The Yomiuri Shimbun
Work to restore electricity to power cooling systems of the troubled reactors at the Fukushima No. 1 nuclear power plant resumed Tuesday morning, 16 hours after all workers were evacuated because gray smoke--raising fears of a fire--was seen rising from the No. 3 nuclear reactor.
Though occasional thin white smoke was still observed at the Nos. 2 and 3 reactors in the morning, Tokyo Electric Power Co., operator of the quake-hit nuclear plant, judged it safe to resume restoration work because it believed the white smoke was not caused by fire and that radiation levels had decreased.
However, since the cause of the smoke was unknown, the situation at the plant remained unpredictable, added the utility.
TEPCO and the Nuclear and Industrial Safety Agency said operations to restore power resumed at the Nos. 1 to 4 reactors at about 8 a.m.
At the No. 4 reactor, workers confirmed at 10:35 a.m. that electricity reached the switchboard-cum-transformer at its turbine building.
At the Nos. 1 and 2 reactors, which already had been connected to external power, workers checked instruments and electrical systems in preparation for distributing electricity. They prioritized restoring power to the No. 2 reactor, whose pressure suppression chamber under its containment vessel has apparently been damaged. Lighting and functions of meters and gauges in the reactor's central control room would be restored by the end of Wednesday, TEPCO added.
Workers were expected to restore instrument functions at the Nos. 3 and 4 reactors central control rooms by Thursday.
TEPCO added it would switch the No. 6 reactor power source from an emergency generator to an outside power source Tuesday afternoon.
Work to restore power at those reactors was suspended after gray smoke was observed at the No. 3 reactor at 3:55 p.m. Monday. White smoke also rose from the No. 2 reactor shortly after 6 p.m. that day.
"Smoke at the No. 2 reactor is believed to be steam from sprayed water," Defense Minister Toshimi Kitazawa said Tuesday. "However, smoke at the No. 3 reactor is likely due to residual materials such as oil inside [the facility], which burned briefly as temperatures there rose."
Meanwhile, a special squad of the Tokyo Fire Department postponed spraying water into the No. 3 reactor's fuel storage pool from Tuesday morning to the afternoon because smoke was observed there Monday.
On Tuesday afternoon, TEPCO began a water dousing operation at the No. 4 reactor with a German-made squeeze pump that can spray water over a long distance using a 58-meter-long arm. The Self-Defense Forces said they would decide whether to blast the No. 4 reactor with water after studying the progress of TEPCO's restoration work.
Meanwhile, TEPCO said the radiation level at the plant's front gate, which is one kilometer west of the Nos. 2 and 3 reactors, decreased to 257.5 microsieverts per hour at 11 a.m. Tuesday, from 1,932 microsieverts at 6:30 p.m. Monday after the gray smoke was emitted from the No. 3 reactor.
(Mar. 23, 2011)
No comments:
Post a Comment