On Aug. 11th, we posted a blog ‘Pilgrim In Hot Water” about Pilgrim Nuclear Power Station being forced to power down on Aug. 9th due to the incoming water used in its cooling system – seawater from Cape Cod Bay – being too warm. Read the original blog here >>

We just updated the blog with the graph below.  Pilgrim’s operating license requires the temperature of incoming sea water be less than than 75⁰F.  After sea water cycles through Pilgrim’s “once-through” cooling system, the plant’s Clean Water Act permit allows the used cooling water to be discharged back into Cape Cod Bay at a maximum of 102⁰F, and up to 32⁰F hotter than Cape Cod Bay’s ambient temperature.

On Aug. 9th, the discharge water was very close to exceeding the permitted limit of 102⁰F (reaching 101.2⁰F), and incoming water temperature exceeded 75⁰F – forcing the plant to power down. See the graph below for Pilgrim’s seawater discharge temperature every two hours on August 9th.

Pilgrim CWIS Temp Aug 9 2015


This graph was produced by Entergy and provided to the U.S. Environmental Protection Agency under the Clean Water Act NPDES permit reporting requirements. Entergy does continuous temperature monitoring of the temperature of Pilgrim’s discharge water and citizen activists keep a close eye on Entergy’s reports.

Read the Event Report submitted by Entergy to the Nuclear Regulatory Commission HERE.