OKUMA, FUKUSHIMA PREF. – Making his first public appearance since the nuclear accident at the Fukushima No. 1 power plant in March, the facility’s general manager, Masao Yoshida, apologized for failing to prevent the triple meltdowns but emphasized that conditions at the plant have “definitely been stabilized.”
Yoshida met reporters at the wrecked power station as Tokyo Electric Power Co., the plant’s operator, allowed reporters to visit the facility for the first time since the March 11 earthquake and tsunami triggered the nuclear crisis.
“The first thing I would like to do is to apologize to the people of Fukushima and in the whole of Japan for causing them great trouble,” Yoshida said.
Yoshida has led the workers trying to contain the Fukushima No. 1 plant’s stricken reactors since the first day of the nuclear crisis. He confessed that he almost gave up on several occasions, and in the first days of the disaster he even feared he could die from excessive radiation exposure.
“Several times during the first week of the crisis, I thought I would soon die,” Yoshida said.
But further hydrogen explosions in the reactor units were prevented and the containment vessels of all three stricken reactors, despite emitting massive amounts of radioactive materials into the environment, have retained most of the melted fuel within the reactor units.
Yoshida pointed out that the temperature at the bottom of the pressure vessels in the three worst-hit reactor units has been kept below 100 degrees for a number of weeks, which means contaminated coolant water is no longer boiling and releasing large amounts of radioactive materials.
“Stabilizing the reactors doesn’t mean the plant can be considered safe. Radiation levels in the compound are still quite high, and it remains dangerous for workers at the site,” Yoshida said. “But the plant has been stabilized sufficiently to ease the fears of local residents to some extent.”
Many nuclear experts basically agree with Yoshida’s views on the current situation at the plant, saying the stable temperatures in the reactors’ pressure vessels makes further large-scale leaks of contaminated materials from the damaged reactors much less likely.
But they also stressed that long-term concerns remain over the strength of the damaged structures and the ad hoc systems that inject coolant water into the plant’s reactors and circulate it, as Tepco will need to keep cooling the reactors with water for at least ten years before the radioactive substances they contain start to decay and weaken, allowing the utility to remove the melted fuel from the reactors.
“In the short-term, it can be said that people don’t need to worry about large emissions of radioactive materials any more,” said Tadashi Narabayashi, a professor of nuclear reactor engineering at Hokkaido University.
“But the coolant water circulation system, which is essential to ensure the safety of the Fukushima plant, has to keep operating smoothly. More work is necessary to protect the plant from another tsunami or earthquake,” Narabayashi told The Japan Times.
On Saturday, two buses carrying reporters, photographers and TV cameramen dressed in white protective gear and wearing full-face masks were allowed to enter the Fukushima plant’s compound. The media tour gave journalists a chance to get close to the damaged reactor buildings and examine their outer structures.
Eight months after 13-meter tsunami swept in from the coast, broken windows still haven’t been repaired in many buildings as Tepco is still concentrating its resources on critical facilities such as the coolant injection and circulation systems for the reactors and the spent fuel pools.
A truck and several other vehicles that were swept up by the monster waves were seen still lying abandoned Saturday near a turbine building facing the sea.
The wrecked reactor buildings, whose iron frames were grotesquely bent and twisted, gave reporters on the media tour an indication of the magnitude of the hydrogen explosion that ripped through the reactor buildings of units 1, 3 and 4 soon after March 11.
The damaged building of unit 4 appeared especially vulnerable in the even of a major aftershock. The upper parts of its concrete walls were almost completely destroyed, and a large crane could be seen above a spent fuel pool.
Kenji Sumita, a professor emeritus at Osaka University and a former deputy chief of the Nuclear Safety Commission of Japan, is also concerned about the vulnerability of the No. 4 unit. “If the spent fuel pool collapses, it would be a disaster,” he said in a phone interview.
Tepco, however, concluded that the quake-resistance of the unit 4 building is sufficient to guard against any large aftershocks, after conducting a computer simulation in May.
In July, Tepco also completed construction of concrete walls and iron pillars that support the bottom part of the spent fuel pool.
On weekdays, about 3,000 workers are undertaking repair work at the Fukushima No. 1 plant, and around 1,500 at weekends.
“What we actually feel here is that the Fukushima No. 1 plant has been stabilized,” Yoshida told Goshi Hosono, minister in charge of the nuclear crisis, during a meeting Saturday at the complex. “If this were not the case, I would refuse to allow thousands of workers to come to the plant and work here.”