Dresden Generating Station

File:Dresden 1 inside.jpg

After the Atomic Energy Act of 1954 allowed private companies to own and operate nuclear facilities, Commonwealth Edison contracted with General Electric to design, construct, and place into operation the 192 MWe Dresden Unit 1 for $45M in 1955.{{cite journal |title=Power reactors |journal=U.S. Atomic Energy Commission, Technical Information |date=1958-05-01 |pages=41–48 |url=https://catalog.hathitrust.org/Record/002027502 |access-date=1 January 2020}} One-third of the contract price was shared by a consortium of eight companies comprising the Nuclear Power Group Inc.

The BWR at GE's Vallecitos Nuclear Center and the AEC's BORAX experiments provided research data and operator training for Dresden.

The core contained 488 fuel subassemblies, 80 control rods, and 8 instrument nozzles. Each subassembly contained 36 fuel rods in a Zircaloy-2 channel. The fuel was uranium dioxide clad in Zircaloy-2 tube. The core thermal power was 626 MWt. The reactor vessel was rated to 1015 psia and measured {{convert|12|ft|2|in}} diameter and {{convert|42|ft}} tall.

File:Dresden 1 Nuclear Flow Diagram.jpg

The reactor featured a dual cycle, with steam coming from both the stream drum and steam generators. This made for rapid response to changes in power demand. Reactor power was regulated by actuation of the secondary admission valve by the turbine's governor. Decreasing the rate of secondary steam reduces reactor power, and vice versa. Thus, the secondary pressure varies with the external load.

The plant has three cooling modes:

• Direct open-cycle mode:{{efn|Currently only allowed when both units are out of service, rarely used.}} Intake from canal leading to the Kankakee River,{{efn|name=lowflow|During periods of low river flow, intake water may also be indirectly drawn from the Des Plaines River.}} discharge directly to the Illinois River. The cooling canal system, cooling lake, and the supplementary cooling towers are completely bypassed in this mode of operation.
• Indirect open-cycle mode:{{efn|Used from June 15 through September 30, or approximately 8.5 months of the year.}} Intake from canal leading to the Kankakee River,{{efn|name=lowflow}}{{efn|Up to {{convert|940,000|usgal/min}} is withdrawn from the river by six pumps each rated at {{convert|157,000|usgal/min}}).}} discharge to cooling canal leading to Dresden Cooling Lake,{{efn|name=liftlake|Water is pumped from the cooling canal into the {{convert|1275|acre}} cooling lake via a lift station with 6 × {{convert|167,000|usgal/min}} pumps. The cooling lake has 5 zones through which the water slowly travels over the course of 2.5 days before it exits the cooling lake.}} discharged from lake through return cooling canal that eventually discharges into the Illinois River. Use of the cooling towers for supplemental cooling of canal system water is usually necessary during this mode of operation.
• Closed-cycle mode:{{efn|Used from October 1 through June 14.}} Intake from return cooling canal leading back from Dresden Cooling Lake,{{efn|Limited amounts (up to {{convert|70,000|usgal/min}}) of makeup water is drawn from the Kankakee River as needed,{{efn|name=lowflow}} and limited discharge (up to {{convert|50,000|usgal/min}}) to the Illinois River happens in order to minimize dissolved solids concentrations in the cooling canals/lake.}} discharge to cooling canal leading to Dresden Cooling Lake.{{efn|name=liftlake}} Use of the cooling towers for supplemental cooling of canal system water is usually not necessary during this mode of operation.

