there's huge defense and depth on these plans. they were designed to operate through an 8.2 quake. they survived this earthquake the tsunami took out some of the back-up systems. the ultimate back of up has been the reactor containment which are working. seawater option was built into the plant. this was not anticipated. it is something you don't want to do. you don't want to put seawater into the facility. but it was planned as an ultimate back-up if you needed it and it is working. >> sean: we hearing meltdown. when we talk about nuclear anything, that i assume people's minds go towards nuclear explosion of some kind. >> there's no question about that sean. a meltdown is basically a nuclear engineering term which simply means that the heat from the radioactive decay is