Tokyo/Fukushima, Apr 8: At least four people were killed and 140 injured in the most powerful aftershock that jolted Japan since the devastating March 11 quake and tsunami, heightening concerns over the crippled Fukushima nuclear plant where engineers battled hard to tackle an atomic crisis.
The tremor with a preliminary magnitude of 7.4 hit the northern and central parts of Miyagi Prefecture, which was the worst affected by last month's magnitude 9.0 quake and tsunami, at 11:32 pm last night.
It triggered panic among residents already being sheltered at local facilities following the last month disaster that has left nearly 30,000 people dead in Japan's northeast.
After the quake, two men, aged 85 and 79 respectively, died in Miyagi while a 63-year-old woman was killed in the neighbouring prefecture of Yamagata, according to the Fire and Disaster Management Agency said. One more person was also reportedly killed in the affected region.
About 140 people were also injured, Jiji Press reported. The National Police Agency said five buildings were totally or partially destroyed in Miyagi and three each burnt down in Miyagi and Iwate.
Tohoku Electric Power Company said as many as four million homes lost power at one point and, despite its restoration effort, the outage continued across Aomori and Iwate and in some areas in Tohoku prefectures till this morning, affecting 3.04 million homes.
Radioactive water spilled from pools holding spent nuclear fuel rods at the Onagawa power plant in Miyagi Prefecture following the strong earthquake last night, the nuclear safety agency was quoted as saying by Kyodo news agency.
However, no abnormalities have so far been reported among nuclear power plants in the region as a result of the new quake. Some external power supply, however, was disrupted at suspended plants and a spent fuel reprocessing facility in Miyagi and Aomori prefectures, causing them to use backup generators.
A spent nuclear fuel disposal facility in the village of Rokkasho, Aomori Prefecture, lost external power supply and switched to an emergency generator but power was restored this morning, according to the government's nuclear safety agency.
The Higashidori nuclear power plant in another village in Aomori also got power from an emergency generator after last night's quake, but its external power supply was restored early this morning. There is also no information that radioactive materials had leaked due to the aftershock.
Higashidori's only reactor was undergoing regular maintenance at the time of the temblor and its fuel rods were not inside the core but stored in a spent fuel pool, the Nuclear and Industrial Safety Agency said.
The spent fuel pools at the Onagawa plant and Higashidori nuclear power station in Aomori Prefecture lost their cooling functions for 20 to 80 minutes after the quake, but their temperature hardly rose, it said.
The Onagawa plant also suffered water leaks at 8 locations, including water that spilled from spent fuel storage pools at each of its 3 reactors. A device to control pressure inside a turbine building was also damaged, national broadcaster NHK reported.
Tohoku Electric's Onagawa nuclear power station in Miyagi Prefecture, whose operations have been suspended since the March 11 quake, lost two of its three external power connections, while its cooling system for spent nuclear fuel pools temporarily stopped.
The Fukushima Daiici plant's operator Tokyo Electric Power Comnay (TEPCO), whose workers have been scrambling hard to stabilise the facility since the March 11 quake, said no new abnormalities have developed in any of the six reactors at the radiation-leaking power station and none of is workers there were hurt.
Its remarks came as engineers continued to pump fresh water into the No.1 to No.3 reactors to prevent them from overheating and inject nitrogen into the No.1 unit to avoid a possible hydrogen blast.
TEPCO also continued to release relatively low-level radioactive water into the Pacific Ocean to make room for far more contaminated water that has flooded the basement of the No.2 reactor's turbine building. The utility would discharge 8,000 tonnes of contaminated water.
The power company today solidified the earth around a cracked pit, from which highly radioactive water had leaked into the sea before it was successfully plugged by injecting sodium silicate or "water glass."
After the leakage stopped, the company observed a 7-cm rise in the level of contaminated water in a vertical tunnel connected to the No.2 reactor building, from which the tainted water is believed to have originated.
Following last night's quake, workers were temporarily evacuated from the crippled plant.
Now that a tsunami warning issued for the area has been lifted, the workers are inspecting the site.
Highly radioactive water that has been filling up underground trenches at the plant for days did not overflow, the nuclear safety agency aid.
TEPCO notified municipalities near the plant of the possibility of an increase in leaks of radioactive materials. PTI