steady smoke curling up from an opening in the reactor floor.

http://www3.nhk.or.jp/daily/english/04_16.html

Steam, high radiation detected at No.1 reactor
The operator of the damaged Fukushima Daiichi nuclear plant says steam was observed coming out of the floor of the No.1 reactor building, and extremely high radiation was detected in the vicinity.

Tokyo Electric Power Company inspected the inside of the No.1 reactor building on Friday with a remote-controlled robot.

TEPCO said it found that steam was rising from a crevice in the floor, and that extremely high radiation of 3,000 to 4,000 millisieverts per hour was measured around the area. The radiation is believed to be the highest detected in the air at the plant.

TEPCO says the steam is likely coming from water at a temperature of 50 degrees Celsius that has accumulated in the basement of the reactor building.

The company sees no major impact from the radiation so far on ongoing work, as it has been detected only within a limited section of the building.

The No.1 reactor is believed to have suffered a meltdown after the March 11th earthquake and tsunami.

It is believed to have created holes in the pressure vessel and damaged the containment vessel, causing highly contaminated water to leak out and accumulate in the basement.

Under the utility's plan to bring the plant under control, a circulatory cooling system is to be installed to decontaminate radioactive water and use it as coolant.
Saturday, June 04, 2011 13:23 +0900 (JST)

More details here here on record radiation reading

http://www.mercurynews.com/business/ci_18205241?nclick_check=1