BIRMINGHAM, Ala. (AP) – A burst pipe forced the shutdown of a nuclear reactor Thursday, two days after it was restarted for the first time in more than two decades.

The pipe caused 600 gallons of fluid to spill at the Browns Ferry Nuclear Plant. The liquid was not radioactive and posed no public-safety threat, the Nuclear Regulatory Commission said.

The Tennessee Valley Authority restarted the Unit 1 reactor Tuesday following a 22-year shutdown over concerns about safety and management. The reactor is not generating power during testing, but the plant’s other two reactors remain online at Browns Ferry, on the Tennessee River in far-north Alabama.

Two maintenance workers were trying to fix a leak in a hydraulic line on a turbine-control system when the pipe burst, spraying fluid on them and covering the floor with liquid, the NRC said.

The workers were taken to a hospital as a precaution, said Ken Clark, an agency spokesman in Atlanta.

The TVA did not immediately return telephone calls seeking comment.

TVA restarted the Unit 1 reactor after a five-year, $1.8 billion renovation. The plant’s other two reactors were restarted in the 1990s after extensive work.