Work started here Thursday to modify the Monju experimental fast-breeder reactor, which has remained shut down since it suffered a sodium leak and fire nearly 10 years ago, the Japan Nuclear Cycle Development Institute said.

The work, expected to last 17 months, is aimed at enhancing the detection of similar accidents and minimizing their impact at the fast-breeder reactor complex, designated as a prototype for future reactor models.

"Human error-induced disasters can be prevented through our efforts. I want you all to proceed with the work with the priority on safety," Yuichi Tonozuka, president of the institute, told about 800 workers who took part in a ceremony launching the work.