The pursuit of a super-efficient fast-breeder reactor, which would be more efficient than the Monju fast breeder reactor seen above, now teeters on the brink of failure amid cost concerns. (Tomohiro Ohsumi/Bloomberg)

Japan’s long and expensive pursuit of a super-efficient nuclear reactor — a model once touted as the key to its energy future — now teeters on the brink of failure amid new government concerns about its runaway costs.

The four-decade project to develop a so-called fast-breeder reactor has consumed more than $13 billion in funding, so far producing only accidents, controversies and a single hour of electricity. The government last month decided on sharp budget cuts for the project, and one top nuclear official in November raised the possibility of scrapping the plan.

But a move to shut down the fast-breeder reactor project would deliver yet another blow to Japan’s nuclear program — already reeling from a major accident at the Fukushima Daiichi plant — because it would all but eliminate the long-held Japanese vision of using its nuclear fuel on a near-endless cycle.

In theory, the fast-breeder reactor can run on the reprocessed uranium and plutonium that conventional light-water reactors give off as a byproduct. The fast-breeders also produce more fuel than they use, allowing for a cycle in which fuel is created by the reactor, harvested from the reactor, and then reprocessed and used anew. With its fast-breeders, Japan could solve its costly resource-scarcity problem, which necessitates fuel imports from across the world.

“It was supposed to be the dream reactor, powering Japan for 100 or 200 years,” Satoru Kondo, director general of Japan’s fast breeder program at the Japan Atomic Energy Agency, said in an interview this week. “I never thought it would take this long.”

Japan’s only prototype fast-breeder, a 280-megawatt reactor known as Monju, sits in this coastal town, roughly 250 miles west of Tokyo. The reactor is idle, and officials here say they have no control over whether it will operate again.

Wasteful spending

That decision will come from Tokyo, where a government with the world’s highest debt-to-gross-domestic-product ratio is trying to eliminate wasteful spending. Based on recommendations from a panel of cost-cutting specialists, officials in December slashed Monju’s $275 million annual budget by roughly 20 percent. They also removed all money reserved for operation of the reactor in 2012. Some politicians say that even with those cuts, Monju is receiving too much, particularly at a time when Japan should be adding safety measures for existing reactors.

“We’re not going to get the fast-breeder reactor,” said Taro Kono, a Japanese parliament member and a critic of nuclear power. “We spend billions of yen every year just to maintain Monju. It’s crazy. We spend so much money just to keep things not running.”

Monju has turned into an easy target for ridicule because of its tormented history. Japanese engineers began work on the fast-breeder technology in the 1960s. They wanted the breeders to be commercially viable by the 1980s. Now the hope is that Japan can create commercial fast breeders by 2050.

But critics and nuclear watchdog groups describe Monju as Japan’s most dangerous reactor because it uses plutonium fuel, even more deadly than uranium, and because it cools its reactor with sodium, which can explode if it comes into contact with water.

The United States and other countries abandoned their fast-breeder development efforts decades ago because of safety and price concerns, but Japan remained committed, even after a 1995 fire caused by a sodium leak. That accident — coupled with an attempted coverup by the plant’s officials — caused a 14-year freeze on operations. Three months after the reactor restarted in May 2010, a 3.3-ton piece of machinery fell into the reactor vessel, causing another delay. The device has been removed, but Monju hasn’t operated since.

Reform and contrition

The odds of a resumption dwindled after the triple meltdown last year at Fukushima Daiichi, a crisis that undermined confidence in Japan’s nuclear safety and prompted a wholesale reevaluation of the country’s pro-nuclear energy policy. Since the accident, Japan has been unable to persuade host communities to sign off on the restart of idled reactors. Some nuclear experts say that Japan, as part of its energy review, could spike the fast-breeder project as public display for its reform and contrition.

As part of its attempt for a closed nuclear-fuel cycle, Japan has also tried to develop a uranium enrichment and reprocessing plant in northern Aomori prefecture. That center would reprocess the waste from Japan’s light-water reactors, turning it into the plutonium-uranium mix used in fast breeders. But the reprocessing center has been held back by dozens of delays, leading to ballooning costs and compounding concerns about the feasibility of the fast-breeder program.

“I understand the public is concerned about nuclear safety, and I understand that politicians have to listen to the public,” said Kondo, of the atomic energy agency. “At the same time, think about the reason the fast-breeder technology was implemented. It was part of a plan to gain energy for years to come. It shouldn’t just be scrapped as part of an emotional decision.”

Special correspondent Ayako Mie contributed to this report.