The Duane Arnold Energy Center (DAEC), with a single unit boiling water nuclear reactor, was Iowa's only nuclear power plant. It is located on a site on the west bank of the Cedar River, north-northeast of Palo, Iowa, USA, or northwest of Cedar Rapids, Iowa.
DAEC started its commercial operation in February 1975. The plant cooling towers were damaged during the August 2020 Midwest derecho, and repairs were deemed uneconomical, as the plant had already been scheduled for decommissioning in October 2020.
The operator and majority owner is NextEra Energy Resources (70%). The Central Iowa Power Cooperative owns 20% and the Corn Belt Power Cooperative owns 10%.
On October 27, 2025, NextEra Energy Resources and Google announced that they had reached an agreement under which the plant would be restarted in 2029, nine years after its shutdown. This is a move which came as a consequence of the growing demand for reliable and green energy from Google's AI data centers.
History 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 U.S. 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 (Grinnell, Iowa) 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 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.Staff Writer (March 29, 2011). "So Who Was Duane Arnold?". Des Moines Public Library. Retrieved January 29, 2018.
Construction was completed and the reactor reached initial criticality on March 23, 1974. The cost was $50 million over budget. The architect/engineering firm was Bechtel. 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 use the full licensed capacity.
In May 2000, the U.S. Nuclear Regulatory Commission (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 of 70 percent ownership from Alliant Energy-Interstate Power and Light.Staff Writer (January 27, 2006). "FPL Energy Completes Purchase of Majority Interest in Duane Arnold Energy Center". NextEra Energy. Retrieved January 29, 2018. FPL Energy (now NextEra Energy Resources) also assumed control of the operations of the plant from NMC.
DAEC remained online during the 2008 Iowa Flood,Smith, Rick (September 5, 2012). "Report Says Nearness of Nuke Plant Helped Cedar Rapids During Flood". The Gazette. Retrieved January 29, 2018. when other power plants along the Cedar River shut down.Staff Writer (January 29, 2009). "Prairie Creek Generating Station Restarts After Flood". Power Engineering. Retrieved January 29, 2018. Practice drills for radiological emergencies from the plant allowed the Linn County Emergency Management Agency to better respond to the flooding.Staff Writer (Fall 2012). "Nuclear Safety Planning Helps Iowa Weather a Flood". Nuclear Energy Institute. Retrieved January 29, 2018.
In December 2010, the NRC granted Duane Arnold a 20-year extension license lasting until 2034, taking the plant beyond the life of its original 40-year operating permit.Staff Writer (December 17, 2010). "Consent for Longer Operation". World Nuclear News. Retrieved January 29, 2018.
In January 2018, NextEra Energy announced that it was unlikely that DAEC would operate beyond 2025.Staff Writer (January 29, 2018). "NextEra: Duane Arnold Nuclear Could Shut Down Early". . Power Engineering. Retrieved January 30, 2018. 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 generated by wind and natural gas.Patane, M. (2015). Iowa nuclear power plant may close in 2025. Cedar Rapids Gazette. January 29, 2018.
In July 2018 the expected closure date was amended to October 2020. That same month, 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.
The unit permanently ceased making power on 10 August 2020, due to storm damage from the winds during the August 2020 Midwest derecho that leveled the site's cooling towers. Repairs were deemed uneconomical, as the plant had already been scheduled for decommissioning in October 2020. An NRC report of the incident stated that "the vacuum drawn in secondary containment by the standby gas treatment system was slightly below the technical specification limit", indicating that the secondary containment system might not have been fully effective had it been challenged. Thus the incident was considered by nuclear safety experts to be "a close call". "Federal regulators estimated the 2020 storm had a one-in-1,000 chance of causing [reactor] core damage because of safeguards", Inside Climate News reported.
Restart
As of September 2024, John Ketchum, NextEra’s chief executive officer said that, under certain conditions, they are willing to revive the plant, as several data centers were interested.
In early 2025, NextEra Energy Duane Arnold, LLC (NextEra), the licensee for DAEC expressed an interest in returning the plant to an operational status and resuming commercial operation. On August 26, 2025, the Federal Energy Regulatory Commission approved a waiver that clears the way to begin the process to restart the plant.
