Note to readers: The following analysis of the Peach Bottom Atomic Power Station extended power uprate amendment comes directly from the beta version of Everstar's Gordian Research platform and was edited only for web formatting and to remove internal Gordian links. It was generated in about two minutes using this prompt: "for the peach bottom epu, produce a detailed summary of this application and all RAIs, RAI responses, and supplements. produce a table of the RAIs including the branch asking them and create a graphical timeline of the correspondence." For more insights, see related posts on uprates or contact hello@everstar.ai to get on the waiting list for an account.

Peach Bottom Extended Power Uprate: Comprehensive Analysis of Application, RAIs, and Regulatory Process

Executive Summary

The Peach Bottom Atomic Power Station (PBAPS) Units 2 and 3 Extended Power Uprate (EPU) application was submitted by Exelon Generation Company, LLC on September 28, 2012. This amendment requested authorization to increase the maximum power level from 3514 megawatts thermal (MWt) to 3951 MWt, representing a significant 12.4% increase above the then-current licensed thermal power level. The application underwent extensive regulatory review, with multiple branches of the Nuclear Regulatory Commission (NRC) issuing Requests for Additional Information (RAIs) that were addressed through numerous supplements. After nearly two years of technical evaluation, the NRC approved the EPU on August 25, 2014. This comprehensive analysis examines the application process, technical areas of focus, and the extensive regulatory correspondence that occurred throughout the review period. [0] [1] [2]

Technical Analysis

EPU Application Overview

The Peach Bottom EPU application proposed substantial modifications to major plant equipment, including the replacement of steam turbines and installation of a Replacement Steam Dryer (RSD). The Power Ascension Program (PAP) was structured into two distinct test levels to ensure proper monitoring and evaluation of plant performance during the power increase:

Test Level A: Baseline data gathering from low power (<25%) to 100% (3514 MWt) of the Current Licensed Power Level (CLTP)

Test Level B: Testing from approximately 100% to 112.4% of CLTP (3514 MWt to 3951 MWt)

The EPU implementation would increase the electrical output of each unit by approximately 140 MWe, bringing significant additional generating capacity to the grid. The application included extensive technical analyses to demonstrate that all safety systems would continue to perform their intended functions under the increased power conditions. [3] [4] [5]

Key Technical Areas Addressed

The EPU application and subsequent RAI responses addressed numerous technical areas critical to nuclear safety and plant operation. The Replacement Steam Dryer (RSD) received particular attention, with extensive analysis of flow-induced vibration concerns, strain gauge data, and predicted EPU signatures. This focus was necessary because steam dryers in boiling water reactors can be susceptible to flow-induced vibration damage at higher steam flows associated with power uprates.

Other significant technical areas included:

Electrical systems analysis, particularly regarding battery capacity during Station Blackout (SBO) events

Human performance considerations, including changes to operator actions, training requirements, and procedure modifications

Safety systems performance under EPU conditions

Containment systems analysis, including questions about cooling water systems and potential water hammer phenomena

Fire protection program impacts and operator manual actions

Radiation protection measures, including changes to radiation levels and shielding requirements

These technical evaluations were necessary to demonstrate that the plant would maintain adequate safety margins under the increased power conditions. [1] [6] [7] [1]

RAI Process and Responses

Following the initial application, the NRC conducted a thorough review and issued multiple rounds of RAIs from various technical branches. Exelon responded with at least 27 supplements to the original application between 2013 and 2014. The most extensive technical exchanges occurred regarding the steam dryer design and analysis, with the Mechanical and Civil Engineering Branch - Steam Dryer (EMCB-SD) issuing at least 41 RAIs that required detailed responses.

The RAI process revealed the depth of the NRC's technical review, with questions focusing on specific engineering analyses, assumptions, methodologies, and safety implications. For example, SCVB RAI-21 requested detailed information about potential water hammer in cooling water lines under EPU conditions and how it would be prevented. Similarly, EMCB-SD RAIs focused extensively on the strain gauge data analysis and predicted EPU signatures for the main steam lines. [4] [8] [9]

Regulatory Considerations

NRC Review Process

The NRC's review of the Peach Bottom EPU application involved multiple technical branches, each focusing on specific aspects of plant safety and operation. Based on the available information, the following branches were involved in the review process:

* Reactor Systems Branch (SRXB)

* Mechanical and Civil Engineering Branch (EMCB)

