North / South America
Alkali-silica reaction affecting Seabrook Nuclear plant
Apr, 30 2012
Seabrook Station nuclear power plant owner NextEra Energy wants to relicense the facility through 2050. Plant engineers and federal officials are determining a course of action to address concrete degradation in several structures at the nuclear plant.
- NRC officials discuss concrete degradation at Seabrook nuke plant
- Structural problem delaying license renewal
- The plant is working on a long-range plan to mitigate the effects of ASR
(HAMPTON, New Hampshire) -- NextEra Energy's application to extend its license to operate the Seabrook Station nuclear power plant to 2050 depends on the company first dealing with concrete degradation problems at the facility, a federal official said Thursday.
Chris Miller, director of reactor safety for the Nuclear Regulatory Commission, said before any extension is granted the plant operators must determine the cause of the concrete degradation and come up with a corrective action plan. The concrete degradation, which has been discovered in several structures at the plant, was the subject of a daylong NRC meeting in Rockville, Md., this past Monday.
The issue was addressed again at Thursday's meeting in Hampton on the plant's safety performance in 2011. The concrete degradation has been linked to an alkali-silica reaction, which occurs when ground water comes into contact with concrete.
Arthur Burritt, branch chief of the NRC, assured members of the public that regulators have independently verified the affected structures at the plant remain safe and operable, noting that concrete walls affected by ASR still meet federal standards.
"We are requiring the licensee to understand what the ASR problem is," Burritt said. "What are the root causes and actions that need to be taken to control the problem? Once they submit that to us and we are satisfied, then we will consider the application for final review."
The issue of alkali-silica reaction was discovered in the "B" electrical tunnel in 2010, shortly after NextEra applied to the NRC for a 20-year extension of its 40-year operating license, which is set to expire in 2030. Since then, ASR concrete degradation has been discovered in the containment enclosure building, RHR vault, EDG building and the EFW building.
ASR is a slow chemical reaction in concrete, which occurs in the presence of water, between the alkaline cement and reactive silica found in some aggregates. It forms a gel that expands, causing microscopic cracks.
"All the important buildings are heavily reinforced, which minimizes any potential changes as a result of ASR," Burritt said.
He added that Seabrook Station is the first nuclear power plant in the country that has identified ASR problems in structures. The problem is common in bridges, roads and airport runways.
"It has to do with the material they used in the concrete," NRC spokesman Neil Sheehan said.
Alan Griffith, spokesman for NextEra, said ASR-affected areas of concrete at Seabrook are relatively small, highly manageable and will not affect the nuclear power plant's ability to operate safely over its lifetime. But he said NextEra is thoroughly studying the issue, including hiring experts such as a University of Texas staff member, to conduct more in-depth testing.
Sheehan said the NRC intends to hold other public meetings on the issue in the Seacoast.
The investigation into the effects of ASR on Seabrook Station have already pushed the license extension process back about 11 months, Sheehan said. The plant, he said, is working on a long-range plan to mitigate the effects of ASR.
"With the additional work going on, it may be pushed back even further to 2014," he said of the license renewal process.
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