* NRC says no immediate threat at Seabrook reactor
* NextEra expects test results on concrete in 2014
* NRC to inspect plant again in early 2013
Dec 4 (Reuters) - U.S. nuclear regulators said on Tuesday concrete degradation at NextEra Energy Inc's 1,247-megawatt (MW) Seabrook nuclear power plant in New Hampshire did not pose an immediate risk to the public or environment.
The U.S. Nuclear Regulatory Commission, however, has told NextEra it must determine the future implications of the degradation and develop a plan to fix it, said Neil Sheehan, an NRC spokesman.
NextEra identified the degradation in below grade concrete structures at Seabrook in June 2009 and confirmed the problem was from alkali silica reaction, or ASR, in August 2010.
ASR is a chemical reaction that can cause expansion and cracking in concrete, potentially resulting in structural problems.
The NRC said this was the first time ASR has affected a nuclear power plant.
ASR has not caused structural problems at Seabrook, in part because the concrete walls are reinforced with rebar, the NRC said.
In its latest report issued Monday, Sheehan said the NRC conducted three weeks of on-site inspections and four months of in-office reviews to assess the adequacy of actions taken by NextEra to address the problem.
Based on these assessments, the NRC decided to close five of 11 items in a Confirmatory Action Letter (CAL) the agency issued to NextEra last May regarding regulatory commitments the company made to address the concrete degradation.
Sheehan said the remaining six confirmatory action letter items will be reviewed during another inspection the agency plans to perform in early 2013.
"We have said previously that no final NRC decision on the plant's license renewal application will be made until we fully understand and approve of NextEra's plans in response to Seabrook concrete degradation," Sheehan said.
Seabrook entered service in 1990. Even though it is one of the newest reactors in the nation, NextEra applied with the NRC to renew the plant's original 40-year license for another 20 years in June 2010. The original license does not expire until 2030.
Although the NRC has completed several non-contentious license renewals at other plants in less than two years, the NRC staff in the Seabrook case still has several reports to complete before the staff can make a recommendation to the commission on the application.
NextEra has told the NRC it does not expect to get results of testing of the degradation from the concrete laboratory at the University of Texas until 2014, so the NRC could not make a decision on the license renewal until at least that time.
That 2014 timeframe also fits with the NRC's self-imposed moratorium in August on issuing new licenses until the agency reviews the environmental impact of storing spent nuclear fuel at temporary sites, like nuclear power plants, due in part to a lack of a permanent waste storage facility. That decision followed a federal court ruling in June.
The commission in September directed the NRC staff to develop the environmental waste confidence study within 24 months.