>> reporter: unlike chernobyl, these japanese reactors are surrounded by six-foot steel and concrete containment vessels, so even multiple reactor meltdowns would not likely be as bad as chernobyl, but if there were meltdowns, how far could the radiation travel? >> if the wind is blowing out to the ocean, as it usually does, then most of the contamination goes out there. if the wind shifts south, well, then all that -- some of the most heavily populated areas of japan are at risk including tokyo itself. >> reporter: how about the u.s.? >> the fires could be so hot that it would send radioactive particles carrying it across the pacific. >> reporter: the nuclear regulatory commission says even if that happened, there is a low likelihood that any harmful radiation would reach the u.s. or its territories. but uncertainty could continue for weeks in a scenario where there is no meltdown but the reactors are not stabilized either. martha raddatz, abc news, washington. and now we turn to what can only be called an absolute