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Operating Reactor Licensing
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Power Uprates
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Power Uprates

NRC regulates the maximum power level at which a commercial nuclear power plant may operate. This power level is used, with other data, in many of the licensing analyses that demonstrate the safety of the plant. This power level is included in the license and technical specifications for the plant. NRC controls any change to a license or technical specification, and the licensee may only change these documents after NRC approves the licensee's application for change.

Some links on this page are to documents in our Agencywide Documents Access and Management System (ADAMS), and others are to documents in Adobe Portable Document Format (PDF). ADAMS documents are provided in either PDF or Tagged Image File Format (TIFF). To obtain free viewers for displaying these formats, see our Plugins, Viewers, and Other Tools page. If you have questions about search techniques or problems with viewing or printing documents from ADAMS, please contact the Public Document Room staff.

Definition of Power Uprate

The process of increasing the maximum power level at which a commercial nuclear power plant may operate is called a power uprate.

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Utilities have been using power uprates since the 1970s as a way to increase the power output of their nuclear plants. To increase the power output of a reactor, typically more highly enriched uranium fuel and/or more fresh fuel is used. This enables the reactor to produce more thermal energy and therefore more steam, driving a turbine generator to produce electricity. In order to accomplish this, components such as pipes, valves, pumps, heat exchangers, electrical transformers and generators, must be able to accommodate the conditions that would exist at the higher power level. For example, a higher power level usually involves higher steam and water flow through the systems used in converting the thermal power into electric power. These systems must be capable of accommodating the higher flows.

In some instances, licensees will modify and/or replace components in order to accommodate a higher power level. Depending on the desired increase in power level and original equipment design, this can involve major and costly modifications to the plant such as the replacement of main turbines. All of these factors must be analyzed by the licensee as part of a request for a power uprate, which is accomplished by amending the plant's operating license. The analyses must demonstrate that the proposed new configuration remains safe and that measures continue to be in place to protect the health and safety of the public. These analyses, which span many technical disciplines and may be complex, are reviewed by the NRC's technical and legal staffs and NRC management before a request for a power uprate is approved.

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Types of Power Uprates

The three categories of power uprates are—

  • measurement uncertainty recapture power uprates
  • stretch power uprates
  • extended power uprates

Measurement uncertainty recapture power uprates are less than 2 percent and are achieved by implementing enhanced techniques for calculating reactor power. This involves the use of state-of-the-art feedwater flow measurement devices to more precisely measure feedwater flow, which is used to calculate reactor power. More precise measurements reduce the degree of uncertainty in the power level, which is used by analysts to predict the ability of the reactor to be safely shutdown under postulated accident conditions.

Stretch power uprates are typically up to 7 percent and are within the design capacity of the plant. The actual value for percentage increase in power a plant can achieve and stay within the stretch power uprate category is plant-specific and depends on the operating margins included in the design of a particular plant. Stretch power uprates usually involve changes to instrumentation setpoints but do not involve major plant modifications.

Extended power uprates are greater than stretch power uprates and have been approved for increases as high as 20 percent. These uprates require significant modifications to major balance-of-plant equipment such as the high pressure turbines, condensate pumps and motors, main generators, and/or transformers.

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Related Regulations and Guidance

Regulations. The process for requesting and approving a change to a plant's power level is governed by 10 CFR 50.90, 50.91, and 50.92. See also Operating Reactors Regulations, Guidance, and Communications.

Guidance. The following table contains guidance related to the power uprate application and review processes. The table will be updated as experience is gained. Please check back frequently to get the latest available information.

  Measurement Uncertainty Recapture Stretch Extended
Guidance RIS 2002-03
RIS 2007-24
Since many of the available stretch power uprates have already been approved by the NRC, and since only a limited number of stretch power uprate applications are expected in the future, there is no specific guidance for stretch power uprates. The NRC, therefore, uses previously approved stretch power uprates, along with RS-001, for guidance RS-001
Recent Safety Evaluations Boiling Water Reactors Pressurized Water Reactors Boiling Water Reactors
Pressurized Water Reactors
Boiling Water Reactors Pressurized Water Reactors
Past Requests for Additional Information Boiling Water Reactors Pressurized Water Reactors Boiling Water Reactors
Pressurized Water Reactors
Boiling Water Reactors Pressurized Water Reactors

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Review Standard for Extended Power Uprates

The staff issued Review Standard (RS)-001, Revision 0, "Review Standard for Extended Power Uprates," in December 2003. The following related links are provided:

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Regulatory Process for Submitting/Reviewing Power Uprate Requests

The process for amending commercial nuclear power plant licenses and technical specifications related to power uprates is the same as the process used for other amendments; therefore, power uprate requests are submitted to NRC as license amendment requests. This process is governed by 10 CFR 50.90, 50.91 and 50.92.

