carrying boats, cars and even buildings with it and destroying nearly everything in its path. More than 7,700 people have been confirmed dead so far, and 11,651 others are missing.

The disaster also damaged the seaside Fukushima nuclear power plant, which remains in crisis as workers are struggling under dangerous conditions to prevent a meltdown and major radiation leaks.

International Responses And Reflections

Australian Prime Minister Julia Gillard said Sunday the nuclear crisis in Japan has no impact on Australia's uranium export and that the federal government is not reconsidering the sale of uranium.

"What is happening in Japan doesn't have any impact on my thinking about uranium exports," Gillard told Sky News.

"We do export uranium and we will continue to export uranium," she said, adding: "Countries around the world will make their own choices about how they source their energy."

Asked if it was time for an international debate on the use of civilian nuclear energy, Australian Foreign Minister Kevin Rudd said there will be a time and a place for a full debate on that given what has happened in Japan, but he did not think that time and place was right "at this very moment."

"All this has given the international community some pause but our focus now is on the crisis," Rudd told Ten Network.

Rudd again urged Australians in Tokyo and northern Honshu of Japan to leave the area, saying Australia remained "deeply concerned" about the state of Japan's damaged nuclear reactors.

In Fiji, a scientist in the Suva-based University of the South Pacific (USP) has confirmed that the country is out of danger from the reported nuclear radiation leak that posed a threat to Pacific island nations.

Dr Atul Raturi, head of the USP school of engineering and physics, said Fiji had nothing to worry about, at least for now.

"The movement of the radiation cloud will be dictated by the wind direction and current estimates show that it might move towards the U.S. west coast," he said.

"In the unlikely event of the radiation cloud moving towards the Pacific islands, it would have largely dispersed before reaching us," he said. "Radiation does not remain constant and if it were to come here, it will lose its potency by the time it reaches Fiji," he added.

Meanwhile, Fiji's weather office in the western city of Nadi has confirmed that no warnings had been issued by international authorities on radiation possibly affecting Fiji.

Alipate Waqaicelua, acting director of Meteorology, also told media that the radiation from the nuclear plants "is not going to come this far as it will only be around and closer to Japan."

"It won't even reach the islands of Guam and the Philippines and it's moving more towards the east than towards us," Waqaicelua said.