The test run of the prototype fast-breeder reactor (FBR) Monju in Tsuruga, Fukui Prefecture, is now expected to start after Golden Week, after prefecture Gov. Issei Nishikawa on April 28 gave the go-ahead for test runs to be conducted. The 280,000 kW reactor — an important part of Japan's planned nuclear fuel cycle — has been inoperative for the 14 years and five months since Dec. 8, 1995, when some 640 kg of secondary-coolant sodium leaked and caused a fire.
This will be the first time for Japan to restart a reactor that has been out of operation for such a long time. Sodium reacts strongly with air and water. Some deterioration of the reactor's components due to old age cannot be ruled out.