A third explosion in four days has rocked the earthquake-damaged Fukushima No.1 nuclear plant in Japan.
The latest explosion was heard at 6.10am local time and follows an explosion at the plant's No. 3 reactor yesterday.
Authorities say the core container is intact and a radiation leak is unlikely. However it hasn't dispelled global fear of a nuclear catastrophe.
Japan's government has now asked America to help it handle the situation.
A team of nuclear experts from the U.S. are headed to Japan to assist local authorities, including two cooling experts.
Radiation leaks have been deemed to be "at a safe level," but more than 200 people have been exposed and dozens hospitalised.
The 40 year old reactor was due to be retired in February, but the Japanese government controversially extended its license for another 10 years.
Perhaps a different decision could have averted the current nuclear threat.
Officials who have been battling the possible partial meltdown are injecting seawater into the reactors to replace lost cooling water.
Experts say a core meltdown at the Fukushima nuclear plant is unlikely to result in a Chernobyl-like disaster, but its impact will still be significant.
The Chernobyl meltdown rated a 7 on an international scale of zero to seven, the people of Japan face a level 4 meltdown.
Over 200,000 people have been evacuated and authorities have declared an evacuation zone within a 30km radius of the plant.
Japan uses nuclear power to generate a third of its electricity - Authorities have announced plans for scheduled rolling power cuts in areas served by TEPCO to make up for the loss of power from crippled nuclear plants.
Across northeast Japan 100 000 soldiers are continuing the search and recovery effort.
The tough assignment is hampered by aftershocks and tsunami warnings.
Millions of people are without food, water or heating and hundreds of thousands are holed up in emergency shelters.
The official death toll stands at nearly 2000, although it is feared tens of thousands of people will have perished.
Hope in Japan was bolstered overnight with the rescue of a 4month old bay girl and her parents in their ruined home.
The Consular Crisis Centre in Canberra had taken nearly 7151 calls from the Australian public. 2217 Australians in Japan had been confirmed as safe, including 103 in areas close to the earthquake and tsunami.
There are 3092 Australians registered as living in Japan, including 261 in affected areas.
The number of safe Australians in the affected areas are 105
However an estimated 11,000 Australians live in Japan, most in Tokyo and Osaka.
Foreign Minister Kevin Rudd said people concerned about family and friends should first try to contact them on mobile phones, followed by landlines and if they still fail to make contact, should provide all details to the DFAT Crisis Centre.
Friday's quake is the strongest in recorded history to hit Japan according to USGS records that date to 1900.
It is now thought that the insurance bill for the earthquake alone will come to around $35 billion and that the combined bill for the earthquake and the tsunami will wipe out insurers profits for the year.