Fukushima Daiichi Nuclear Power Plant
After the back-up diesel generators pumps broke down, emergency batteries ran low after about eight hours. Batteries from other nuclear plants were sent to the site and mobile electric and diesel generators arrived within 13 hours, but work to connect portable generating equipment to power water pumps was still continuing. The diesel generators  would normally be connected by switching gears in a basement area of the power station's buildings, but this had been flooded by the tsunami.