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UCS Issues Report on Seabrook Nuke Cement Cracks

CAMBRIDGE (April 23, 2012)—The Union of Concerned Scientists (UCS) released a report today about potentially serious concrete degradation at the Seabrook nuclear power plant in Seabrook, New Hampshire. The report was written by Paul Brown, a professor of ceramic science and engineering at Penn State University. (An executive summary also is available on line.)

After reviewing publicly available documents, Brown concluded that neither plant owner NextEra Energy nor the Nuclear Regulatory Commission (NRC) fully understand the scope or origins of the problem and therefore cannot adequately assess the plant’s structural status.

The report provides a list of key questions the NRC and NextEra Energy need to address before they can assure nearby communities they are not at heightened risk.

The NRC has a meeting scheduled today at its Rockville, Maryland, headquarters with NextEra officials to discuss the issue and the company’s plans for further testing, evaluation and monitoring. There will be a 15-minute public comment period at the end of the meeting.

The problem was first officially noted a year ago, when NRC inspectors confirmed that widespread cracks in the plant’s concrete due to a process called alkali-silica reaction (ASR) resulted in a “moderate to severe” reduction in concrete strength in five buildings. ASR can occur when certain forms of silica in the bulk material in concrete such as crushed rock and sand react in the presence of water with such chemicals as sodium or potassium, which are commonly found in the cement paste. This reaction produces a gel that forms in the pores of the concrete and then expands, causing stress and cracking. Over time, those cracks can join together to form larger fissures in the cement and compromise the concrete’s structural integrity.

In his report, Brown said that NextEra and the NRC must determine to what extent ASR is occurring, what other negative reactions—including corrosion of embedded steel in the concrete—are occurring, and what basis is there for knowing which steps will be effective in addressing these problems.

In 2010, NextEra Energy applied to the Nuclear Regulatory Commission (NRC) to renew Seabrook’s operating license for 20 more years, even though its license was issued in 1990 and does not expire until 2030. The license renewal would allow Seabrook to operate until 2050.

“The NRC must take seriously its responsibility to protect the public and fully understand the origin, extent and implications of the concrete problem at Seabrook,” said David Wright, co-director of UCS’s Global Security Program. “That will be no easy task given the many questions Paul Brown’s report says still need to be answered.”


The Union of Concerned Scientists is the leading U.S. science-based nonprofit organization working for a healthy environment and a safer world. Founded in 1969, UCS is headquartered in Cambridge, Massachusetts, and also has offices in Berkeley, Chicago and Washington, D.C.