Radiation levels at the Fukushima Daiichi nuclear power station have dropped slightly, giving rise to hope that efforts to cool fuel rods in the unit 3 reactor have been successful.
From the air and from the ground, crews attempted to spray sea water into the storage pool of the unit through the hole in the building’s roof caused by an explosion at the reactor on Monday.
Aerial footage taken on Wednesday of the reactor showed extensive damage to the roof and walls of unit 3, and Tokyo Electric Power Company could not confirm whether the reactor’s cooling pool still contained water prompting the company to focus their efforts on the unit.
At 3.47pm (7.47pm NZT) a police water cannon truck attempted to fire water through the gap into the reactor, but the water could not reach the target and the operation was suspended, NHK World reported.
At 5.30 two Self Defence Force fire trucks were brought in and from 7.35pm (10.35pm NZT) to 8.09pm (11.09pm NZT) successfully sprayed three tonnes of sea water in to the troubled reactor.
Earlier in the day, two CH-47 Chinook helicopters, fixed with lead plates to protect the crew from the high radiation levels, sprayed four loads of 7.5 tonnes on the building from an altitude of 90m.
TEPCO said overnight the operations were effective, although radiation levels were only down slightly after the operation, according to NHK World.
In a press conference this morning, TEPCO said radiation dropped by nearly 20 points to 292 microsieverts per hour at 8.40pm (11.40pm NZT) at the west gate of the plant.
By 11pm (3am NZT) the radiation level dropped again to 289 microsieverts per hour and steam seen billowing from the unit 3 building after the water injection indicated the operation had been successful, the company said.
TEPCO said the operation would begin again today.
Situation not worsening
The International Atomic Energy Agency reported the situation at the plant remained serious but not significantly worsened in the wake of the operation.
TEPCO officials have asked to ramp up the efforts today with the help of the Japanese Government, the BBC has reported.
Meanwhile, efforts are continuing to restore emergency power to the stricken plant.
Hidehiko Nishiyama, an TEPCO spokesman, said a power line to the plant could be completed today or tomorrow, Kyodo News reports.
That will allow seawater to be injected into the storage pools for spent fuel at the plant’s reactors.
Spent fuel from a nuclear reactor generates intense heat and is typically stored in a water-filled spent fuel pool to cool it and provide protection from its radioactivity.
Those pools have been damaged and in some reported cases, completely drained, at some of the Fukushima plant’s reactors in the wake of the Japan earthquake and tsunami.
That means fuel can become exposed and create a risk of radioactive release or meltdown, the IAEA reports.
At the last reading, the water in the storage pool at its unit 4 reactor was 84C, according to the IAEA.
Temperatures of the storage pool water at units 5 and 6 are also above normal – at the last reading it was 62.7C in unit 5, and 60C in unit 6.
The water is usually 40C.
Death toll rises
Meanwhile, the death toll from the Japan earthquake and tsunami has risen to 5692, with nearly 10,000 people still missing in snow and freezing weather.
Japanese police have confirmed the rising toll as a humanitarian crisis escalates in the devastated north-east of the country.
It includes 3,158 people dead and 2,157 missing in Miyagi province – many from its capital city Sendai, NHK World News reports.
More than 305,000 people have sought refuge in about 2,260 shelters, the news service reports.
Many have voiced frustration at the Japanese Government’s efforts to provide essentials to those evacuees.
Governor of Fukushima prefecture, Yuhei Sato, said evacuation centres did not have enough hot meals, medical supplies or petrol.
“We’re lacking everything.”.
“Anxiety and anger felt by people have reached boiling point,” he said.