LOS ANGELES (AP) — A federal inspector says the Nuclear Regulatory Commission missed opportunities to spot potential trouble with an equipment swap that led to the installation of faulty machinery in a Southland nuclear plant.

The San Onofre plant was closed last year by SoCal Edison after a battle over whether it was safe to operate. It had been idle since 2012, after a small radiation leak led to the discovery of excessive wear in tubing inside virtually new steam generators.

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A report Tuesday by the NRC’s Inspector General said a 2009 agency inspection failed to recognize “shortcomings” in the way the swap of steam generators was evaluated.

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It also raises questions about why Edison was allowed to install the new generators without seeking a change in its federal operating license.

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