On Thursday, the Japanese military employed their CH-47 Chinook helicopters to dump seawater on the damaged reactor of reactors No. 3 and 4 at the troubled Fukushima Daiichi plant. The dumping is meant to cool the overheated reactors — and replenish the water that contains the spent fuel rods. Earlier today, the military dumped four loads on the reactor, but experts say at least a hundred would be necessary for the operation to succeed. The process has been slow and painstaking: Each crew can only operate for 40 minutes before they must switch off because of radiation exposure. “We are afraid that the water level at unit 4 is the lowest,” said Hikaru Kuroda, facilities management official at Tokyo Electric Power Co. But he added, “Because we cannot get near it, the only way to monitor the situation is visually from far away.” Engineers were also focused on restoring power to the plant, which has been cut off since Friday. Once power is restored, the plant’s reactors will be cooled once again with seawater.