# Byron Generating Station

PJM Nuclear · https://askthegrid.com/assets/facilities/byron-generating-station

Byron Generating Station is a nuclear power facility with 2,449.8 MW of EIA-reported nameplate capacity in Ogle County, Illinois, registered as EIA Plant ID 6023. Constellation Nuclear owns and operates the plant. The plant's generating configuration is two operating nuclear units, each a Westinghouse four-loop pressurized-water reactor (PWR). The facility interconnects at COMED at 345 kV.
COMED · 345 kV · Commonwealth Edison Company (ComEd).

## Key facts

- Technology: Nuclear
- Power capacity: 2449.8 MW
- Operating status: operating

## Grid and market context

- ISO/RTO: PJM
- Balancing authority: PJM Interconnection, LLC
- Interconnection voltage: 345 kV

## Source-backed facts

- Owner logo domain: constellationenergy.com — Byron Clean Energy Center | Constellation Energy Locations · confidence: medium
- Identifiers: [{"value":"6023","system":"EIA plant ID"},{"value":"1","system":"EIA generator ID"},{"value":"2","system":"EIA generator ID"},{"value":"PJM","system":"ISO/RTO"},{"value":"COMED","system":"PJM market zone"},{"value":"BYRON NUCLEAR 1","system":"PJM market resource"},{"value":"BYRON NUCLEAR 2","system":"PJM market resource"},{"value":"50-454 (Unit 1)","system":"NRC docket"},{"value":"50-455 (Unit 2)","system":"NRC docket"},{"value":"NPF-37 (Unit 1)","system":"NRC facility operating license"},{"value":"NPF-66 (Unit 2)","system":"NRC facility operating license"}] — 2026 Generation · confidence: high
- Identifiers: [{"value":"6023","system":"EIA plant ID"},{"value":"1","system":"EIA generator ID"},{"value":"2","system":"EIA generator ID"},{"value":"PJM","system":"ISO/RTO"},{"value":"COMED","system":"PJM market zone"},{"value":"BYRON NUCLEAR 1","system":"PJM market resource"},{"value":"BYRON NUCLEAR 2","system":"PJM market resource"},{"value":"50-454 (Unit 1)","system":"NRC docket"},{"value":"50-455 (Unit 2)","system":"NRC docket"},{"value":"NPF-37 (Unit 1)","system":"NRC facility operating license"},{"value":"NPF-66 (Unit 2)","system":"NRC facility operating license"}] — Nuclear reactor Ownership · confidence: high
- Identifiers: [{"value":"6023","system":"EIA plant ID"},{"value":"1","system":"EIA generator ID"},{"value":"2","system":"EIA generator ID"},{"value":"PJM","system":"ISO/RTO"},{"value":"COMED","system":"PJM market zone"},{"value":"BYRON NUCLEAR 1","system":"PJM market resource"},{"value":"BYRON NUCLEAR 2","system":"PJM market resource"},{"value":"50-454 (Unit 1)","system":"NRC docket"},{"value":"50-455 (Unit 2)","system":"NRC docket"},{"value":"NPF-37 (Unit 1)","system":"NRC facility operating license"},{"value":"NPF-66 (Unit 2)","system":"NRC facility operating license"}] — Source · confidence: high
- Identifiers: [{"value":"6023","system":"EIA plant ID"},{"value":"1","system":"EIA generator ID"},{"value":"2","system":"EIA generator ID"},{"value":"PJM","system":"ISO/RTO"},{"value":"COMED","system":"PJM market zone"},{"value":"BYRON NUCLEAR 1","system":"PJM market resource"},{"value":"BYRON NUCLEAR 2","system":"PJM market resource"},{"value":"50-454 (Unit 1)","system":"NRC docket"},{"value":"50-455 (Unit 2)","system":"NRC docket"},{"value":"NPF-37 (Unit 1)","system":"NRC facility operating license"},{"value":"NPF-66 (Unit 2)","system":"NRC facility operating license"}] — Federal Register, Volume 74 Issue 173 (Wednesday, September... · confidence: high
- Identifiers: [{"value":"6023","system":"EIA plant ID"},{"value":"1","system":"EIA generator ID"},{"value":"2","system":"EIA generator ID"},{"value":"PJM","system":"ISO/RTO"},{"value":"COMED","system":"PJM market zone"},{"value":"BYRON NUCLEAR 1","system":"PJM market resource"},{"value":"BYRON NUCLEAR 2","system":"PJM market resource"},{"value":"50-454 (Unit 1)","system":"NRC docket"},{"value":"50-455 (Unit 2)","system":"NRC docket"},{"value":"NPF-37 (Unit 1)","system":"NRC facility operating license"},{"value":"NPF-66 (Unit 2)","system":"NRC facility operating license"}] — Exelon Generation Company, LLC; Byron Station, Unit Nos... · confidence: high
