Senior Public Affairs Officer
The Arkansas Nuclear One power plant, in Russellville, Ark., is coming under increased NRC focus as a result of flood protection problems.
Beginning in 2013, Entergy Operations officials and the NRC began extensive inspections of the flood protection program at ANO. Many problems were discovered and are described in a Sept. 9, 2014, NRC inspection report.
All told, more than 100 previously unknown flood barrier deficiencies creating flooding pathways into the site’s two auxiliary buildings were found. These included defective floor seals, flooding barriers that were designed, but never installed, and seals that had deteriorated over time. In one case, a special hatch that was supposed to be close a ventilation duct in the Unit 1 auxiliary building in the event of flooding had never been installed.
In the unlikely event of extreme flooding – a kind not seen since weather records have been kept for the area – significant amounts of water could have entered the auxiliary buildings. This could have submerged vital plant equipment, as well as the emergency diesel generator fuel vaults. The licensee has replaced degraded seals, installed new flood barriers and adopted new measures to better protect the site from flooding.
NRC held a regulatory conference with Entergy officials on Oct. 28, 2014. After considering information provided by the company, NRC determined violations related to flood protection have substantial safety significance, or are “yellow.” (The NRC evaluates regulatory performance at nuclear plants with a color coded process that classifies inspection findings as green, white, yellow or red, in order of increasing safety significance.)
The NRC divides plants into five performance categories, or columns on its Action Matrix. ANO Units 1 and 2 received yellow violations in June 2014 because electrical equipment damaged during an industrial incident increased risk to the plant. Workers were moving a 525-ton component out of the plant’s turbine building when a temporary lifting rig collapsed on March 13, 2013, damaging plant equipment. Those violations moved both units from Column 1 to Column 3 of the NRC’s Action Matrix. The agency increases its oversight of plants as performance declines.
The new violations will lead NRC to reassess whether even more inspection resources need to be focused on ANO. The NRC will determine the appropriate level of agency oversight and notify Entergy officials of that decision in a separate letter.