Dresden Generating Station
| Company type | Nuclear power plant |
|---|---|
| Industry | Energy |
| Founded | 1960 |
| Headquarters | Morris , United States |
Area served | Chicago and northern Illinois |
| Products | Electricity |
| Owner | Constellation Energy (Units 2 and 3), Exelon (Unit 1) |
| Website | http://www.eia.gov/cneaf/nuclear/state_profiles/illinois/il.html#_ftn4 |
Dresden Generating Station—also referred to as the Dresden Nuclear Power Plant—holds the distinction of being the first nuclear power facility in the United States funded through private investment. Dresden Unit 1 was in service from 1960 until its decommissioning in 1978. Units 2 and 3, each a General Electric BWR-3 boiling water reactor, have been operational since 1970 and 1971, respectively. Situated on a site in Grundy County, Illinois near Morris, Illinois, the plant occupies a strategic location at the origin of the Illinois River, where the Des Plaines River converges with the Kankakee River. It is located adjacent to the Morris Operation, recognized as the only practical high-level radioactive waste storage facility within the United States.
The Dresden facility supplies electricity to Chicago and northern Illinois, with each reactor generating roughly 867 megawatts of power—sufficient to meet the energy needs of over one million typical American households. In 2004, the Nuclear Regulatory Commission extended the operating licenses for both reactors, prolonging their authorized lifespan from forty to sixty years.
Unit 1
In response to the Atomic Energy Act of 1954, Commonwealth Edison engaged General Electric in 1955 to design and construct Dresden Unit 1, a 192 MWe reactor, at a cost of $45 million. A consortium comprising eight companies under Nuclear Power Group Inc. contributed to covering one-third of this contract expense.
Research initiatives and operator training utilized GE's Vallecitos Nuclear Center boiling water reactor alongside data from the AEC's BORAX experiments. The reactor core consisted of 488 fuel subassemblies, each containing 36 uranium dioxide fuel rods clad in Zircaloy-2. It operated at a thermal power output of 626 MWt, housed within a pressure vessel rated for 1015 psia, measuring 12 feet 2 inches in diameter and standing 42 feet tall.
The reactor utilized a dual-cycle system that generated steam from both the steam drum and steam generators, allowing swift adjustments to fluctuations in power demand. Regulation of power output was achieved through the turbine governor controlling the secondary admission valve, which modulated secondary steam flow and consequently adjusted reactor power levels.
Cooling
The station employs three distinct cooling methods:
- Direct open-cycle mode: Water is drawn straight from a canal connected to the Kankakee River and discharged directly into the Illinois River, bypassing cooling canals, lake reservoirs, and cooling towers.
- Indirect open-cycle mode: Water intake from the Kankakee River is routed through cooling canals into Dresden Cooling Lake (covering 1,275 acres), where it circulates through five zones over an approximate period of 2.5 days before being released into the Illinois River. During this process, cooling towers assist in reducing water temperature within the canal system.
- Closed-cycle mode: Water is recirculated between the return cooling canal and Dresden Cooling Lake with limited replenishment water—up to 70,000 US gallons per minute—from the Kankakee River and minimal discharge—up to 50,000 US gallons per minute—to manage dissolved solids. Typically, cooling towers are not required under this mode.
Four cooling towers provide supplemental heat dissipation: one single-wide tower with 12 cells dedicated to cold canal water, plus three hot canal towers consisting of two double-wide units with 18 cells each and one single-wide tower with six cells, totaling 54 cells altogether. The hot canal towers operate with seven pumps delivering an aggregate flow near 735,469 US gallons per minute; meanwhile, the cold canal tower employs 24 pumps with a combined capacity around 211,200 US gallons per minute.
An additional six-cell tower was installed between 2003 and 2004 to support a +17% power uprate on Units 2 and 3 that received approval in December 2001. This enhancement increased thermal output demands necessitating improved cooling capabilities; however, deployment encountered delays linked to issues involving steam dryer cracking.
