The Nuclear Safety Commission on Feb. 22 gave the go-ahead to starting the test run of the prototype fast-breeder reactor (FBR) Monju in Tsuruga, Fukui Prefecture. If the prefectural and municipal governments give their consent, the test run should begin by the end of March at the earliest.
The 280,000 kW FBR, which uses a mixed nuclear fuel of uranium and plutonium and is intended to produce more fuel than it burns, is an important part of a nuclear fuel cycle Japan hopes to establish. In the cycle, spent nuclear fuel will be processed to extract plutonium, which will be then used as nuclear fuel.
Monju started transmitting electricity Aug. 29, 1995. When it was operating at 40 percent of total output on Dec. 8 that year, some 640 kg of sodium used as secondary coolant leaked, causing a fire. The test run is about to start 14 years after the FBR became inoperative. Utmost care should be taken to ensure safety.