Generation for the 104 plants in the U.S. fell 0.4 percent from yesterday to 94,171 megawatts, or 93 percent of capacity, the lowest level for this time of year since 2003, according to reports from the U.S. Nuclear Regulatory Commission and data compiled by Bloomberg. The total is down 2.6 percent from the five-year average for today of 96,725 megawatts.
“We’ve had a fast decay of summer output this month and that corresponds to the high heat and droughts,” Pax Saunders, an analyst at Gelber & Associates in Houston, said. “Plants are not able to operate at the levels they can.”
FirstEnergy Corp. (FE)’s Perry 1 reactor in Ohio lowered production to 95 percent of capacity today because of above- average temperatures, while Entergy Corp. (ETR)’s Vermont Yankee has limited output four times this month. Nuclear plants require sufficient water to cool during operation, and rivers or lakes may get overheated or fall in times of high temperatures and drought, according to the NRC.
Dry conditions have worsened in the past week, with at least 63.9 percent of the contiguous 48 U.S. states now affected by moderate to severe drought, the U.S. Drought Monitor said today. That compares with 63.5 in the previous week.
Temperatures will rise about 3 degrees above normal in the U.S. Northeast from Aug. 4 to Aug. 8 and computer modeling shows another heat wave may arrive the week of Aug. 6, according to Commodity Weather Group President Matt Rogers.
“Heat is the main issue, because if the river is getting warmer the water going into the plant is warmer and makes it harder to cool,” David McIntyre, an NRC spokesman, said.
Production at FirstEnergy’s 1,261-megawatt Perry 1 reactor dropped by 63 megawatts early today in preparation for high temperatures and humidity, according to Todd Schneider, a company spokesman in Akron, Ohio.
The region is under a weather advisory from noon to 7 p.m. today, with heat index values as high as 102 degrees Fahrenheit (39 degrees Celsius), according to a report from AccuWeather Inc. Perry 1, 35 miles northeast of Cleveland, has slowed production four times since July 1.
“Output has fluctuated throughout July because of the weather conditions including outside temperature and humidity,” Schneider said by phone today. “The higher temperatures make it more difficult to run at 100 percent.”
Vermont Yankee, the 620-megawatt plant operated by Entergy Corp., reduced power to 83 percent of capacity on July 17 because of low river flow and heat, according to Rob Williams, a company spokesman based in Brattleboro, Vermont.
The reactor has lowered generation at least once every week since July 1, according to commission data.
“We’ve been having to do it with the warmer weather conditions,” Williams said. “The weather dictates how much electricity we can produce and it’s the nature of doing business on a river with variable flow and variable temperatures.”
Exelon’s Byron 1 and Byron 2 plants in Illinois have been operating below full capacity since June 28, according to filings with the NRC and data compiled by Bloomberg. The plants are preparing for a yearlong maintenance project that will upgrade equipment inside the cooling towers.
Generation at the 1,164-megawatt Byron 1 reactor slowed to 80 percent of capacity today, while Byron 2 operated at 84 percent. Production has fluctuated because adjustments to cooling tower operations vary with weather conditions, Paul Dempsey, communications manager at the plant, said by phone from Byron, Illinois.
As long as the heat persists, Saunders of Gelber & Associates expects nuclear supply to stay low while demand continues to climb.
Hotter-than-normal weather in the large cities along the East Coast usually raises demand for electricity as people turn to air conditioners to cool off. Generation in the region was 24,043 megawatts today, 3.8 percent lower than a year ago.
Production in the Southeast was 4.9 percent lower than a year earlier, compared with 6.6 percent for the Midwest and 4.1 percent for the West, according to commission data.
“We expect the trend of things getting tighter and tighter to persist,” Saunders said in a phone interview. “The impact of the last few weeks have been the largest of the summer.”
To contact the editor responsible for this story: Bill Banker at email@example.com