RS-14-092, Responses to NRC Requests for Additional Information, Set 15, Dated March 11, 2014, Related to the Braidwood Station, Units 1 and 2, and Byron Station, Units 1 and 2, License Renewal Application

Responses to NRC Requests for Additional Information, Set 15, Dated March 11, 2014, Related to the Braidwood Station, Units 1 and 2, and Byron Station, Units 1 and 2, License Renewal Application

ML14098A230
Person / Time
Site:	Byron, Braidwood
Issue date:	04/08/2014
From:	Gallagher M Exelon Generation Co
To:	Document Control Desk, Division of License Renewal
References
RS-14-092
Download: ML14098A230 (12)

Text

10 CFR 50 10 CFR 51 10 CFR 54 RS-14-092 April 8, 2014 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555-0001 Braidwood Station, Units 1 and 2 Facility Operating License Nos. NPF-72 and NPF-77 NRC Docket Nos. STN 50-456 and STN 50-457 Byron Station, Units 1 and 2 Facility Operating License Nos. NPF-37 and NPF-66 NRC Docket Nos. STN 50-454 and STN 50-455

Subject:

Responses to NRC Requests for Additional Information, Set 15, dated March 11, 2014, related to the Braidwood Station, Units 1 and 2, and Byron Station, Units 1 and 2, License Renewal Application

References:

1. Letter from Michael P. Gallagher, Exelon Generation Company LLC (Exelon) to NRC Document Control Desk, dated May 29, 2013, "Application for Renewed Operating Licenses."

2. Letter from Lindsay R. Robinson, US NRC to Michael P. Gallagher, Exelon, dated March 11, 2014, "Requests for Additional Information for the Review of the Byron Station, Units 1 and 2, and Braidwood Station, Units 1 and 2, License Renewal Application, Set 15 (TAC NOS. MF1879, MF1880, MF1881, and MF1882)

In the Reference 1 letter, Exelon Generation Company, LLC (Exelon) submitted the License Renewal Application (LRA) for the Byron Station, Units 1 and 2, and Braidwood Station, Units 1 and 2 (BBS). In the Reference 2 letter, the NRC requested additional information to support the staffs' review of the LRA.

Enclosure A contains the responses to these requests for additional information.

Enclosure B contains updates to sections of the LRA affected by the responses.

There are no new or revised regulatory commitments contained in this letter.

April 8, 2014 U.S. Nuclear Regulatory Commission Page 2 If you have any questions, please contact Mr. AI Fulvio, Manager, Exelon License Renewal, at 61 0-765-5936.

I declare under penalty of perjury that the foregoing is true and correct.

Executed on i-- 8 .. Zl>l<f Respectfully,

---

Vice President - License Renewal Projects Exelon Generation Company, LLC

Enclosures:

A. Responses to Requests for Additional Information B. Updates to affected LRA sections cc: Regional Administrator- NRC Region Ill NRC Project Manager (Safety Review), NRR-DLR NRC Project Manager (Environmental Review), NRR-DLR NRC Senior Resident Inspector, Braidwood Station NRC Senior Resident Inspector, Byron Station NRC Project Manager, NRR-DORL-Braidwood and Byron Stations Illinois Emergency Management Agency- Division of Nuclear Safety

RS-14-092 Enclosure A Page 1 of 7 Enclosure A Byron and Braidwood Stations (BBS), Units 1 and 2 License Renewal Application Responses to Requests for Additional Information RAI 4.2.3-1 RAI B.1.4-1 RAI B.1.4-2

RS-14-092 Enclosure A Page 2 of 7 RAI 4.2.3-1 Applicability:

Braidwood Station (Braidwood), Unit 2

Background:

License renewal application (LRA) Table 4.2.3-4 provides the numbers used by the applicant to calculate the reference temperature pressurized thermal shock (RTPTS) values for the Braidwood, Unit 2, reactor pressure vessel materials in accordance with Equation 4 in 10 CFR 50.61. In that equation, one of the terms used to calculate RTPTS is the reference temperature for the material in the pre-service or unirradiated condition (RTNDT(U)).

Issue:

For the Nozzle Shell Forging-to-Intermediate Shell Forging Circ. Weld Seam (Heat # H4498) material, LRA Table 4.2.3-4 identifies RTNDT(U) to be -25°F. However, the Updated Final Safety Analysis Report (UFSAR) Table 5.3-10 identifies RTNDT(U) for the same material (identified as the Upper Circumferential Weld) to be -30°F.

Request:

For this material, explain the discrepancy between the RTNDT(U) value in the LRA and the RTNDT(U) value in the UFSAR. Identify the correct value and substantiate it with supporting documentation from the pre-service RTNDT(U) measurements. If necessary, revise LRA Table 4.2.3-4 accordingly.

