The Abe administration may rethink the research project to commercialize the Monju prototype fast-breeder reactor, a move that could affect Japan's long-held goal of recycling spent nuclear fuel, sources said Friday.

It could be an option to use the troubled Monju mainly for studying ways to reduce the amount of high-level radioactive waste generated through reprocessing spent fuel.

The latest development comes as the administration is working on the medium- to long-term energy policy in light of the Fukushima meltdown disaster. The Basic Energy Plan compiled in 2010 says the government would seek to develop a commercial fast-breeder reactor before 2050.

Minister of Economy, Trade and Industry Toshimitsu Motegi, in charge of compiling the new energy plan, told a news conference the administration has not decided whether to use Monju for waste-reduction studies.

The facility, located in Tsuruga, Fukui Prefecture, and operated by the Japan Atomic Energy Agency, has been regarded as central to achieving the ideal nuclear fuel cycle, in which spent nuclear fuel is reprocessed and the extracted plutonium and uranium is reused as reactor fuel.

Using the extracted plutonium and uranium, Monju would theoretically produce more fuel than it consumes.

But the reactor has remained largely offline since first achieving criticality in 1994 due to a raft of problems, casting doubt on the project's viability. It has also been effectively banned from operation since last May following the revelation of lax safety inspections.