cannons as opposed to the helicopter drops. that means putting more personnel in harm's way. the u.s. military helped a japanese crew to learn how to use two water cannons the military had. they have donated those. but it is very difficult. they are trying to pour -- literally pour water on top of these fuel rods to get them covered to cool them down. but at great personal risk to themselves. i want to bring in dr. sanjay gupta. what is the greatest risk for people in the outlying areas? >> well, the greatest risk is that these radiation levels we've been talking about start to go up. you try to cool down these rods, but that's a continuous process. are they going to continue shooting water at it? it doesn't make a lot of sense for the longer term. the radiation levels go up, if they get higher into the air and can disburse more as a result of that, then these evacuation