SEABROOK — A recent inspection report by the Nuclear Regulatory Commission finds that NextEra Energy Seabrook has shown that the nuclear power plant’s staff is taking necessary steps to address the plant’s concrete degradation, leading the NRC to close all of the remaining action items first issued by the commission to address the situation.
By closing the last of the items ordered to address the alkali-silica reaction concrete degradation evaluation at the power plant, the commission has found that appropriate corrective actions are being carried out, according to an NRC spokesman.
However, the results of more testing, ongoing at the University of Texas, are necessary to determine a long-term solution for the problem as it relates to the NextEra’s request for a 20-year extension of the plant’s operating license. The result of that testing isn’t expected until some time in 2014.
On June 27, a team from the NRC completed a weeks-long inspection at Seabrook Station. The team reviewed procedures and records, observed activities and interviewed station personnel regarding the adequacy of NextEra’s actions to address the impact of alkali-silica reaction on reinforced concrete structures, according to the letter written by Raymond Lorson, director of reactor safety for the NRC.
The team also examined the plant’s safety and compliance with agency rules and regulations.
Alkali-silica reaction is a slow chemical reaction among water, the alkaline cement and reactive silica found in some aggregates used to make concrete. ASR forms a gel that expands, causing cracks that affect concrete properties, but which can take five to 15 years to show up.
More commonly found in transportation structures like dams, bridges and roads, where it has been successfully mitigated, Seabrook Station was the first nuclear power plant to discover and report the presence of ASR in 2009. It was found in an electrical conduit tunnel located about 40 feet below ground level, in one of the deepest sections of the plant. The tunnel contains wires that lead from the control room to the rest of the plant. The tunnel holds wiring that connects the plant’s controls to machinery throughout the facility.
The NRC has repeatedly assured the public that the ASR has not affected the safety of Seabrook Station because the affected parts of the 2-foot-thick walls still meet federal standards for load-bearing capacity due to the lattice of steel rebar within the walls.
However, the discovery grew into a major concern for many antinuclear advocates, state and federal officials, especially when NextEra filed an application with the NRC requesting a 20-year extension of its operating license from 2030 to 2050.
On May 16, 2012, a “confirmation action letter” spelling out actions the power plant had to take to resolve the issue was sent to Seabrook Station by the NRC. The letter had 11 commitments made by NextEra in regard to evaluating the ASR-affected reinforced concrete at Seabrook Station. Based on its initial inspections, the NRC late last year closed five of the original 11 items listed in the letter.
According to NRC regional spokesman Neil Sheehan, the closure of the remaining actions on their letter indicates that NextEra has satisfactorily implemented steps now and in the near future that show appropriate corrective actions are being carried out.
“Based on our reviews,” Sheehan said, “we have found that an acceptable basis has been established to assure that the continued operability of Seabrook (Station’s) concrete structures will be maintained.”
This recently issued report is the result of several weeks of onsite inspection by agency inspectors at Seabrook Station, as well as two weeks of inspection at the Ferguson Structural Engineering Laboratory at the University of Texas-Austin, where ASR’s possible long-term impact on reinforced concrete structures at Seabrook Station is being assessed.
According to the NRC, it independently verified that NextEra determined that all ASR-affected structures remain operable. Their team also confirmed that the root cause evaluation was thorough, while identifying appropriate corrective actions.
Sheehan said the closure of the Confirmatory Action Letter commitments does not mean the conclusion of the agency’s review of Seabrook Station’s concrete degradation issues. The ongoing testing at the University of Texas will help the NRC determine the efficacy of the plant’s long-term plans to address the issue, Sheehan said.
Sheehan added that NRC plans a public meeting in the Seabrook area with NextEra in October to discuss the company’s future testing program and actions.