NRC wants more information on Seabrook concrete tests
WASHINGTON, D.C. — Seeking to understand the testing initiated by owners of NextEra Energy Seabrook nuclear power plant on its concrete problem, staff from the Nuclear Regulatory Commission spent three days auditing the regimen being conducted at the University of Texas.
The purpose of the NRC’s October review at the University of Texas’ Ferguson Structural Engineering Laboratory in Austin was for auditors to get a better understanding of the large-scale testing program that seeks to determine the longterm impact of concrete degradation problem found at Seabrook Station, according to Neil Sheehan, spokesman for Region 1 of the NRC. One conclusion of the NRC audit is that more information is needed before a final determination can be made on how to handle the problem in the long term.
“The NRC is still reviewing NextEra’s plans for addressing concrete degradation, also known as alkalai silica reaction, at the Seabrook nuclear power plant and how it might impact the facility during a license extension period (of) an additional 20 years of operation past the original 40-year operating license,” Sheehan said. “While there, the five-member NRC team observed a sample of the testing. This included two large-scale shear load tests on concrete beams to failure and material property testing.”
In May, 2010, Seabrook Station made application to the NRC to extend its 40-year operating license period from 2030 to 2050. However, while preparing the application, staff at the power plant discovered signs of alkalai-silica reaction in some of the concrete walls of an electrical tunnel deep underground. NextEra staff reported the issue to the NRC. Since then, ASR has been discovered in more walls throughout the power plant.
The issues of if an how the concrete problem could impact the aging of the nuclear power plant is being investigated as the nuclear regulatory agency considers whether to approve the 20-year extension of Seabrook Station’s operating license.
Alkali-silica reaction, or ASR, is a slow chemical reaction between the alkaline cement and reactive silica found in some concrete aggregates when moisture is present. Commonly found in dams and bridges, ASR forms a gel that expands, causing micro-cracks that affect concrete strength. ASR can take five to 15 years to show up.
Seabrook Station is currently the only nuclear power plant in the United States known to have ASR issues, although power plants located in Canada and Europe have experienced the problem.