- Description: Byron Generating Station, also branded Byron Clean Energy Center, is a two-unit nuclear facility outside Byron, Illinois. Its two units are Westinghouse pressurized-water reactors that entered commercial service in 1985 and 1987. Constellation’s official fact sheet lists 2,347 MW of total site net generation, and NRC renewed facility operating licenses NPF-37 and NPF-66 for Units 1 and 2, respectively. — Byron Clean Energy Center | Constellation Energy Locations · confidence: high
- Description: Byron Generating Station, also branded Byron Clean Energy Center, is a two-unit nuclear facility outside Byron, Illinois. Its two units are Westinghouse pressurized-water reactors that entered commercial service in 1985 and 1987. Constellation’s official fact sheet lists 2,347 MW of total site net generation, and NRC renewed facility operating licenses NPF-37 and NPF-66 for Units 1 and 2, respectively. — Source · confidence: high
- Description: Byron Generating Station, also branded Byron Clean Energy Center, is a two-unit nuclear facility outside Byron, Illinois. Its two units are Westinghouse pressurized-water reactors that entered commercial service in 1985 and 1987. Constellation’s official fact sheet lists 2,347 MW of total site net generation, and NRC renewed facility operating licenses NPF-37 and NPF-66 for Units 1 and 2, respectively. — Safety Evaluation Report, Related to the License Renewal of Byron Station, Units 1 and 2, and Braidwood Station, Units 1 and 2 – Docket Nos. 50-454, 50-455, 50-456, and 50-457 – Exelon Generation Company, LLC – Sections 1 to 3 (NUREG-2190, Volume 1) | Nuclear Regulatory Commission · confidence: high
- Parties: [{"relationship":"Owner, 100 percent","name":"Constellation Energy","official_url":"https://www.constellationenergy.com"},{"relationship":"Operator","name":"Constellation Nuclear","official_url":"https://www.constellationenergy.com"},{"relationship":"NRC licensee","name":"Constellation Energy Generation, LLC","official_url":"https://www.constellationenergy.com"},{"relationship":"Reactor and turbine-generator OEM","name":"Westinghouse Electric Corporation","official_url":"https://www.westinghousenuclear.com"},{"relationship":"Architect-engineer","name":"Sargent & Lundy","official_url":"https://www.sargentlundy.com"},{"relationship":"Unit 1 steam-generator supplier","name":"Babcock & Wilcox","official_url":"https://www.babcock.com"},{"relationship":"Unit 2 steam-generator supplier","name":"Westinghouse Electric Corporation","official_url":"https://www.westinghousenuclear.com"}] — Source · confidence: high
- Parties: [{"relationship":"Owner, 100 percent","name":"Constellation Energy","official_url":"https://www.constellationenergy.com"},{"relationship":"Operator","name":"Constellation Nuclear","official_url":"https://www.constellationenergy.com"},{"relationship":"NRC licensee","name":"Constellation Energy Generation, LLC","official_url":"https://www.constellationenergy.com"},{"relationship":"Reactor and turbine-generator OEM","name":"Westinghouse Electric Corporation","official_url":"https://www.westinghousenuclear.com"},{"relationship":"Architect-engineer","name":"Sargent & Lundy","official_url":"https://www.sargentlundy.com"},{"relationship":"Unit 1 steam-generator supplier","name":"Babcock & Wilcox","official_url":"https://www.babcock.com"},{"relationship":"Unit 2 steam-generator supplier","name":"Westinghouse Electric Corporation","official_url":"https://www.westinghousenuclear.com"}] — Federal Register :: Constellation Energy Generation, LLC; Braidwood Station, Units 1 and 2, Byron Station, Unit Nos. 1 and 2, and LaSalle County Station, Units 1 and 2; Environmental Assessment and Finding of No Significant Impact · confidence: high
