An official from the Nuclear Regulatory Commission said in a statement that the situation was not handled appropriately, and Entergy staff in Vernon did not follow proper procedures.
The suspicious item was a length of pipe that was "capped" on both ends, according to a condition report that was submitted by an anonymous Entergy employee.
Vernon police were called to the plant Nov. 4 and the officer who responded turned off his portable radios and cellphones as he approached the pipe in the "south forty," a shipping and receiving area outside the "protected area" where nuclear power production buildings are located at the plant, according to the report.
The officer recommended that the security manager and superintendent call in the bomb squad.
Against the advice of the police, Entergy employees duct taped a piece of string to the pipe, stood back and pulled the string to see if it "went off," according to the report.
Rob Williams, a spokesman for the plant, said local law enforcement authorities were contacted, and "there was never a threat to employee or public safety."
"It is our policy not to comment on security events," Williams said.
Neil Sheehan, regional spokesman for the NRC, said that Entergy performed an evaluation to identify "the causes of human performance errors and the corrective actions needed to address them." Most of the actions, Sheehan wrote in an email, have been put in place.
"It is the NRC's expectation that conditions at U.S. nuclear power plants adverse to quality be promptly identified and corrected," Sheehan wrote. "Condition Reports are internal to the plant; they are submitted by plant employees so that emergent issues can be prioritized and addressed. NRC inspectors review condition reports on a regular basis."
Sheehan downplayed the significance of the incident. The suspicious item he said was a well pump that was being thrown away.
"It did not pose a threat to the plant's safety or the safety of Yankee personnel or the public," Sheehan said.
Neither Entergy nor the Nuclear Regulatory Commission notified the public or the media about the incident.