"No. 1 plant's air radiation highest measured so far"
"Tepco said Saturday it has detected radiation of up to 4,000 millisieverts per hour at the building housing the No. 1 reactor at the Fukushima No. 1 nuclear plant.
The radiation reading, which was taken when Tokyo Electric Power Co. sent a robot into the No. 1 reactor building on Friday, is believed to be the largest detected in the air at the plant so far.
On Friday, Tepco found that steam was spewing from the reactor floor. Nationally televised news Saturday showed blurry video of steady smoke curling up from an opening in the floor.
...Tepco has said radioactive water could start overflowing from temporary storage areas on June 20, or possibly sooner if there is heavy rainfall.
...Several explosions have scattered radioactive debris around the plant, and reactors are spewing radiation into the air.
...Nuclear fuel rods are believed to have melted almost completely and sunk to the bottom of three reactors' containers, although falling short of a complete meltdown, in which case the fuel would have melted entirely through the container bottoms."