- Parties: [{"relationship":"Owner, 100 percent","name":"Constellation Energy","official_url":"https://www.constellationenergy.com"},{"relationship":"Operator","name":"Constellation Nuclear","official_url":"https://www.constellationenergy.com"},{"relationship":"NRC licensee","name":"Constellation Energy Generation, LLC","official_url":"https://www.constellationenergy.com"},{"relationship":"Reactor and turbine-generator OEM","name":"Westinghouse Electric Corporation","official_url":"https://www.westinghousenuclear.com"},{"relationship":"Architect-engineer","name":"Sargent & Lundy","official_url":"https://www.sargentlundy.com"},{"relationship":"Unit 1 steam-generator supplier","name":"Babcock & Wilcox","official_url":"https://www.babcock.com"},{"relationship":"Unit 2 steam-generator supplier","name":"Westinghouse Electric Corporation","official_url":"https://www.westinghousenuclear.com"}] — Safety Evaluation Report, Related to the License Renewal of Byron Station, Units 1 and 2, and Braidwood Station, Units 1 and 2 – Docket Nos. 50-454, 50-455, 50-456, and 50-457 – Exelon Generation Company, LLC – Sections 1 to 3 (NUREG-2190, Volume 1) | Nuclear Regulatory Commission · confidence: high
- Identifiers.0: {"value":"6023","system":"EIA plant ID"} — 2026 Generation · confidence: high
- Identifiers.1: {"value":"1","system":"EIA generator ID"} — Nuclear reactor Ownership · confidence: high
- Identifiers.2: {"value":"2","system":"EIA generator ID"} — Nuclear reactor Ownership · confidence: high
- Identifiers.3: {"value":"PJM","system":"ISO/RTO"} — Source · confidence: medium
- Identifiers.4: {"value":"COMED","system":"PJM market zone"} — Source · confidence: high
- Identifiers.5: {"value":"BYRON NUCLEAR 1","system":"PJM market resource"} — Source · confidence: high
- Identifiers.6: {"value":"BYRON NUCLEAR 2","system":"PJM market resource"} — Source · confidence: high
- Identifiers.7: {"value":"50-454 (Unit 1)","system":"NRC docket"} — Federal Register, Volume 74 Issue 173 (Wednesday, September... · confidence: high
- Identifiers.8: {"value":"50-455 (Unit 2)","system":"NRC docket"} — Federal Register, Volume 74 Issue 173 (Wednesday, September... · confidence: high
- Identifiers.9: {"value":"NPF-37 (Unit 1)","system":"NRC facility operating license"} — Exelon Generation Company, LLC; Byron Station, Unit Nos... · confidence: high
- Identifiers.10: {"value":"NPF-66 (Unit 2)","system":"NRC facility operating license"} — Exelon Generation Company, LLC; Byron Station, Unit Nos... · confidence: high
- Parties.0: {"relationship":"Owner, 100 percent","name":"Constellation Energy","official_url":"https://www.constellationenergy.com"} — Source · confidence: high
- Parties.2: {"relationship":"NRC licensee","name":"Constellation Energy Generation, LLC","official_url":"https://www.constellationenergy.com"} — Federal Register :: Constellation Energy Generation, LLC; Braidwood Station, Units 1 and 2, Byron Station, Unit Nos. 1 and 2, and LaSalle County Station, Units 1 and 2; Environmental Assessment and Finding of No Significant Impact · confidence: high
- Parties.3: {"relationship":"Reactor and turbine-generator OEM","name":"Westinghouse Electric Corporation","official_url":"https://www.westinghousenuclear.com"} — Safety Evaluation Report, Related to the License Renewal of Byron Station, Units 1 and 2, and Braidwood Station, Units 1 and 2 – Docket Nos. 50-454, 50-455, 50-456, and 50-457 – Exelon Generation Company, LLC – Sections 1 to 3 (NUREG-2190, Volume 1) | Nuclear Regulatory Commission · confidence: high
- Parties.4: {"relationship":"Architect-engineer","name":"Sargent & Lundy","official_url":"https://www.sargentlundy.com"} — Safety Evaluation Report, Related to the License Renewal of Byron Station, Units 1 and 2, and Braidwood Station, Units 1 and 2 – Docket Nos. 50-454, 50-455, 50-456, and 50-457 – Exelon Generation Company, LLC – Sections 1 to 3 (NUREG-2190, Volume 1) | Nuclear Regulatory Commission · confidence: high
