Cracking steam generator tubes are now the focus of an in-depth examination by the U.S. Nuclear Regulatory Commission, which on April 28 ordered the operators of the nation's 71 pressurized water reactors to justify why they should be allowed to continue operations.
Nuclear power critics, including Robert Pollard, a former NRC engineer now with the Union for Concerned Scientists in Washington, D.C., say the unusual April 28 order didn't go far enough, and that the NRC is bending over backwards to allow plants to stay open that it cannot be sure are safe.
The reports were due in late June, and the NRC is still deciding how to evaluate them.
Ken Karwoski, an engineer and one of the lead technical reviewers with the NRC in Rockville, Md., said various factors, including the ages of the plants and materials used in them, will be evaluated to determine if plants should be closed.
The Wolf Creek nuclear power plant near Burlington has 22,504 tubes in its four steam generators. The tubes, three quarters of an inch in diameter with walls about the thickness of a dime, are tested for cracks during routine shutdowns for refueling, and thus far no cracks have been detected. The next tests are planned during a refueling shutdown that starts in March 1996.