RALEIGH, N.C. (AP) – Federal regulators say the shutdown of a North Carolina nuclear plant in May is leading Duke Energy to change some procedures after missing a tiny crack near the reactor core last year.

The Nuclear Regulatory Commission’s final report released Thursday found the operators of the Shearon Harris nuclear plant near Raleigh violated a reporting requirement, but it had very low safety significance.

The NRC said last month an outside contractor hired to search inside the nuclear reactor missed the quarter-inch spot last year, when four smaller flaws were found and fixed.

The report says Duke Energy now plans to keep multiple teams of analysts separated as they review data.

A spokeswoman for the nuclear plant said Duke Energy is reviewing the report and looking for ways to improve inspections.