- Parties.5: {"relationship":"Unit 1 steam-generator supplier","name":"Babcock & Wilcox","official_url":"https://www.babcock.com"} — Safety Evaluation Report, Related to the License Renewal of Byron Station, Units 1 and 2, and Braidwood Station, Units 1 and 2 – Docket Nos. 50-454, 50-455, 50-456, and 50-457 – Exelon Generation Company, LLC – Sections 1 to 3 (NUREG-2190, Volume 1) | Nuclear Regulatory Commission · confidence: high
- Parties.6: {"relationship":"Unit 2 steam-generator supplier","name":"Westinghouse Electric Corporation","official_url":"https://www.westinghousenuclear.com"} — Safety Evaluation Report, Related to the License Renewal of Byron Station, Units 1 and 2, and Braidwood Station, Units 1 and 2 – Docket Nos. 50-454, 50-455, 50-456, and 50-457 – Exelon Generation Company, LLC – Sections 1 to 3 (NUREG-2190, Volume 1) | Nuclear Regulatory Commission · confidence: high
- Site acres: 1782 — Byron Clean Energy Center · confidence: medium
- Unit configuration: Two operating nuclear units, each a Westinghouse four-loop pressurized-water reactor (PWR). — Byron Clean Energy Center · confidence: medium
- Unit configuration: Two operating nuclear units, each a Westinghouse four-loop pressurized-water reactor (PWR). — Source · confidence: medium
- Commercial operation date: Unit 1: 1985-09-16; Unit 2: 1987-08-02 — Byron Clean Energy Center · confidence: high
- Unit count: 2 — Byron Clean Energy Center · confidence: high
- Product url: https://westinghousenuclear.com/nuclear-fuel/pressurized-water-reactor-pwr/ — Pressurized Water Reactor (PWR) | Westinghouse Nuclear · confidence: medium
- Product url: https://westinghousenuclear.com/nuclear-fuel/pressurized-water-reactor-pwr/ — AP1000® Pressurized Water Reactor | Westinghouse Nuclear · confidence: medium
- Kind: nuclear — Byron Clean Energy Center · confidence: high
- Manufacturer domain: westinghousenuclear.com — Safety Evaluation Report, Related to the License Renewal of Byron Station, Units 1 and 2, and Braidwood Station, Units 1 and 2 – Docket Nos. 50-454, 50-455, 50-456, and 50-457 – Exelon Generation Company, LLC – Sections 1 to 3 (NUREG-2190, Volume 1) | Nuclear Regulatory Commission · confidence: high
- Equipment models: [{"manufacturer_domain":"westinghousenuclear.com","product_url":"https://westinghousenuclear.com/nuclear-fuel/pressurized-water-reactor-pwr/","count":2,"unit_mw":null,"name":"Westinghouse four-loop pressurized-water reactor (PWR)"},{"manufacturer_domain":"westinghousenuclear.com","product_url":"https://westinghousenuclear.com/operating-plants/outage-services/turbine-services/","count":1,"unit_mw":1268.043,"name":"Westinghouse 1,800-rpm tandem-compound turbine-generator, Byron Unit 1"},{"manufacturer_domain":"westinghousenuclear.com","product_url":"https://westinghousenuclear.com/operating-plants/outage-services/turbine-services/","count":1,"unit_mw":1241.366,"name":"Westinghouse 1,800-rpm tandem-compound turbine-generator, Byron Unit 2"},{"manufacturer_domain":"babcock.com","product_url":"https://www.babcock.com/home/products-services/steam-generators/steam-generators","count":4,"unit_mw":null,"name":"Babcock & Wilcox replacement steam generators, Byron Unit 1"},{"manufacturer_domain":"westinghousenuclear.com","product_url":"https://westinghousenuclear.com/operating-plants/outage-services/steam-generator-services/","count":4,"unit_mw":null,"name":"Westinghouse Model D5 steam generators, Byron Unit 2"}] — Safety Evaluation Report, Related to the License Renewal of Byron Station, Units 1 and 2, and Braidwood Station, Units 1 and 2 – Docket Nos. 50-454, 50-455, 50-456, and 50-457 – Exelon Generation Company, LLC – Sections 1 to 3 (NUREG-2190, Volume 1) | Nuclear Regulatory Commission · confidence: medium
