Federal regulators will conduct additional inspections and reviews to independently verify and assess work being done to address degrading concrete at the Seabrook Station Nuclear Plant.
Plant officials discovered cracking in the plant's control building in August. 2010. In December 2011, the Nuclear Regulatory Commission issued a general alert to all of its facilities and applicants regarding the risk of the same problem elsewhere.
Nuclear Regulatory Commission
|Patterned cracking like this can be indicative of ASR-induced degradation. The Nuclear Regulatory Commission distributed the photo as a generic example from outside the nuclear industry.|
NRC documents also now indicate the problem is affecting multiple structures at Seabrook.
The problem is known as Alkali-Silica Reaction-induced (ASR) concrete degradation, a slow chemical degradation process that occurs when alkalis—usually from cement—react with certain types of silica in the aggregate when moisture is present.
The reaction produces an alkali-silica gel that can absorb water and expand to cause micro-cracking of the concrete. Excessive expansion of the gel can lead to significant cracking.
On Friday (Sept. 14), the NRC announced the additional reviews—a deviation from the general Reactor Oversight Process—at New Hampshire’s Seabrook plant, which is operated by NextEra Energy Seabrook LLC.
Matthew Trump / Creative Commons
|The Seabrook Station Nuclear Plant has found ASR-induced concrete degradation in multiple structures on site.|
Although the agency’s process does not require the increased oversight, NRC’s “staff believes the additional inspections and assessments are needed to support the review of licensee commitments and planned large-scale concrete specimen testing by the licensee, the development of staff technical guidance, and stakeholder communications and outreach activities,” NRC Region I Administrator Bill Dean wrote in a memorandum to Executive Director for Operations William Borchardt.
That request for further resources has now been approved via a “Deviation Memorandum,” which refers to a deviation from the Reactor Oversight Process, the NRC said in a statement.
The NRC continues to say that the problem does not threaten the structures’ integrity, but the agency is still investigating.
“While the extent of the problem at Seabrook is still being evaluated, the NRC has determined that the structures identified to be affected by ASR can perform their safety function when called upon,” the agency said in a statement.
Copies of the Deviation Memorandum and other documents related to the Seabrook ASR issue are available at www.nrc.gov.