the drill was held north of tokyo, at the nuclear power plant in niigata prefecture. about 1500 people took part. the participants included central and local government officials as well as residents within a 30 kilometer radius of the plant. the drill assumed the quake had increased the risk of a radiation leak. the details were not given. the plant's operator, tokyo electric power company, set up a task force. workers rushed to confirm that emergency generators used for cooling reactors were working. and there were no other problems. at the prefectureal office officials were divided over how to evacuate residents. the niigata governor said they should evacuate immediately while radiation levels were low. but a central government official said they should stay indoors. health officials practiced making iodine medicine, used to protect young children's thyroid glands from radiation exposure. >>> japanese scientists say they have developed a method to detect alzheimer's disease in its early stages from just a few drops of blood. scientists at the national center for ge