On May 13, the Nuclear Regulation Authority announced that the nuclear fuel reprocessing plant in Rokkasho, Aomori Prefecture, had met new safety standards created after the March 11, 2011, earthquake and tsunami.

The NRA’s approval means the long-troubled and controversial plant has moved closer to going into operation. Here’s a look at the Rokkasho plant and the problems it has faced.

What is the Rokkasho reprocessing plant?

The plant at Rokkasho is a 3.8 million square meter facility designed to reprocess spent nuclear fuel from the nation’s nuclear reactors.

Construction began in 1993. Once in operation, the plant’s maximum daily reprocessing capacity will be a cumulative total of 800 tons per year.

During reprocessing, uranium and plutonium are extracted, and the Rokkasho plant is expected to generate up to eight tons of plutonium annually. Both are then turned into a mixed uranium-plutonium oxide (MOX) fuel at a separate MOX fabrication plant, also located in Rokkasho, for use in commercial reactors. Construction on the MOX facility began in 2010 and it’s expected to be completed in 2022.

The Rokkasho reprocessing plant can store up to 3,000 tons of spent nuclear fuel from the nation’s power plants on-site. It’s nearly full however, with over 2,900 tons of high-level waste already waiting to be reprocessed.

Why has it taken until now for the Rokkasho plant to secure approval from the nuclear watchdog?

Decades of technical problems and the new safety standards for nuclear power that went into effect after the 2011 triple meltdown at the power plant in Fukushima Prefecture have delayed Rokkasho’s completion date 24 times so far. It took six years for the plant to win approval under the post-3/11 safety standards.

There has also long been concern and unease over the entire project — and not just among traditional anti-nuclear activists — which the government has been forced to address. Japan is the only non-nuclear weapons state pursuing reprocessing. But as far back as the 1970s, as Japan was debating a nuclear reprocessing program, the United States became concerned about a plant producing plutonium that could be used for a nuclear weapons program.

The issue was raised at a Feb. 1, 1977, meeting between U.S. Vice President Walter Mondale and Prime Minister Takeo Fukuda.

“Reprocessing facilities which could produce weapons grade material are simply bomb factories,” noted a declassified U.S. State Department cable on the meeting. “We want to cooperate (with Japan) to keep the problem under control.”

Japan promised plutonium produced would be for peaceful use only and the U.S. dropped its opposition to a reprocessing program. Japan’s first reprocessing plant opened in Tokai, Ibaraki Prefecture, in 1977.

The U.S. allowed Japan to reprocess fuel at Tokai on a case-by-case basis, with each case reviewed for its possible risk to the nuclear nonproliferation regime.

Nor did the U.S. oppose the Rokkasho plant’s construction in 1993, following an agreement in 1988 between the two countries on nuclear cooperation. The plant at Rokkasho was seen as a replacement for the facility at Tokai. The U.S.-Japan nuclear agreement meant the U.S. would give advance consent for Japan to send spent nuclear fuel to the United Kingdom and France — states with nuclear weapons — for reprocessing until Rokkasho was running at full-scale.

However, technical mishaps led to plans being made and then scrapped for many years, while arms control experts continued to worry that Japan could end up stockpiling plutonium that could lead to proliferation problems.

After the 2011 disaster, the NRA created tougher measures to minimize damage from natural disasters, forcing more construction and upgrades at the plant, leading to higher costs.

The Tokai plant halted operations in 2007. The decision to scrap it was made in 2014, as it was judged to be unable to meet the new safety standards. But little progress is being made, due to uncertainty over where to store all of the radioactive waste.

Safety concerns over the Rokkasho plant have remained, especially since 2017 when it was revealed that Japan Nuclear Fuel had not carried out mandatory safety standards for 14 years.

By the time of the NRA announcement on May 13, the price tag for work at the Rokkasho plant had reached nearly ¥14 trillion.

What happens next?

The NRA is soliciting public comment on its decision until June 12, but the Ministry of Economy, Trade, and Industry is expected to formally approve the decision. After that, the Aomori governor would be asked to give his approval, though that is not a legal requirement. The last bureaucratic hurdles would then have been cleared to start operations at the plant by the spring of 2022.

However, there are other issues that could force a delay to the start of reprocessing. Japan had originally envisioned MOX fuel powering between 16 and 18 of the nation’s 54 commercial reactors that were operating before 2011, in place of conventional uranium.

But only four reactors are using it out of the current total of nine officially in operation. MOX fuel is more expensive than conventional uranium fuel, raising questions about how much reprocessed fuel the facilities would need, or want.

When the U.S. and Japan automatically extended the 1988 agreement in 2018, Japan made a pledge to address its plutonium stockpile through domestic consumption.

Currently, the nation has nearly 45 tons of plutonium stockpiled, including nine tons held by domestic utilities. Another 21.2 tons is in the United Kingdom and France is holding 15.5 tons under overseas reprocessing contracts.

Thus, Japan finds itself caught between promises to the international community to reduce its plutonium stockpile through reprocessing at Rokkasho, and questions about whether MOX is still an economically, and politically, viable resource — given the expenses involved and the availability of other fossil fuel and renewable energy resources.