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Japan:Researchers say meltdown could have been avoided

Friday, September 16, 2011

A group of researchers says the meltdown of a reactor at the Fukushima Daiichi nuclear power plant could have been avoided if water injection had been carried out 4 hours earlier than it was.

The researchers at the Japan Atomic Energy Agency on Thursday reported the finding based on a computer simulation of the accident at the plant’s No. 2 reactor.

The core meltdown took place within a few days after the reactor’s cooling system failed due to the major earthquake and tsunami on March 11th.

The Tokyo Electric Power Company, or TEPCO, said earlier that data analysis shows that the cooling system may have stopped working shortly after 1 PM on March 14th.

The utility started injecting water to cool the reactor at around 8 PM that day, after reducing pressure in the facility. But by 8 PM the next day — around 100 hours after the quake — much of the reactor’s fuel had melted and collected at the bottom of the reactor’s pressure vessel.

The simulation suggests that if water had been injected by around 4 PM, it could have prevented the meltdown by lowering the temperature of the fuel before it reached 1,200 degrees Celsius, destroying the fuel’s container.

Group leader Masashi Hirano says the damage to the fuel could have been avoided, and that he wonders why TEPCO did not start injecting water earlier despite difficulties.

TEPCO says it doesn’t believe the operation was delayed, adding that workers did their best amid high radiation levels and other severe conditions.

Of the plant’s 6 reactors, the No. 1 to No. 3 suffered meltdowns after losing cooling functions.

At the No. 2 reactor, a hydrogen explosion on March 15th caused the release and spread of massive amounts of radioactive substances.