May 5, 2011
Workers at Japan’s Fukushima nuclear plant have entered one of its reactor buildings for the first time since it was hit by a powerful earthquake on 11 March, officials say.
They are installing ventilation systems in the No 1 reactor to filter out radioactive material from the air.
The quake disabled reactor cooling systems, causing fuel rods to overheat.
Radiation levels inside reactor buildings must be lowered before new cooling systems can be installed.
The No 1 reactor was one of four damaged by explosions in the days immediately after the earthquake and tsunami. Water is being pumped in to cool the reactors.