# Limerick

PJM Nuclear · https://askthegrid.com/assets/facilities/limerick

Limerick is a nuclear power facility with 2,277 MW of EIA-reported nameplate capacity in Montgomery County, Pennsylvania, registered as EIA Plant ID 6105. Constellation Nuclear owns and operates the plant. The plant's generating configuration is two operating General Electric boiling-water nuclear reactors. Reported commercial-operation dates are February 1, 1986 (Unit 1); January 8, 1990 (Unit 2).

## Key facts

- Technology: Nuclear
- Power capacity: 2277 MW
- Operating status: operating

## Grid and market context

- ISO/RTO: PJM
- Balancing authority: PJM Interconnection, LLC (PJM)
- Transmission owner: PECO Energy Co.
- Interconnection voltage: 500 kV

## Source-backed facts

- Owner logo domain: constellationenergy.com — Limerick Clean Energy Center | Constellation Energy Locations · confidence: medium
- Identifiers: [{"value":"6105","system":"EIA plant ID"},{"value":"1","system":"EIA generator ID — Unit 1"},{"value":"2","system":"EIA generator ID — Unit 2"},{"value":"LIMERICK 1","system":"PJM resource — Unit 1"},{"value":"LIMERICK 2","system":"PJM resource — Unit 2"},{"value":"50-352","system":"NRC docket — Unit 1"},{"value":"50-353","system":"NRC docket — Unit 2"},{"value":"NPF-39","system":"NRC renewed facility operating license — Unit 1"},{"value":"NPF-85","system":"NRC renewed facility operating license — Unit 2"}] — 2026 Generation · confidence: medium
- Identifiers: [{"value":"6105","system":"EIA plant ID"},{"value":"1","system":"EIA generator ID — Unit 1"},{"value":"2","system":"EIA generator ID — Unit 2"},{"value":"LIMERICK 1","system":"PJM resource — Unit 1"},{"value":"LIMERICK 2","system":"PJM resource — Unit 2"},{"value":"50-352","system":"NRC docket — Unit 1"},{"value":"50-353","system":"NRC docket — Unit 2"},{"value":"NPF-39","system":"NRC renewed facility operating license — Unit 1"},{"value":"NPF-85","system":"NRC renewed facility operating license — Unit 2"}] — Nuclear Reactor Ownership · confidence: medium
- Identifiers: [{"value":"6105","system":"EIA plant ID"},{"value":"1","system":"EIA generator ID — Unit 1"},{"value":"2","system":"EIA generator ID — Unit 2"},{"value":"LIMERICK 1","system":"PJM resource — Unit 1"},{"value":"LIMERICK 2","system":"PJM resource — Unit 2"},{"value":"50-352","system":"NRC docket — Unit 1"},{"value":"50-353","system":"NRC docket — Unit 2"},{"value":"NPF-39","system":"NRC renewed facility operating license — Unit 1"},{"value":"NPF-85","system":"NRC renewed facility operating license — Unit 2"}] — Source · confidence: medium
- Identifiers: [{"value":"6105","system":"EIA plant ID"},{"value":"1","system":"EIA generator ID — Unit 1"},{"value":"2","system":"EIA generator ID — Unit 2"},{"value":"LIMERICK 1","system":"PJM resource — Unit 1"},{"value":"LIMERICK 2","system":"PJM resource — Unit 2"},{"value":"50-352","system":"NRC docket — Unit 1"},{"value":"50-353","system":"NRC docket — Unit 2"},{"value":"NPF-39","system":"NRC renewed facility operating license — Unit 1"},{"value":"NPF-85","system":"NRC renewed facility operating license — Unit 2"}] — Limerick Generating Station, Units 1 and 2, License Amendment Request Supplement for Implementation of Digital Modernization Project – Correction of Revision Numbers and Revised Proposed License Condition · confidence: medium
- Owner name: Constellation Nuclear — Nuclear Reactor Ownership · confidence: high
- Description: Limerick Clean Energy Center is a two-reactor nuclear facility in Pottstown, Montgomery County, Pennsylvania. Constellation states that the facility can produce up to 2,317 MW of clean, emissions-free electricity and draws cooling water from the Schuylkill River. The two units operate under NRC renewed facility operating licenses NPF-39 and NPF-85, associated with NRC docket numbers 50-352 and 50-353. — Limerick Clean Energy Center | Constellation Energy Locations · confidence: medium
- Description: Limerick Clean Energy Center is a two-reactor nuclear facility in Pottstown, Montgomery County, Pennsylvania. Constellation states that the facility can produce up to 2,317 MW of clean, emissions-free electricity and draws cooling water from the Schuylkill River. The two units operate under NRC renewed facility operating licenses NPF-39 and NPF-85, associated with NRC docket numbers 50-352 and 50-353. — Limerick Generating Station, Units 1 and 2, License Amendment Request Supplement for Implementation of Digital Modernization Project – Correction of Revision Numbers and Revised Proposed License Condition · confidence: medium
