Relying on government officials in an emergency may be hazardous to your health and well-being.
Nagaoka City, where the drill was carried out, is located in Niigata Prefecture, close to Kashiwazaki-Kariwa NPP. Good luck residents, because the governor of Niigata has declared he won't allow venting in a severe nuclear accident, even if it's the filtered vent, unless the municipalities and supposedly he himself approve.
NHK World (10/13/2013; emphasis is mine):
Nuclear disaster drill uses wind direction data
The Japanese city of Nagaoka has held a rather unusual evacuation drill for a nuclear disaster. The participants used data on wind direction to avoid exposure to radiation.
About 6,400 residents living close to the Kashiwazaki-Kariwa power plant in Nagaoka City took part in Sunday's drill.
Officials of the city's taskforce studied forecasts that said winds would blow to the southeast. They ordered the residents to escape to one of 3 evacuation centers not located on the downwind side.
But winds were observed blowing northward at an observation point in the middle of the city for about 30 minutes while the residents were on their way to the center in a bus.
This means the residents evacuated to a place relatively close to the direction in which radioactive materials were presumed to be spreading from the plant.
A city official in charge of nuclear safety, Yoichi Kojima, says he hopes to find ways to quickly determine escape routes while gauging the wind direction.
Tokyo Electric Power Company applied in September for safety screening of 2 of the idle reactors at the Kashiwazaki-Kariwa plant.
At present, all of Japan's 50 nuclear reactors have been taken offline, mostly for inspections.