Electricity generation
| Year | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual (Total) |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 2001 | 1,193,458 | 1,054,333 | 1,187,102 | 981,943 | 1,132,442 | 1,127,280 | 1,031,337 | 1,135,702 | 932,498 | 892,446 | 945,681 | 924,451 | 12,538,673 |
| 2002 | 1,234,842 | 1,108,990 | 1,059,816 | 1,186,361 | 1,210,951 | 1,176,948 | 1,133,199 | 1,210,328 | 1,097,968 | 797,663 | 1,223,682 | 1,145,176 | 13,585,924 |
| 2003 | 1,246,460 | 1,160,493 | 1,250,523 | 1,242,216 | 1,212,105 | 1,058,939 | 1,293,159 | 1,291,997 | 1,230,004 | 847,958 | 941,888 | 901,425 | 13,677,167 |
| 2004 | 1,216,081 | 1,157,391 | 1,286,564 | 1,113,658 | 954,565 | 1,250,516 | 1,294,621 | 1,075,250 | 1,006,250 | 1,131,669 | 1,176</ small > | < small > 858 , 976 < / small > | 12.346.717 |
| 2005 | < small > 1296266 < / small > | < small > 1149577 < / small > | < small > 1203983 < / small > | < small > 1153170 < / small > | < small > 1211033 < / small > | < small > 1220520 < / small > | < small > 1288247 < / small > | < small > 1227178 < / small > | < small > 943039 < / small > | < small > 1264403 < / small > | < small > 373412 < / small > | < small > 1291625 < / small > | 13.622.453 |
| 2006 | < small > 1295498 < / small > | < small > 1164240 < / small > | < small > 1292561 < / small > | < small > 1248987 < / small > | < small > 1281759 < / small > | < small > 1245263 < / small > | < small > 1232623 < / small > | < small > 1284318 < / small > | < small > 1246890 < / small > | < small > 1290115 | < smal l >568728 | < smal l >1291064 | 14.442.046 |
| 2007 | < smal l >1294287 | < smal l >1163545 | < smal l >1293573 | < smal l >1253535 | < smal l >1199725 | < smal l >1248937 | < smal l >1291916 | < smal l >1281698 | < smal l >1202803 | < smal l >1228109 | < smal l >783991 | < smal l >1288662 | 14.530.781 |
| 2008 | < smal l >1085546 | < smal l >1211845 | < smal l >1289661 | < smal l >1252854 | < smal l >1292759 | < smal l >1248659 | < smal l >1291802 | < smal l >1283863 | < smal l >1092984 | < smal l >1208852 | < smal l >832043 | < smal l >1293977 | 14.384.845 |
| 2009 |
Incidents
From the 1970s until 1996, Dresden incurred fines totaling $1.6 million due to 25 reported incidents.
- June 5, 1970: A malfunction in the Dresden II reactor’s pressure control system generated a false high-pressure alert, causing turbine valves to release steam and initiating an automatic SCRAM. The resulting void collapse in the reactor water caused unstable water levels and variable feedwater flow. An operator was misled by a stuck water level recorder needle and manually increased feedwater flow, which flooded the main steam lines. This led to a hydrostatic shock that opened a safety valve, raised drywell pressure, and triggered safety injection systems. Reactor conditions stabilized after approximately two hours. This incident served as inspiration for the movie The China Syndrome.
- December 8, 1971: Dresden III experienced comparable issues involving fluctuations in reactor water levels and activation of safety mechanisms.
- May 15, 1996: A reduction in water levels surrounding unit 3’s nuclear fuel resulted in a plant shutdown and placed Dresden on the Nuclear Regulatory Commission (NRC) "watch list" for heightened regulatory oversight. Between 1987 and 1996, Dresden was listed for six out of nine years, longer than any other nuclear facility in the United States.
- July 15, 2011: An Alert was issued after a sodium hypochlorite leak restricted access to an area containing essential cooling water pumps.
Surrounding population
The Nuclear Regulatory Commission designates two emergency planning zones around nuclear facilities: a 10-mile plume exposure pathway zone aimed at airborne radioactive threats, and a 50-mile ingestion pathway zone focused on potential contamination of food and beverages.
In 2010, the population residing within a 10-mile radius of Dresden reached 83,049—a growth of 47.6% compared to ten years earlier. Within a 50-mile radius, the population totaled 7,305,482, marking a 3.5% increase since 2000. Notable cities within this area include Chicago, located approximately 43 miles away.
Ownership
The current operators and owners of the two active units are Constellation Energy, following their separation from Exelon. Exelon continues to hold ownership and decommissioning duties for Unit 1. Prior to August 3, 2000, all three units were under the ownership of Commonwealth Edison.
Seismic risk
A Nuclear Regulatory Commission study conducted in 2010 estimated that the annual probability of an earthquake causing core damage at Dresden is about one in 52,632.
Averted closure
In August 2020, Exelon revealed intentions to shut down the plant by November 2021 due to economic challenges, despite having licenses valid for roughly another decade with potential extensions for an additional twenty years. However, on September 13, 2021, the Illinois state senate approved legislation providing subsidies for both the Byron and Dresden plants. Governor J. B. Pritzker signed this bill into law on September 15. Subsequently, Exelon announced plans to refuel both facilities, ensuring their continued operation and supporting Illinois’ clean energy objectives.