It's designed to recycle spent uranium from Japan's nuclear power plants, consists of more than three dozen buildings spread over 740 hectares , costs almost US$25 billion (NZ$37 billion) and has been under construction for nearly three decades.
Amount of fuel successfully reprocessed for commercial use: zero.
Under construction since the late 1980s, the complex is designed to turn nuclear waste into fuel by separating out plutonium and usable uranium.
The start date of the project has now been pushed back for the 23rd time, with operations set to commence in 2018.
The money continuing to pour into the Rokkasho reprocessing complex in a northeast corner of Japan's main island of Honshu is raising speculation that attention is being diverted from more-promising avenues of energy development, including renewables.
"Reprocessing is an idea that seemed good to many in the nuclear industry when it was first proposed, but with time and experience has proven to be uneconomical," M. V. Ramana, a professor at Princeton University's Nuclear Futures Laboratory, said.
"There is a lot of sense in the idea that Japan should just cut its losses and stop trying to get this plant to operate."
The idea for Rokkasho can be traced to the 1960s when Japan decided to pursue a "closed nuclear fuel cycle" -- a system which would allow the resource-poor country to recycle old fuel in order to reduce import dependence and insulate itself from fluctuating prices.
Japan's insistence on developing a closed fuel cycle has diverted funds, as well as generations of scientists and engineers, from renewables and other alternatives, according to Ramana.
From the point of view of a nation with few natural resources, completion and stable operation of the nuclear fuel cycle is extremely important.
"From the point of view of a nation with few natural resources, completion and stable operation of the nuclear fuel cycle is extremely important," said Makoto Yagi, chairman of the facility's operator, known as Japan Nuclear Fuel Ltd.
Construction on Rokkasho, the heart of the endeavor, was supposed to be completed by 1997. Delays due to technical and safety issues have kept it from operating commercially while costs ballooned to an estimated 2.94 trillion yen ($24.6 billion), according to Japan Nuclear Fuel.
The Japanese government and the country's power industry view fuel reprocessing generally, and Rokkasho specifically, as one of the only ways to lower import dependence and find a home for thousands of tons of highly radioactive spent fuel.
In the short term, recycling is not economically advantageous, but it does things like reduce your volume [of spent fuel].
The facility was originally intended to separate plutonium from spent fuel for use in so-called fast-breeder reactors -- plants that produce more fuel than they consume.
While the nation's first prototype fast-breeder reactor has remained closed due to its own technical issues, Rokkasho expanded construction to include a facility that processes plutonium-uranium mixed-oxide fuel, known as MOX, that can be used in some of Japan's existing reactors.
In its most-recent delay, Japan Nuclear Fuel announced in November that commercial startup of its plutonium reprocessing facility would be delayed to 2018 due to post-Fukushima safety requirements. Start of the MOX facility was delayed to 2019.
Even when reprocessing begins, the recycled fuel won't be any cheaper than uranium, which has slumped about 49 per cent on the spot market since the March 2011 Fukushima disaster.
"In the short term, recycling is not economically advantageous," Dale Klein, former chief of the US Nuclear Regulatory Commission, said in an interview in Tokyo. "But it does things like reduce your volume" of spent fuel.