After a single control rod dropped into the reactor core during electrical testing, Calvert Cliffs Nuclear Power Plant shut down its Unit 2 reactor Thursday, officials said.
The Lusby, MD, plant’s technical specifications require a shutdown if workers cannot realign the control rod within six hours, said U.S. Nuclear Regulatory Commission (NRC) spokesman Neil Sheehan.
NRC resident inspectors at the plant learned of the incident immediately, and the controlled shutdown occurred without any complications and there was no impact to the public or plant staff, he said.
“Plant personnel will now have to troubleshoot what caused the problem,” Sheehan said. “Our inspectors will continue to follow those troubleshooting and repair activities.”
Kory Raftery, plant spokesman, said Calvert Cliffs owner Constellation Energy Nuclear Group’s plant operators manually shut down unit 2 to perform the required maintenance and “followed their training and procedures and the plant shut down as expected.”
“The plant is in stable condition,” the email continues. “… The safety of Calvert Cliffs and the public was maintained at all times during the shutdown.”
Preliminary information indicates the equipment involved requires electrical maintenance, Raftery said.
While unit 1 remains at 100 percent power, Raftery said, “we’ll have [unit 2] back up once maintenance is safely completed.”
Sheehan said the plant is equipped with 77 control rods designed to control the “fissioning of atoms in the reactor.” In August 2012, Calvert Cliffs Unit 1 experienced a single control rod drop as well. “As we said after that event,” Sheehan said, “nuclear power plants have specific procedures on what to do if a control rod drop occurs.”