- Product family: Westinghouse four-loop pressurized-water reactor (PWR) — Safety Evaluation Report, Related to the License Renewal of Byron Station, Units 1 and 2, and Braidwood Station, Units 1 and 2 – Docket Nos. 50-454, 50-455, 50-456, and 50-457 – Exelon Generation Company, LLC – Sections 1 to 3 (NUREG-2190, Volume 1) | Nuclear Regulatory Commission · confidence: high
- Product family: Westinghouse four-loop pressurized-water reactor (PWR) — Pressurized Water Reactor (PWR) | Westinghouse Nuclear · confidence: high
- Manufacturer name: Westinghouse Electric Corporation — Safety Evaluation Report, Related to the License Renewal of Byron Station, Units 1 and 2, and Braidwood Station, Units 1 and 2 – Docket Nos. 50-454, 50-455, 50-456, and 50-457 – Exelon Generation Company, LLC – Sections 1 to 3 (NUREG-2190, Volume 1) | Nuclear Regulatory Commission · confidence: high
- Equipment models.0: {"manufacturer_domain":"westinghousenuclear.com","product_url":"https://westinghousenuclear.com/nuclear-fuel/pressurized-water-reactor-pwr/","count":2,"unit_mw":null,"name":"Westinghouse four-loop pressurized-water reactor (PWR)"} — Safety Evaluation Report, Related to the License Renewal of Byron Station, Units 1 and 2, and Braidwood Station, Units 1 and 2 – Docket Nos. 50-454, 50-455, 50-456, and 50-457 – Exelon Generation Company, LLC – Sections 1 to 3 (NUREG-2190, Volume 1) | Nuclear Regulatory Commission · confidence: high
- Equipment models.1: {"manufacturer_domain":"westinghousenuclear.com","product_url":"https://westinghousenuclear.com/operating-plants/outage-services/turbine-services/","count":1,"unit_mw":1268.043,"name":"Westinghouse 1,800-rpm tandem-compound turbine-generator, Byron Unit 1"} — Turbine Services · confidence: medium
- Equipment models.2: {"manufacturer_domain":"westinghousenuclear.com","product_url":"https://westinghousenuclear.com/operating-plants/outage-services/turbine-services/","count":1,"unit_mw":1241.366,"name":"Westinghouse 1,800-rpm tandem-compound turbine-generator, Byron Unit 2"} — Turbine Services · confidence: medium
- Significance: Byron Clean Energy Center is a 2,347 MW net, two-unit nuclear facility whose emissions-free generation can supply the equivalent of more than 1.7 million homes. — Byron Clean Energy Center | Constellation Energy Locations · confidence: high
- Description: Byron Generating Station, also branded Byron Clean Energy Center, is located near Byron in Ogle County, Illinois. It consists of two Westinghouse four-loop pressurized-water reactors, with Unit 1 entering commercial service in 1985 and Unit 2 in 1987. Constellation Energy owns the facility, while Constellation Nuclear operates it; the site was formerly associated with Commonwealth Edison and Exelon Generation. The NRC renewed the units' operating licenses in 2015, authorizing operation through 2044 for Unit 1 and 2046 for Unit 2. — Safety Evaluation Report, Related to the License Renewal of Byron Station, Units 1 and 2, and Braidwood Station, Units 1 and 2 – Docket Nos. 50-454, 50-455, 50-456, and 50-457 – Exelon Generation Company, LLC – Sections 1 to 3 (NUREG-2190, Volume 1) | Nuclear Regulatory Commission · confidence: medium
- Description: Byron Generating Station, also branded Byron Clean Energy Center, is located near Byron in Ogle County, Illinois. It consists of two Westinghouse four-loop pressurized-water reactors, with Unit 1 entering commercial service in 1985 and Unit 2 in 1987. Constellation Energy owns the facility, while Constellation Nuclear operates it; the site was formerly associated with Commonwealth Edison and Exelon Generation. The NRC renewed the units' operating licenses in 2015, authorizing operation through 2044 for Unit 1 and 2046 for Unit 2. — Source · confidence: medium
