As utilities seek to build new nuclear power plants in the U.S. and around the world, the latest generation of reactors feature improvements over older technologies. But even as attention focuses on nuclear as an alternative to fossil fuels, questions remain about whether the newer reactors are sufficiently foolproof to be adopted on a large scale.

In 2007, the first application to build a new reactor in the United States in more than three decades was filed with the Nuclear Regulatory Commission (NRC). By the end of that year, four more applications had landed at the agency. In 2008, 12 additional applications arrived, with one more filed in 2009. Nuclear backers proclaimed a "renaissance" underway.

The NRC, which over the years had lost personnel because of a shortage of work, geared up, hiring 1,000 new staffers to handle the licensing requests. Things got so crowded at the Office of New Reactors that in May the agency broke ground for a third office building in suburban Washington.

A new generation of nuclear power is indeed taking shape, driven, in large part, by a growing sense among environmentalists and policymakers that any strategy to wean the U.S. off planet-warming fossil fuels must include construction of more nuclear power plants. But how safe will this new generation of nuclear power plants be in comparison to the existing fleet of 104 plants that currently generate 20 percent of the nation's electricity?

Perhaps the most critical difference is that the new designs are simpler and rely less on human or mechanical intervention in the case of accidents. Settling on a standard design was one recommendation made after the 1979 accident at Three Mile Island. Some designs, for example, use gravity to provide emergency cooling water rather than pumps, which can fail. Some reactors now have redundant safety features, like extra pumps. In addition, the NRC has increased regulatory scrutiny of the new designs, ordering, for example, additional safety features or engineering changes to improve delivery of emergency cooling water.

Russ Bell, director of new plant licensing at the industry’s Nuclear Energy Institute in Washington, maintains that the new plants will be extraordinarily safe. Government risk assessments for the new reactor designs say that an accident that could damage the reactors' cores would likely occur once every 10 million years — an order or two of magnitude lower than the U.S's existing nuclear power plants. And even were a core-damaging accident to occur, Bell says that does not mean radiation would escape, since the reactors have containment buildings and systems designed to prevent releases of radioactivity.

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3.21 Copyright (C) 2007 Alain Georgette / Copyright (C) 2006 Frantisek Hliva. All rights reserved."