The U.S. Nuclear Regulatory Commission (NRC) found in an annual assessment of the nation’s nuclear power plants that 11 percent of the facilities operate at a “degraded level of performance” or worse.

Of highest concern are two facilities: the Browns Ferry 1 power plant in Alabama and the Fort Calhoun plant in Nebraska. The NRC ranked both in its fourth designation, having “a safety finding of high significance” that will require higher oversight, according to the report released recently. The Fort Calhoun plant had only just restarted in December 2013 after flooding forced the plant to close for two years.

The assessments "are an annual report card on the performance of the nation's nuclear power plants," Ho Nieh, director of NRC's division of inspection and regional support, said in a statement. "We ensure nuclear power plants are safe, inspecting them and rating their performance regularly, as part of our mission to protect people and the environment."

The NRC graded nine additional power plants with a “degraded level of performance.” Those include: Browns Ferry 2 in Alabama, Duane Arnold in Iowa, Monticello in Minnesota, Pilgrim in Massachusetts, Point Beach 1 in Wisconsin, Susquehanna 2 in Pennsylvania, Sequoyah 1 and 2 in Tennessee and Watts Bar 1 in Tennessee.

The Sequoyah and Watts Bar facilities resolved their problems after the reporting period ended Dec. 31 and moved up to the highest category, and the remaining seven will undergo NRC scrutiny until they adequately address safety concerns. The increased oversight could include more inspections and attention to senior management regarding the cause of the degraded performance.

Eighty of the 100 power plants operating in the U.S. met all the safety and security performance objectives set by the NRC, and nine more only needed to resolve one or two objectives of “low safety significance.”

Public meetings will be held over the spring and summer near each nuclear power plant to discuss the assessments, NRC said.