After a licensee submits an application to change the power level at which it operates its plant, the NRC notifies the public, by issuing a public notice in the Federal Register, that the NRC is considering the application. The public has 30 days to comment on the licensee's request and 60 days to request a hearing. The NRC thoroughly reviews the application, any public comments, and any requests for hearings received from the public. After completing its review and considering and addressing any public comments and requests for hearings related to the application, the NRC issues its findings in a safety evaluation and notifies the public in another Federal Register notice of the NRC decision related to the application. On the basis of its findings, the NRC may approve or deny the request. Press releases are issued if a power uprate is approved.

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Status of Power Uprate Applications

Licensees have been applying for power uprates since the 1970s. The NRC has reviewed and approved many applications for power uprates. For more specific statistics about power uprate applications, see the following tables:

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Public Involvement

The NRC considers public involvement in our activities to be a cornerstone of strong, fair regulation of the nuclear industry. The public is invited to comment on proposed regulations and various other documents in addition to observing or participating in certain workshops and meetings. See our Public Involvement pages for more information.

Opportunities for public involvement in the power uprate arena exist in many forms. Licensees usually request pre-application meetings with the NRC staff to discuss their plans for power uprate applications. The staff issues meeting notices for these meetings to provide the public with an opportunity to attend. Portions of meetings during which proprietary information is presented will be closed to the public. Once an application is received, the NRC issues notices in the Federal Register to notify the public that the NRC is considering the application. This notice also provides 30 days for interested members of the public to submit comments related to the application and 60 days for interested members of the public to request hearings on the application. For some power uprate applications, the NRC staff will conduct briefings to the Advisory Committee on Reactor Safeguards (ACRS) on the results of the staff's review of the applications. These briefings are also open to the public and meeting notices for these briefings are issued to provide the public with an opportunity to attend. ACRS meeting schedules are also included on the ACRS Web site. Portions of these meetings during which proprietary information is presented will be closed to the public. For some power uprates, the NRC staff prepares environmental assessements that consider environmental issues related to the power uprates. For each extended power uprate, the NRC staff issues a draft environmental assessment and provides 30 days for the public to submit comments on the draft environmental assessment. The NRC staff considers and addresses all comments received on the draft environmental assessment before finalizing it.

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Upcoming Meetings

For information about upcoming workshops or meetings related to power uprates, see our Public Meeting Schedule page.

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Past Meetings

Date Description

ACRS Full Committee Meeting - Millstone 3


ACRS Subcommittee Meeting - Millstone 3


ACRS Full Committee Meeting - Hope Creek


ACRS Subcommittee Meeting - Hope Creek


ACRS Subcommittee Meeting - Hope Creek


ACRS Subcommittee Meeting - Susquehanna


ACRS Full Committee Meeting - Susquehanna


ACRS Subcommittee Meeting - Susquehanna


ACRS Subcommittee Meeting - Susquehanna


ACRS Full Committee Meeting - Browns Ferry 1


ACRS Subcommittee Meeting - Browns Ferry 1


ACRS Subcommittee Meeting - Browns Ferry 1


ACRS Full Committee Meeting - Beaver Valley


ACRS Subcommittee Meeting - Beaver Valley

04/25/06 ACRS Subcommittee Meeting - Beaver Valley
05/04/06 ACRS Full Committee Meeting - Ginna

ACRS Subcommittee Meeting - Ginna


ACRS Subcommittee Meeting - Ginna

03/15/06 ACRS Subcommittee Meeting - Ginna

12/07/05 ACRS Full Committee Meeting - Vermont Yankee
11/30/05 ACRS Subcommittee Meeting - Vermont Yankee
11/29/05 ACRS Subcommittee Meeting - Vermont Yankee
11/16/05 ACRS Subcommittee Meeting - Vermont Yankee
11/15/05 ACS Subcommittee Meeting - Vermont Yankee
04/20/05 Commission Meeting - Brief on NRR Programs, Performance, and Plans
02/10/05 ACRS Full Committee Meeting - Power Uprate for Waterford
12/09/04 Commission Meeting - Briefing on Reactor Safety and Licensing Activities
05/07/04 ACRS Full Committee Meeting - Potential Adverse Effects from Power Uprates
04/14/04 ACRS Plant License Renewal Subcommittee Meeting - Dresden and Quad Cities
10/15/03 Commission Meeting - Briefing on License Renewal Program, Power Uprate Activities, and High Priority Activities
09/11/03 ACRS Full Committee Meeting - Review Standard for Extended Power Uprates (RS-001)
08/19/03 ACRS Subcommittee Meeting - Review Standard for Extended Power Uprates (RS-001)

06/11/03 Meeting with Vermont State Nuclear Advisory Panel Regarding NRC Reviews of Extended Power Uprates
12/06/02 ACRS Meeting - Status of the Development of the Review Standard for Extended Power Uprates
07/11/02 ACRS Meeting on Development of Review Standard for Reviewing Core Power Uprate Applications

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Related Information

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  • Contact the Branch Chief, Generic Communication & Power Uprate Branch (PGCB), Division of Policy and Rulemaking, Office of Nuclear Reactor Regulation
  • It is preferred that licensees contact their assigned NRC plant project manager, who will then forward the question to PGCB

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Tuesday, September 09, 2008