Work to restore an outside electric power source resumed Tuesday morning at the crippled Fukushima No. 1 nuclear power plant after smoke from two reactors halted operations Monday.
Work to restore an outside electric power source resumed Tuesday morning at the crippled Fukushima No. 1 nuclear power plant after smoke from two reactors halted operations Monday.
Workers were temporarily evacuated on Monday after black smoke was observed spewing from the No. 3 reactor and white smoke was seen rising from the No. 2 reactor.
Officials of Tokyo Electric Power Co., the operator of the Fukushima plant, said Tuesday that almost no smoke was billowing from the No. 2 reactor on Tuesday morning. They also said that black smoke could not be confirmed emerging from the No. 3 reactor.
TEPCO officials concluded Tuesday there was no danger to resuming work to restore electric power because radiation levels near the Fukushima plant had not changed drastically from earlier in the morning.
TEPCO officials said the near-absence of smoke from the No. 2 reactor on Tuesday morning and the fact that smoke from the No. 3 reactor had turned from black to white indicated the situation was settling down.
TEPCO officials determined that steam, not smoke, was now being emitted.
Work to restore an outside power source to the No. 3 and No. 4 reactors began around 7 a.m. Tuesday, while efforts to restore electricity to the No. 1 and No. 2 reactors got under way from about 8 a.m.
A cable has already been connected to the No. 2 reactor that can provide electricity from a power transmission line. Workers are now checking the central control room that operates and monitors the reactor and replacing damaged equipment parts before taking the crucial step of restoring the outside power source.
TEPCO officials plan to restore electric power to the No. 2 reactor on Wednesday.
Cables were also connected to the No. 3 and No. 4 reactors. TEPCO officials confirmed at 10:35 a.m. that an electrical connection was operational with the No. 4 reactor. Technicians were gearing up to check equipment for damage before starting the flow of electricity.
They were also weighing whether to resume water-spraying operations for the No. 3 and No. 4 reactors.
In addition to water spraying by the Tokyo Fire Department and the Self-Defense Forces, TEPCO workers were also preparing a concrete pump vehicle that can spray water by remote control from a height of about 50 meters.
The radiation level near the main entrance to the Fukushima plant about 1 kilometer from the No. 2 reactor was 264 microsieverts per hour as of 6 a.m. Tuesday. The radiation level had risen to 1,932 microsieverts per hour as of 6:30 p.m. Monday, but had begun decreasing thereafter.
The No. 5 reactor switched to an outside power source on Monday, allowing for regular cooling of the reactor core. TEPCO officials also want to switch the No. 6 reactor to an outside power source by the end of Tuesday. The No. 6 reactor is now using a diesel generator that is ordinarily used in emergencies.
Meanwhile, Bill Borchardt, the executive director of operations at the U.S. Nuclear Regulatory Commission, said at a meeting Monday that the situation at the Fukushima plant was stabilizing.
"I would say optimistically that things appear to be on the verge of stabilizing," Borchardt said.
Borchardt gave as reasons for his optimistic outlook the fact that the function to contain radioactive materials appeared to have been maintained at the three reactors, including the No. 2 reactor. The suppression pool connected to the core containment vessel of the No. 2 reactor is believed to be damaged.
He also said the pumping of seawater to cool the reactors was another factor for the assessment.