The NRC grades each reactor based on data submitted quarterly by plant operators (“performance indicators”) and inspections by resident inspectors and regional staff. Its mid-year assessment places each operating unit within one of four levels of regulatory response, with the agency’s scrutiny increasing as plant performance declines:

1.  The top-rated plants, judged to be meeting all of the agency’s objectives, are subject to the “baseline” inspection program.
2. Plants with no more than two white findings — indicating problems causing minimal reductions in safety margin — fall into the second category, subjecting them to additional inspections and oversight by NRC regional officials.
3. Reactors with “degraded” performance, for example those receiving a yellow finding indicating a moderate reduction in safety margin are subject to higher scrutiny, including involvement of senior regional officials.
4. NRC headquarters officials take part in scrutiny of plants with multiple yellow findings or a red finding, indicating a significant reduction in safety margin.
5. Not Operating: Plants with unacceptable reductions in safety margins are not permitted to operate and may have their licenses revoked.