The operator of Japan's fuel reprocessing plant says it has decided to postpone its opening to as late as September 2018, citing regulators' lengthy inspection procedures and time needed for safety upgrades.

The Japan Nuclear Fuel Ltd. said Monday that it was delaying the targeted completion of the reprocessing plant, which separates plutonium from spent fuel for reuse as fuel, by as much as 2 1/2 years.

The delay-plagued plant was set to open March 2016.

JNFL president Kenji Kudo said a separate plant to produce plutonium-based fuel has been delayed until 2019.

Japan already has tons of plutonium on hand and no use for it, with most of its reactor fleet still offline since the 2011 Fukushima disaster. The plutonium is for generating electricity but has raised proliferation concerns.