These have appeared at the main NEI Website. Note especially the link to the Fact Sheet about used fuel storage at Fukushima Daiichi:
UPDATE AS OF 4:30 P.M. EDT, WEDNESDAY, MARCH 16:
Japanese authorities have reported concerns today about the condition of the used nuclear fuel pools at Fukushima Daiichi reactor 3 and reactor 4.
Officials also are preparing to spray water into reactor 4 from ground positions and possibly later into reactor 3. Some debris on the ground from the March 14 explosion at reactor 3 may need to be removed before the spraying can begin.
Most plants store used fuel in steel-lined, concrete vaults filled with water, which acts as a natural barrier for radiation from the used fuel. The water also keeps the fuel cool while the radiation decays—or becomes less radioactive. The water itself does not leave the used fuel pool.
Used nuclear fuel at the Fukushima-Daiichi plant is stored in seven pools (one at each reactor and a shared pool) and in a dry container storage facility (containing nine casks.)
The used fuel pools are designed so that the water in the pool cannot drain down as a result of damage to the piping or cooling systems. The pools do not have drains in the sides or the floor of the pool structure. The only way to rapidly drain down the pool is to have structural damage of the walls or the floor.
For more information on used fuel pools, see our new fact sheet, “Used Nuclear Fuel Storage at the Fukushima Daiichi Nuclear Power Plant.”
The U.S. government on Wednesday recommended that Americans within 50 miles of the Fukushima Daiichi plant evacuate the area. The Nuclear Regulatory Commission has posted this news release on its website regarding the evacuation recommendation.
The information contained in NRC’s recent press release is new and industry is still evaluating the radiation dose calculations since there is little context for the numbers provided in the press release. On the surface, the estimated doses look to be extremely conservative, but we have no additional information on which to evaluate them.