In the days following Japan's March 11 earthquake, the Fukushima Daiichi nuclear plant there suffered increasing damage as its cooling systems failed, probably causing a buildup of hydrogen gas that led to explosions at three of its reactor units.

Since then, the Japan Self Defense Force and National Police Agency have worked to refill the power plant's spent-fuel pools with water, but a Japan Atomic Industrial Forum (JAIF) statement on March 18 said it is unclear how much coolant has reached the pools. The JAIF statement also said their monitors in the area have not detected radiation levels high enough to have an immediate effect on human health.

View a slide show of day-by-day satellite views of the power plant site.