An inspection report on Seabrook Station, released last week by the Nuclear Regulatory Commission, found that a concrete safety structure compromised by years of ground water infiltration is “operable but degraded’’ and chided the plant operator for failing to fully evaluate certain areas related to the degradation.
The safety structure, an electric control tunnel at the nuclear power plant that supports the cooling system used when the reactor is shut down, is showing signs of alkali-silica reaction (ASR), a chemical reaction that occurs over time when the kind of concrete used at Seabrook Station comes in contact with water. ASR forms a gel that expands, causing micro-cracks that change physical structural properties of the concrete.
The NRC report deems Seabrook Station safe, noting that concrete walls affected by ASR still meet federal support standards. However, the report raises concerns about ASR’s long-term impact, noting that plant operator NextEra Energy Resources failed to take into account the “aggressive ground water environment along with the presence of ASR’’ in its evaluations of structural integrity.
“We are pleased that once again the NRC has made clear it has no immediate safety concerns at Seabrook Station,’’ said NextEra spokesman Alan Griffith. “We share with the NRC the desire to complete ASR analysis and testing so that we fully understand any potential long-term impact ASR may have on our safety-related systems and structures.
“We have a comprehensive strategy in place to effectively manage ASR that includes augmented monitoring, improved analysis techniques, and potential ASR mitigation actions, if ever needed. Most importantly, ASR has not, and will not, impact our ability to operate our plant safely.’’
That strategy will be discussed April 23, when top management officials from NextEra are scheduled to meet with an NRC team at the commission’s headquarters in Rockville, Md., to talk about the concrete degradation and Seabrook Station’s plan to address it. The findings of the NRC inspectors will be central to that discussion.
The 10-page NRC inspection report notes that the methods used by the plant operator to evaluate structural integrity of the tunnel under normal conditions and upset conditions, such as a seismic event, relied upon mathematical formulas used to assess non-degraded concrete. The methods did not take into account the concrete’s degraded condition or the effects of ASR on the concrete’s mechanical properties and stresses in the rebar.
“The inspection was carried out by six NRC inspectors over many months,’’ said NRC spokesman Neil Sheehan. “We made use of concrete/structural integrity expertise at our headquarters office. We also had an inspector in our suburban Chicago office observe lab tests in Northfield, Ill., of concrete core samples taken from Seabrook.
“Overall, we found that the affected structure remains ‘operable but degraded,’ ’’ Sheehan said. The NRC based that conclusion on several factors, including the fact that the ASR is limited to localized areas and that the concrete degradation is taking place slowly.
NextEra discovered the ASR in 2010 and has spent many months analyzing the issue. The company is expected to submit a summary of its engineering evaluation to the NRC tomorrow. That summary will lead to more back-and-forth between the two parties, Sheehan said, adding that the NRC is “far from done with our reviews in this area.’’
The concrete degradation at Seabrook Station was also addressed recently by the International Atomic Energy Association in an 88-page audit report. The association’s findings, released March 22, reveal that ground water seepage issues at the power plant were discovered and assessed shortly after construction of the facility was completed, but that more than two decades passed before test borings were done to reassess the condition of the concrete.
According to Griffith, NextEra did not find ASR in the intervening years “because it didn’t exist. ASR can be latent. It can take 15, 20, 30, 40, or 50 years to manifest itself.’’
Griffith said Seabrook’s participation in the IAEA review was voluntary, and “demonstrates our commitment to continuous improvement. We’re recognized as one of the top nuclear power plants, and have been for the past 12 years.’’
Still, release of the IAEA audit, which says the plant “in some cases demonstrates a lack of aggressive and proactive resolution on long-term issues,’’ and the findings of the NRC inspectors have reignited calls for a halt to the relicensing process for Seabrook Station. NextEra is hoping to receive NRC approval to add another 20 years to its 40-year operating license, which is set to expire in 2030.
“With recent reports indicating several safety-related issues are affecting important structures at Seabrook, the NRC should not relicense Seabrook for another 20 years until these issues are fixed, especially when these problems are being identified in Seabrook’s nuclear adolescence,’’ said US Representative Edward J. Markey, senior member of the House Energy and Commerce Committee.
Markey has been joined by US Representative John F. Tierney and, in the wake of the IAEA audit’s public release, by Senator John Kerry in calling on the NRC to take immediate steps to address the concrete degradation at Seabrook. Local activists and politicians - including state Representative Michael A. Costello and state Senator Steven A. Baddour - have also called on the NRC to require that NextEra repair the concrete, stop the ground water infiltration, and monitor the effectiveness of the fix before the NRC considers relicensing the plant.
The IAEA audit “shows that the Seabrook nuclear power plant completely botched the handling of the concrete degradation from the start,’’ said Bruce Skud, 62, of Newburyport, a cofounder of No More Fujishimas, a grass-roots group that has become a driving force behind local opposition to the plant’s relicensing request. “They ignored the ASR problem for years, only addressing it after it became obviously severe, posing a risk to our safety.’’
The Newburyport City Council in February adopted a resolution calling on the NRC to suspend the relicensing process until “safe operation of this reactor can be assured.’’ West Newbury is mulling a request to take similar action. Salisbury is expected to hold a public workshop on the issue.
In Newbury, the Board of Selectmen is drafting a letter to the NRC, which it hopes to finalize at its next meeting, on April 10. The five-member board plans to base its comments on the recently released reports. “It would be real easy to copy a letter from some other town or politician, but we want to write something that will make a difference,’’ said board chairman Joseph Story. “We want to write something that will really hit the nail on the head.’’
To date, the NRC has not halted the relicensing process, but has said that no decision on the license renewal will be made until the extent of the concrete degradation is “fully understood.’’