Sea Level Rise May Add to Flood Risks at Seabrook Nuclear Plant

This morning, New Hampshire's NPR radio station broadcast an interesting story about how the small town of Seabrook, N.H. is beginning to plan for sea level rise and the increased risk of devastating storm surges. With this part of the Northeast coast exposed to both sea level rise, which is currently happening at about 1.2 inches every decade (similar to the global average rate), as well as the and natural sinking of the coastal land (known as subsidence), the beach homes around Seabrook are now facing a creeping shoreline.

As NPR's Andrea Muraskin reports:

With funds from the New Hampshire Department of Environmental Services (DES), the Rockingham Planning Commission conducted a study two years ago in Seabrook. That study recommended Seabrook plan for a 3 to 5 feet mean sea level rise by the year 2100, and at least 1.5 feet by mid-century. Slowly, the town has started to take action.

Though sea level rise by itself may be enough to threaten some of the homes built directly on the beach, the real risk comes from what the higher water level means for storm surges from fall and winter storms, known in the area as “Nor'easters” due to their strong northeasterly winds. In the article, Muraskin interviewed Ted Diers, from the state's DES, who says:

Seabrook is starting to see 100 year floods more frequently. “It’s statistically significant that we’re getting more and more rain on fewer and fewer precipitation events. Where we sit here is particularly vulnerable at the interface between the ocean and these rivers. Because as these rivers have increasing flooding, and if we have increasing tidal surges, those together can really magnify to cause severe floods, and we’ve seen that in the Mother’s Day and the Patriots’ Day storms of late.”

What Muraskin's report doesn't address is what sea level rise at Seabrook means for the nuclear power plant located just a couple miles inland from the coast. While much of the town's development is spread along a narrow sandy penninsula, there is also an extensive network of brackish and freshwater marshes extending westward from the coast. And on the far side of the wetlands lies the Seabrook Station nuclear power plant. Operated by NextEra Energy (a subsidiary of the Florida Power & Light company), the plant supplies power to more than 900,000 homes. 

The Seabrook Station nuclear power plant in Seabrook, N.H.. Credit: Wikimedia.

A few weeks ago, we reported on how sea level rise can increase the height of storm surges that could inundate coastal nuclear power plants in the U.S., and at the Turkey Point nuclear facility south of Miami, Fla., in particular. At Turkey Point, where two new reactors are currently being considered, sea level rise in the coming years will have an important influence on whether a storm surge brought in from a powerful hurricane will inundate the property. In the event of a major hurricane, for example, the safe operation of the nuclear plant could be threatened. We found that the utility company has not included calcuations of future sea level rise that are consistent with what most scientists say can be expected in southern Florida during the operating lifetime of the reactors. 

In New Hampshire, the risk is not so much from hurricanes, but from powerful Nor'easters that can also bring intense storm surges. However, Seabrook's property is much farther inland than some other nuclear plants, and has been elevated above 20 feet, leaving the plant far less vulnerable to storm surges, even with sea level rise. According to an analysis by Evergreen State College masters student Natalie Kopytko, even with the expected sea level rise towards the end of this century, it's unlikely the Seabrook Station will be completely inundated by a major storm.

On the other hand, with sea level rise during the next century, a powerful Nor'easter could cause flooding around the plant's property through a combination of a storm surge as well as river flooding from heavy rainfall, and Kopytko says, at Seabrook “changes in wave height and strength due to sea level rise and storms could become a concern in the future.”