WASHINGTON (AP) -- Companies that operate U.S. nuclear power plants are not telling the government about some equipment defects that could create safety risks, according to a report released Thursday.
An audit by the inspector general of the Nuclear Regulatory Commission also raised questions about the agency's oversight, saying reporting guidelines for the nuclear industry are "contradictory and unclear."
Reflecting that confusion, the report said the NRC has not levied any civil penalties or significant enforcement actions against nuclear plant operators for lapses in reporting equipment defects in at least eight years.
The study comes as questions are raised about the safety of U.S. nuclear facilities in the wake of the nuclear crisis in Japan. The NRC voted Wednesday to conduct two safety reviews of the 104 nuclear reactors operating in the U.S.
Unless the NRC takes steps to improve its reporting guidelines, "the margin of safety for operating reactors could be reduced," the IG report said.
NRC inspectors found at least 24 instances where possible equipment defects were identified but not reported to the agency from December 2009 through September 2010, according to the study.
Eliot Brenner, a spokesman for the agency, said utilities and NRC inspectors both have procedures to identify and report manufacturing defects. The IG report mostly addresses how these defects are reported to the government, he said.
"The NRC has a variety of other regulations that effectively encompass reporting all defects, and the NRC continues to conclude plants are operating safely," Brenner said.
The agency will look at the report to see if its reporting systems can be strengthened, he added.
In its 18-page report, the inspector general said the NRC's baseline inspection program does not require inspectors to review an operator's reporting on equipment defects.
Confusion over the regulations "could reduce the margin of safety for operating nuclear power reactors, as NRC may remain unaware of component failures that have resulted from manufacturing defects," the report said.
For example, an operator might not report a basic component that failed due to a design defect. As a result, other operators that use the same component -- and even component manufacturers -- may be unaware of the problem, the report said. Without knowledge of specific manufacturing defects, the NRC could miss crucial trends, the report said.
Rep. Edward Markey, D-Mass., called the report troubling and said it raises questions about the self-policing allowed at commercial nuclear plants.
"While there are no specific examples listed in the report, it is apparent that confusion and omissions regarding the reporting of defects at nuclear facilities are commonplace," Markey said.
A spokesman for the Nuclear Energy Institute, an industry group, cautioned that the report did not identify any actual safety problems.
Reporting possible equipment defects, while important, "is one sliver within a much broader regulatory regimen that shows U.S. nuclear power plants are operating at high margins of safety," spokesman Steve Kerekes said.
Kerekes cited annual NRC reports dating to 2005 that show no "abnormal occurrences" throughout the U.S. nuclear energy industry. Abnormal occurrences are events that the agency considers threats to public health or safety.