File:Dresden Cooling Lake.jpg

It also has cooling towers{{efn|Prior to 2000, supplemental cooling was provided via spray canals (spray systems installed in both the hot and cold (return) cooling canals) rather than the current cooling towers.}}{{efn|1 × 12-cell tower (single-wide, built between 2000 and 2001), 2 × 18-cell towers (double-wide, built in 2000), and 1 × 6-cell tower (single-wide, built between 2003 and 2004) with an overall total of 54 cells. The 12-cell tower is only used for supplementary cooling of the cold (return) cooling canal as necessary in order to maintain discharge water temperatures within permitted levels, while the three other cooling towers are used for the supplementary cooling of water in the hot cooling canal. The three hot canal cooling towers are fed by 7 pumps rated at {{convert|135,067|usgal/min}} each (total flow of {{convert|735,469|usgal/min}}). The single 12-cell cold (return) canal cooling tower is fed by 24 pumps rated at {{convert|8800|usgal/min}} each (total flow of {{convert|211,200|usgal/min}}). The 6-cell tower was added to provide additional cooling for the extended power uprates (+17%) on Units 2 & 3 that Exelon requested in December 2000, which were approved by the NRC in December 2001, although it was not until the end of 2002 that the uprates were implemented at both units (the units were also not operated at the uprated power for most of 2003 due to steam dryer cracking problems), and this additional cooling tower meant to provide additional cooling capacity to accommodate the additional thermal output from the outrate was not added until sometime between 2003 and 2004.}}

Between the 1970s and 1996, Dresden was fined $1.6 million for 25 incidents.

• June 5, 1970: A false high pressure signal due to instrument failure on the Dresden II reactor pressure control system caused turbine valves to dump steam (a "turbine trip"), which in turn automatically initiated a SCRAM. Void collapse in the reactor water caused the reactor water level to drop, which resulted in an automatic increase in feedwater flow. The feedwater pumps then tripped on low suction pressure. One pump turned back on automatically when the low suction pressure signal reset, feeding water rapidly into the now lower-pressure reactor vessel. Water level in the reactor rose rapidly until water entered the main steam lines. At this point, the false high pressure signal disappeared. The turbine dump valves closed, increasing back pressure in the reactor vessel and slowing the feedwater inlet flow. Cooling reactor water temperature caused further void collapse. Reactor water level began to rapidly lower once again. This again automatically caused the feedwater system to increase the flow rate into the vessel, and began to raise reactor water level. As cooler feedwater was again rapidly pumped into the reactor, void collapse caused water level to lower. The feedwater system responded by increasing feedwater flow. However, the indicator needle on the water level recorder stuck, which caused the operator to assume level had stopped rising in the reactor. The operator began increasing feedwater flow in order to raise water level in the reactor, manually overriding the automatic control system. The operator never checked a second indicator that showed the increasing level. Reactor water level continued rising and flooded the main steam lines. Two minutes later, the operator tapped on the water level recorder and the water level needle became unstuck, at which point the operator began reacting to the now high water level by manually reducing feedwater flow. At this point, the operator manually opened a steam line relief valve to reduce rising reactor pressure. However, due to the earlier introduction of water into the main steam lines, a hydrostatic shock occurred in the steam lines, which caused a safety valve to open, admitting steam and water into the drywell causing drywell pressure to increase. This caused the initiation of safety injection systems, and for the next 30 minutes reactor water level and pressure seesawed as the operators attempted to stabilize the reactor. It was not until two hours later that reactor level, reactor pressure and drywell pressure were reduced to normal.{{cite book |url=https://archive.org/stream/congressionalrec118funit/congressionalrec118funit_djvu.txt |quote="This action was forbidden..." |title= 92nd CONGRESS |date=22 March – 10 April 1972}} The movie The China Syndrome bases its initial plot device on this event, with the needle becoming unstuck when the operator taps the recorder.{{cite web|last=Ebert |first=Roger |url=http://www.rogerebert.com/reviews/the-china-syndrome-1979 |title=The China Syndrome Movie Review (1979) |publisher=Roger Ebert |date=1979-01-01 |access-date=2013-12-30}}
• December 8, 1971: Events similar to the ones the year earlier on Dresden II occur on Dresden III.
• May 15, 1996: Lowering water levels around the nuclear fuel in unit 3[https://www.nrc.gov/docs/ML0037/ML003706185.pdf NRC dispatches special inspection team to Dresden Nuclear Plant to review reactor shutdown on May 15 (RIII-96-17)] U.S. Nuclear Regulatory Commission (NRC). May 16, 1996. Retrieved 10 June 2016. reactor's core prompt a shut down at Dresden Generating Station and placement on the NRC's "watch list" that merit closer scrutiny by regulators. Dresden was on the NRC watch list six out of nine years between 1987 and 1996, longer than any of the 70 other operating plants in the nation.{{cite web |url=https://www.chicagotribune.com/1996/06/26/dresden-plant-placed-on-nrc-watch-list-again/ |title=Dresden Plant Placed On Nrc Watch List Again - tribunedigital-chicagotribune |website=Chicago Tribune |url-status=live |archive-url=https://web.archive.org/web/20150929133913/http://articles.chicagotribune.com/1996-06-26/news/9606260054_1_nuclear-power-plant-nuclear-regulatory-commission-station-manager |archive-date=2015-09-29}}
• July 15, 2011: Plant declared an Alert at 10:16 a.m after a chemical leak of sodium hypochlorite restricted access to a vital area that houses plant cooling water pumps.{{cite web |url=http://www.firedirect.net/index.php/2011/07/nrc-responds-to-alert-to-dresden-nuclear-power-plant/ |title=NRC responds to alert to Dresden Nuclear Power Plant | FireDirect |access-date=2013-05-05 |url-status=dead |archive-url= https://archive.today/20130616152643/http://www.firedirect.net/index.php/2011/07/nrc-responds-to-alert-to-dresden-nuclear-power-plant/ |archive-date=2013-06-16 }}

