After the 9.0-magnitude earthquake and tsunami in Japan, four of the troubled Fukushima Daiichi plant's six reactor units have seen fires, explosions or partial meltdowns, and workers are risking their lives day and night to try and cool the overheating reactors.
Low levels of radiation have been detected well beyond Tokyo (220km south of Fukushima) and the zone within 20km of the plant has been evacuated, while people within 30km were told to stay indoors; and yet officials insist that hazardous levels are limited to the plant itself.
The largest concentration of radioactive material which is found in this cloud is Iodine-131, which has a half-life of 8 days. This means that the amount of this substance will be dropped by a factor of two in 8 days. [Half or it will have decayed after 8 days, and half of that in another 8 days etc.]
2) Do you believe the experts will be able to contain the radiation leak and avoid a nuclear disaster? What is the long-term prognosis for Japan?