Source:
NHK WorldTokyo Electric Power has found it difficult to spray water from a helicopter to cool down a storage pool for spent nuclear fuel inside the No.4 reactor at the Fukushima Daiichi nuclear power plant.
The reactor was undergoing an inspection when the quake occurred. The firm says the temperature of the storage pool for spent nuclear fuel was 84 degrees Celsius on Monday morning, more than double the normal level. More recent temperatures are not available due to a technical failure.
On Tuesday morning, an explosion was heard and the roof of the building that houses the No.4 reactor was damaged. Tokyo Electric Power, the operator of the plant, says it appears a lack of coolant caused the fuel rods to be exposed, adding that a hydrogen explosion might have occurred. If the reactor can't be cooled, the fuel rods may emit hydrogen or melt down. Tokyo Electric Power considering pouring water onto the storage pool in the containment vessel through a hole on the roof created by the blast.
However, the firm concluded that it would be extremely difficult to spray water from a helicopter as the hole is dozens of meters from the storage pool and a helicopter can only carry a limited amount of water on a single flight.
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