[STORY UPDATED 8:08PM PT, FOLLOWING THE CONCLUSION OF CHIEF CABINET SECRETARY SPOKESMAN YUKIO EDANO'S PRESS CONFERENCE.]
The smoke seen rising above from Fukushima's Daiichi nuclear power planet is believed to be emanating from reactor Unit 3, according to the Japanese government's chief spokesperson Yukio Edano who just completed a press conference moments ago. Due to high radiation levels, all workers were evacuated from the plant, and all work suspended for a time. [Update: Reuters now confirms that workers were allowed back in after radiation levels fell, as we'd originally reported.]
Edano said that at approximately 8:30am local time, white smoke began coming out of the No. 3 reactor, but that the joint task force between the government and the plant's operators, Tokyo Electric Power Co. (TEPCO), are still trying to determine the cause. It's believed the smoke is actually vapor coming from a rupture in the reactor's containment vessel, he said. Steam was to be let out to allow workers to pump in more sea water in hopes of keeping the reactor cool.
Earlier today there were reports of rising radiation levels near the gate of the facility, leading to the evacuation of all workers at the plant, leaving no one to fight the fire. Last night, all but 50 workers had been evacuated after an explosion at Unit 2 and a fire at Unit 4 (which had been off-line for maintenance prior to last Friday's earthquake and tsunami, and storing spent fuel rods in a pool which may have caught fire.)
While workers had suspended operations, radiation levels have since begun to decrease, Edano said. They have now returned to continuing pumping sea water into Units 1, 2 and 3 in the ongoing attempts to cool down the reactors' fuel rods following failure of their emergency cooling systems.
At the same time, TEPCO released a photograph of the damage at the reactor Unit 4 building following the explosion there on Sunday...