Duane Arnold Energy Center

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Duane Arnold Energy Center
DAEC in winter
DAEC in winter
CountryUnited States
LocationFayette Township, Linn County, near Palo, Iowa
Coordinates42°6′2″N 91°46′38″W / 42.10056°N 91.77722°W / 42.10056; -91.77722Coordinates: 42°6′2″N 91°46′38″W / 42.10056°N 91.77722°W / 42.10056; -91.77722
StatusBeing decommissioned
Construction beganMay 22, 1970 (1970-05-22)
Commission dateFebruary 1, 1975
Decommission date
  • November 2020
Construction cost$1.165 billion (2007 USD)[1]
Operator(s)NextEra Energy Resources
Nuclear power station
Reactor typeBWR
Reactor supplierGeneral Electric
Cooling towers2 × Mechanical Draft
Cooling sourceCedar River
Thermal capacity1 × 1912 MWth
Power generation
Units operational1 × 601 MW
Make and modelBWR-4 (Mark 1)
Nameplate capacity601 MW
Capacity factor99.04% (2017)
78.3% (lifetime)
Annual net output5214 GWh (2017)
External links
WebsiteDuane Arnold Energy Center
CommonsRelated media on Commons

The Duane Arnold Energy Center (DAEC) was Iowa's only nuclear power plant. It is located on a 500-acre (200 ha) site on the west bank of the Cedar River, two miles (3.2 km) north-northeast of Palo, Iowa, USA, or eight miles (13 km) northwest of Cedar Rapids.

DAEC entered operation in February 1975. On August 10, 2020, the plant cooling towers were damaged during a derecho and repairs were deemed uneconomical as the plant was scheduled for closure in October 2020.[2]

The majority owner and operator is NextEra Energy Resources (70%). The Central Iowa Power Cooperative owns 20% and the Corn Belt Power Cooperative owns 10%.

In January 2018, NextEra Energy announced that it was unlikely that DAEC would operate beyond 2025.[3] The plant was given a 20-year license extension to 2034 but considered closing after Alliant Energy, which contracts for 70% of the plant's electricity, announced it would instead be buying electricity from less expensive sources such as wind and natural gas.[4] In July 2018 the expected closure date was amended to October 2020. The unit made power for the last time on 10 August 2020 due to storm damage from the August 2020 Midwest derecho.[5][6] An NRC report of the incident—what nuclear safety experts called "a close call"[7]—found that containment of a radiological release to the environment might not have been complete, because "the vacuum drawn in secondary containment by the standby gas treatment system was slightly below the technical specification (TS) limit."[8]

Surrounding population[edit]

The Nuclear Regulatory Commission defines two emergency planning zones around nuclear power plants: a plume exposure pathway zone with a radius of 10 miles (16 km), concerned primarily with exposure to, and inhalation of, airborne radioactive contamination, and an ingestion pathway zone of about 50 miles (80 km), concerned primarily with ingestion of food and liquid contaminated by radioactivity.[9]

The 2010 U.S. population within 10 miles (16 km) of Duane Arnold was 107,880, an increase of 8.2 percent in a decade, according to an analysis of U.S. Census data for msnbc.com. The 2010 U.S. population within 50 miles (80 km) was 658,634, an increase of 7.1 percent since 2000. Cities within 50 miles include Cedar Rapids (10 miles to city center).[10]


In the late 1960s, Iowa Electric Light & Power Co. (now Alliant Energy – West), Central Iowa Power Cooperative and Corn Belt Power Cooperative applied for a nuclear plant license with the Atomic Energy Commission (AEC). On June 17, 1970 a construction permit was granted and work began. The original plan was to complete construction in 40 months at an estimated cost of $250 million.

The energy center was named after Duane Arnold who grew up in Sanborn, Iowa. Arnold was educated at Grinnell College and went to work for Iowa Electric Light and Power Company in 1946. At the time of his death in 1983, at the age of 65, he was chairman of the board and CEO of that company, marrying along the way the daughter, Henrietta, of the previous chairman Sutherland Dows. Arnold was very committed to nuclear energy despite the controversy surrounding that source of energy, and oversaw the construction and opening in 1974 of the plant that bears his name. “In my opinion, nuclear power is the most beneficial method of anything we could possibly do to provide energy to our customers in the future,” Mr. Arnold stated in a 1979 interview with the Des Moines Register, about a month after the Three Mile Island accident. Controversies did not end with Mr. Arnold's death. His son and four daughters went to court to force Iowa Electric to continue payments of a deferred compensation plan that the company stopped after Henrietta's death in 1986.[11]

Construction was completed and the reactor reached initial criticality on March 23, 1974. The cost was $50 million over budget. Commercial operations began on February 1, 1975. The plant was licensed for 1,658 MWt. However, power operations were restricted to 1593MWt (about 535 MWe) until plant modifications were completed in 1985 to utilize the full licensed capacity.