- Parties: [{"relationship":"Owner","name":"Constellation Nuclear","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":"Historical reactor OEM","name":"General Electric (GE)","official_url":"https://www.ge.com"}] — Nuclear Reactor Ownership · confidence: medium
- Parties: [{"relationship":"Owner","name":"Constellation Nuclear","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":"Historical reactor OEM","name":"General Electric (GE)","official_url":"https://www.ge.com"}] — Limerick Generating Station, Units 1 and 2, License Amendment Request Supplement for Implementation of Digital Modernization Project – Correction of Revision Numbers and Revised Proposed License Condition · confidence: medium
- Parties: [{"relationship":"Owner","name":"Constellation Nuclear","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":"Historical reactor OEM","name":"General Electric (GE)","official_url":"https://www.ge.com"}] — Limerick Generating Station, Units 1 & 2, Revision 20 to... · confidence: medium
- Canonical name: Limerick — Nuclear Reactor Ownership · confidence: high
- Identifiers.0: {"value":"6105","system":"EIA plant ID"} — 2026 Generation · confidence: high
- Identifiers.1: {"value":"1","system":"EIA generator ID — Unit 1"} — Nuclear Reactor Ownership · confidence: medium
- Identifiers.2: {"value":"2","system":"EIA generator ID — Unit 2"} — Nuclear Reactor Ownership · confidence: medium
- Identifiers.3: {"value":"LIMERICK 1","system":"PJM resource — Unit 1"} — Source · confidence: high
- Identifiers.4: {"value":"LIMERICK 2","system":"PJM resource — Unit 2"} — Source · confidence: high
- Identifiers.5: {"value":"50-352","system":"NRC docket — Unit 1"} — Limerick Generating Station, Units 1 and 2, License Amendment Request Supplement for Implementation of Digital Modernization Project – Correction of Revision Numbers and Revised Proposed License Condition · confidence: high
- Identifiers.6: {"value":"50-353","system":"NRC docket — Unit 2"} — Limerick Generating Station, Units 1 and 2, License Amendment Request Supplement for Implementation of Digital Modernization Project – Correction of Revision Numbers and Revised Proposed License Condition · confidence: high
- Identifiers.7: {"value":"NPF-39","system":"NRC renewed facility operating license — Unit 1"} — Limerick Generating Station, Units 1 and 2, License Amendment Request Supplement for Implementation of Digital Modernization Project – Correction of Revision Numbers and Revised Proposed License Condition · confidence: medium
- Identifiers.8: {"value":"NPF-85","system":"NRC renewed facility operating license — Unit 2"} — Limerick Generating Station, Units 1 and 2, License Amendment Request Supplement for Implementation of Digital Modernization Project – Correction of Revision Numbers and Revised Proposed License Condition · confidence: medium
- Parties.0: {"relationship":"Owner","name":"Constellation Nuclear","official_url":"https://www.constellationenergy.com"} — Nuclear Reactor Ownership · confidence: high
- Parties.1: {"relationship":"Operator","name":"Constellation Nuclear","official_url":"https://www.constellationenergy.com"} — Nuclear Reactor Ownership · confidence: high
- Parties.2: {"relationship":"NRC licensee","name":"Constellation Energy Generation, LLC","official_url":"https://www.constellationenergy.com"} — Limerick Generating Station, Units 1 and 2, License Amendment Request Supplement for Implementation of Digital Modernization Project – Correction of Revision Numbers and Revised Proposed License Condition · confidence: high
- Parties.3: {"relationship":"Historical reactor OEM","name":"General Electric (GE)","official_url":"https://www.ge.com"} — Limerick Generating Station, Units 1 & 2, Revision 20 to... · confidence: medium
- Site acres: 600 — Limerick Clean Energy Center · confidence: medium
- Commercial operation date: 1986-02-01 (Unit 1); 1990-01-08 (Unit 2) — Limerick Clean Energy Center · confidence: high
- Unit count: 2 — Limerick Clean Energy Center · confidence: high
- Product url: https://www.gevernova.com/nuclear/carbon-free-power/large-reactors — Large nuclear boiling water reactor | GE Vernova Hitachi · confidence: medium
- Kind: nuclear — Limerick Clean Energy Center | Constellation Energy Locations · confidence: high
