TOKYO — Japan is preparing to expand the evacuation zone around a crippled nuclear power plant to address concerns over long-term exposure to radiation, the government announced Monday.
Thousands of people bowed their heads in silence Monday at 2:46 p.m. local time, marking the passage of exactly one month since a magnitude-9.0 earthquake and ensuing tsunami brought widespread destruction to a wide swath of Japan’s northeast Pacific coast.
The mourning was punctuated by another strong aftershock off Japan’s Pacific coast that briefly set off a tsunami warning, killed at least one person and knocked out cooling at the crippled Fukushima Daiichi Nuclear Power Plant for almost an hour, underscoring the vulnerability of the plant’s reactors to continuing seismic activity.
Japanese authorities have already ordered people living in a 12-mile radius around the plant to evacuate, and recommended that people avoid the area within a wider radius of 18 miles. The government’s new measures on Monday came in response to high readings of radiation in certain spots beyond those areas, highlighting how difficult it has been to predict the ways radiation has spread from the damaged plant.
Instead of spreading in even circles from the plant, the radiation has been directed to some areas and not others by weather patterns and the terrain. Iitate, one of the communities told Monday to prepare for evacuation, lies well beyond the 18-mile radius, but the winds over the past month have tended to blow northwest from the Fukushima plant toward Iitate, which may explain why high readings were detected there.
Yukio Edano, the government’s chief cabinet secretary, said that the government would order Iitate and four other towns and villages to prepare to evacuate.
The fear is that these areas are being exposed to radiation equivalent to at least 20 millisieverts a year, he said, which could be harmful to human health over the long term. Evacuation orders will come within a month for Katsurao, Namie, Iitate and parts of Minamisoma and Kawamata, Edano said.
People in five other areas may also be told to evacuate if there is a worsening of the crisis at the Fukushima Daiichi station, Edano said. Those areas are Hirono, Naraha, Kawauchi, Tamura and other sections of Minamisoma.
“This measure is not an order for you to evacuate or take actions immediately,” he said. “We arrived at this decision by taking into account the risks of remaining in the area in the long term,” he added, appealing for calm.
He said that the chance of a large-scale radiation leak from the Fukushima Daiichi plant had, in fact, decreased.
Edano also said Monday that pregnant women, children and hospital patients should stay out of the 18-mile radius, and that schools in that zone would remain closed.
The Japanese government had so far refused to officially widen the zone, despite urging from the International Atomic Energy Agency. Countries like the United States and Australia have advised their citizens to stay 50 miles from the plant.
Norio Kanno, the mayor of Iitate, expressed dismay at the evacuation order.
“A full evacuation, a hollowing out of the village, is something I would have liked to avoid,” Kanno told the public broadcaster, NHK.
Monday’s aftershock came on the heels of Edano’s announcement. The U.S. Geological Survey measured the aftershock’s magnitude at 6.6, only about one hundred-thousandth the strength of the March 11 quake, and the tsunami warning was lifted after 45 minutes when no sizable waves were detected. Still, the temblor touched off a landslide that killed a 16-year-old girl.
It also caused a spate of other injuries and left 220,000 homes in three prefectures in the areas without power, including those already experiencing blackouts in the aftermath of the March 11 quake, according to the public broadcaster, NHK.
The extent of the blackouts following the March 11 quake and its many aftershocks illustrate the vulnerability of Japan’s power grid to seismic shocks. Almost 4 million households lost power immediately following last month’s quake. That weakness is in stark contrast to the stringent building standards that experts say may have helped limit structural damage to homes and businesses. Most of the deaths last month were caused by surging tsunami waves, not by falling buildings.
Monday’s aftershock again knocked out the external power supply to the Fukushima Daiichi plant, temporarily stopping pumps there from sending cooling water into the facility’s three most severely damaged reactors, according to Japan’s nuclear regulator. The tsunami warning also obliged workers at the plant to evacuate temporarily.
Using emergency pumps to cool the nuclear fuel rods within the reactors and in spent-fuel pools above the reactors has been a top priority for the operator of the plant, Tokyo Electric Power Co., since the March 11 quake and tsunami damaged the reactors’ usual circulation systems. But Monday’s aftershock appeared to have exposed a big vulnerability in that approach.
The backup power and pumping systems that have been brought to the plant since March 11, including emergency diesel generators, fire trucks on standby and other generator trucks — all require workers to operate them manually, according to the Nuclear and Industrial Safety Agency. That makes them useless when workers must evacuate the reactors.
Hidehiko Nishiyama, deputy director-general of the Nuclear and Industrial Safety Agency, Japan’s nuclear watchdog, acknowledged the lack of an automatic backup power supply, but did not offer any solutions.
