A worker at Japan's troubled Fukushima Daiichi nuclear plant has died, but Tokyo Electric Power says his body shows no signs of radiation overexposure. Still, the first death in the effort to stabilize the reactor raises concerns about conditions at the plant, where workers must operate in a cramped and sweltering environment and rotate in and out so as not to be exposed to dangerous levels of radiation. Tepco says the worker, a subcontractor in his 60s, had begun work at the plant only the day before. He had been exposed to 0.17 millisieverts of radiation on Saturday, about the equivalent of a chest X-ray, and no radioactive material was found on his body. The cause of death is unknown.