- Equipment models: [{"manufacturer_domain":"gevernova.com","product_url":"https://www.gevernova.com/nuclear/carbon-free-power/large-reactors","count":2,"unit_mw":1231,"name":"General Electric BWR boiling-water reactors (BWR/4 designation)"},{"manufacturer_domain":"gevernova.com","product_url":"https://www.gevernova.com/steam-power/nuclear-turbine-island","count":2,"unit_mw":1231.1,"name":"General Electric tandem-compound main turbine-generators"},{"manufacturer_domain":"siemens-energy.com","product_url":"https://www.siemens-energy.com/global/en/home/products-services/product/nuclear-power-plant-solutions.html","count":8,"unit_mw":null,"name":"Siemens replacement HP and LP turbine rotors"},{"manufacturer_domain":"fairbanksmorsedefense.com","product_url":"https://www.fairbanksmorsedefense.com/solutions/engines/fm-38d-8-18/","count":8,"unit_mw":3,"name":"Fairbanks Morse 38 8-1/8 emergency diesel-generator sets"},{"manufacturer_domain":null,"product_url":null,"count":2,"unit_mw":null,"name":"Hyperbolic natural-draft cooling towers"}] — Limerick Generating Station · confidence: medium
- Equipment models.0: {"manufacturer_domain":"gevernova.com","product_url":"https://www.gevernova.com/nuclear/carbon-free-power/large-reactors","count":2,"unit_mw":1231,"name":"General Electric BWR boiling-water reactors (BWR/4 designation)"} — Project: Limerick Generating Station – Advanced Nuclear · confidence: medium
- Equipment models.0: {"manufacturer_domain":"gevernova.com","product_url":"https://www.gevernova.com/nuclear/carbon-free-power/large-reactors","count":2,"unit_mw":1231,"name":"General Electric BWR boiling-water reactors (BWR/4 designation)"} — Limerick Generating Station, Units 1 and 2 · confidence: medium
- Equipment models.1: {"manufacturer_domain":"gevernova.com","product_url":"https://www.gevernova.com/steam-power/nuclear-turbine-island","count":2,"unit_mw":1231.1,"name":"General Electric tandem-compound main turbine-generators"} — Limerick Generating Station, Units 1 & 2, Revision 20 to Updated Final Safety Analysis Report, Chapter 1, Sections 1.1 though 1.6 · confidence: medium
- Equipment models.3: {"manufacturer_domain":"fairbanksmorsedefense.com","product_url":"https://www.fairbanksmorsedefense.com/solutions/engines/fm-38d-8-18/","count":8,"unit_mw":3,"name":"Fairbanks Morse 38 8-1/8 emergency diesel-generator sets"} — Limerick Generating Station · confidence: medium
- Significance: Limerick is a two-unit, GE-designed boiling-water reactor station with owner-stated capability of up to 2,317 MW, enough to supply the equivalent of more than 1.7 million homes. It occupies a 600-acre site and uses the Schuylkill River for cooling. — Constellation Invests $90 Million in Limerick Refueling Outage, Boosting Local Economy · confidence: high
- Quality notes: ["The 2,317 MW figure is the owner- and county-stated combined capability; plant datasets may use different net-capacity or generator-rating conventions.","The ownership changes were corporate restructurings rather than documented plant-level sales: PECO became part of Exelon in October 2000, and Exelon's generation business was separated into Constellation in February 2022.","The identified 2026 capital work consists of digital control-system modernization, refueling-outage work, cooling-tower upgrades, and generator-component replacements. No retirement or repowering milestone is identified in the cited history through 2026-08-02."] — Limerick Clean Energy Center | Constellation Energy Locations · confidence: medium
- Quality notes: ["The 2,317 MW figure is the owner- and county-stated combined capability; plant datasets may use different net-capacity or generator-rating conventions.","The ownership changes were corporate restructurings rather than documented plant-level sales: PECO became part of Exelon in October 2000, and Exelon's generation business was separated into Constellation in February 2022.","The identified 2026 capital work consists of digital control-system modernization, refueling-outage work, cooling-tower upgrades, and generator-component replacements. No retirement or repowering milestone is identified in the cited history through 2026-08-02."] — NRC Greenlights Constellation's $167 Million Digital Modernization Plan for Limerick Clean Energy Center; State-of-the-Art Technology Upgrades Will Enhance Reliability, Diagnostic Capability and Cyber Resilience · confidence: medium