- Description: Byron Generating Station, also branded Byron Clean Energy Center, is located near Byron in Ogle County, Illinois. It consists of two Westinghouse four-loop pressurized-water reactors, with Unit 1 entering commercial service in 1985 and Unit 2 in 1987. Constellation Energy owns the facility, while Constellation Nuclear operates it; the site was formerly associated with Commonwealth Edison and Exelon Generation. The NRC renewed the units' operating licenses in 2015, authorizing operation through 2044 for Unit 1 and 2046 for Unit 2. — Byron Clean Energy Center | Constellation Energy Locations · confidence: medium
- Quality notes: ["The official owner fact sheet reports 2,347 MW of total site net generation; NRC records separately describe licensed thermal and gross electrical output, so capacity figures should not be mixed across bases.","The announced $800 million uprate program covers both Byron and Braidwood; the disclosed sources do not allocate a Byron-only investment amount or Byron-only megawatt increase.","The $1.75 billion payment disclosed in the 2022 Exelon-Constellation separation was a corporate separation payment, not stated sale consideration for Byron. No standalone Byron project-finance facility or project-specific acquisition price was disclosed in the cited record."] — Byron Clean Energy Center · confidence: medium
- Quality notes: ["The official owner fact sheet reports 2,347 MW of total site net generation; NRC records separately describe licensed thermal and gross electrical output, so capacity figures should not be mixed across bases.","The announced $800 million uprate program covers both Byron and Braidwood; the disclosed sources do not allocate a Byron-only investment amount or Byron-only megawatt increase.","The $1.75 billion payment disclosed in the 2022 Exelon-Constellation separation was a corporate separation payment, not stated sale consideration for Byron. No standalone Byron project-finance facility or project-specific acquisition price was disclosed in the cited record."] — Constellation Making Major Investment in Two Illinois Nuclear Plants to Increase Clean Energy Output · confidence: medium
- Quality notes: ["The official owner fact sheet reports 2,347 MW of total site net generation; NRC records separately describe licensed thermal and gross electrical output, so capacity figures should not be mixed across bases.","The announced $800 million uprate program covers both Byron and Braidwood; the disclosed sources do not allocate a Byron-only investment amount or Byron-only megawatt increase.","The $1.75 billion payment disclosed in the 2022 Exelon-Constellation separation was a corporate separation payment, not stated sale consideration for Byron. No standalone Byron project-finance facility or project-specific acquisition price was disclosed in the cited record."] — Source · confidence: medium
- Financing summary: No standalone project-finance debt facility or Byron-specific sale price was disclosed. In connection with the February 1, 2022 corporate separation, Exelon entered four term loans totaling $2.0 billion—$1.15 billion for 364 days and three 18-month loans of $300 million, $300 million, and $250 million—primarily to fund a $1.75 billion cash payment to Constellation and for general corporate purposes. Exelon also contributed its equity ownership interest in Generation to Constellation; the $1.75 billion payment was therefore separation financing and consideration between the parent companies, not identified purchase consideration for Byron. — Source · confidence: medium
- Quality notes.0: The official owner fact sheet reports 2,347 MW of total site net generation; NRC records separately describe licensed thermal and gross electrical output, so capacity figures should not be mixed across bases. — Byron Clean Energy Center · confidence: high
- Quality notes.1: The announced $800 million uprate program covers both Byron and Braidwood; the disclosed sources do not allocate a Byron-only investment amount or Byron-only megawatt increase. — Constellation Making Major Investment in Two Illinois Nuclear Plants to Increase Clean Energy Output · confidence: high