On Monday, October 27, 2025, NextEra Energy Resources and Google announced that they had reached an agreement under which the 615 megawatt plant would be restarted in 2029, nine years after its shutdown. This is a move which came as a consequence of the growing demand for reliable and green energy from Google's artificial intelligence (AI) data centers. with "excess power strengthening local grid reliability". The cost to prepare the plant for restart was estimated in 2025 at $1.6 billion. According to the contract, which is set to last for 25 years, Google will buy electric energy from the nuclear power plant to power its cloud and AI data centers in the state of Iowa. This will also mean significant economic investments for the region and an estimated at $9 billion in economic benefits for the state.
Reuters reported that the chief executive officer of NextEra said that in support of the purchase agreement with Google, major equipment including a power generator and cooling towers had been ordered. It is the third nuclear reactor to have recently attempted to be restarted in the United States along with Three Mile Island in Pennsylvania and Palisades nuclear power plant in Michigan.
To restart DAEC, NextEra would need to gain NRC approval to restore the licensing basis of the plant to an operational status, return plant components to a status that supports safe operation, and make any upgrades necessary to meet the proposed operational licensing basis. This includes replacing transformers, work on the cooling towers, and building a new administration building. The earliest the plant could reopen is the fourth quarter of 2028.
NRC staff will review the regulatory and licensing documents for the plant, inspect new and restored components necessary to operate, and continue ongoing oversight to ensure sufficiency of all plant systems and programs.
The NRC will engage in several pre-submittal interactions with the DAEC staff on topics related to the potential for restart, and will continue hosting public meetings related to the potential for the DAEC to resume power operations throughout the project.
On September 10, 2026, NextEra announced that it had received approval for a $1.9 billion loan from the US Department of Energy to fund the reopening of the plant.Betz, Bradford, "US loans $1.9B to restart shuttered Iowa nuclear plant", Fox News, 10 September 2026
Electricity production During last full year of operation in 2019, Duane Arnold generated 5,235 GWh of electricity. +Generation (MWh) of Duane Arnold Energy CenterYearJanFebMarAprMayJunJulAugSepOctNovDecAnnual (Total)2001382,045355,555392,652140,46825,150334,683371,033346,686387,653299,934385,585431,2783,852,7222002419,086389,255341,087415,917362,672413,091420,340297,088256,177415,893414,668428,6844,573,9582003426,122174,819315,195129,836428,226412,413421,188419,019414,515428,83947,782369,7033,987,6572004436,867406,472435,372348,679430,021412,259425,362424,868410,790358,931405,590433,7374,928,9482005435,019389,371335,065-3,758350,046417,219430,679436,209424,708440,751433,268449,7364,538,3132006447,826404,283446,131408,722440,321422,145428,371430,874406,505442,826364,834452,6045,095,4422007447,61839,080112,431389,138450,516424,532446,502442,377429,795445,362437,740453,7844,518,8752008457,143427,569452,124440,067450,927425,093440,375430,578431,845451,846438,708435,9275,282,2022009394,2445,357360,881399,821452,957433,616452,271451,155430,826400,789444,369452,6454,678,9312010448,384416,381451,812365,407410,842428,419444,885442,437417,963323,312-3,723304,5214,450,6402011459,664413,726452,839442,326453,393429,706443,408327,685439,116454,320437,920461,1265,215,2292012460,908423,779454,876440,969446,229431,359439,675429,765395,53557,03629,454337,4104,346,9952013455,731409,782458,752441,980452,246431,369447,624447,147430,065449,169439,814457,1065,320,7852014455,018406,629454,318437,773440,692427,081428,435417,752389,55731,44932,761231,0034,152,4682015418,537414,738453,805438,786434,472431,512434,796444,377430,791446,190439,209456,2335,243,4462016451,835427,035453,576437,215442,094329,420433,422427,221402,80020,861417,958459,2284,702,6652017458,665411,012456,960438,264446,374430,857427,637440,204428,408382,121439,912453,0955,213,5092018454,361410,060450,580435,050437,412421,904426,623411,903137,946409,884442,856456,8204,895,3992019448,846411,424453,075376,139450,708432,612441,330445,597429,336451,258439,593455,7985,235,7162020456,363425,228452,682419,860392,817289,107358,850109,9560------2,904,863 Not operational from 2021–2028 (estimated)2029–
Plant equipment