The Fugen advanced thermal reactor in Tsuruga, Fukui Prefecture, which resumed operations Monday after standing idle for 11 months due to a tritium leak, was shut down again Tuesday morning after a small amount of steam containing radiation leaked, the operator said.
The government's Japan Nuclear Cycle Development Institute said it shut down the reactor shortly after 5 a.m. after an employee patrolling the turbine building found the steam leaking from a pipe at a pressure gauge at around 11 p.m. Monday.
A monitor in the building did not detect any high-level radioactivity and the leak has not affected areas outside the facility, according to the institute.
The 165,000-kw reactor had been restarted Monday following checks after it was shut down last May because of a radiation leak.
The reactor, in a nuclear facility on the Sea of Japan coast, is scheduled to be finally shut down at the end of next March.
Last May, a tritium leak was detected in the area between the outside of the reactor container and the concrete wall surrounding the facility.