The fate of the nation’s troubled prototype fast-breeder reactor is up in the air amid continued questions over its safety and cost. Political challenges to the country’s nuclear policy are also taking a toll.

Taro Kono, the anti-nuclear Cabinet minister in charge of administrative reforms, has himself started attacking the Monju project, openly questioning the feasibility of the plant after a high-profile budget review by a team of experts Wednesday in Tokyo.

In a separate move, the Nuclear Regulation Authority was set to lodge a formal request for a change in the plant's ownership. It was to ask the education and science ministry Friday to find a new operator after decades of serious problems that have shaken confidence.