http://www.stripes.com/first-militar...and+Stripes%29

About 233 of the 240 seats on the flight from Yokota to Seattle were filled, according to the Air Force, which said it was able to place all residents who wanted to leave Saturday on the flight.
As of 3 p.m. Saturday, 556 people at Yokota have signed up for the flights, according to the base public affairs office. There are expected to be 11 flights between now and March 27 out of Yokota.
Misawa base officials couldn’t say by 2 p.m. Saturday how many family members they think will want to fly out of Misawa. They were also still coordinating flights, and were unable to predict when the first planes carrying families would depart.
Misawa AB is the closest USFJ installation to the reactors, and a reasonable candidate IMHO for mandatory NEO.

At Naval Air Facility Atsugi, near Tokyo, officials began mustering families with pregnant women, infants and special needs at the base movie theater around 9:30 a.m., only to cancel the muster shortly afterward. Dozens of families had shown up at the theater with their luggage and pets. Officials issued a statement apologizing for the inconvenience, stating that things are very fluid right now.

Base officials were meeting Saturday afternoon to discuss departure times for the first flights.
USAEUR did no NEO for Chernobyl. By the time they knew what had happened everybody had pretty much absorbed their dose, sucked it up and drove on.