Exelon Response:

The discrepancy between the RTNDT(U) value in the LRA and the RTNDT(U) value in the UFSAR is a historical issue. A review of the raw Charpy V-notch data provided in the certified material test report of the Braidwood Unit 2, Nozzle Shell Forging-to-Intermediate Shell Forging Circ. Weld Seam (Heat # H4498/WF-645) indicates that the difference was due to the interpretation of the raw data by different vendors performing the analyses. Both values of RTNDT(U) have been used in past pressurized thermal shock analyses and submitted in docketed correspondence. The current licensing basis utilizes a RTNDT(U) of -25 degrees Fahrenheit for the Braidwood Unit 2, Nozzle Shell Forging-to-Intermediate Shell Forging Circ. Weld Seam (Heat # H4498/WF-645).

For the subject heat number, a RTNDT(U) of -30 degrees Fahrenheit was used in an earlier analysis and submitted under Commonwealth Edison letter, Byron Station Units 1 and 2, Braidwood Station Units 1 and 2, Pressurized Thermal Shock, dated July 12, 1990 (Accession Number 9007170424) and Commonwealth Edison letter, GL 92-01, Reactor Vessel Structural Integrity Update, Braidwood Station Units 1 and 2, dated August 8, 1994 (Accession Number 9408170055).

For the subject heat number, a RTNDT(U) of -25 degrees Fahrenheit was used in later analyses, including the current licensing basis, and submitted under Commonwealth Edison letter, Byron Station Units 1 and 2, Braidwood Station Units 1 and 2, Response to Request for Additional

RS-14-092 Enclosure A Page 3 of 7 Information Regarding Reactor Pressure Vessel, dated September 3, 1998 (Accession Number 9809110026) and Exelon Generation letter, Braidwood Station Units 1 and 2, Pressure and Temperature Limits Reports (PTLRs), Braidwood Station, Units 1 and 2, dated February 28, 2014 (Accession Number ML14059A124).

Of the two (2) RTNDT(U) values, a value of -25 degrees Fahrenheit for the subject heat number is conservative and is used in the current licensing basis pressurized thermal shock analysis. No change to the LRA is necessary since the current licensing basis value was used to support the license renewal analysis. This issue had been previously identified and entered into the corrective action program to update the affected licensing and design documents as necessary.

RS-14-092 Enclosure A Page 4 of 7 RAI B.1.4-1 Applicability:

Byron and Braidwood

Background:

LRA Section B.1.4 describes the applicants process for reviewing future operating experience for the aging management programs (AMPs). The LRA states that operating experience from plant-specific and industry sources will be captured and systematically reviewed on an ongoing basis in accordance with the Quality Assurance program and the Operating Experience program. In addition, the LRA describes several enhancements to the operating experience review process that the applicant will make in order to ensure the effective use of internal and external operating experience related to aging management.

Issue:

LRA Section B.1.4 states that the Operating Experience program will be enhanced to require station personnel to periodically assess the performance of the AMPs, including insights obtained through operating experience. However, based on the description of this particular enhancement, it is unclear to the NRC staff under what circumstances the applicant will assess the performance of the AMPs. Specifically, it is unclear if the applicant will conduct these assessments regardless of whether the acceptance criteria of the AMPs have been met or not met.

LRA Section B.1.4 further states that the Operating Experience program will be enhanced to provide training to those personnel responsible for screening, evaluating, and communicating operating experience items related to aging management and age-related degradation.

However, the LRA does not demonstrate that this training will specifically include topics on age-related degradation and aging management.

Request:

1. Describe the circumstances under which the performance of the AMPs will be evaluated and describe how adverse performance results will be identified and processed. Provide justification if these evaluations will only be conducted when the AMP acceptance criteria are not met.

2. Demonstrate that the content of the training activities will include topics on age-related degradation and aging management. Provide justification if the content of the training will not specifically include aging topics.

3. Based on these responses, revise the summary descriptions in LRA Sections A.1.6 and B.1.4 accordingly.

Exelon Response:

1. As stated in LRA Section B.1.4 Enhancement 3, the Operating Experience program will be enhanced to require that station personnel periodically assess the performance of the

RS-14-092 Enclosure A Page 5 of 7 aging management programs, including insights obtained through operating experience.

Adverse trends are entered into the corrective action program for evaluation. This could lead to AMP revisions or the establishment of new AMPs, as appropriate. These evaluations described in the LRA will be performed regardless of whether or not AMP acceptance criteria are met.

AMPs will be continually informed through the review of internal and external operating experience (OPEX). For example, Station AMP owners will review completed work activities credited for implementation of license renewal commitments on an ongoing basis to determine if AMP acceptance criteria are exceeded, or aging related degradation in excess of expectations has occurred. Such conditions would be entered into the corrective action program for evaluation and disposition, including consideration of whether new AMPs or revisions to existing AMPs are required.

In addition, operating experience external to Byron and Braidwood will be regularly screened to identify OPEX that involves age-related degradation or aging management issues. As described in LRA Section B.1.4, Enhancement 1, NRC and industry guidance documents and standards applicable to aging management are considered part of this information.

When such issues are identified, guidance will require that the issues are entered into the corrective action program and evaluated for applicability to Byron and Braidwood. These evaluations would also consider whether new AMPs or revisions to existing AMPs are required.

Further, as part of self assessment activities, AMP reviews will be performed, such that all AMPs credited for aging management will be assessed periodically. Again, these reviews will not be limited to cases where AMP acceptance criteria are not met.

