I was reading on the MITNSE blog this morning how the Japanese government/TEPCO was using Chinook helicopters to drop water on the stressed reactors. From the post:

Crews began aerial water spraying operations from helicopters to cool reactor 3 at Fukushima Daiichi shortly before 9 p.m. EDT on Wednesday, March 16. The operation was planned for the previous day, but was postponed because of high radiation levels at the plant. News sources said temperatures at reactor 3 were rising. Each helicopter is capable of releasing 7.5 tons of water. Spokesmen for TEPCO and Japan’s regulatory agency, Nuclear and Industry Safety Agency, on March 17 Japan time refuted reports that there was a complete loss of cooling water in the used fuel pool at Fukushima Daiichi reactor 4. Listening to Anderson Cooper on CNN and Rachel Maddow on MSNBC last night, I remembered a few facts. These spent nuclear fuel pools are large, much bigger than a normal swimming pool, and much deeper. CNN said about 40 feet deep of water, at least. Now my parents used to have a swimming pool at their old house, in their back yard. It was a standard 20 x 40 foot swimming pool. This is by far the most common size for a swimming pool that would be at a residential home. I specifically remember that our pool took 33,000 gallons of water to fill it. In the "deep end" of the pool, it was 9 1/2 feet deep. The "shallow end" was 3 1/2 feet. I'm going to hypothesize, given that these spent nuclear fuel pools are rectangular, and have no "shallow end", and are over 40 feet deep, that they have a LOT more water in them (or are supposed to have). I'm going to guess that it would take many more times the water from my parents' old pool to fill them. How much? 5 times (165,000 gallons)? 10 times (330,000 gallons)? More? No idea...but a lot. Now - from the MITNSE article quoted above, they were dropping 7.5 tons of water on this pool at a time. I watched it happen live and the commentators said that they made 4 drops before giving up. Why did they give up? They mostly missed their target. Why did they miss? Because the helicopters cannot get low enough to the ground to accurately drop their water without exposing the helicopter crews to too much radiation. So most of the water missed. Seven and a half tons of water sounds like a lot. But in the back of my mind, I was suspicious. I kept asking myself, doesn't water weigh a lot to begin with? After a bit of quick math, I determined that 7.5 tons of water is 15,000 pounds. One gallon of water is approximately 8.35 lb therefore 15,000 pounds of water is 1,796.4 gallons of water. So in a pool that is at least over 33,000 gallons - probably more like 100,000-500,000 gallons, they're attempting to drop less than 2000 gallons on it at a time, from several hundred feet in the air and only hit the target with 1 of 4 attempted drops. You really have to ask yourself of the competency of the Japanese nuclear regulatory officials and TEPCO at this point. Or are they just doing things like this for the benefit of the cameras because they've completely lost control of the situation and have run out of ideas?