Damaged nuclear plants
Two nuclear plants at the coast of Fukushima Prefecture suffered damage from the earthquake and tsunami. Authorities have issued evacuation orders to people living within 20 kilometers of the first plant and within 10 kilometers of the second plant. Furthermore, people living within 30 kilometers of the first plant are asked not to remain indoors and close all windows.
No radiation dangerous to human health has been measured outside of the evacuation area. Prospective travelers to Japan should keep an eye on the quickly evolving matter, but avoid the sensationalist type of media as their source of information.
My Tokyo Guide Adventures 