High gas prices and the prospect of future energy supply problems are reviving support for nuclear power, but the foundation for a nuclear "renaissance" is turning out to be surprisingly weak. For years the Nuclear Regulatory Commission has warned that a retiring generation of nuclear plant operators and professors of nuclear science is not being replaced fast enough. Now it appears that some new plant designs that seemed close to approval have problems that will take years to solve.

An example is the Westinghouse AP 1000 design, a design the NRC had approved in principle in 2005. But the devil is in the details, apparently, because the design has been revised 16 times since then, and the NRC now says the uncertainties about key components are such that the design for plants planned for North and South Carolina, Georgia, Alabama and Florida may not be approved until 2011 or later. This means that the information on which the utilities are basing their financial estimates and timetables for building new nuclear plants is shaky, possibly creating a disincentive for the power industry.

There are similar problems with other designs, such as the General Electric Economic Simplified Boiling Water Reactor. One ESBWR is proposed for Virginia, another for Michigan. By approving generic designs like the AP 1000 and ESBWR so that the permit process for a given plant would only involve site-specific issues (such as the presence of geological faults or the source of cooling water), the NRC had hoped to eliminate the delays and overruns common to earlier generations of nuclear power plants. But holdups with NRC certification for the ESBWR as well as the AP 100 now mean that generic certification won't come through before the utilities file applications for the particular plants, which will cause administrative log jams and unpredictable expenses.

In the Carolinas, the problems with the AP 1000 design are very bad news, since those states had agreed that ratepayers could be charged for $230 million in preconstruction costs for the plants. Public interest groups are calling for those agreements to be revoked.