c.2014 New York Times News Service
The Indian Point power plant north of New York is one of 10 sites considered most in need for a re-evaluation of earthquake vulnerability, the Nuclear Regulatory Commission announced Friday.
Dozens of reactors at more than 20 sites across the eastern and central parts of the country need to be re-evaluated, the commission said, because of new estimates from the U.S. Geological Survey. The agency’s study compared the maximum amount of ground movement that was predicted when the plants were designed, and the amount calculated more recently. Sites on the West Coast will be evaluated later.
The orders issued Friday are part of a broad effort that began before the earthquake and resulting tsunami caused a triple meltdown at the Fukushima Daiichi reactors in Japan in 2011, but the project gained urgency after that event.
Because there are few engineers qualified to do the work, the commission prioritized 10, including Indian Point in Westchester County, setting a deadline for submitting a detailed risk analysis by June 2017.
The commission has described the work as important but not requiring instant action. It asked for a quick review of key systems that would keep nuclear fuel cool after an earthquake, in addition to a detailed analysis of the plant. If problems are found in those systems, they would have to be corrected by the end of 2016.
But Eric Leeds, director of the commission’s Office of Nuclear Reactor Regulation, said in a statement, “We’re confident the plants are safe to continue operating.”
The commission included the Oyster Creek plant, in Forked River, New Jersey, in a second list of sites that must submit an analysis by December 2019. The owners of Oyster Creek, the oldest commercial reactor in the United States, have agreed with state environmental regulators to retire the plant by the end of 2019 because its cooling system has killed marine life.
Estimating the occurrence of significant earthquakes has always been difficult. In 2011, an earthquake centered in Mineral, Virginia, near the North Anna reactors, shook the East Coast and exceeded the safety standards that the plant had been designed to meet. Engineers found only cosmetic damage after weeks of study.
Analysis for the two operating reactors at Indian Point is estimated to cost around $10 million. The owner of the reactors, Entergy, had already taken steps the company hoped would forestall the need for the analysis, including tearing down a smokestack from a long-retired reactor that had the potential, during a quake, of toppling onto a control room of a working reactor.
So the company, among other changes, tore down most of the stack. As a result, Entergy said, the probability of an earthquake causing core damage at that reactor fell to once in 125,000 years, from 68,966 years.
Even the estimates that predicted such events more frequently overstated the risk, said Jerry Nappi, a spokesman for Entergy, because a second set of controls outside the control room is available to shut down the reactor if necessary. The analysis “did not take credit” for that ability, he said.
But Lynn R. Sykes, a professor emeritus at Columbia University and a researcher at the university’s Lamont-Doherty Earth Observatory, said that while some plant parts were undoubtedly stronger than what was assumed in the earthquake analyses, it would be harder to assure that all the relevant parts were.
Nuclear plants have been shown to be vulnerable to high-frequency ground motion, he said, meaning when the ground shakes back and forth quickly. That was the risk the Geological Survey determined was higher than previously thought.
The Nuclear Regulatory Commission has been studying the issue for about 20 years, he said. “I think that the time is really long past for some action,” he said, “rather than giving them yet another chance to have another study done.”
Other sites in the first group to be reassessed include the Pilgrim plant near Cape Cod, Massachusetts, and Peach Bottom, in the Pennsylvania town of the same name.United States government - U.S. Nuclear Regulatory Commission