Mid-Life Crisis for Nukes

By Christine Gorman

Like many of the technicians and engineers who run them, nuclear power plants in the U.S. are pushing middle age. So far, only nine of the nation's 112 commercial reactors, which were designed and licensed to run for 40 years, have passed the midpoint of their careers. But by 1995, 40 more plants will celebrate their 20th birthday. Because of that, and because no new plants have been ordered since 1978, within four years 44% of America's atomic facilities will be past their prime. At a time when the Bush Administration is pushing for a renewed emphasis on nuclear power, there is growing concern about the safety of the country's geriatric plants.

Fueling these worries is a new rule, scheduled to be enacted in June by the Nuclear Regulatory Commission, that would stretch the legal life-span of many atomic plants to 60 years. Although the NRC says it will ensure that the industry addresses age-related issues, some scientists charge that the agency's safety guidelines are not stringent enough to prevent catastrophic accidents. Forty years ago, "these nuclear plants, after concerted study, were granted a finite number of years to operate," says M.I.T. physicist Henry Kendall, who shared a Nobel Prize last year for discovering subatomic particles called quarks. "Now the industry wants to extend that time by 20 years. They're changing the rules of the game." Nuclear officials dispute the charge, pointing out that the 1954 Atomic Energy Act contained provisions for license renewal.

First in line for a new lease on life is the oldest commercial reactor in the U.S., the 30-year-old Yankee nuclear power plant in Rowe, Mass. "Yankee Rowe" reliably produces more than 1 billion kW-h of electricity a year -- about one-sixth the capacity of its more modern counterparts -- and boasts an excellent safety record. However, after decades of absorbing the high- energy neutrons that are released during nuclear reactions, the walls of Yankee Rowe's reactor vessel have begun to weaken. Just how much is not clear. This so-called reactor embrittlement is potentially the most dangerous problem faced by aging atomic plants, because a crack in these walls could expose the highly radioactive reactor core.

At an NRC hearing last September, Neal Randall, one of the agency's engineers, testified that based on worst-case calculations, he believed the "Yankee Rowe vessel is quite brittle" and was therefore unsafe to operate even for the remainder of its license. The precise extent of the problem is uncertain because the utility has run out of easily accessible test samples of the original steel used in building the vessel. Ideally, such samples are periodically examined for hidden cracks, allowing scientists to determine how much embrittlement has occurred. Although Randall's opinion was a minority view, it electrified the plant's critics. The utility has promised to take new weld samples from within the reactor vessel sometime next year.

"We're not saying that aging problems do not exist," says Andrew Kadak, the Rowe plant's chief executive officer. "But we address them constantly. It cost $40 million to build this plant, and we've put another $40 million into it to keep it current and efficient." Kadak insists that Yankee's reactor vessel can operate safely for another 20 years: "We believe we can prove that." Among other things, he says, engineers use more advanced techniques to detect flaws and are developing an annealing process that would strengthen irradiated metal. The key point "is the size and thickness of our vessel," he argues. "At eight inches, the walls are as thick as at brand-new plants."

Surprisingly, most of the age-related problems in nuclear facilities are not triggered by radiation but are due to more ordinary kinds of wear and tear. Corrosion can lead to leaks in the steam generators of some reactors, causing the eventual rupture of component tubes and the escape of radioactive water. Such a sequence of events was probably responsible for the accident in Mihama, Japan, last month, which resulted in the release of a small amount of radiation into the sea and air.

Of course, faulty design or parts would exacerbate the problems of aging. In one of the most acrimonious legal battles ever to hit the nuclear industry, the Duke Power Co. of Charlotte, N.C., has accused Pittsburgh-based Westinghouse of fraudulently selling it 16 defective steam generators. The utility claims that the generators, which were installed at two of its plants in the late 1970s, cost more to maintain than normal and may have to be replaced as soon as 1995, long before the end of their life-span. Duke estimates the cost of putting in new generators to be in excess of $600 million. Others in the industry are closely following the case, which is scheduled for trial in 1993, since identical Westinghouse generators are in place at 14 other U.S. facilities.

Aging is a concern even outside the containment structures of nuclear reactors. Although the pipes that crisscross such facilities have been designed to withstand tremendous changes in pressure and temperature, they are not immune to corrosion. Nuclear engineers confidently predict that they can find and replace worn-out equipment before it presents a hazard. But as many a householder can sadly attest, pipes do not always signal when they are about to burst. For nuclear reactors as for human beings, growing old frequently brings on unexpected -- and irreversible -- problems.

With reporting by Robert Ajemian/Boston