The problem was not discovered at Seabrook Station until June 2009 when NextEra itself identified areas of ASR in underground structures at the power plant and reported the findings to the NRC. Found first in the 2-foot thick, steel rebar reinforced concrete walls of an electrical tunnel about 40 feet below ground, after further investigation it was determined that ASR is present in 131 areas throughout the power plant.
Since its discovery, the NRC has repeatedly, including at Wednesday night’s meeting, assured the public that the ASR has not affected the safety of Seabrook Station. The plant and its walls are still structurally sound, NRC officials said, because the parts of the 2-foot thick walls affected still meet federal standards for load-bearing capacity due to the lattice of steel rebar within the walls. The plant was built with such a large margin of safety, NRC engineers say, that the physical integrity of the structure remains sound and safe.
The NRC has conducted a number of ASR related in depth inspections since the initial discovery, to make its determination that the plant is currently safe, according to David Lew, NRC Deputy Regional Director of Region 1, the branch of the NRC that oversees Seabrook Station. In addition, Lew said, NextEra has contracted with the University of Texas at Austin to determine the impact ASR could have on the long-term structural integrity of the plant, which is currently licensed to operate until 2030.
However, ASR has become a huge concern for many antinuclear advocates, as well as for local, state and federal officials, since NextEra filed an application in 2010 with the NRC requesting a 20-year extension of its operating license from 2030 to 2050.
“Although testing and monitoring of the (ASR) problem has been undertaken since (its discovery),” the Congressional delegation wrote, “it seems unlikely that would enable the licensee (NextEra) to predict any future impact of ASR.”
Even though ASR can be found in many bridges, dams and airport runways throughout the nation, Seabrook Station is the first nuclear power plant in the United States to report its presence in its concrete structure. Nuclear power plants in Canada and Belgium have also reported the presence of ASR.