BBC: For the first time since the Tohoku earthquake of 11 March, workers have entered the Fukushima Daiichi power plant. Twelve engineers will work inside the number 1 reactor building in 10-minute shiftsfour people at a timeto install ventilation systems to filter out radioactive material from the air. The quake disabled reactor cooling systems, which caused fuel rods to overheat, but radiation levels must be lowered before new cooling systems can be installed. The Tokyo Electric Power Company plans to begin ventilation later today and then connect a new, external cooling system to reduce temperatures inside the building.