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SAN LUIS OBISPO, Calif. (KTLA) — A reactor at the Diablo Canyon nuclear power plant was shut down Wednesday after the discovery of a small leak, according to Pacific Gas & Electric Co.

diablo-canyon-nuke-plantThe utility company said the leak was found in Unit 1 during routine maintenance.

The leak occurred in equipment that helps manage coolant used to control temperatures within the reactor, according to the utility.

“PG&E made the decision to take Unit 1 offline after routine inspections detected a small buildup of boric acid on the residual heat removal system,” spokesman Thomas Cuddy said.

The leak was contained within the plant and no radiation was released, Cuddy said.

PG&E informed the NRC and appropriate local and state officials about the shutdown.

The utility gave no indication on when the reactor would be back online.

After the permanent closure of the San Onofre plant, Diablo Canyon became the only nuclear plant operating in California.