UPDATE 2:50 P.M. EST — NRC Chairman Gregory Jaczko had been quoted as saying that the spent fuel storage at Fukushima Daiici unit 4 is dry, and that high radiation levels around the unit could effect crews' ability to take "corrective measures."
Jaczko, in congressional testimony, also said he's received reports that the unit 3 spent fuel tank may have a crack in it that could lead to a loss of water inside.
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Workers at the Fukushima Daiichi nuclear plant were
evacuated briefly late Tuesday night after radiation levels at the gate of the
power plant peaked at 6.4 millisieverts per hour.
They returned after radiation levels fell again. Tuesday also
saw the Japanese government increase the legal radiation exposure for nuclear
workers to 250 millisieverts.
Tepco had cut the number of workers at the plant to just 50
following a fire Monday in unit 4 and subsequent increased radiation readings.
Crews continue to try vent steam and pump seawater into
units 1, 2 and 3 to prevent containment damage from excess pressure and heat.
Explosions have ripped through the outer buildings of all three reactors in the
last few days, indicating a buildup of hydrogen that could be caused by water
contacting damaged fuel cladding.
The New York Times reported Tuesday that the U.S. military has
helped put out fires at the plant, and other news agencies indicated U.S.
forces may be asked to increase their assistance at the plant.
For more information on units at Fukushima Daiichi, please see the updated reactor status list in our most recent post.