Fukushima Fallout: Next Few Days Critical
4:50pm UK, Sunday March 13, 2011
4:50pm UK, Sunday March 13, 2011
Nuclear experts have warned the next few days will be crucial in determining exactly how bad the fallout from the Fukushima power plant disaster could be.
They say advanced Japanese engineering at the 40-year-old facility will avoid a Chernobyl-style disaster, but any radiation leak could still have disastrous consequences.
During Friday's megaquake most of Japan's 50 nuclear power stations shut down as expected, but at Fukushima's Daiichi nuclear plant the system failed.
A hydrogen blast at its number one reactor has destroyed part of the building but did not prompt a major radiation leak.
However, experts have warned there could be a second explosion at the plant's number three reactor.
Reactors convert the energy stored in nuclear fuel rods into electricity, and in doing so generate immense heat.
Water is circulated through the reactor core to keep the fuel rods from overheating.
In case of an emergency each power station has a back-up system to keep reactors cool.
An official scans a woman for signs of radiation in Nihonmatsu City
But during the quake - which has been upgraded to 9 on theRichter scale - power at the Fukushima facility was lost and the back-up system failed.
Diesel generators should have kicked in to provide emergency cooling, but they were also damaged and coolant stopped circulating.
The remaining water is likely to eventually boil away, exposing the fuel rods.
If a cooling system is not restored, it could lead to what is known as a meltdown - when the core melts and radiation escapes into the atmosphere.
Officials were now pumping seawater into reactor number three to keep its temperature down.
The Tokyo Electric Power Company (TEPCO) said radiation levels at the Fukushima plant had risen above the safety limit but there was no "immediate threat" to humans.
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