The Nuclear Regulatory Commission defines two emergency planning zones around nuclear power plants: a plume exposure pathway zone with a radius of {{convert|10|mi}}, concerned primarily with exposure to, and inhalation of, airborne radioactive contamination, and an ingestion pathway zone of about {{convert|50|mi}}, concerned primarily with ingestion of food and liquid contaminated by radioactivity.{{cite web|url=https://www.nrc.gov/reading-rm/doc-collections/fact-sheets/emerg-plan-prep-nuc-power-bg.html |title=NRC: Backgrounder on Emergency Preparedness at Nuclear Power Plants |publisher=Nrc.gov |access-date=2012-08-17 |url-status=dead |archive-url=https://web.archive.org/web/20061002131207/http://www.nrc.gov/reading-rm/doc-collections/fact-sheets/emerg-plan-prep-nuc-power-bg.html |archive-date=2006-10-02 }}

The 2010 U.S. population within {{convert|10|mi}} of Dresden was 83,049, an increase of 47.6 percent in a decade, according to an analysis of U.S. Census data for msnbc.com. The 2010 U.S. population within {{convert|50|mi}} was 7,305,482, an increase of 3.5 percent since 2000. Cities within 50 miles include Chicago (43 miles to city center).{{Cite web |date=2011-04-14 |title=Nuclear neighbors: Population rises near US reactors |url=https://www.nbcnews.com/id/wbna42555888 |access-date=2024-08-16 |website=NBC News |language=en}}

Both currently operating units are owned and operated by Constellation Energy following separation from Exelon, which also owns and is responsible for the decommissioning of Unit 1. Prior to August 3, 2000, all three units were owned by Commonwealth Edison.{{cite report|author1=United States General Accounting Office|author-link1=Government Accountability Office|title=NRC's Liability Insurance Requirements for Nuclear Power Plants Owned by Limited Liability Companies|date=8 May 2004|page=16|publisher=United States General Accounting Office|url=https://www.gao.gov/products/GAO-04-654 |access-date=29 April 2018|format=PDF|oclc=56982748|id=GAO-04-654|lccn=2004398843}}{{cite web|author1=Nuclear Regulatory Commission|author-link1=Nuclear Regulatory Commission|title=Commonwealth Edison Company; Dresden Nuclear Power Station, Units 1, 2 and 3; Notice of Consideration of Approval of Application Regarding Proposed Corporate Restructuring and Opportunity for a Hearing|url=https://www.federalregister.gov/documents/2000/08/31/00-22337/commonwealth-edison-company-dresden-nuclear-power-station-units-1-2-and-3-notice-of-consideration-of |website=Federal Register|publisher=Office of the Federal Register|access-date=29 April 2018|date=31 August 2000}}

