Tokyo Electric Power Co. has disclosed that a 35-ton piece of machinery debris might be resting on the inner gate of the spent fuel pool for reactor 3 of the Fukushima No. 1 power plant and that the gate is slightly out of position.

Tepco said Thursday that a fuel-handling machine dislodged during the March 2011 quake, tsunami and meltdown-triggered hydrogen explosions is touching one of two gates that stand between the pool and the reactor containment vessel.

The utility confirmed by underwater camera that both of the 8-meter-high, 1.6-meter-wide gates are slightly out of position but said the pool remains properly sealed due to water pressure and does not appear to be leaking.

A plan to remove the debris is being hammered out. If the gates are damaged, it might trigger a water leak from the pool, which contains 566 spent fuel assemblies, the utility said.

Tepco was planning to finish debris removal at the No. 3 reactor pool by the end of June and start removing the old fuel rods by the end of September. Tepco said it is not clear whether the latest setback will change that.