* Mechanical and Civil Engineering Branch - Steam Dryer (EMCB-SD)

* Electrical Engineering Branch (EEEB)

* Health Physics and Human Performance Branch (AHPB)

* Fire Protection Branch (AFPB)

* Containment and Ventilation Branch (SCVB)

* Steam Generator Tube Integrity and Chemical Engineering Branch (ESGB)

* Accident Dose Branch (AADB)

This multi-disciplinary approach ensured comprehensive evaluation of all safety aspects related to the proposed power increase. The review process followed established regulatory frameworks for evaluating power uprate applications, with particular attention to areas where the power increase could affect safety margins or equipment reliability. [10] [11] [8]

Table of RAIs by NRC Branch

The following table summarizes the RAIs by NRC branch based on the available information:

This table demonstrates the breadth of technical areas examined during the review process and the significant number of questions that required resolution before approval could be granted. [10] [9] [11] [4]

Chronological Timeline of EPU Correspondence

The EPU application process spanned nearly two years, with extensive correspondence between Exelon and the NRC:

September 28, 2012: Initial EPU License Amendment Request submitted by Exelon

March 28, 2013: NRC issues first round of RAIs (Reactor Systems Branch)

April 26, 2013: NRC issues RAIs from multiple branches

May 7, 2013: Exelon submits Supplement 2 (Response to SRXB RAIs)

May 24, 2013: Exelon submits Supplement 3 (Response to AFPB, ESGB, AHPB, and EEEB RAIs)

June 4, 2013: Exelon submits Supplement 4 (Response to EEEB RAIs 1-3)

June 27, 2013: Exelon submits Supplement 5

July 1, 2013: NRC issues RAIs from Containment and Ventilation Branch

July 31, 2013: Exelon submits responses to most SCVB RAIs

August 5, 2013: Exelon submits Supplement 8 (Follow-up responses to AFPB and ESGB RAIs)

August 15, 2013: NRC issues additional RAIs

August 22, 2013: Exelon submits Supplement 9 (Responses to SRXB and AADB RAIs)

August 30, 2013: Exelon submits Supplement 10 (Responses to SCVB RAI-21 and RAI-25)

September 13, 2013: Exelon submits Supplement 11

September 18, 2013: NRC issues additional RAIs

October 1, 2013: NRC issues RAIs related to Steam Dryer

October 11, 2013: Exelon submits Supplement 12 (Responses to EMCB RAIs 1-24)

October 31, 2013: Exelon submits Supplement 14 (Responses to EMCB-SD RAIs 1-4, 6-7, 11-12, 14)

November 1, 2013: NRC issues additional RAIs related to Human Performance

December 6, 2013: Exelon submits Supplement 15 (Response to EMCB-SD RAI-10)

December 20, 2013: Exelon submits Supplement 16 (Responses to AHPB RAIs 8-10, corrections)

January 15, 2014: NRC issues additional RAIs

February 2014: Exelon submits Supplement 19 (Responses to EMCB-SD RAIs)

February 27, 2014: NRC issues RAI related to EMCB-18

March 2014: Exelon submits Supplement 21 (Responses to EMCB-SD RAIs)

March 2014: Exelon submits Supplement 23 (Response to EMCB RAI-37)

April 18, 2014: Exelon submits Supplement 25 (Responses to EMCB-SD RAIs)

June 5, 2014: Exelon submits Supplement 27 (Supplemental information)

August 25, 2014: NRC approves the EPU for both units

This timeline illustrates the iterative nature of the regulatory review process and the extensive technical exchanges required to resolve all safety questions. [17] [18] [4]

Graphical Timeline of Correspondence

Legend:

LAR: License Amendment Request

RAIs: Requests for Additional Information

S#: Supplement Number

Branch acronyms indicate which NRC branch issued RAIs

This graphical representation shows the concentration of regulatory activity throughout 2013 and early 2014, with final approval coming in August 2014. [12]

Uncertainties and Limitations

While the available information provides a comprehensive overview of the Peach Bottom EPU application process, several limitations should be noted:

The complete content of all RAIs and responses is not available in the provided sources, making it difficult to assess the full technical depth of certain issues.

The exact number of RAIs from each branch is uncertain, as the available information suggests there were more than the explicitly numbered questions (e.g., "1-30+" for SRXB).

