The top level of the Fukushima No. 1 nuclear plant's No. 3 reactor building was opened to the news media on Nov. 21.

The Ministry of Economy, Trade and Industry along with plant operator Tokyo Electric Power Co. (TEPCO) guided reporters to the reactor building's top floor for a tour lasting about 15 minutes.

The building was badly damaged by a hydrogen explosion in the first days of the Fukushima nuclear crisis in March 2011. However, the debris has been cleared away, and radiation that had stood at 800 millisieverts per hour just after the reactor meltdowns was measured at 0.08 mSv/h on the 7-meter-high platform, on which fuel removal equipment and other devices have been installed, on Nov. 21. Closer to the fuel pool, the figure rose to 0.7 mSv/h. According to TEPCO, workers are limited to just one to two hours on the platform.

Fuel removal equipment is seen beneath a semi-cylindrical cover atop the No. 3 reactor building. (Mainichi)

The top floor is about 30 meters from the ground. The spent fuel pool currently contains 566 fuel assemblies, and preparations are underway to start the removal process as early as mid-fiscal 2018, with equipment for the job already installed on the platform. A net currently covers the pool to prevent anything -- or anyone -- from falling in.

A semi-cylindrical cover is also being constructed to prevent radioactive materials from escaping when fuel removal operations begin.