SEABROOK — A problem with degradation of concrete in the Control Building at the Seabrook Station nuclear power plant has prompted the U.S. Nuclear Regulatory Commission to issue a warning to operators of nuclear power plants across the country.

SEABROOK — A problem with degradation of concrete in the Control Building at the Seabrook Station nuclear power plant has prompted the U.S. Nuclear Regulatory Commission to issue a warning to operators of nuclear power plants across the country.



"The NRC has issued an information notice to all U.S. nuclear power plant operators regarding the issue of alkali-silica reaction-induced (ASR) concrete degradation," NRC Region 1 spokesman Neil Sheehan said. "This notice was prompted by the identification of ASR at the Seabrook nuclear power plant. NRC information notices are generic communications designed to make all plants aware of issues, with the expectation they will review the information for applicability to their facility and consider actions, if necessary to avoid similar problems."



The notice, however, does not require plant operators to take action other than to be on the lookout for this problem at their facilities, the NRC document states.



"The NRC expects that recipients (of the notice) will review the information for applicability to their facilities and consider actions, as appropriate, to avoid similar problems," the notice reads. "However, suggestions contained in this (notice) are not NRC requirements; therefore, no specific actions or written response is required."



With respect to the ASR identified at Seabrook, the NRC is continuing to evaluate the condition as part of its review of a license renewal application for the plant, Sheehan said. NextEra Energy Resources, operator of the plant, has asked the NRC to extend Seabrook's operating license to 2050, though the current license will not expire until 2030.



"Seabrook is the first plant to address ASR-induced concrete degradation as part of a license renewal review," Sheehan said.



NRC inspectors reviewing Seabrook Station for its fitness to have its license extended noted the deterioration, which was discovered by the plant's staff and recorded in an inspection report dated May 23.



"The walk-down inspections discovered the following plant material conditions (at Seabrook Station); (a) large amount of groundwater infiltration, (b) large amount of calcium carbonate deposits, (c) corroded steel supports, base plates and piping, (d) corroded anchor bolts, (e) pooling of water and (f) cracking and spalling of concrete," the NRC's report states. "The inspection further noted that the below-grade, exterior walls in the Control Building B Electrical Tunnel ... have random cracking and for several years have been saturated by groundwater infiltration.



"The severity of the cracking and groundwater infiltration varies from location to location," the report continues. "A comparison of the 2010 concrete compression test results to the 1979 concrete compression test results indicated a 21.7 percent reduction in the compressive strength of the concrete."



Because of these findings, the issuance of the preliminary Safety Evaluation Report for the license extension that was to be completed in June was pushed back to May 2012. That delays the issuance of the final version of that report from January 2012 to December 2012, Sheehan previously stated.



Typically, the license extension approval process takes 30 months, when opponents call for a public hearing on the merits of that extension. Several nuclear safety organizations, including the Exeter-based Seacoast Anti-Pollution League, have been granted intervener status in the Seabrook license extension process, creating the need for such a hearing.



"This ongoing groundwater infiltration and weakening of the plant foundations doesn't sound good, considering that it is only about one-third of the way through its prospective life," SAPL Executive Director Doug Bogen said after the May 23 release of the report. "This is exactly the kind of problem we're concerned about as the plant enters its middle and old age, and it doesn't bode well for future safety and reliability if the problem worsens in coming years."



At a June 8 meeting in Hampton on safety at the local nuclear plant, NRC Branch Chief Arthur Burritt noted that the problem of concrete deteriorating when in contact with groundwater is, so far, unique to Seabrook Station. Burritt said that because this is a new problem, he is not yet confident in NextEra Energy LLC's ability to control the degradation.



"This is the first time this has come to our attention," Burritt said. "Most plants are not affected. It's because of the concrete aggregates used at Seabrook that we have this problem. We have not been able to draw any conclusions about the ability of the utility to maintain these buildings."



Alan Griffith, spokesman for NextEra Energy Resources, said the issue for plant officials is not when the license extension will be granted, but how best to alleviate the ASR problem so the plant can continue to operate safely. "We're not overly concerned with the schedule," he said. "It's about taking the time we need to develop strategies for safe operation."



Griffith said the plant still meets or exceeds all design specifications. He added NextEra has hired third-party ASR experts, who are currently on site assisting plant personnel in coming up with repair strategies.