In May 2000, the NRC granted a license transfer of the DAEC to Nuclear Management Company LLC (NMC). Ownership of the plant remained with Alliant, Central Iowa Power Cooperative and Corn Belt Power Cooperative, but NMC would manage the operation of the plant.

In 2001, a power uprate was approved by the NRC to 1,912 MWt. Scheduled outages since that time have added modifications to the plant that have allowed this power level to be sustained without restrictions or challenges to nuclear or industrial safety.

On January 27, 2006, FPL Energy (a subsidiary of FPL Group) closed the sale transaction of 70 percent ownership from Alliant Energy-Interstate Power and Light.[12] FPL Energy (now NextEra Energy Resources) also took control of the operations of the plant from NMC.

DAEC remained online during the 2008 Iowa Flood,[13] when other power plants along the Cedar shut down.[14] Practice drills for radiological emergencies from the plant allowed the Linn County Emergency Management Agency to better respond to the flooding.[15]

In December 2010, the Nuclear Regulatory Commission granted Duane Arnold a 20-year extension license lasting until 2034, taking the plant beyond the life of its original 40-year operating permit.[16]

In July 2018, NextEra and Alliant Energy agreed to shorten their power purchase agreement by five years in return for a $110 million buyout payment from Alliant, making the expected closure date 2020.[5]

Plant equipment[edit]

DAEC has a single GE BWR-4 reactor with a Mark I containment. Twenty-four mechanical draft cooling towers utilize water from the Cedar River as a heat sink. Facilities exist to process all contaminated water onsite and the DAEC operates with a "zero release" policy to not discharge any contaminated water back to the Cedar River. Facilities exist on site for dry storage of spent fuel with capacity for the entire life of the plant (including license renewal).[17]

Known Problems[edit]

The Mark I containment was undersized in the original design; the Nuclear Regulatory Commission's Harold Denton estimated a 90% probability of explosive failure if the pressure containment system were ever needed in a severe accident.[18] This design flaw may have been the reason that the tsunami in 2011 led to explosions and fire in Fukushima Daiichi nuclear disaster.[19]

Accident Analysis[edit]

In 2010, the Nuclear Regulatory Commission estimated that the risk of an earthquake causing core damage to the reactor at Duane Arnold was 1 in 31,250 each year.[20]

In 2013, in response to the Fukushima Daiichi nuclear disaster, the Nuclear Regulatory Commission ordered Duane Arnold "to install a reliable hardened venting capability for pre-core damage and under severe accident conditions, including those involving a breach of the reactor vessel by molten core debris" due to the similarity in reactor design.[21]

Community impact[edit]

DAEC employs hundreds of people in the Cedar Rapids area. Some of these workers are represented by the International Brotherhood of Electrical Workers, others by Security, Police and Fire Professionals of America.

Emergency warning towers are maintained by DAEC and provide a means for tornado warnings as well as plant emergencies. The Emergency Planning organization at DAEC works with local, county, and state officials to maintain an emergency plan. The emergency plan can be found in the front of area phonebooks. Drills are conducted on a regular basis in accordance with requirements from the Nuclear Regulatory Commission (NRC) and the Federal Emergency Management Agency (FEMA).

Tax revenues from DAEC amount to about 1% of the total revenues for Linn County, Iowa. Pleasant Creek Reservoir, a 410-acre (1.7 km2) lake, was developed by Alliant Energy and the Iowa Conservation Commission to provide a recreation area and act as a source of cooling water during times of low flow in the Cedar River.

While the DAEC site covers 500 acres (2.0 km2), only a portion of that is used for power production. The remainder is leased to farmers for crop production or is left in its natural habitat.

