A safety mechanism installed at the reactor No.2 had shut it down automatically, said Anne-Sophie Huge, a spokeswoman for energy company Electrabel.
The mechanism is designed to force the reactor to shut down “when an abnormality is detected,” she added, saying the causes of Friday’s interruption are now being assessed by specialists.
The operator said it was “certain” the problem was somewhere “in the secondary part of the plant,” such as an engine room, and not in the nuclear zone.
“The incident shows that the safety system works. The plant is in total safety because the Tihange 2 unit is stopped,” she said, as cited by RTBF.
The Tihange plant is one of Belgium’stwo large-scale nuclear power stations, and is located some 100km (62 miles) from the capital city of Brussels.
Earlier this year, work was interrupted at another Belgian nuclear plant, Doel, which is 40 years old. A similar safety mechanism shut its reactor down just three days after it had been re-launched. In April, Germany asked Belgium to take two of its nuclear reactors at both Tihange and Doel offline, citing safety concerns. Brussels said it took its neighbor’s concerns “seriously,” but promised that its reactors met the strictest safety standards.