- Quality notes: ["The 2,317 MW figure is the owner- and county-stated combined capability; plant datasets may use different net-capacity or generator-rating conventions.","The ownership changes were corporate restructurings rather than documented plant-level sales: PECO became part of Exelon in October 2000, and Exelon's generation business was separated into Constellation in February 2022.","The identified 2026 capital work consists of digital control-system modernization, refueling-outage work, cooling-tower upgrades, and generator-component replacements. No retirement or repowering milestone is identified in the cited history through 2026-08-02."] — Constellation Invests $90 Million in Limerick Refueling Outage, Boosting Local Economy · confidence: medium
- Financing summary: The cited records do not identify a separate plant-level project-finance loan or Limerick sale consideration. During construction, the Pennsylvania Public Utility Commission required PECO Energy shareholders to absorb $369 million of Unit 1 costs and approximately $215 million of Unit 2 costs; Unit 2 was restarted under a $3.197 billion cost cap including Allowance for Funds Used During Construction (AFUDC), which is a construction-cost financing allowance rather than a disclosed project-finance facility. The October 20, 2000 PECO-Unicom merger was a corporate transaction: Unicom shareholders received 0.875 Exelon shares plus $3.00 cash per Unicom share. In the February 2, 2022 separation, Exelon shareholders received one Constellation share for every three Exelon shares; neither transaction disclosed Limerick-specific sale consideration. — Source · confidence: medium
- Financing summary: The cited records do not identify a separate plant-level project-finance loan or Limerick sale consideration. During construction, the Pennsylvania Public Utility Commission required PECO Energy shareholders to absorb $369 million of Unit 1 costs and approximately $215 million of Unit 2 costs; Unit 2 was restarted under a $3.197 billion cost cap including Allowance for Funds Used During Construction (AFUDC), which is a construction-cost financing allowance rather than a disclosed project-finance facility. The October 20, 2000 PECO-Unicom merger was a corporate transaction: Unicom shareholders received 0.875 Exelon shares plus $3.00 cash per Unicom share. In the February 2, 2022 separation, Exelon shareholders received one Constellation share for every three Exelon shares; neither transaction disclosed Limerick-specific sale consideration. — title: Limerick Generating Station Unit 2 description: Limerick Generating Station Unit 2 is a nuclear plant in Pennsylvania (United States) which went into commercial operation in January of 1990, eight months ahead of schedule and $400 under budget. This article overviews this project, which was awarded the 1990 PMI Project of the Year Award. Construction of the plant was managed by Philadelphia Electric Company (PE), working with Bechtel Power Corporation and General Electric. Harmonious labor-management relations were governed by a project labor agreement with the Philadelphia Building and Construction Trades Council that enabled work to be done safely, efficiently, and without strikes or delays. Part of this agreement was the Built-Rite Program, designed to save costs, improve communication and problem solving, and increase project safety and worker involvement. The project area coordinator (PAC) approach allowed the project to be divided into more manageable pieces. Other aspects of the project discussed include its aggressive scheduling, the establishment of pacing milestones for each management area, and successful teamwork. image: //www.pmi.org/-/media/pmi/headless-images/global/pmi-logos/pmi_logo_ogshare.png?h=120&iar=0&w=400&rev=88b8335698e04a74999fe8a6fe4037d2&dianoga=false · confidence: medium
- Financing summary: The cited records do not identify a separate plant-level project-finance loan or Limerick sale consideration. During construction, the Pennsylvania Public Utility Commission required PECO Energy shareholders to absorb $369 million of Unit 1 costs and approximately $215 million of Unit 2 costs; Unit 2 was restarted under a $3.197 billion cost cap including Allowance for Funds Used During Construction (AFUDC), which is a construction-cost financing allowance rather than a disclosed project-finance facility. The October 20, 2000 PECO-Unicom merger was a corporate transaction: Unicom shareholders received 0.875 Exelon shares plus $3.00 cash per Unicom share. In the February 2, 2022 separation, Exelon shareholders received one Constellation share for every three Exelon shares; neither transaction disclosed Limerick-specific sale consideration. — Exelon Completes Separation of Constellation, Moving Forward as Nation’s Premier Transmission and Distribution Utility Company · confidence: medium
