New York Times:
Earlier Thursday the military forces dumped seawater from a helicopter on Reactor No. 3, making four passes and dropping a total of about 8,000 gallons over it as a plume of white smoke billowed. The Japanese government said that the reactor typically needs 50 tons of water, or about 12,000 gallons, a day to keep from overheating.
The Self-Defense Forces later said the measure had little effect on reducing the temperature in the pool where the spent rods are stored.