Black smoke rising from the No. 3 reactor at the crippled Fukushima No. 1 nuclear power plant Wednesday suspended work to cool reactor cores and storage pools containing spent fuel rods.
Black smoke rising from the No. 3 reactor at the crippled Fukushima No. 1 nuclear power plant Wednesday suspended work to cool reactor cores and storage pools containing spent fuel rods.
No fire was confirmed.
Workers in the buildings housing the No. 3 and No. 4 reactors who were trying to restore an outside power source were temporarily evacuated.
Officials of Tokyo Electric Power Co., which operates the Fukushima plant, said there was no noticeable change in radiation levels in the plant vicinity before and after the smoke was spotted.
Before the smoke, workers battling high radiation levels to restore power to the reactors at the plant said they were making headway.
Progress was notable at the troubled No. 3 reactor. Officials of TEPCO, which operates the quake-stricken Fukushima plant, said they planned to resume operating a pump to deliver fresh water to the reactor core by Thursday at the earliest.
TEPCO officials released photos of the central control room of the No. 3 reactor after lighting was restored there Tuesday evening.
Lighting was restored after electricity from an outside source was connected to the central control room, which made monitoring of vital equipment that much easier.
An outside power source to the monitoring equipment in the No. 4 reactor was restored at 9:52 p.m. Tuesday and to the monitoring equipment in the No. 1 reactor at 1:40 a.m. Wednesday. Work to resume operations of the central control rooms for those two reactors is also continuing.
The upper part of the building housing the No. 3 reactor was damaged in a hydrogen explosion, but pictures released by TEPCO officials showed little damage to the central control room that is located next to the reactor building.
Electrical connections from an outside source have been made to all six reactors at the Fukushima No. 1 plant.
Work is continuing to prepare for transmitting electricity to equipment at the No. 1 to No. 4 reactors.
However, work at the No. 2 reactor is stymied by water-soaked equipment and high radiation levels in the building housing the turbines.
Although an aftershock with an intensity of upper 5 on the Japanese scale of 7 was recorded in Iwaki, Fukushima Prefecture, south of the nuclear plant on Wednesday morning, it did not affect the reactors.
TEPCO officials also said the temperature in the core of the No. 1 reactor had risen to about 400 degrees, above the design limit of 302 degrees. The amount of seawater supplied to the core was increased early Wednesday from 2 cubic meters an hour to 18 cubic meters an hour.
The Self-Defense Forces were also planning to conduct surveillance of the No. 1 reactor from Wednesday afternoon by using a vehicle designed to protect against chemical exposure.
Meanwhile, work continued Wednesday to spray water on the storage pool containing spent fuel rods at the No. 4 reactor. A special truck used in construction projects to pour liquid concrete by remote control from a height of 50 meters was used again.
On Wednesday, 35 tons of seawater was pumped through pipes into the storage pool at the No. 3 reactor. Similar measures will be taken to pump in seawater on Thursday to the No. 4 reactor and on Friday to the No. 1 reactor.
TEPCO officials also revealed that neutron rays were observed on 13 occasions near the main entrance of the Fukushima plant between March 13 and 15.