This story is part of a special series that explores energy issues. For more, visit The Great Energy Challenge. Their faces obscured by breathing masks, workers pore over data in the control room for the now-ruined Unit 1 and Unit 2 reactors at Japan's Fukushima Daiichi nuclear power plant on Wednesday. Although some power has now been restored to the facility, the workers known as the Fukushima 50 face a difficult job getting pumps and circuits to operate the crucial systems that provide cooling for the reactors and the spent fuel stored on site. The photos released by Japan’s Nuclear and Industrial Safety Agency are the first look inside the plant since the devastating March 11 earthquake and tsunami that flooded the facility and crippled the backup generators needed to cool the radioactive fuel. (Related: "Would a New Nuclear Plant Fare Better than Fukushima?") —Marianne Lavelle