Modernizing for more megawatts: Columbia’s EPU journey

Columbia Generating Station is the third-largest power-generating resource in Washington state and the region's only operating nuclear plant.

It has long served the Bonneville Power Administration's (BPA's) public power customers as a 24/7, not-for-profit baseload complement to hydropower, providing operational flexibility during low-water months and supporting grid stability as renewables scale up and contribute their power on a variable basis. Under BPA's net billing framework, Columbia's output is marketed at cost, integrating clean, firm capacity into a hydro-dominant system that increasingly faces volatility and growing load.

Now, the plant is advancing a major extended power uprate (EPU) that will add approximately 162 MWe to the northwestern U.S. power grid by 2031. In preparation for this power increase, new and upgraded equipment will be installed between now and 2031, adding an additional 24 MWe through a series of efficiency improvements executed during scheduled refueling outages.

Columbia has previously implemented two smaller uprates that increased its output to 106.7 percent of its originally licensed thermal power-a stretch power uprate approved in 1999 and a measurement uncertainty recapture uprate approved in 2017-building foundational experience for the larger EPU now underway.

Against this backdrop of rising regional demand and the need for dependable, carbon-free supply, uprating existing nuclear units offers a near-term bridge, adding firm capacity at lower cost and reduced schedule risk compared to greenfield builds. The Nuclear Regulatory Commission has approved more than 170 uprates since the 1970s, with EPUs (denoting an increase of more than 7 percent of the plant's output) requiring significant component upgrades and rigorous licensing analyses to demonstrate continued safety margins.

Columbia is currently licensed to operate through 2043, with Energy Northwest planning to pursue subsequent license renewal to provide an additional 20 years of operation and a long runway for capturing the full value of uprate investments.

From feasibility review to full commitment

The EPU project marks a significant milestone in the ongoing partnership between Energy Northwest and BPA, showcasing a shared commitment to advancing reliable energy solutions.

Energy Northwest began EPU feasibility work in 2020 and formalized the study in July 2023. From 2023 to 2025, Energy Northwest and BPA conducted a detailed business-case evaluation that identified approximately 30 capital projects necessary for EPU implementation, nearly half of which overlapped with Columbia's planned life cycle management work. This alignment reduced incremental uprate cost from approximately $1.2 billion to $700 million (in 2025 dollars).

Modeling showed a high probability of positive net present value across multiple operating and tax credit scenarios, and BPA's 2024 Resource Program addendum determined that the EPU was included in all least-cost resource portfolios evaluated.

Energy Northwest's executive board approved the business case in April 2025, and BPA approved implementation in May 2025, advancing the uprate to execution planning.

"The pivot from evaluation to commitment followed a disciplined look at safety margins, outage integration, and life cycle timing," said Alex Javorik, Energy Northwest's chief projects officer, who has overseen the EPU effort since its earliest concept. "With BPA's support, we are able to integrate the uprate scopes into established outage sequences, which is essential for managing technical risk and ensuring predictable execution."

From a regulatory standpoint, Energy Northwest intends to submit the uprate license amendment request to the NRC in 2028, consistent with the agency's RS-001 review standard for EPUs and evolving industry/NRC graded-approach efficiencies that aim to streamline technical reviews while preserving rigor.

Outage-integrated execution

The Columbia EPU is notable for its staged implementation across three refueling outages-in 2027, 2029, and 2031-to complete roughly 30 individual modifications while maintaining operational excellence between outages. Tactically, the plan prioritizes turbine generator and heat exchanger upgrades, pump and motor upgrades, and electrical distribution improvements, sequenced to fit outage windows and align with asset life cycle replacements already in flight.

Columbia's target of increasing its output to 120 percent of its original licensed thermal power aligns with the standardized uprate process developed by General Electric and approved by the NRC in the late 1990s, a benchmark already achieved by 12 of the 31 operating boiling water reactors in the United States (see graph).

With refueling and maintenance outage 28 (R-28) approaching next spring, Columbia will be entering a period of increased field activity to position the station for long-term EPU execution. Recent progress includes completing 100 percent design for key valve upgrades, executing a contract for steam dryer materials, and establishing regular coordination with BPA on the 115-kV substation work. During R-28, the project team will focus on moisture separator reheater valve and nozzle upgrades, heater drain valve replacements, selected piping support improvements, in-vessel measurements, and turbine inspections-targeted work that supports both equipment readiness and reliable performance across future uprate outage windows.

Columbia's current nameplate capacity is 1,207 MWe, with an uprate target that increases net electric output by about 162 MWe (the equivalent of powering about 125,000 homes). An additional 24 MWe will be captured through energy-efficiency projects incorporated during the same outages, for a total increase of about 186 MWe by completion.

Executing the project

Planning and regulatory engagement

Energy Northwest's planning road map follows the NRC's EPU expectations, thermal-hydraulic analyses, accident/transient evaluations, and component qualification while leveraging an industry/NRC-graded approach that prioritizes staff resources and precedent-based reviews. This structured approach helps ensure the licensing scope remains focused on plant-specific needs. Like other EPUs, Columbia's uprate will also require additional fuel to support the higher thermal power level and increased electrical generation.

The EPU licensing strategy is sequenced to align with outage execution, supported by early preapplication engagement, bundled submittals where appropriate, and power ascension testing plans consistent with RS-001 and current NRC/Nuclear Energy Institute review timelines.

