SEABROOK — One hour and 35 minutes to five hours and five minutes — that’s the estimated time, under a myriad of scenarios, that it would take to evacuate 90 percent of the 164,207 residents living within the 10-mile radius of NextEra Energy Seabrook nuclear power plant.
An updated analysis of the estimated evacuation times was recently submitted to the Nuclear Regulatory Commission by NextEra Energy.
According to NRC Region I spokesman Neil Sheehan, updates of evacuation estimates are required at least once every decade, or more frequently if local conditions change. Sheehan said the Federal Emergency Management Agency is responsible for assessing off-site emergency response plans for nuclear power plants.
FEMA will review the 242-page report as part of its larger emergency plan assessment, Sheehan said.
“We rely on FEMA to determine, on an ongoing basis, whether there is `reasonable assurance’ that an emergency plan remains effective,” Sheehan said.
The report, commissioned by NextEra and conducted by KLD Engineering, P.C. of New York, took 10 months to complete. It describes the process undertaken to determine the evacuation time estimates as well as the results.
The report’s purpose is to provide local and state governments with site-specific evacuation time estimates for the 23 communities, its education venues and other special populations within 10 miles of Seabrook Station.
The communities in the evacuation planning zone are further narrowed to a smaller 2.5-mile radius to the plant. Based on their proximity to the power plant, communities are divided further into seven emergency response planning areas.
Not surprisingly, Seabrook and Hampton Falls, closest to the plant, are in the A-level emergency response planning area. Salisbury and Amesbury are in the B-level, South Hampton and Kensington in the C-Level, Hampton and North Hampton fall into the D-Level; and Newburyport, Newbury, West Newbury and Merrimac in the E-level.
While the city of Portsmouth, with four suburbs, is farthest away and in the G-level ERPA, it represents the single largest populated and congested planning area.
The report also analyzed evacuation time estimates of “shadow regions,” which extend beyond the 10-mile radius by another 5 miles.
Numerous evacuation scenarios are explored: weather (good, rain or snow), seasons (winter or summer), day of week (midweek or weekend) and time of day. The report also discusses evacuation scenarios that include special events, such as a Fourth of July fireworks show at Hampton Beach or the shutdown of a highway lane on a major evacuation route.
“General population (evacuation time estimates) were computed for 266 unique cases,” according to the report, “(generated from) a combination of 19 unique evacuation regions and 14 evacuation scenarios.”
Calling it a “data-rich” report, Sheehan said it includes scores of tables charting the estimated evacuation time in every emergency response planning area — school, hospital and populated areas — during every scenario on the basis of moving 90 percent and 100 percent of the populace.
Sheehan said the complete Evacuation Time Estimate Update for Seabrook Station is available online within the NRC’s electronic documents system at http://adams.nrc.gov/wba/.