One of the biggest upgrades of its kind in an operational nuclear facility in the United States has been approved by the U.S. Nuclear Regulatory Commission for a “$167 million digital modernization” of the Constellation-owned Limerick Clean Energy Center in Pennsylvania.

With this approval, Constellation will replace certain areas of Limerick’s analog instrumentation and control systems with digital platforms for several significant safety protection functions. This is set to be done in several phases when refueling outages occur. The approval was given as an amendment to its license.

It represents the first major use of such an electronic safety system at an operational nuclear facility in the U.S., and it is funded through the U.S. Department of Energy’s Light Water Reactor Sustainability Program, whose aim is to extend the life and performance of the nation’s existing reactors.

First-of-its-kind safety upgrade

Constellation expects this upgrade will enhance diagnostic and monitoring capabilities of the equipment and bolster cybersecurity. The Limerick facility produces a combined 2,317 megawatts of power, supplying clean electricity to more than 1.7 million households in the Philadelphia area.

Part of broader $5.1B investment

This upgrade is a part of an overall investment program of $5.1 billion that Constellation is pursuing in Pennsylvania itself to protect about 5,100 megawatts of existing capacity and further add 1,200 megawatts. This project is being undertaken due to rising demands for reliability from the growing use of data centers and other power-intensive sectors.

The installation of the new digital systems will occur during the refueling outages, which will be when the facility is offline and maintenance is performed. It is estimated that the project will bring a few thousand highly skilled workers to the area during the refueling outages.

Operated along the Schuylkill River, approximately 35 miles northwest of Philadelphia, the Limerick facility is considered one of the country’s largest power producers. Government regulators have, however, begun citing upgrades at facilities like the Limerick as essential for ensuring the continued feasibility of the current nuclear-powered electric generation mix within the US.

The Limerick digital modernization project forms part of a broader wave of investments that aim to revive the U.S. nuclear energy sector. Utilities across the country upgrade existing reactors and build new ones while adopting advanced technologies to extend plant lifespans, improve reliability, and meet growing demand for carbon-free electricity, driven in part by the surge in energy needs from data centers and other power-intensive industries.

Limerick Clean Energy Center Digital Modernization Project Factsheet

Project Overview

Owner/Operator: Constellation

Total Investment: $167 million

Regulatory Status: NRC License Amendment Request approved (January 6, 2026)

Project Significance: First large-scale demonstration of digital safety system upgrade at an operating U.S. nuclear plant

Facility Information

Location: Montgomery County, Pennsylvania (approximately 35 miles northwest of Philadelphia)

Site: Along the Schuylkill River

Capacity: 2,317 megawatts from two nuclear units

Service Area: Powers more than 1.7 million homes

Energy Type: Carbon-free, around-the-clock baseload electricity

Project Scope and Objectives

The Digital Modernization Project represents a comprehensive upgrade of major control and protection systems, replacing select analog instrumentation and control equipment with state-of-the-art digital platforms.

Primary Objectives:

Enhanced reliability and operational performance

Improved diagnostic capability and equipment monitoring

Strengthened cyber resilience

Broader range of automation capabilities

Additional operational flexibility

Limerick Clean Energy Center Modernization: Strategic Context

Pennsylvania Investment Program:

This project is part of Constellation’s broader $5.1 billion investment across Pennsylvania to:

Preserve nearly 5,100 MWs of existing nuclear generation

Add 1,200 MWs of new capacity

Stabilize energy prices during a critical period

Support growing demand from data-driven industries

Regional Impact:

The modernization supports Pennsylvania’s clean energy goals while providing reliable baseload power for homes, businesses, and emerging data center infrastructure creating regional jobs.

Implementation Approach

Phased Installation Strategy:

Carefully managed implementation to ensure safety and operational continuity

Physical installation during scheduled refueling outages

Thousands of additional skilled craft workers during outage periods

Economic boost to local communities through increased lodging, dining, and service spending

Technology and Innovation

Digital Platform Features:

Advanced equipment monitoring systems

Enhanced automation capabilities

Improved diagnostic tools

Modern cyber security protections

Greater operational flexibility