Workforce readiness

EPU execution is staffed with a blend of internal engineering and maintenance teams and specialized contractors for turbine, generator, and balance-of-plant equipment. Because Columbia's EPU upgrades coincide with its biennial refueling outages, the project creates incremental skilled-craft demand without extending outages beyond the duration already required for the replacement of aging equipment. Securing contracts early with original equipment manufacturers and key equipment suppliers ensures components and technical expertise are committed well ahead of outage windows, reducing schedule and delivery risks.

"Our staffing model deliberately assesses and identifies the skills and resources needed to maximize the outage windows required for EPU and long-range asset management modifications without adversely affecting ongoing plant operations," said Columbia site vice president Stephanie Banker. "Discipline, execution, and predictability are key to meeting our commitments in both outage performance and in delivering the EPU."

BPA's approval enables multiyear procurement of long-lead components, including turbine rotors/diaphragms, reheaters, large motors/pumps, and generator elements, with deliveries matched to outage windows. From Energy Northwest's perspective, this work represents one of the most comprehensive balance-of-plant modernization efforts ever undertaken at Columbia. The scope includes upgrades that will accommodate higher steam and water flows, improve overall thermal performance, and align several uprate-related replacements with existing life cycle management commitments. This integration is essential to controlling outage duration, protecting critical paths, and preparing Columbia's systems to operate reliably at uprated conditions.

To mitigate supply risk, Energy Northwest front-loads engineering, finalizes technical specifications early, and conducts progressive design reviews with original equipment manufacturers to confirm manufacturability and delivery sequencing. The team also works closely with suppliers to secure raw-material slots for large forgings and castings, establish alternate procurement pathways when appropriate, and align vendor quality control and on-site rigging plans well ahead of outage deployment. This proactive approach has been essential to maintaining schedule certainty across multiple uprate-related outage windows.

Coordinating this scope of work requires sustained alignment across Columbia's engineering, maintenance, supply chain, and project management teams. More than two dozen technical disciplines are involved in planning and sequencing modifications that must be executed over multiple outage windows, often in parallel with major life cycle management replacements. Teams have navigated challenges such as vendor manufacturing lead times, integrating uprate components into existing outage critical paths, and ensuring that quality and rigging plans are fully developed well ahead of field deployment. This cross-functional coordination has been essential to keeping the uprate on schedule and maintaining predictable execution across successive outages.

Balancing operational excellence and nuclear investments

A central concern in the industry is avoiding distraction from current operations while pursuing new nuclear or other major projects. Columbia's approach treats EPU as plant-centered reliability work, embedded in refueling outages and life cycle maintenance rather than an external overlay. Between outages, the station continues to operate as a 100 percent power baseload resource while retaining BPA-requested load-following flexibility.

In parallel, Energy Northwest is progressing the Cascade Advanced Energy Facility with X-energy and partners, an initial four-module, 320-MWe Xe-100 build near Columbia, for potential expansion to 12 modules (960 MWe). Development activities are deliberately staged, with construction expected by the end of the decade, operations targeted to begin in the 2030s, and timelines designed to not impinge on EPU execution but to complement it as part of long-term capacity planning.

"Upgrading Columbia strengthens the reliability of an existing resource to meet the region's growing demand, helps keep rates low, and complements the long-term work underway on advanced reactors," said Dawn Sileo, Energy Northwest's chief nuclear officer.

Lessons learned

Drawing from Columbia's early uprate planning and execution work, Javorik, who has provided strategic oversight of the EPU effort since its inception, together with teams across engineering, operations, maintenance, and supply chain, has emphasized several insights that may help utilities evaluating similar uprate strategies. The following lessons reflect themes shaped by the collective experience and may offer useful perspectives to organizations beginning their own uprate evaluations.

1. Decide with life cycle alignment in mind. The decision to commit to an EPU was strengthened by synchronizing uprate scopes with planned asset replacements, compressing risk and cost into existing maintenance windows.

2. Stage the work across outages and bundle the licensing. Sequencing work in multiple outages avoids overconcentration, while bundling related license amendment requests leverages analytical synergy and supports the NRC's graded review efficiency.

3. Secure long-lead components early. Turbine, generator, and heat exchanger supply chains are tight, so early technical freezes and dual-sourcing strategies can protect outage-critical paths.

4. Keep operating discipline front and center. Treat the EPU as reliability and modernization work integrated with refueling cycles. Maintain focus on run days, start-up discipline, and capacity factor performance between outages.

5. Coordinate with your energy-marketing partner. BPA's involvement, from analysis to approval, was pivotal to cost discipline and regional value realization.

6. Use industry precedents and guidance. The NRC's RS-001 and emerging NEI process-improvement frameworks can cut months off review time without sacrificing rigor, especially with the preparation of high-quality, precedent-based submittals.

As Columbia progresses through each outage window, the EPU is demonstrating how disciplined planning, early supply chain coordination, and alignment with life cycle maintenance can turn a complex uprate into a predictable, well-managed modernization effort. At the same time, the station continues to operate as a dependable baseload resource while Energy Northwest advances future nuclear development through the Cascade project. Together, these efforts show how a plant can strengthen today's performance while preparing for tomorrow's capacity needs. For other utilities weighing similar uprates, Columbia's experience offers a practical, replicable model-one grounded in rigor, long-range planning, and a clear view of how near-term modernization supports the industry's broader carbon-free future.

Angela Smith is the chief communication officer at Energy Northwest.