Mysterious vibrations in an electrical generator forced engineers to shut down a reactor at Browns Ferry Nuclear Plant on Sunday.

Ray Golden, a spokesman with TVA, said the reactor was shut down at about 4:20 p.m. and posed no threat to the public or TVA employees.

He said “higher than normal vibrations” were felt from bearings associated with the generator. Operators lowered the power, but it had no effect on the vibrations. Engineers are now conducting tests for the vibrations and making repairs as necessary.

“The operators made the right call,” Golden said of the decision to power down the reactor. “This can happen at any of the plants that generate electricity; it’s a common factor. They’re pretty sophisticated pieces of equipment and time to time, they can have problems.”

He said the problem was identified in the control room where the vibrations are measured and went through “normal shutdown” procedures.

“The problem had nothing to do with the nuclear part of the plant,” Golden said.