Local residents last month questioned whether the U.S. Nuclear Regulatory Commission knew of local faults when the Limerick power plant was planned for construction.
"The short answer is, 'yes,'" said Diane Screnci, NRC senior public affairs officer.
Folks at a meeting in Limerick Township last month showed NRC officials a document which referred to "the Sanatoga fault" and asked whether the NRC was aware of its proximity to the Limerick site prior to initial licensing.
The NRC hosted the meeting – which included workers from the commission and Exelon – to discuss with the public an annual safety performance assessment of Exelon's Limerick nuclear power plant.
At that time, members of The Alliance For A Clean Environment brought copies of the nearly 40-year-old report, produced by Dames and Moore for the Philadelphia Electric Company, and a geologic map that shows several faults near the Limerick plant.
ACE – a non-profit founded in the late 1980s that disbanded, rejuvenated in 1995 and has roughly 1,000 members – works to protect the environment and address public health issues in Berks, Chester and Montgomery counties.
"There are some faults that are in the vicinity of the plant," Andrew Rosebrook, NRC senior project engineer, said at the meeting. The Ramapo Fault is about 17 miles from Limerick and the Chalfont Fault is nearly nine miles from the nuclear plant, he said adding that a fault is basically a weak spot in the ground.
"These faults are extremely old," Rosebrook said and added it's "pretty unlikely" the faults would become active.
The plant was designed with layers of safety features to withstand an earthquake measuring about six on the Richter scale, he said.
Recently, Screnci followed up on the issue.
"NUREG-0991, dated August 1983, is the NRC’s Safety Evaluation Report for the operating licenses for the Limerick units," Screnci said via email. "The NRC noted that three faults have been mapped and investigated within (two) miles of the site, including the Sanatoga fault."
A panel of experts in Appalachian geology and the NRC staff concluded the faults experienced their last displacements more than 500,000 years ago, she said.
"The SER concluded that there were no capable faults in the site area," Screnci said.