A report by the Union of Concerned Scientists finds that a series of significant safety lapses at U.S. nuclear power plants in 2011 happened because plant owners—and often the Nuclear Regulatory Commission (NRC)—tolerated known problems or failed to address them adequately. None of the 15 incidents or “near misses” that triggered special inspections in 2011 harmed plant employees or the public, but their frequency—on average more than one per month—is high for a mature industry, the report says. The report identifies special inspections NRC conducted in response to safety equipment problems and security shortcomings at 13 plants. It also gives examples of where NRC did an outstanding job addressing safety problems before they could lead to a dangerous situation. But the report also finds instances in which NRC negligence let plant owners flout agency regulations, sometimes for decades. In response, NRC says the report shows the commission hard at work ensuring the safety of nuclear power plants. “NRC’s oversight program is designed to catch and correct problems well before they become anything approaching a ‘near miss.’ There is nothing new in this report,” the agency says.