- Quality notes.0: The 2,317 MW figure is the owner- and county-stated combined capability; plant datasets may use different net-capacity or generator-rating conventions. — Limerick Clean Energy Center | Constellation Energy Locations · confidence: high
- Quality notes.2: The identified 2026 capital work consists of digital control-system modernization, refueling-outage work, cooling-tower upgrades, and generator-component replacements. No retirement or repowering milestone is identified in the cited history through 2026-08-02. — NRC Greenlights Constellation's $167 Million Digital Modernization Plan for Limerick Clean Energy Center; State-of-the-Art Technology Upgrades Will Enhance Reliability, Diagnostic Capability and Cyber Resilience · confidence: medium
- Quality notes.2: The identified 2026 capital work consists of digital control-system modernization, refueling-outage work, cooling-tower upgrades, and generator-component replacements. No retirement or repowering milestone is identified in the cited history through 2026-08-02. — Constellation Invests $90 Million in Limerick Refueling Outage, Boosting Local Economy · confidence: medium
- Commercial parties.1: {"relationship":"NRC licensee","name":"Constellation Energy Generation, LLC","detail":"Current holder of the renewed facility operating licenses for Limerick Units 1 and 2.","official_url":"https://www.constellationenergy.com"} — Federal Register :: Constellation Energy Generation, LLC; Limerick Generating Station, Units 1 and 2 · confidence: high
- Commercial parties.1: {"relationship":"NRC licensee","name":"Constellation Energy Generation, LLC","detail":"Current holder of the renewed facility operating licenses for Limerick Units 1 and 2.","official_url":"https://www.constellationenergy.com"} — Limerick Generating Station, Units 1 and 2, License Amendment Request Supplement for Implementation of Digital Modernization Project – Correction of Revision Numbers and Revised Proposed License Condition · confidence: high
- Commercial parties.4: {"relationship":"Reactor designer and historical OEM","name":"General Electric","detail":"Designed the station's two boiling-water reactors and worked with Philadelphia Electric on the project.","official_url":"https://www.ge.com"} — title: Limerick Generating Station Unit 2 description: Limerick Generating Station Unit 2 is a nuclear plant in Pennsylvania (United States) which went into commercial operation in January of 1990, eight months ahead of schedule and $400 under budget. This article overviews this project, which was awarded the 1990 PMI Project of the Year Award. Construction of the plant was managed by Philadelphia Electric Company (PE), working with Bechtel Power Corporation and General Electric. Harmonious labor-management relations were governed by a project labor agreement with the Philadelphia Building and Construction Trades Council that enabled work to be done safely, efficiently, and without strikes or delays. Part of this agreement was the Built-Rite Program, designed to save costs, improve communication and problem solving, and increase project safety and worker involvement. The project area coordinator (PAC) approach allowed the project to be divided into more manageable pieces. Other aspects of the project discussed include its aggressive scheduling, the establishment of pacing milestones for each management area, and successful teamwork. image: //www.pmi.org/-/media/pmi/headless-images/global/pmi-logos/pmi_logo_ogshare.png?h=120&iar=0&w=400&rev=88b8335698e04a74999fe8a6fe4037d2&dianoga=false · confidence: high
- Timeline.1: {"event":"Unit 2 construction suspended","date":"1982-06","detail":"The Pennsylvania Public Utility Commission ordered Unit 2 construction stopped when the unit was approximately 30% complete; Unit 1 continued toward completion."