A spent nuclear fuel reprocessing plant in the village of Rokkasho, Aomori Prefecture, looks set to gain approval for full operation following the completion of most of its safety review.

The Nuclear Regulation Authority checked the remaining safety measures against the risks of earthquakes and volcanic eruptions on Friday, and its members made no objections.

Japan Nuclear Fuel Ltd. expects construction of the plant to finish in the first half of fiscal 2021. The project is more than 20 years behind schedule.

The Rokkasho plant will be a pillar in Japan's nuclear fuel reprocessing policy, even though questions remain about whether the reprocessing cycle will work effectively.

When completed, the Rokkasho plant will be able to extract about 8 tons of plutonium a year by reprocessing spent fuel.

Spent fuel from reactors is reprocessed to extract uranium and plutonium, which is then recycled into fuel called mixed oxide, or MOX, for use in fast-breeder reactors or conventional nuclear reactors.

However, most of the nation's nuclear plants remain offline, making it likely that plutonium stockpiles will increase unless more reactors that can burn MOX resume operations.

The Japan Atomic Energy Commission said in an updated guideline in July that Japan will reduce its plutonium stocks amid growing concern by other countries about the issue.

The operator filed for the regulator's safety review in January 2014. Due to a series of problems found at the plant, however, the review was suspended between October 2017 and May.

In August last year, about 800 liters of rainwater was found to have seeped into a building housing the plant's key emergency power sources.