[en] Since operating nuclear power plants age like any other type of industrial facility and most will expire in the early 21st century, some utilities are beginning to examine the possibility of extending plant life. A description of actions taken to extend the life of four units covers the programs at Fort Calhoun at Omaha, ANO-1 in Arkansas, San Onofre-1 in Southern California, and Commonwealth Edison's Dresden-2 and -3 units. Programs at each unit stress maintenance, component replacement instead of repair, and materials aging