Many of the serious safety or security lapses at U.S. nuclear power plants in 2010 happened because plant owners -- and often the Nuclear Regulatory Commission (NRC) -- failed to address known safety problems, according to a report released today by the Union of Concerned Scientists (UCS).

In 2010, the NRC reported on 14 special inspections it launched in response to troubling events, safety equipment problems, and security shortcomings at nuclear power plants. The UCS says that many of these significant events occurred because reactor owners, and often the NRC, tolerated known safety problems.

"While none of the safety problems in 2010 caused harm to plant employees or the public, their frequency -- more than one per month -- is high for a mature industry," the UCS says.

For example, the owner of the Calvert Cliffs plant in Maryland ended a program to routinely replace safety components before launching a new program to monitor degradation of those components. As a result, an electrical device that had been in use for longer than its service lifetime failed, disabling critical safety components.

In another example, after declaring an emergency at its Brunswick nuclear plant in North Carolina, the owner failed to staff its emergency response teams within the required amount of time. That lapse occurred because workers did not know how to activate the automated system that summons emergency workers to the site.

The UCS report also provides three examples where onsite NRC inspectors made "outstanding catches" of safety problems at the Oconee, Browns Ferry, and Kewaunee nuclear plants— "before these impairments could lead to events requiring special inspections, or to major accidents."

However, the report says that the NRC did not always serve the public well in 2010. It analyzes serious safety problems at Peach Bottom, Indian Point, and Vermont Yankee that the NRC overlooked or dismissed.

The NRC audits only about five percent of activities at nuclear plants each year, according to the UCS, which says the NCR can learn lessons from the 14 near-misses and how it should apply its limited resources to reap the greatest returns to public safety.

The report says the three positive and three negative examples do not represent the agency's best and worst performances in 2010.

"Instead, the examples highlight patterns of NRC behavior that contributed to these outcomes. The positive examples clearly show that the NRC can be an effective regulator. The negative examples attest that the agency still has work to do to become the regulator of nuclear power that the public deserves," the report says.

The scientists say that the chances of a disaster at a nuclear plant are low. But "[t]he more owners sweep safety problems under the rug and the longer safety problems remain uncorrected, the higher the risk climbs," the report says.

The Union of Concerned Scientists is a U.S. science-based nonprofit organization headquartered in Cambridge, Mass. It also has offices in Berkeley, Chicago and Washington, D.C.