PORT GIBSON, Miss. (AP) - Entergy Nuclear has locked out union security workers at its nuclear plant near Port Gibson, Miss., after contract negotiations with the United Government Security Officers of America Local 36 failed.

The current contract with plant security officers expired at midnight Sunday.

Mike Balduzzi, Entergy Nuclear's senior vice president of nuclear technical services, says in a statement that since the union workers could leave their posts and strike at any time, the company decided to replace them.

Balduzzi says experienced individuals at Grand Gulf and from other Entergy nuclear plants and professional security firms will be filling those positions.

Union officials could not be immediately reached for comment.

Copyright 2012 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.