data that comes into the center. we have the terrain, land use, the kind of buildings and structures available. we use all that information to basically attempt to estimate the impact that occur downwind from the release point. >> how quickly can you track what it is and where it's going? >> so the models will typically run fast in five to ten minutes, we get a close picture to what occurred on the ground. >> winds over japan have been blowing eastward to the pacific coast. the information from narac is vital to federal officials who would decide whether to move anyone out of the potential danger zone. >> that is used by decision makers whether they're emergency responders, firefighters, police departments, state emergency operation centers, the federal government giving advice on where you should take basic actions basically to protect the environment or the public. >> four reactors are at risk. if they fail, something scientists are furiously trying to prevent, you could effecti