## Timeline

- 1975-12-31 — NRC construction permit issued
  The NRC issued Byron's construction permit.
  Source: Safety Evaluation Report, Related to the License Renewal of Byron Station, Units 1 and 2, and Braidwood Station, Units 1 and 2 – Docket Nos. 50-454, 50-455, 50-456, and 50-457 – Exelon Generation Company, LLC – Sections 1 to 3 (NUREG-2190, Volume 1) | Nuclear Regulatory Commission (https://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr2190/v1/index)
- 2015-11-19 — License renewal
  The NRC approved initial license renewal, authorizing Byron Unit 1 to operate through 2044 and Unit 2 through 2046.
  Source: Byron Clean Energy Center | Constellation Energy Locations (https://www.constellationenergy.com/about/locations/byron-clean-energy-center.html)
- 2020-08-27 — Planned retirement announced
  Exelon Generation announced an intention to retire Byron in September 2021.
  Source: Exelon Generation to Retire Illinois’ Byron and Dresden Nuclear Plants in 2021 (https://www.constellationenergy.com/news/2020/exelon-generation-to-retire-illinois--byron-and-dresden-nuclear-.html)
- 2022-02-01 — Transfer to Constellation through corporate separation
  Exelon completed the separation of Constellation. Exelon contributed its equity interest in Generation to Constellation, and Exelon shareholders received Constellation shares; this was not described as a standalone sale of Byron.
  Source: Source (https://www.sec.gov/Archives/edgar/data/9466/000110935724000053/R51.htm)
- 2023-02-21 — Joint turbine uprate program announced
  Constellation announced an $800 million equipment program for the Byron and Braidwood stations, involving replacement of the main turbines. The combined projects were expected to add approximately 135 MW, with increased output beginning as early as 2026 and full uprated output by 2029.
  Source: Constellation Making Major Investment in Two Illinois Nuclear Plants to Increase Clean Energy Output (https://www.constellationenergy.com/news/2023/Constellation-Making-Major-Investment-in-Two-Illinois-Nuclear-Plants-to-Increase-Clean-Energy-Output.html)

