Seems you can pretty much send the family anyplace you are comfortable with. This rule is correct; the family talks it over and decides where they want to go, back home or to a location closer to Japan. Taipei is not quite a 4 hour flight from Tokyo.
You can read the latest evacuation news from Japan in the Pacific Edition of Stars and Stripes.
I decided to look at the possibility of heading for Taiwan under the "Voluntary Evacuation" program.
I would have been one of the first to put my folks on the plane if I was stationed in Japan. It's just not worth taking a chance, anything could happen. Those nuclear plants are already a disaster, what else might happen.
Taiwan Per Diem rates are very sufficient, especially in Taipei.
Interesting to see how it could work out.