Federal inspectors have identified new questions related to California's troubled San Onofre nuclear power plant.
A Nuclear Regulatory Commission report says a Japanese company that manufactured the plant's troubled steam generators failed to meet requirements with some equipment it's using to test possible long-term repairs.
NRC inspectors who visited Mitsubishi Heavy Industries found workers failed to verify that more than 1,000 tubes being used in generator models to explore potential fixes matched specifications for tubing in the California generators.
It raises the possibility Mitsubishi is looking for fixes on the wrong-sized equipment.
The plant between has been dark since January after a tube break released a trace of radiation. Investigators later found heavy wear to hundreds of generator tubes.