} — title: Limerick Generating Station Unit 2 description: Limerick Generating Station Unit 2 is a nuclear plant in Pennsylvania (United States) which went into commercial operation in January of 1990, eight months ahead of schedule and $400 under budget. This article overviews this project, which was awarded the 1990 PMI Project of the Year Award. Construction of the plant was managed by Philadelphia Electric Company (PE), working with Bechtel Power Corporation and General Electric. Harmonious labor-management relations were governed by a project labor agreement with the Philadelphia Building and Construction Trades Council that enabled work to be done safely, efficiently, and without strikes or delays. Part of this agreement was the Built-Rite Program, designed to save costs, improve communication and problem solving, and increase project safety and worker involvement. The project area coordinator (PAC) approach allowed the project to be divided into more manageable pieces. Other aspects of the project discussed include its aggressive scheduling, the establishment of pacing milestones for each management area, and successful teamwork. image: //www.pmi.org/-/media/pmi/headless-images/global/pmi-logos/pmi_logo_ogshare.png?h=120&iar=0&w=400&rev=88b8335698e04a74999fe8a6fe4037d2&dianoga=false · confidence: high
- Timeline.2: {"event":"Unit 2 completion approved under cost cap","date":"1985-12","detail":"Philadelphia Electric received Pennsylvania Public Utility Commission permission to resume Unit 2 construction under a $3.197 billion cost cap, including AFUDC."} — title: Limerick Generating Station Unit 2 description: Limerick Generating Station Unit 2 is a nuclear plant in Pennsylvania (United States) which went into commercial operation in January of 1990, eight months ahead of schedule and $400 under budget. This article overviews this project, which was awarded the 1990 PMI Project of the Year Award. Construction of the plant was managed by Philadelphia Electric Company (PE), working with Bechtel Power Corporation and General Electric. Harmonious labor-management relations were governed by a project labor agreement with the Philadelphia Building and Construction Trades Council that enabled work to be done safely, efficiently, and without strikes or delays. Part of this agreement was the Built-Rite Program, designed to save costs, improve communication and problem solving, and increase project safety and worker involvement. The project area coordinator (PAC) approach allowed the project to be divided into more manageable pieces. Other aspects of the project discussed include its aggressive scheduling, the establishment of pacing milestones for each management area, and successful teamwork. image: //www.pmi.org/-/media/pmi/headless-images/global/pmi-logos/pmi_logo_ogshare.png?h=120&iar=0&w=400&rev=88b8335698e04a74999fe8a6fe4037d2&dianoga=false · confidence: high
- Timeline.3: {"event":"Unit 2 construction restarted","date":"1986-02-03","detail":"Construction of Unit 2 resumed after the cost-cap approval, with the unit approximately 30% complete."} — title: Limerick Generating Station Unit 2 description: Limerick Generating Station Unit 2 is a nuclear plant in Pennsylvania (United States) which went into commercial operation in January of 1990, eight months ahead of schedule and $400 under budget. This article overviews this project, which was awarded the 1990 PMI Project of the Year Award. Construction of the plant was managed by Philadelphia Electric Company (PE), working with Bechtel Power Corporation and General Electric. Harmonious labor-management relations were governed by a project labor agreement with the Philadelphia Building and Construction Trades Council that enabled work to be done safely, efficiently, and without strikes or delays. Part of this agreement was the Built-Rite Program, designed to save costs, improve communication and problem solving, and increase project safety and worker involvement. The project area coordinator (PAC) approach allowed the project to be divided into more manageable pieces. Other aspects of the project discussed include its aggressive scheduling, the establishment of pacing milestones for each management area, and successful teamwork. image: //www.pmi.org/-/media/pmi/headless-images/global/pmi-logos/pmi_logo_ogshare.png?h=120&iar=0&w=400&rev=88b8335698e04a74999fe8a6fe4037d2&dianoga=false · confidence: high
- Timeline.4: {"event":"Unit 1 commercial operation","date":"1986-02-01","detail":"Limerick Unit 1 began commercial operation."} — Limerick Clean Energy Center | Montgomery County, PA · confidence: high
- Timeline.5: {"event":"Unit 2 commercial operation","date":"1990-01-08","detail":"Limerick Unit 2 began commercial operation after completing construction under the PaPUC cost cap."} — Limerick Clean Energy Center | Montgomery County, PA · confidence: high
- Timeline.7: {"event":"Initial license renewal approved","date":"2014-10-20","detail":"The NRC approved renewed operating authority for Unit 1 through 2044 and Unit 2 through 2049."} — Limerick Clean Energy Center | Constellation Energy Locations · confidence: high