In 2014, the Nuclear Energy Institute released a study showing the positive impact of DAEC on the economy and environment. Key findings are listed below.[22]

  • DAEC employs nearly 600 full-time workers that earn more than double the average pay amount of workers in Benton County and approximately 55 percent more than those in Linn County
  • DAEC contributes $246 million of economic activity locally and contributes approximately $255 million to Iowa's economy each year
  • For every dollar DAEC spent, the Iowa economy produced $1.27
  • DAEC produces more than 1,100 direct and secondary jobs
  • DAEC's operation helps avoid the emission of nearly 4 million tons of carbon dioxide annually, which is the equivalent of taking almost 800,000 cars off the road


  1. ^ Energy Information Administration (April 26, 2012). "State Nuclear Profiles". United States Department of Energy. Retrieved January 29, 2018.
  2. ^ Steppe, John (August 24, 2020). "Duane Arnold nuclear plant won't restart after Iowa derecho damage". The Gazette. Archived from the original on 2020-08-27.
  3. ^ Staff Writer (January 29, 2018). "NextEra: Duane Arnold Nuclear Could Shut Down Early". Power Engineering. Retrieved January 30, 2018.
  4. ^ Patane, M. (2015). Iowa nuclear power plant may close in 2025. Cedar Rapids Gazette. January 29, 2018.
  5. ^ a b "Iowa nuclear plant to close in 2020". World Nuclear News. 30 July 2018. Retrieved 30 July 2018.
  6. ^ "Early decommissioning for US Duane Arnold following storm damage". Nuclear Engineering International. 27 August 2020. Retrieved 27 August 2020.
  7. ^ "Fukushima 10 years later: It still could happen here". Beyond Nuclear. Retrieved 2021-04-01.
  8. ^ "Final ASP Analysis – Precursor" (PDF). United States Nuclear Regulatory Commission. 4 March 2021.
  9. ^ Staff Writer (February 17, 2017). "Backgrounder on Emergency Preparedness at Nuclear Power Plants". Nuclear Regulatory Commission. Retrieved January 29, 2018.
  10. ^ Dedman, Bill (April 14, 2011). "Nuclear Neighbors: Population Rises Near U.S. Reactors". NBC News. Retrieved January 29, 2018.
  11. ^ Staff Writer (March 29, 2011). "So Who Was Duane Arnold?". Des Moines Public Library. Retrieved January 29, 2018.
  12. ^ Staff Writer (January 27, 2006). "FPL Energy Completes Purchase of Majority Interest in Duane Arnold Energy Center". NextEra Energy. Retrieved January 29, 2018.
  13. ^ Smith, Rick (September 5, 2012). "Report Says Nearness of Nuke Plant Helped Cedar Rapids During Flood". The Gazette. Retrieved January 29, 2018.
  14. ^ Staff Writer (January 29, 2009). "Prairie Creek Generating Station Restarts After Flood". Power Engineering. Retrieved January 29, 2018.
  15. ^ Staff Writer (Fall 2012). "Nuclear Safety Planning Helps Iowa Weather a Flood". Nuclear Energy Institute. Retrieved January 29, 2018.
  16. ^ Staff Writer (December 17, 2010). "Consent for Longer Operation". World Nuclear News. Retrieved January 29, 2018.
  17. ^ "Duane Arnold Energy Center Fact Sheet". NextEra Energy. Retrieved January 30, 2018.
  18. ^ Zeller, Tom. (2011). Experts had long criticized potential weakness in design of stricken reactor. [1]
  19. ^ Lochbaum, David, Lyman, E., and Stranahan, S.Q. (2015). Fukushima: The story of a nuclear disaster.
  20. ^ Dedman, Bill (March 17, 2011). "What are the Odds? US Nuke Plants Ranked by Quake Risk". NBC News. Retrieved January 30, 2018.
  21. ^ Vehec, T. A. (December 22, 2015). "NextEra Energy Duane Arnold, LLC's Six-Month Status Report and Phase 1 and 2 Overall Integrated Plan in Response to June 6, 2013 Commission Order Modifying Licenses with Regqard to Reliable Hardened Containment Vents Capable of Operation Under Severe Accident Conditions (Order Number EA-1 3-109)". Nuclear Regulatory Commission. Retrieved January 30, 2018.
  22. ^ Staff Writer (May 14, 2014). "Economic Study: Duane Arnold’s Impact Tops $250 Million/Yr. in Iowa". Nuclear Energy Institute. Retrieved January 30, 2018.

External links[edit]