The implementation timeline for the approved EPU is partially documented, with information indicating that Unit 2's uprate was planned for implementation during a refueling outage in late 2014 and Unit 3's during a refueling outage in late 2015, but confirmation of the actual implementation dates is not available in the provided sources.

The specific technical challenges that received the most attention during the review process can be inferred from the number and focus of RAIs, but the relative significance of each issue from a safety perspective is not explicitly stated.

These limitations reflect the partial nature of the available documentation rather than deficiencies in the regulatory process itself. [4]

Recommendations and Next Steps

Based on the comprehensive analysis of the Peach Bottom EPU application process, several recommendations and insights can be offered:

Documentation Organization: Future EPU applications would benefit from a more structured approach to organizing RAI responses and supplements, potentially using a standardized numbering system that clearly identifies the technical branch, topic area, and sequence number.

Focus Areas for Future EPUs: The extensive focus on steam dryer analysis in the Peach Bottom EPU suggests that this remains a critical area for BWR power uprates. Future applicants should anticipate significant regulatory scrutiny in this area and prepare accordingly.

Implementation Lessons: The nearly two-year review process for the Peach Bottom EPU highlights the importance of thorough pre-application preparation and engagement with the NRC. Future applicants should consider early interactions with the NRC to identify and address potential issues before formal application submission.

Post-Implementation Monitoring: While not explicitly covered in the available documentation, the experience with other EPUs suggests that robust post-implementation monitoring programs are essential, particularly for components like the replacement steam dryer that received significant attention during the review process.

Knowledge Transfer: The Peach Bottom EPU application process generated valuable technical information and regulatory precedents that should be captured and shared within the industry to improve future power uprate applications.

These recommendations reflect the lessons learned from the Peach Bottom EPU application process and could help streamline future power uprate applications while maintaining the high standards of safety and technical rigor demonstrated in this case. [18] [4]

[1] Peach Bottom, Units 2 and 3, Extended Power Uprate License Amendment Request - Supplement 8 Response to Request for Additional Information - Extended Power Uprate.: ML13217A431

[2] Peach Bottom, Units 2 & 3, Extended Power Uprate License Amendment Request- Supplement 16 Corrections, Clarifications and Additional Information - Extended Power Uprate.: ML13358A083

[3] Peach Bottom, Units 2 and 3, Supplement 25 Response for Additional Information Extended Power Uprate License Amendment Request.: ML14111A316

[4] Peach Bottom, Units 2 and 3 - Extended Power Uprate License Amendment Request - Supplement 13 Response to Request for Additional Information.: ML13289A300

[5] Peach Bottom, Units 2 and 3, Extended Power Uprate License Amendment Request - Supplement 27 Supplemental Information.: ML14160A699

[6] Peach Bottom, Units 2 and 3, Extended Power Uprate License Amendment Request - Supplement 19 Response to Request for Additional Information.: ML14035A158

[7] Peach Bottom, Units 2 and 3 - Extended Power Uprate License Amendment Request - Supplement 21 Response to Request for Additional Information.: ML14070A142

[8] Peach Bottom, Units 2 & 3 - Extended Power Uprate License Amendment Request - Supplement 14, Response to Request for Additional Information.: ML13308A331

[9] Peach Bottom Atomic Power Station, Units 2 and 3, Supplement 15 Response to Request for Additional Information Extended Power Uprate License Amendment Request.: ML13345A687

[10] Peach Bottom, Units 2 & 3, License Amendment Request - Extended Power Uprate, Attachment 15, WCAP-17654-NP, Rev. 2 - Enclosure B.4U2, Replacement Steam Dryer Power Ascension Program Description for Extended Power Update.: ML12286A057

[11] Peach Bottom, Units 2 & 3, License Amendment Request - Extended Power Uprate, WCAP-17655-NP, Revision 2, Peach Bottom Unit 3 Replacement Steam Dryer Power Ascension Program Description for Extended Power Uprate.: ML12286A058

[12] Peach Bottom, Units 2 and 3, Extended Power Uprate License Amendment Request - Supplement 10 Response to Request for Additional Information.: ML13241A418

[17] Approved Applications For Power Uprates | NRC.gov: https://www.nrc.gov/reactors/operating/licensing/power-uprates/status-power-apps/approved-applications.html

[18] Uprates approved for Peach Bottom reactors - World Nuclear News: https://www.world-nuclear-news.org/Articles/Uprates-approved-for-Peach-Bottom-reactors

Photo courtesy of NRC.