NextEra Energy’s Seabrook nuclear power plant’s application to extend its operating license 20 years will gain one phase of approval if it fixes seven still outstanding issues, Nuclear Regulatory Commission (NRC) officials said.

The 770-page report is a technical review of safety concerns at Seabrook, NH’s Seabrook Station required in the commission’s lengthy process of reviewing licensing at the nation’s nuclear power plants. The safety evaluation report is one of two license-related reviews. The second review is an environmental review, not yet issued.

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NextEra Energy Seabrook is trying to have its operating license extended from 2030 to 2050.

The focus of the license renewal process is on the aging management programs for key safety systems, structures and components, said NRC Region 1 spokesman Neil Sheehan.

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“We seek assurance that the systems, structures and components will be able to continue to safely perform their functions for an additional 20 years of operation,” he said. “Such plans may include replacement of a component, such as a pump or electrical system, at some point during the license renewal period.”

For nearly all the systems reviewed, commission staff concluded that Seabrook Station demonstrated it met the NRC’s requirements. However, seven issues remain open and the plant must fix them before the NRC can make a final determination on its safety evaluation, according to the letter sent to Seabrook Station by Brian Holian of the license renewal division of the NRC.

As expected, one of the seven open items relates to concrete degradation found in some areas of Seabrook Station’s subterranean walls, due to alkali-silica reaction within the concrete. ASR is more commonly in transportation structures like bridges and roads, where mitigation has been successful. But Seabrook Station is the first nuclear power plant to discover and report its presence within parts of the plant’s structure.

Occurring when moisture is present, alkali-silica reaction is a slow chemical reaction between the alkaline cement and reactive silica found in some aggregates used to make concrete. ASR forms a gel that expands, causing micro-cracks that affect concrete properties, but which can take five to 15 years to show up.

According to the safety evaluation report, the other six items include:
• Staff concern Seabrook Station has not, until now, implemented procedures and inspections to keep space between containment and containment enclosure buildings in a dewatered state.
• NextEra did not fully describe how it will use future operating experience to ensure the aging management program will remain effective for managing the aging effects during the period of extended operation, nor make clear how it intends to implement monitor operating experience on an ongoing basis to ensure effectiveness.
• Sufficient information was lacking to evaluate pressure-retaining bolting and component external surfaces surrounded by seal cap enclosures that may end up submerged due to ongoing leakage within the exposure.
• Sufficient information was lacking to judge if treated borated water environments will have sufficient control to determine if there will be adequate management of components.
• NRC staff had concerns whether the methodology used to develop pressure-temperature limits is consistent with requirements.
• NRC staff has concerns over the management of cracking due to primary water stress corrosion cracking on the primary coolant side of steam generator tube-to-tubesheet welds made or clad with nickle alloy.

Sheehan said there needs to be a resolution of all of the open items before the NRC will be able to issue a final decision on Seabrook Station’s application to operate for an additional 20 years.

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