LOS ANGELES (AP) — The company that runs the troubled San Onofre nuclear power plant sparred with environmental activists Friday over the details of a once-confidential report that shows industry engineers were aware of problems with steam quality inside equipment that later malfunctioned.

San Onofre, located between Los Angeles and San Diego, was shut down more than a year ago after a tube break released a trace of radiation. Investigators later found unusual damage to hundreds of tubes that carry radioactive water inside the plant’s steam generators.