Seabrook nuke plant safety report: Concrete degradation still a challenge - Seacoastonline.com

Seabrook nuke plant safety report: Concrete degradation still a challenge

Seabrook nuclear plant faces ongoing challenge of managing concrete degradation

SEABROOK — The Nuclear Regulatory Commission reported NextEra Energy Seabrook nuclear power plant’s overall performance last year “preserved public health and safety.”

The power plant’s annual assessment was presented to the public by the NRC’s team of experts at a meeting in Hampton last month. Agency officials assured the public that following 4,000 hours of inspections throughout 2022, the nuclear power plant in their backyard was safe.

But agency officials also discussed the problem that’s dogged the power plant’s concrete for more than a decade: alkali-silica reaction. NextEra, they noted, will have to bring resources to bear on a continual basis to address ASR as Seabrook Station ages to comply with the conditions of its operating license. A 2023 report shows concrete degradation has expanded from seven to 10 structures at the Seabrook plant.

History of NextEra Energy Seabrook and ASR

Discovered and reported by NextEra’s personnel in 2009, ASR is a slow-developing type of degradation that can occur in some concrete when moisture is present. Found most often in dams and bridges, ASR manifests as micro-cracking, staining, expansion and deformation of concrete. So far, the NRC’s repeated inspections determined ASR in Seabrook Station’s structures poses no immediate threat to public safety.

And according to NRC officials, to date, no structure has ever collapsed due to ASR.

Alkali-silica reaction was discovered in some walls and structures at Seabrook Station just as NextEra applied for a 20-year extension to its original 40-year operating license from 2030 to 2050. Nuclear power plants operating successfully for 20 years can apply for license extensions, and most do. Seabrook Station, which became fully operational in 1990, met the criteria to apply for a license extension.

Although ASR has been detected in a nuclear power plant outside the United States, Seabrook Station is currently the only American nuclear power plant exhibiting ASR, according to the NRC.

A new phenomenon in the nation’s fleet of nuclear power plants, following the report of ASR at Seabrook Station, NRC officials told plant owner NextEra that no license extension would be approved until the federal agency was sure the ASR in Seabrook Station’s walls could be monitored and managed successfully as the plant ages.

NextEra engaged in years-long testing of the effects of ASR on concrete at the University of Texas. After years of study, investigation and inspections by the power plant and NRC staff in March 2019, NextEra Energy Seabrook nuclear power plant was re-licensed to 2050.

However, there are amendments to the plant’s license specific to NextEra’s maintenance and monitoring of its ASR-implicated structures as conditions for its relicensing. They related to how NextEra must address the ASR phenomenon, including methodologies for measuring its progression, along with procedures directed toward mitigation and modifications, should that become necessary.

Inspectors monitoring ASR at Seabrook plant

The NRC maintains consistent eyes and ears on all the nation’s nuclear power plants with inspectors stationed on-site at each facility. Referred to as resident inspectors, daily they watch plant activities and check safety requirements. At Seabrook Station, the resident inspectors are Seamus Flanigan and Travis Daun.

NRC specialists also regularly visit each facility throughout the year. They and the resident inspectors have “unfettered access to all plant activities and related nuclear safety and security,” according to the NRC.

In Seabrook Station’s case, that includes inspecting to ensure plant personnel correctly monitor ASR according to the conditions set in its relicensing.

In its annual assessment letter, the NRC reported the plant operated safely from Jan. 1 through Dec. 31, 2022.

The annual assessment and a recent March 2023 inspection report on the effects of ASR at the plant, however, indicate NextEra will have to bring resources to bear on a continual basis to address ASR as Seabrook Station ages to comply with the conditions of its operating license.

It is a responsibility NextEra said it is prepared to meet.

“Safety will always be our highest priority,” according to NextEra senior communication strategist Lindsay Robertson. “We are making significant investments to enhance some of our concrete structures. This ensures that Seabrook will continue to meet the region’s energy needs for years to come. Seabrook has generated safe, clean, emissions-free energy that has helped power New England for decades.”

An example of ASR’s continuing footprint at the plant can be found in the NRC’s report on a March ASR-related inspection. According to the report, late last fall three additional structures were added to the existing seven that had “specific structural elements that would require physical modification and additional analysis to comply with their current licensing and design bases requirements.”

Currently, all 10 structures are performing their function safely, according to NRC senior engineer Nik Floyd and Branch Chief Matt Young. But the federal agency continues to monitor them closely to ensure the plant maintains industry standards and complies with regulations.

Should ASR cause expansion ranges that exceed acceptable ratios, according to Gray, remedies are available through modifications. If retrofitting should be required, some types of modification have already been identified, he said.

And the NRC will be on the job to make sure all structural standards are met to ensure the public’s safety, on ASR and all other concerns at the power plant, Floyd added.

“We continue to inspect Seabrook’s implementation and oversight of its structural monitoring program regarding alkali-silica, to ensure issues are identified, managed and corrected in a timely manner that supports continued safe operation of the plant,” according to NRC spokesman Neil Sheehan. “Currently, all structures maintain their functionality based on the supporting structural evaluations and monitoring data.”