TOKYO -- The prototype Monju fast breeder reactor, once viewed as a panacea for Japan's energy woes, is likely to be downgraded to a nuclear waste processing unit under a new energy policy.
With myriad technical challenges and astronomical costs, the government will likely abandon its quest for what could have been an infinite energy source when it adopts a new planning document as early as this month.
Monju, using reprocessed fuel from other reactors, was to generate power while producing more fuel than it consumed. A ministry official touting the project said the process could be repeated for "thousands of years."
Facing insurmountable challenges, most developed countries exited development. Monju reached criticality in 1994, starting a sustained nuclear chain reaction, but was shut down for nearly 14 years after a sodium coolant leak. It barely operated at all during the past 20 years while racking up maintenance costs.
The Fukushima disaster of March 2011 has fueled the debate over scrapping the trouble-prone reactor. One alternative that would save Monju from decommissioning is to use it for processing nuclear waste generated by Japan's 48 nuclear reactors.
Processing waste with a fast breeder reactor would accelerate nuclear decay, limiting the period in which high-level radioactivity is released from more than 10,000 years to several hundred. It would also reduce the waste's volume.
But the key question is what to do with the Japanese nuclear fuel cycle program.
Without a breeder reactor's ability to produce fuel indefinitely, the cycle loses an essential link. A 2 trillion yen ($19.49 billion) facility for reprocessing spent nuclear fuel for use in Monju is near completion in Aomori Prefecture. It is to generate up to 8 tons of plutonium a year.
The government's last resort is mixing the plutonium with uranium to fuel standard reactors. Plants that can use this mixture include the Takahama facility operated by Kansai Electric Power and the Genkai site run by Kyushu Electric Power, both of which are preparing to resume operations.
But unlike breeder reactors, standard thermal reactors cannot reuse the fuel repeatedly, making them a less economical option. It would be pointless, as one ministry insider notes, to spend so much money on reprocessing.
The U.S. and the international community allow Japan to produce plutonium as long as it is used for peaceful purposes. The nuclear cooperation agreement between Washington and Tokyo is slated for revision in 2018. If Monju marks the end of Japanese efforts to realize a fast breeder reactor, the country would have less of a case for making plutonium.