Closed-Cycle Cooling and Pilgrim Nuclear Power Station

“Did You Know?” Closed-Cycle Cooling and Pilgrim Power Plant

By Shalen Lowell

Did you know that every day the Pilgrim Nuclear Power Station in Plymouth, Massachusetts absorbs 510 million gallons of water from Cape Cod Bay? In operation since 1972 and owned by Entergy, the Pilgrim Station poses a continual threat to the surrounding ecosystem and residences, due to its outdated, once-through cooling system. Last May, Pilgrim renewed its 20-year operating license, and this action further motivated activists to unceasingly protest its ongoing harm to the ecological community.

Pilgrim runs on a once-through cooling system, in which it sucks in water from the Bay. That water absorbs heat from the plant operations and is then discharged. This “once-though” water can be up to 30 degrees warmer than the existing water in the Bay, which not only harms species that prefer cooler water, but which also enables the growth of invasive species.

Pilgrim is required to install screens to prevent larger organisms from getting sucked into the plant. However, fish often get impinged (or trapped) on these screens, and die as a result. Some smaller organisms are sucked through the screens and cycle through the cooling system with the water, in a process called entrainment. Very few organisms survive entrainment.

In a closed-cycle cooling system, however, after the water that a plant takes in circulates through the system, it is recycled through the reactor instead of being discharged. The heat in the water is removed in the process and is released into the atmosphere. Closed-cycle cooling does not emit warm, polluted water back into its source.

The Pilgrim Station sits on the Plymouth-Carver Sole Source Aquifer, which supplies drinking water to residences in the area. Pilgrim is continuously contaminating Plymouth’s aquifer by polluting its groundwater. One way in which this occurs is through expulsion of a radioactive type of hydrogen called tritium, which combines with the oxygen in the water to make it radioactive. Another concern is the plant’s waste-water treatment facilities on site, which emit nitrogen into the water and contaminate the aquifer.

The Pilgrim Plant is one reason there is a drastic decline in river herring, specifically blueback herring and alewives, and they are thus species of great concern. In an annual report, “Impingement of Organisms on the Intake Screens at Pilgrim Nuclear Power Station,” submitted to Entergy in 2010 by its consultant Normandeau Associates, Inc., alewife were the second most impinged fish, with a count of 12,680 trapped in Pilgrim’s screens. Herring, a source of food for larger marine mammals, face many adversities in their habitats in southeastern Massachusetts such as dams, pollution, and impingement, all of which contribute to low numbers of herring returning to streams to spawn.

To draw attention to some of these issues surrounding the Pilgrim Station and to also celebrate World Oceans Day, Cape Cod Bay Watch sponsored a “Save Our Bay” Flotilla. This rally’s participants emphasized Pilgrim’s outmoded cooling system, suggesting its functionality is inefficient and harmful to the Cape Cod community. If Pilgrim were outfitted with a closed-cycle cooling system, its operations would reduce damage to Cape Cod Bay.

If you would like to volunteer and join the effort in improving water quality for the safety of your family and your environment, contact your local watershed association today. You can find out what watershed you live in and how to contact your watershed association, and learn more about the issues at www.watershedaction.org.