## Timeline

- 1986-02-01 — Unit 1 commercial operation
  Limerick Unit 1 began commercial operation.
  Source: Limerick Clean Energy Center | Montgomery County, PA (https://www.montgomerycountypa.gov/departments/department-public-safety/division-emergency-management/limerick-clean-energy-center)
- 1986-02-01 (Unit 1); 1990-01-08 (Unit 2) — Commercial operation
  Limerick entered commercial operation.
  Source: Limerick Clean Energy Center | Montgomery County, PA (https://www.montgomerycountypa.gov/departments/department-public-safety/division-emergency-management/limerick-clean-energy-center)
- 2014-10-20 — Initial license renewal approved
  The NRC approved renewed operating authority for Unit 1 through 2044 and Unit 2 through 2049.
  Source: Limerick Clean Energy Center | Constellation Energy Locations (https://www.constellationenergy.com/about/locations/limerick-clean-energy-center.html)
- 2022-02-02 — Generation business separated into Constellation
  Exelon completed the separation of Constellation Energy, its former generation and competitive-energy business. Constellation Energy Generation, LLC subsequently appears as the NRC licensee for Limerick.
  Source: Exelon Completes Separation of Constellation, Moving Forward as Nation’s Premier Transmission and Distribution Utility Company (https://www.exeloncorp.com/newsroom/exelon-completes-separation-of-constellation)
- 2026-01-06 — Digital modernization approved
  The NRC approved Constellation's $167 million Digital Modernization Project, replacing selected analog instrumentation and control equipment with digital systems; installation is planned in phases during refueling outages.
  Source: NRC Greenlights Constellation's $167 Million Digital Modernization Plan for Limerick Clean Energy Center; State-of-the-Art Technology Upgrades Will Enhance Reliability, Diagnostic Capability and Cyber Resilience (https://www.constellationenergy.com/news/2026/01/nrc-greenlights-constellations-167-million-digital-modernization-plan-for-limerick-clean-energy-center.html)
- 2026-06-09 — Refueling-outage upgrades completed
  Constellation reported a $90 million Limerick refueling and maintenance outage involving cooling-tower performance upgrades, generator-component replacements, and related work.
  Source: Constellation Invests $90 Million in Limerick Refueling Outage, Boosting Local Economy (https://www.constellationenergy.com/news/2026/06/constellation-invests-90-million-in-limerick-refueling-outage-boosting-local-economy.html)

