Problem forces dramatic power reduction at Calvert Cliffs 1

The Calvert Cliffs 1 nuclear unit in Maryland was listed at only 12% generation early July 25 after the facility, run by Exelon (NYSE:EXC), encountered a problem the night before.

An event notification report filed with the Nuclear Regulatory Commission (NRC) said that a reactor coolant system (RCS) “pressure boundary leakage” was discovered shortly after 11 p.m. on July 24.

Calvert Cliffs 1 started plant shutdown, as required by its technical specifications, according to the NRC report.

New information was then submitted to NRC early July 25.

“The licensee reduced reactor power to 10 percent and entered containment. The pressure boundary leak was isolated and the licensee exited the Technical Specification 3.4.13 Action B. The Technical Specification required shutdown was terminated. The licensee is making preparation to increase power to full load,” according to the NRC report.

The situation trigged a condition where, under its license, Calvert Cliffs 1 had to either go into shutdown mode or repair the problem within 36 hours, an Exelon spokesperson told GenerationHub.

So Exelon reduced power to 12% and had workers address the situation, the spokesperson said. Calvert Cliffs 1 will now increase generation to about 82%, which is where it will stay for a couple of days, he added.

Calvert Cliffs Units 1 and 2 are each roughly 900-MW pressurized water reactors (PWRs) located in Lusby, Md. The units, which were commissioned in the mid-1970s, are owned by Constellation Energy Nuclear Group (CENG). CENG nuclear units are jointly owned by Exelon and EDF Group and are now operated by Exelon.

Calvert Cliffs Units 1 and 2 are each roughly 900-MW pressurized water reactors (PWRs) located in Lusby, Md. The units, which were commissioned in the mid-1970s, are owned by Constellation Energy Nuclear Group (CENG). CENG nuclear units are jointly owned by Exelon and EDF Group and are now operated by Exelon.

About Wayne Barber 4201 Articles
Wayne Barber, Chief Analyst for the GenerationHub, has been covering power generation, energy and natural resources issues at national publications for more than 20 years. Prior to joining PennWell he was editor of Generation Markets Week at SNL Financial for nine years. He has also worked as a business journalist at both McGraw-Hill and Financial Times Energy. Wayne also worked as a newspaper reporter for several years. During his career has visited nuclear reactors and coal mines as well as coal and natural gas power plants. Wayne can be reached at wayneb@pennwell.com.