That “stain” is water, plain and simple. I have lived by the plant my whole life, and been there many times. Whenever it rains the water stains the side like that. The last report that I saw and the guys that I know that work at the plant said it was turbine #2. In regards to what someone said about nuclear power, this is a coal plant (the largest in the country and second in the Western Hemisphere). Only a few minor wounds, most were treated on site. A lot of emergency crews were dispatched from neighboring counties but only remained for an hour or two. A lot of people are being kept on site though (the restaurant I work at sent food) and I herd reports of a few stranded on various floors, but I’m not sure.
Odd the other towers were not similarly “stained” with water