The Japanese military on Thursday used trucks and helicopters to dump tonnes of water onto the quake-hit Fukushima nuclear plant in a bid to douse fuel rods and prevent a disastrous radiation release.
Four twin-rotor CH-47 Chinooks ran the first mission to empty large buckets that hold more than seven tonnes of water each onto the facility damaged by Friday’s massive earthquake and tsunami.
The operation aims to keep the fuel rods inside reactors and containment pools submerged under water, to stop them from degrading when they are exposed to air and emitting dangerous radioactive material.
The helicopter mission started in the morning under a clear sky after a similar effort the previous day was called off shortly before darkness fell by officials citing strong radiation and high winds.
Late in the day, two special Self-Defence Forces (SDF) fire trucks joined the crucial emergency effort at the plant, some 250 kilometres northeast of the Japanese capital.
A police water cannon was unable to operate, however, due to strong radiation at the facility.
Defence Minister Toshimi Kitazawa said that more military vehicles would be deployed to help with efforts to cool the reactors, while pumps supplied by the US armed forces were also being transferred.
The government’s nuclear safety agency has said the top priority should be pouring water into the fuel-rod pools at reactors three and four, which may be boiling and are not fully covered by roofs that would reduce radiation leaks.
An official at plant operator Tokyo Electric Power Co (TEPCO) said on Thursday the pool at the number-four reactor “seemed to have water” on Wednesday, based on aerial observations carried out by the military helicopters.
Another TEPCO spokesman said: “We have not confirmed how much water was left inside but we have not had information that spent fuel rods are exposed.”
Chief government spokesman Yukio Edano said it would take some time to know whether the operation had led to any significant improvement.
“Based on what experts have told us, it’s important to have a certain level of water (in the pools) before we can start to see any positive effect,” Edano told reporters.
“We are closely monitoring the data,” he said.
TEPCO said earlier it was concentrating on restoring the power supply to reactivate its crippled cooling systems, which were knocked out in the dual calamity that hit Japan.
“We cannot tell when, but we want to restore the power source as soon as possible,” TEPCO spokesman Naohiro Omura said.
TEPCO was preparing to restore outside power lines from Tohoku Electric Power Co., which serves the region, and connect its damaged electric transmission system with unaffected lines.
“At the moment, we are concentrating our efforts on this work,” the spokesman said.
“If the restoration work is completed, we will be able to activate various electric pumps and pour water into reactors and pools for spent nuclear fuel.”
The 9.0-magnitude quake, the biggest on record to strike Japan, knocked down electricity pylons which Tohoku had used to supply power to the TEPCO plant.
Some 70 workers have been using pumps to pour seawater to cool reactors at the plant, according to media reports, using electricity from borrowed mobile generators.
In Fukushima prefecture, where a zone within 20 kilometres of the plant has already been evacuated, about 10,000 people were to be screened at 26 locations for radiation exposure, Kyodo News reported, citing local officials.
So far, radioactivity has been detected on six people, whose faces and hands were wiped clean, the report said.