Japan is missing its own deadline to find a new operator for a prototype nuclear power program that has failed to succeed in the two decades since it was built, threatening the resource-poor country’s support of a technology other nations have abandoned.

The country’s nuclear regulator in November demanded that a replacement for the government-backed Japan Atomic Energy Agency be found within six months for the troubled Monju fast-breeder reactor in Fukui Prefecture. Monju, which has functioned for less than a year since its completion more than 20 years ago, now faces the possibility of being scrapped.

The fast-breeder reactor — a cornerstone of Japan’s atomic energy strategy dating back to the 1950s — uses spent nuclear fuel from other atomic plants and is designed to produce more fuel that it consumes. The reactor, named after the Buddhist deity of wisdom, has cost the nation more than ¥1 trillion and has barely operated since it first generated electricity in 1995, the year it suffered a sodium leak that led to a fire and subsequent attempted cover-up. Safety problems have continued to plague the facility ever since.

“The potential closure of Monju would be a major blow not just to the fast-breeder community in Japan, but also those supporting reprocessing of spent fuel,” M.V. Ramana, a professor at Princeton University’s Nuclear Futures Laboratory, said by email. “I wonder if the government will allow Monju to be shut down? I would expect that they will simply create a new agency to oversee Monju.”

Monju is currently operated by the JAEA, a quasi-government organization that is under the Ministry of Education, Culture, Sports, Science and Technology. JAEA declined comment. The nation’s nuclear watchdog, the Nuclear Regulation Authority, did not respond to emailed questions regarding the status of Monju.

“We don’t have plans to decommission the reactor,” said Hiroki Takaya, director of the ministry’s International Nuclear and Fusion Energy Affairs Division, which oversees Monju. “We are exploring many different options for who will operate the reactor — either a new entity or an existing company.”

The NRA said in November the science ministry must find a new operator or consider decommissioning. The ministry drafted criteria for a new operator, but has yet to name a replacement, it said on May 27. The ministry hopes to find an operator as soon as possible, but has not set a concrete deadline.

“These turn out to be very expensive technologies to build,” Allison MacFarlane, a former chairman of the U.S. Nuclear Regulatory Commission, said by email. “Many countries have tried over and over. What is truly impressive is that these many governments continue to fund a demonstrably failed technology.”

While the science ministry seeks a new operator of Monju, no power utility has stepped forward.

“Monju’s reactor design is quite different from a normal reactor, and utilities don’t have the expertise to handle it,” Makoto Yagi, chairman of the Federation of Electric Power Companies of Japan, told reporters in May. “Monju is currently in a research and development phase by the government; it isn’t the matter for a private company.”