Tokyo Electric Power Co. started a yearlong operation Monday to remove hundreds of nuclear fuel assemblies stored atop reactor 4 at the Fukushima No. 1 power plant to prevent the rods from causing another radiation catastrophe.

The building housing reactor 4 was hit by a hydrogen explosion in the early stages of the triple meltdown triggered by the March 11, 2011, Great East Japan Earthquake and giant tsunami it spawned.

The explosion blew off the roof, exposing the spent-fuel pool on the fifth floor to the sky and falling debris. Tepco has since built a steel-framed cover to protect it from the elements, but getting the fuel out of the damaged building will allow the utility to monitor and safeguard it more easily and safely.