## Sources

- [Byron Clean Energy Center | Constellation Energy Locations](https://www.constellationenergy.com/about/locations/byron-clean-energy-center.html) — constellationenergy.com · tier other
- [2026 Generation](https://www.eia.gov/nuclear/generation/xls/usreact26.xlsx) — eia.gov · tier regulatory
- [Nuclear reactor Ownership](https://www.eia.gov/nuclear/reactors/reactorcapacity.php) — eia.gov · tier regulatory
- [Source](https://www.pjm.com/-/media/DotCom/etools/capacity-exchange/erpm-designated.csv) — pjm.com · tier other
- [Federal Register, Volume 74 Issue 173 (Wednesday, September ...](https://www.govinfo.gov/content/pkg/FR-2009-09-09/html/E9-21697.htm) — govinfo.gov · tier regulatory
- [Exelon Generation Company, LLC; Byron Station, Unit Nos ...](https://www.federalregister.gov/documents/2021/10/01/2021-21436/exelon-generation-company-llc-byron-station-unit-nos-1-and-2) — federalregister.gov · tier regulatory
- [Byron Clean Energy Center](https://www.constellationenergy.com/content/dam/constellationenergy/pdfs/fact-sheets/Byron_Clean_Energy_Center_Fact_Sheet.pdf) — constellationenergy.com · tier other
- [Safety Evaluation Report, Related to the License Renewal of Byron Station, Units 1 and 2, and Braidwood Station, Units 1 and 2 – Docket Nos. 50-454, 50-455, 50-456, and 50-457 – Exelon Generation Company, LLC – Sections 1 to 3 (NUREG-2190, Volume 1) | Nuclear Regulatory Commission](https://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr2190/v1/index) — nrc.gov · tier regulatory
- [Federal Register :: Constellation Energy Generation, LLC; Braidwood Station, Units 1 and 2, Byron Station, Unit Nos. 1 and 2, and LaSalle County Station, Units 1 and 2; Environmental Assessment and Finding of No Significant Impact](https://www.federalregister.gov/documents/2026/04/21/2026-07701/constellation-energy-generation-llc-braidwood-station-units-1-and-2-byron-station-unit-nos-1-and-2) — federalregister.gov · tier regulatory
- [Byron, Units 1 and 2 - Environmental Report, Part 1.](https://www.nrc.gov/docs/ml1315/ML13155A422.pdf) — nrc.gov · tier regulatory
- [Pressurized Water Reactor (PWR) | Westinghouse Nuclear](https://westinghousenuclear.com/nuclear-fuel/pressurized-water-reactor-pwr/) — westinghousenuclear.com · tier other
- [AP1000® Pressurized Water Reactor | Westinghouse Nuclear](https://westinghousenuclear.com/new-plants/ap1000-pwr/) — westinghousenuclear.com · tier other
- [Turbine Services](https://westinghousenuclear.com/operating-plants/outage-services/turbine-services/) — westinghousenuclear.com · tier other
- [Source](https://constellationenergy.com/content/dam/constellationenergy/pdfs/fact-sheets/Byron_Clean_Energy_Center_Fact_Sheet.pdf) — constellationenergy.com · tier other
- [Constellation Making Major Investment in Two Illinois Nuclear Plants to Increase Clean Energy Output](https://www.constellationenergy.com/news/2023/Constellation-Making-Major-Investment-in-Two-Illinois-Nuclear-Plants-to-Increase-Clean-Energy-Output.html) — constellationenergy.com · tier other
- [Source](https://www.sec.gov/Archives/edgar/data/9466/000110935724000053/R51.htm) — sec.gov · tier regulatory
- [Source](https://en.wikipedia.org/wiki/Byron_Nuclear_Generating_Station) — en.wikipedia.org · tier other
- [Byron Station, Units 1 and 2, Submittal of the Snubber Program ...](https://www.nrc.gov/docs/ML2604/ML26043A105.pdf) — nrc.gov · tier regulatory
- [Exelon Generation to Retire Illinois’ Byron and Dresden Nuclear Plants in 2021](https://www.constellationenergy.com/news/2020/exelon-generation-to-retire-illinois--byron-and-dresden-nuclear-.html) — constellationenergy.com · tier other
- [Sheet1](https://www.pjm.com/-/media/DotCom/markets-ops/rpm/rpm-auction-info/2025-2026/2025-2026-rpm-existing-resource-list-post.xlsx) — pjm.com · tier other

## Data quality

- The official owner fact sheet reports 2,347 MW of total site net generation; NRC records separately describe licensed thermal and gross electrical output, so capacity figures should not be mixed across bases. The announced $800 million uprate program covers both Byron and Braidwood; the disclosed sources do not allocate a Byron-only investment amount or Byron-only megawatt increase. The $1.75 billion payment disclosed in the 2022 Exelon-Constellation separation was a corporate separation payment, not stated sale consideration for Byron. No standalone Byron project-finance facility or project-specific acquisition price was disclosed in the cited record.

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