Washington, Feb 29 (IANS/EFE): The US Nuclear Regulatory Commission (NRC) carried out 15 special inspections last year spurred by potentially serious incidents at power plants, the Union of Concerned Scientists said in a report released Tuesday.

A large number of those "near-misses" occurred because plant operators and regulators "either tolerated known problems or failed to address them adequately", the UCS said in "The NRC and Nuclear Power Plant Safety in 2011: Living on Borrowed Time."

The report, however, also praises the NRC for instances where regulators "did an outstanding job addressing safety problems before they could lead to a potentially dangerous situation".

"Last year's record shows that the NRC is quite capable of being an effective watchdog that protects the public and saves the nuclear industry from its worst tendencies," report author Dave Lochbaum, director of UCS's Nuclear Safety Project, said.

"But the agency too often does not live up to its potential, and we are still finding significant problems at nuclear plants that could too easily trigger a serious accident," the veteran nuclear engineer added.

Lax supervision by the NRC has allowed some problems to worsen over the course of decades, according to the UCS, which said that almost half of the 104 US reactors "still do not comply with a fire regulation the NRC established in 1980 and amended in 2004".

"The serious accidents at the Fermi plant outside Detroit in 1966, Three Mile Island in 1979, Chernobyl in 1986, and Fukushima Daiichi last year happened when a handful of known, uncorrected problems resulted in a catastrophe," Lochbaum said.