The Nuclear Regulatory Commission's estimate of the risk each year of an earthquake intense enough to cause core damage to the reactor at Dresden was 1 in 52,632, according to an NRC study published in August 2010.{{Cite web |date=2011-03-16 |title=What are the odds? US nuke plants ranked by quake risk |url=https://www.nbcnews.com/id/wbna42103936 |access-date=2024-08-16 |website=NBC News |language=en}}{{Cite web |url=http://msnbcmedia.msn.com/i/msnbc/Sections/NEWS/quake%20nrc%20risk%20estimates.pdf |title=Archived copy |access-date=2011-04-19 |archive-url= https://web.archive.org/web/20170525170632/http://msnbcmedia.msn.com/i/msnbc/Sections/NEWS/quake%20nrc%20risk%20estimates.pdf |archive-date=2017-05-25 |url-status=dead }}

In August 2020, Exelon announced they would close the plant in November 2021 for economic reasons, despite the plant having licenses to operate for about another 10 years and the ability to renew the licenses for an additional 20 years beyond that. On September 13, 2021, the Illinois state senate passed a bill subsidizing the Byron and Dresden nuclear plants,{{Cite news|last=Gardner|first=Timothy|date=2021-09-13|title=Illinois approves $700 million in subsidies to Exelon, prevents nuclear plant closures|language=en|work=Reuters|url=https://www.reuters.com/world/us/illinois-senate-close-providing-lifeline-3-nuclear-power-plants-2021-09-13/|access-date=2021-09-26}} which Governor J. B. Pritzker signed into law on September 15,{{Cite web|title=Gov. Pritzker Signs Transformative Legislation Establishing Illinois as a National Leader on Climate Action|url=https://www.illinois.gov/news/press-release.23893.html|url-status=live|access-date=September 26, 2021|website=Illinois.gov|archive-url=https://web.archive.org/web/20210916125439/https://www.illinois.gov/news/press-release.23893.html |archive-date=2021-09-16 }} and Exelon announced it would refuel the plants.{{Cite web|title=Passage of Illinois Energy Legislation Preserves Nuclear Plants and Strengthens State's Clean Energy Leadership|url=https://www.exeloncorp.com:443/newsroom/passage-of-illinois-energy-legislation-preserves-nuclear-plants-and-strengthens-states-clean-energy-leadership|access-date=2021-09-26|website=www.exeloncorp.com|language=en-US}}

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• {{cite web

| url = http://www.eia.doe.gov/cneaf/nuclear/page/at_a_glance/reactors/dresden.html

| archive-url = http://arquivo.pt/wayback/20090710070953/http://www.eia.doe.gov/cneaf/nuclear/page/at_a_glance/reactors/dresden.html

| url-status = dead

| archive-date = July 10, 2009

| title = Dresden Nuclear Power Plant, Illinois

| date = August 22, 2008

| publisher = Energy Information Administration, U.S. Department of Energy (DOE)

| access-date = 2008-11-19 }}

• http://www.eia.gov/cneaf/nuclear/state_profiles/illinois/il.html#_ftn4
• https://www.nrc.gov/info-finder/decommissioning/power-reactor/dresden-nuclear-power-station-unit-1.html
• {{cite web

| url = https://www.nrc.gov/info-finder/reactor/dres2.html

| title = Dresden 2 Boiling Water Reactor

| date = February 14, 2008 | work= Operating Nuclear Power Reactors

| publisher = U.S. Nuclear Regulatory Commission (NRC)

| access-date = 2008-11-19 }}

• {{cite web

| url = https://www.nrc.gov/info-finder/reactor/dres3.html

| title = Dresden 3 Boiling Water Reactor

| date = February 14, 2008 | work= Operating Nuclear Power Reactors | publisher= NRC

| access-date = 2008-11-19 }}

{{Nuclear power in the United States}}

Category:Energy infrastructure completed in 1960

Category:Energy infrastructure completed in 1970

Category:Energy infrastructure completed in 1971

Category:Nuclear power plants in Illinois

Category:Buildings and structures in Grundy County, Illinois

Category:Illinois River

Category:Exelon