## Sources

- [Limerick Clean Energy Center | Constellation Energy Locations](https://www.constellationenergy.com/about/locations/limerick-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/ownership.php) — eia.gov · tier regulatory
- [Source](https://www.pjm.com/-/media/DotCom/etools/capacity-exchange/erpm-designated.csv) — pjm.com · tier other
- [Limerick Generating Station, Units 1 and 2, License Amendment Request Supplement for Implementation of Digital Modernization Project – Correction of Revision Numbers and Revised Proposed License Condition](https://www.nrc.gov/docs/ML2525/ML25251A214.pdf) — nrc.gov · tier regulatory
- [Limerick Generating Station, Units 1 & 2, Revision 20 to Updated Final Safety Analysis Report, Chapter 1, Sections 1.1 though 1.6](https://www.nrc.gov/docs/ML2113/ML21133A080.pdf) — nrc.gov · tier regulatory
- [Limerick Clean Energy Center](https://www.constellationenergy.com/content/dam/constellationenergy/pdfs/fact-sheets/Limerick_Clean_Energy_Center_Fact_Sheet.pdf) — constellationenergy.com · tier other
- [Limerick Clean Energy Center | Montgomery County, PA](https://www.montgomerycountypa.gov/departments/department-public-safety/division-emergency-management/limerick-clean-energy-center) — montgomerycountypa.gov · tier regulatory
- [Project: Limerick Generating Station – Advanced Nuclear](https://www.advancednuclear.com/project-gallery/limerick-generating-station/) — advancednuclear.com · tier other
- [Source](https://www.nrc.gov/docs/ML2020/ML20202B594.pdf) — nrc.gov · tier regulatory
- [LER 2023-001-00 for Limerick Generating Station, Unit 1, Emergency Diesel Generator Lube Oil Pressure Sensing Line Leak Resulting in a Condition Prohibited by Technical Specifications](https://www.nrc.gov/docs/ML2317/ML23177A232.pdf) — nrc.gov · tier regulatory
- [NRC Greenlights Constellation's $167 Million Digital Modernization Plan for Limerick Clean Energy Center; State-of-the-Art Technology Upgrades Will Enhance Reliability, Diagnostic Capability and Cyber Resilience](https://www.constellationenergy.com/news/2026/01/nrc-greenlights-constellations-167-million-digital-modernization-plan-for-limerick-clean-energy-center.html) — constellationenergy.com · tier other
- [Large nuclear boiling water reactor | GE Vernova Hitachi](https://www.gevernova.com/nuclear/carbon-free-power/large-reactors) — gevernova.com · tier other
- [Limerick Generating Station](https://en.wikipedia.org/wiki/Limerick_Generating_Station) — en.wikipedia.org · tier other
- [Limerick Generating Station, Units 1 and 2](https://www.nrc.gov/docs/ML2429/ML24299A264.pdf) — nrc.gov · tier regulatory
- [Constellation Invests $90 Million in Limerick Refueling Outage, Boosting Local Economy](https://www.constellationenergy.com/news/2026/06/constellation-invests-90-million-in-limerick-refueling-outage-boosting-local-economy.html) — constellationenergy.com · tier other
- [Exelon Completes Separation of Constellation, Moving Forward as Nation’s Premier Transmission and Distribution Utility Company](https://www.exeloncorp.com/newsroom/exelon-completes-separation-of-constellation) — exeloncorp.com · tier other
- [Federal Register :: Constellation Energy Generation, LLC; Limerick Generating Station, Units 1 and 2](https://www.federalregister.gov/documents/2023/05/23/2023-10974/constellation-energy-generation-llc-limerick-generating-station-units-1-and-2) — federalregister.gov · tier regulatory
- [Source](https://www.puc.pa.gov/pcdocs/1236880.pdf) — puc.pa.gov · tier regulatory
- [title: Limerick Generating Station Unit 2 description: Limerick Generating Station Unit 2 is a nuclear plant in Pennsylvania (United States) which went into commercial operation in January of 1990, eight months ahead of schedule and $400 under budget. This article overviews this project, which was awarded the 1990 PMI Project of the Year Award. Construction of the plant was managed by Philadelphia Electric Company (PE), working with Bechtel Power Corporation and General Electric. Harmonious labor-management relations were governed by a project labor agreement with the Philadelphia Building and Construction Trades Council that enabled work to be done safely, efficiently, and without strikes or delays. Part of this agreement was the Built-Rite Program, designed to save costs, improve communication and problem solving, and increase project safety and worker involvement. The project area coordinator (PAC) approach allowed the project to be divided into more manageable pieces. Other aspects of the project discussed include its aggressive scheduling, the establishment of pacing milestones for each management area, and successful teamwork. image: //www.pmi.org/-/media/pmi/headless-images/global/pmi-logos/pmi_logo_ogshare.png?h=120&iar=0&w=400&rev=88b8335698e04a74999fe8a6fe4037d2&dianoga=false](https://www.pmi.org/learning/library/built-rite-program-nuclear-plant-5075) — pmi.org · tier other
- [Source](https://www.nrc.gov/docs/ML2204/ML22046A064.pdf) — nrc.gov · tier regulatory
- [Exelon completes separation of Constellation](https://www.pottsmerc.com/2022/02/04/exelon-completes-separation-of-constellation/) — pottsmerc.com · tier other
- [Federal Register :: Constellation Energy Generation, LLC; Limerick Generating Station, Units 1 and 2](https://www.federalregister.gov/documents/2023/10/27/2023-23766/constellation-energy-generation-llc-limerick-generating-station-units-1-and-2) — federalregister.gov · tier regulatory
- [Limerick LRA Appendix E - Web Format](https://www.nrc.gov/reactors/operating/licensing/renewal/applications/limerick/lgs-er-web.pdf) — nrc.gov · tier regulatory
- [Constellation Commits to Billions of Dollars in Energy Investments at Inaugural Pennsylvania Energy and Innovation Summit](https://www.constellationenergy.com/news/2025/constellation-commits-to-billions-of-dollars-in-energy-investments-at-inaugural-pennsylvania-energy-and-innovation-summit.html) — constellationenergy.com · tier other
- [PJM Manual 39:](https://www.pjm.com/-/media/DotCom/documents/manuals/m39.pdf) — pjm.com · tier other

## Data quality

- The 2,317 MW figure is the owner- and county-stated combined capability; plant datasets may use different net-capacity or generator-rating conventions. The ownership changes were corporate restructurings rather than documented plant-level sales: PECO became part of Exelon in October 2000, and Exelon's generation business was separated into Constellation in February 2022. The identified 2026 capital work consists of digital control-system modernization, refueling-outage work, cooling-tower upgrades, and generator-component replacements. No retirement or repowering milestone is identified in the cited history through August 2, 2026.

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Canonical page: https://askthegrid.com/assets/facilities/limerick

Source: Ask the Grid — https://askthegrid.com/