Florida Nuclear Reactor Shows Its Age

 November 23, 2009, 5:00 PM

By MATTHEW L. WALD

The Associated Press

Workers found a gap in a concrete containment dome at Florida’s Crystal River nuclear power plant.

Almost every plan for limiting carbon dioxide output includes keeping old nuclear plants running. But as those plants age, they turn up new problems.

The latest is at a plant owned by Progress Energy in Crystal River, Fla., where a gap was found inside the thick concrete of a containment dome.

A schematic of the void was provided by Progress Energy. Click image to enlarge.

The plant had been temporarily shut in late September so workers could replace the aging steam generators — which required them to cut a hole in the dome. (The steam generators at many aging nuclear reactors were intended to last the life of the plant, so no way for swapping them out was designed.)

About 9 inches into the 42-inch-thick structure, workers discovered a gap that varied from 2 inches down to an eighth of an inch, over a roughly 60-foot wide patch of wall.

“It appears that other similar plants that have gone through the steam generator replacement process have not seen the same phenomenon,” said Roger Hannah, a spokesman for the Nuclear Regulatory Commission, which is conducting a special inspection to find out, among other things, where the gap came from.

One possibility is that it was created when the hole was cut, which would be reassuring because it implies that the problem does not exist at other plants. Tests at Crystal River have determined that the only place in that dome with the problem is just above the hole cut for the steam generator replacement project.

It is also possible that the Crystal River design was more vulnerable than others. All containment domes have steel re-inforcement bars, but this one also has steel cables under tension. The crack could be related to workers cutting some of those cables to make the hole.

Still, containment buildings like the one at Crystal River are intended to withstand pressures in the neighborhood of 50 pounds per square inch in case of catastrophic accident. The Crystal River plant has not had such an accident, however, exactly how much strength the Crystal River building lost as a result of the gap is unknown.

Florida Power placed an order to build Crystal River in February, 1967, and it entered commercial service in March, 1977. Progress Energy has applied to extend its license 20 years beyond the initial 40 year period.

The plant will stay shut until engineers figure out now to fix it, according to Progress Energy.