TOKYO — The Japanese government on Tuesday raised the Fukushima nuclear accident level from five to seven, the same severity assigned to the Chernobyl disaster, Kyodo News reported.
The crippled Fukushima nuclear plant had been releasing up to 10,000 terabecquerels of radioactive materials per hour following the massive earthquake and tsunami on March 11.
Preliminary estimates from the Nuclear Safety Commission of Japan (NSC) released Monday night suggested that more radiation than was previously thought might have escaped in the initial hours after the quake.
However, the government said that the amount of radioactive substances released from Fukushima was 10 percent of the amount released in the aftermath of Chernobyl.
“In terms of volume of radioactive materials released, our estimate shows it is about 10 percent of what was released by Chernobyl,” a nuclear safety agency spokesman said.
The 1986 meltdown at Chernobyl in the then-Soviet Union spewed a large volume of toxic radiation, poisoning large areas of land and affecting thousands of lives. The exact number of people who subsequently died prematurely from radiation exposure is not known but it was believed to be in the tens of thousands, at the least.
One week after Japan’s twin disasters, the agency rated Fukushima’s problems a five, the same as the Three Mile Island nuclear accident in the US in 1979. No one died in the incident in Pennsylvania, where the plant is still operating.
Workers struggling to prevent a nuclear catastrophe at the Japanese plant have been hampered by risks of radiation contamination and repeated aftershocks, some of them triggering tsunami warnings.
On Tuesday morning, a fire broke out a reactor No. 2 but it was quickly extinguished. Plant-operator Tokyo Electric Power Co. (TEPCO) said it did not detect any changes in radiation levels at the reactor during the blaze.
Earlier in the day, a strong offshore earthquake rocked Tokyo, swaying buildings in the Japanese capital and stopping subway services, AFP reported.
The US Geological Agency put the magnitude at 6.4, at a depth of 8.1 miles (13.1 kilometers), 48 miles (77 kilometers) east of Tokyo. The Japan Meteorological Agency had measured it at 6.3.
The quake hit at 8:08am local time off the coast of Chiba prefecture, just east of the capital. There were no immediate reports of fresh damage, and no tsunami warning was issued.
Subway services in Tokyo temporarily stopped, but resumed operations shortly afterwards. The shinkansen bullet train services running to the northern region were briefly interrupted.
The runways of Narita international airport in the prefecture were temporarily closed for checks but later reopened, Kyodo said.
Japan has experienced more than 400 aftershocks stronger than magnitude 5.0 since March 11.
On the tragedy’s one-month anniversary Monday, a strong aftershock, measuring 7.1 on the Richter scale, struck the region, triggering mudslides which killed four people, broadcaster NHK reported.
In Iwaki City, rescuers found a 16-year-old girl dead and three of her family members, trapped inside a house, seriously injured.
Another two bodies — believed to be a man, 63, and his mother, 84 — were recovered from a nearby house also buried by mud.
In neighboring Ibaraki prefecture, a man, 46, was found unconscious at a parking lot where he apparently fell during the tremor and hit his head. He was taken to a hospital and later confirmed dead.
As of Monday, 26,848 people were listed as dead or missing since the twin disasters, the National Police Agency said. The number excludes the four who were killed Monday but includes other deaths from aftershocks since March 11.
About 83 percent of bodies have been identified and handed over to family members, while the number of people reported missing stood at 13,718.