ASLB adds conditions to Seabrook license amendment

September 15, 2020, 7:03AMNuclear News

An ASLB calls for closer scrutiny of concrete degradation at Seabrook.

An Atomic Safety and Licensing Board has rendered its decision on a challenge to a license amendment concerning concrete degradation—known as alkali-silica reaction, or ASR—at the Seabrook nuclear power plant, upholding the amendment but imposing four additional conditions. The board found the new conditions to be necessary to provide adequate protection of public health and safety, according to a September 11 Nuclear Regulatory Commission press release. (The ASLB is the NRC’s independent body charged with conducting adjudicatory hearings and deciding legal challenges to the agency’s licensing and enforcement actions.)

The challenge to NextEra Energy’s license amendment for Seabrook was brought in 2017 by the C-10 Research and Education Foundation, an opponent of license renewal for the New Hampshire facility, which houses one 1,248-MWe four-loop pressurized water reactor.

The conditions: The ASLB concluded that the amended license will meet the NRC’s requirements when the agency’s Office of Nuclear Reactor Regulation imposes the following conditions:

■ NextEra will monitor certain devices measuring concrete expansion every six months, rather than starting in 2025 and every 10 years after that.

■ If stress analyses show degradation-related expansion and other forces will exceed the strength of rebar in the concrete, NextEra must monitor the affected rebar to ensure it has not yielded or failed, or detect such failure if it has already occurred.

■ If the degradation-related expansion rate in any area of a “seismic Category I” structure significantly exceeds a certain limit, NextEra will evaluate whether to implement more frequent monitoring.

■ Each concrete core extracted from Seabrook must undergo a detailed microscopic evaluation to detect degradation-related features.

What they’re saying: Declaring partial victory, C-10’s executive director, Natalie Hildt Treat, said, “NextEra Energy Seabrook has been sent back to the drawing board with this extremely detailed ruling. While the [ASLB] ultimately accepted the company’s concrete testing program, it did so with several important conditions that will do more to ensure the health and safety of the public.”

In a statement, Peter Robbins, NextEra’s director of nuclear communications, expressed satisfaction that the license amendment had been upheld, adding, “Seabrook’s program to monitor and manage ASR is comprehensive and effective. Nothing is more important than the safety of employees and the public, and our robust ASR program is part of that commitment to safety. Public dialogue is an ongoing component of the NRC’s regulatory process, and we appreciate having had the opportunity to share the scientific basis of our testing and monitoring programs with the ASLB.”

Background: NextEra discovered concrete degradation at Seabrook a decade ago, during actions related to its license renewal application for the plant. The cause of the problem was later identified as ASR, a chemical reaction between water and concrete that results in the formation of a gel that can expand and cause “micro-cracks.” The phenomenon is also known as “concrete cancer.”

In 2016, NextEra submitted the license amendment request (LAR) to alter Seabrook’s license to include appropriate management and analysis of ASR-affected components. More specifically, the request called for revising the plant’s updated final safety analysis report to include methods for analyzing seismic Category I structures with concrete affected by ASR. According to the LAR, approval by the NRC would allow NextEra “to proceed in an optimum, safe, and effective manner toward a long-term solution for ASR degradation at Seabrook Station. The proposed methodology changes are necessary to reconcile the design basis of the containment building and other seismic Category I structures that are affected by ASR.”

In April 2017, however, C-10 filed a request for a hearing on the LAR, and later that year, the ASLB issued a 100-page ruling that admitted five of the group’s contentions, combining them into one reformulated contention: “The large-scale test program, undertaken for NextEra at the Ferguson Structural Engineering Laboratory, has yielded data that are not representative of the progression of ASR at Seabrook. As a result, the proposed monitoring, acceptance criteria, and inspection intervals are not adequate.”

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