Now we have a possible nuclear fallout

THE operator of a quake-hit Japanese nuclear plant says the cooling system of another reactor is not working and there's a risk of an explosion.
"All the functions to keep cooling water levels in No 3 reactor have failed at the Fukushima No. 1 plant,'' a spokesman of Tokyo Electric Power (Tepco) said on Sunday.
``As of 5.30am (07.30 AEDT), water injection stopped and inside pressure is rising slightly,'' he said, adding the operator filed an emergency report on the plant's condition with the government.
The massive earthquake and tsunami on Friday left more than 1,000 dead and at least 10,000 unaccounted for.
In its wake there was an explosion that blew off the roof and walls of the structure around the No 1 reactor at the Fukushima No 1 atomic plant, about 250km northeast of Tokyo.
Radiation leaked from the plant, but the government moved to calm fears of a meltdown, saying the blast did not rupture the container surrounding the reactor and that radiation levels had fallen afterwards.
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Japan's nuclear safety agency rated the accident at four on the international scale of 0 to 7. The 1979 Three Mile Island accident in the United States was rated five while the 1986 Chernobyl disaster was a seven.Work to bring the situation under control is ongoing to prevent cooling liquid from evaporating and exposing the fuel rods to the air, which could trigger a major radiation leak.
"We have decided to douse the (reactor) container with sea water in order to reduce risks as quickly as possible,'' Kan's top spokesman Yukio Edano told reporters on Saturday.
Kyodo and Jiji reported before the explosion that the plant ``may be experiencing nuclear meltdown'', while NHK quoted the safety agency as saying metal tubes that contain uranium fuel may have melted.
An evacuation order for tens of thousands of residents was expanded to 20km around the Fukushima plant, and thousands more were shifted from another damaged plant, Fukushima No 2.
Meanwhile, the US Nuclear Regulatory Commission in Washington said on Saturday it has sent two experts to Japan.
"We have some of the most expert people in this field in the world working for the NRC and we stand ready to assist in any way possible,'' commission chairman Gregory Jaczko said in a statement announcing the deployment.
The NRC - an independent agency mandated by Congress to regulate US commercial nuclear power plants and other nuclear materials - said the pair were experts in boiling water nuclear reactors and are part of a broader US aid team sent to the disaster zone.
The commission has activated ``its Maryland-based headquarters Operations Center since the beginning of the emergency in Japan, and is operating on a 24-hour basis'', the statement added.
As workers doused the stricken reactor with sea water on Saturday to try to avert catastrophe, Japan's Prime Minister Naoto Kan said the chaos unleashed by Friday's 8.9-magnitude quake was an "unprecedented national disaster''.
The quake, one of the biggest ever recorded, unleashed a terrifying 10-metre wave that tore through towns and cities on Japan's northeastern coast, destroying everything in its path.
There are concerns for the safety of at least 160 Australians in the worst-hit areas of Japan.
In the small port town of Minamisanriku alone, about 10,000 people are unaccounted for -- more than half the population -- public broadcaster NHK reported.
Even as Japan struggled to assess the full extent of the devastation, the nation faced an atomic emergency as cooling systems damaged by the quake failed at two nuclear reactors.
An evacuation order for tens of thousands of residents was expanded to 20km around the Fukushima plant, and thousands more were shifted from another damaged plant, Fukushima No 2.
Media reports said three residents -- bedridden patients evacuated from a hospital near the plant -- had been found to be exposed to radiation after spending a long time in the open waiting for rescue.
Ron Chesser, director for the Centre for Environmental Radiation Studies at Texas Tech University, said it's critical to cool the reactor core to avoid a meltdown that would result in ``a large release of radiation''.
"Reactors are not like your car that you can turn off and walk away. They're going to continue generating a great amount of heat until the core is disassembled,'' he told the US-based ScienceDaily website.
The raging tsunami picked up shipping containers, cars and the debris of shattered homes. It crashed through the streets of Sendai and across open fields, forming a mud slick that covered vast tracts of land.
"There are so many people who lost their lives,'' an elderly man told TV reporters before breaking down in tears. "I have no words to say.''
Police reportedly said 200-300 bodies had been found in the city of Sendai. Up to 400 bodies were recovered in Rikuzentakata, a coastal town of about 23,000 people, NHK quoted the military as saying.
The premier's spokesman said at least 1000 people were believed to have lost their lives. Police said more than 215,000 people were huddled in emergency shelters.
"What used to be residential areas were mostly swept away in many coastal areas and fires are still blazing there,'' Kan said after surveying the damage by helicopter.
About 50,000 military and other rescue personnel are spearheading a Herculean rescue and recovery effort, with hundreds of ships, aircraft and vehicles headed to the Pacific coast area.
The towering wave set off alerts across the Pacific, sparking evacuations in Hawaii and on the US West Coast.
The Bank of Japan said it would do its "utmost'' to ensure the stability of financial markets after the quake brought huge disruption to key industries, raising short-term concerns for the nation's struggling economy.
In quake-hit areas, 5.6 million households had no power on Saturday and more than one million households were without water. Telecommunications networks were also hit.
In a rare piece of good news, a ship that was earlier reported missing was found swept out to sea and all 81 people aboard were airlifted to safety.
Leading international offers of help, which saw foreign rescue teams begin arriving in Japan on Saturday, President Barack Obama mobilised the US military to provide emergency aid after what he called a ``simply heartbreaking'' disaster.
The United States, which has nearly 50,000 military personnel in Japan, ordered a flotilla including two aircraft carriers and support ships to the region to provide aid.
The quake hit at 2:46pm (1646 AEDT) on Friday and lasted about two minutes, making buildings sway in greater Tokyo, the world's largest urban area and home to about 30 million people.
More than a day after the first, massive quake struck just under 400km northeast of Tokyo, aftershocks were still rattling the region, including a strong 6.8 magnitude tremor on Saturday.
Japan sits on the "Pacific Ring of Fire'' and Tokyo is in one of its most dangerous areas, where three continental plates are slowly grinding against each other, building up enormous seismic pressure.
The government has long warned of the likelihood that a devastating magnitude-eight quake will strike within the next 30 years in the Kanto plains, home to Tokyo's vast urban sprawl.