2. As stated in LRA Sections A.1.4 and B.1.4 Enhancement 5, training will be provided to those responsible for screening, evaluating and communicating operating experience items related to aging management and aging-related degradation. In response to the staff request for Exelon to demonstrate that such training will be conducted, the following information is provided.

Exelon has developed training to educate Engineering and appropriate Maintenance personnel responsible for screening, evaluating and communicating operating experience items related to aging management and aging-related degradation. This training covers a broad range of relevant topics, including:

Key license renewal process concepts, including scoping and screening, aging management and documentation Aging-related degradation mechanisms and indicators for various materials Common stressors in the plant and the relationship between stressors and potential or ongoing aging-related degradation of plant SSCs Identification of aging and aging-related degradation, including aging assessment process terms Discussion of Aging Management Programs credited for license renewal and where to locate them in the UFSAR and NRC SER The need for management of plant SSCs aging-related degradation

RS-14-092 Enclosure A Page 6 of 7 Roles and responsibilities in detecting and managing aging-related degradation of the plant SSC Ongoing review of operating experience as it relates to AMPs Identifying potential aging issues and properly screening and evaluating them The training attributes described above are contained in Exelons current training module associated with license renewal. The content may undergo changes and improvements as experience is gained and operating experience applied.

Personnel outside of Engineering and Maintenance will be trained, commensurate with their role in the process, on Potential Aging Issue recognition and follow-up actions. They will be trained on how to recognize a Potential Aging Issue and how to contact the Site Subject Matter Expert (SME). The SME will make the final determination if the issue needs to be entered into the Corrective Action Program.

The detail provided above demonstrates that the content of the training activities referred to in Enhancement 5 of LRA Sections A.1.6 and B.1.4 will include topics on age-related degradation and aging management.

3. In response to Requests 1 and 2 above, additional detailed information, beyond that contained in the LRA, has been provided with regard to:

a. Performance of AMP evaluations and identification and processing of adverse results, and

b. Demonstrating that the content of the training activities will include topics on age-related degradation and aging management.

Exelon believes that providing these implementing details on the Byron and Braidwood dockets in this RAI response should be adequate to allow the staff to evaluate the adequacy of these aspects of the ongoing review of operating experience, as it relates to aging management. In addition, it is noted that the Byron and Braidwood LRA content was developed addressing the key aspects of LR-ISG-2011-05, Ongoing Review of Operating Experience, including incorporating the guidance pertaining to expected content of the UFSAR supplement (LRA Section A.1.6). As documented in NRCs Summary of Telephone Conference Call Held on February 27, 2014, between the U.S. Nuclear Regulatory Commission and Exelon Generation Company, LLC concerning Draft Request for Additional Information pertaining to the Byron and Braidwood Station, License Renewal Application (TAC NOS MF 1879, MF 1880, MF1881, MF1882), dated March 11, 2014, it was agreed that revisions to LRA Sections A.1.6 and B.1.4 may not be required. Based upon the information provided above, revisions to LRA Sections A.1.6 and B.1.4 are not planned.

RS-14-092 Enclosure A Page 7 of 7 RAI B.1.4-2 Applicability:

Byron and Braidwood

Background:

LRA Section A.1.6 provides the UFSAR supplement description of the Operating Experience program and identifies enhancements that will be implemented to ensure that plant-specific and industry operating experience related to aging management will be used effectively.

Issue:

LRA Section B.1.4 states that the ongoing evaluation of operating experience related to aging management will consider: (a) systems, structures, and components, (b) materials, (c) environments, (d) aging effects, (e) aging mechanisms, (f) AMPs, and (g) activities, criteria, and evaluations integral to the elements of the AMPs. However, LRA Section A.1.6 does not reflect that the evaluation will consider this information.

Request:

Revise LRA Section A.1.6 to reflect the specific information that is considered in the ongoing evaluation of operating experience related to aging management, as stated in LRA Section B.1.4. Otherwise, provide a justification for not including this information in the UFSAR supplement.

Exelon Response:

As shown in Enclosure B, LRA Section A.1.6 is revised to reflect the specific information that is considered in the ongoing evaluation of operating experience related to aging management, as stated in LRA Section B.1.4.

RS-14-092 Enclosure B Page 1 of 3 Enclosure B Byron and Braidwood Stations, Units 1 and 2 License Renewal Application (LRA) updates Resulting from the response to the following RAI:

RAI B.1.4-2 Note: To facilitate understanding, portions of the original LRA have been repeated in this Enclosure, with revisions indicated. Existing LRA text is shown in normal font. Changes are highlighted with bolded italics for inserted text.

RS-14-092 Enclosure B Page 2 of 3 As a result of the response to RAI B.1.4-2 provided in Enclosure A of this letter, LRA Appendix A, Section A.1.6, is revised as shown below. Additions are indicated with bolded italics.

A.1.6 Operating Experience Operating experience from plant-specific and industry sources is captured and systematically reviewed on an ongoing basis in accordance with the Quality Assurance program, which meets the requirements of 10 CFR Appendix B, and the Operating Experience program, which meets the requirements of NUREG-0737, Clarification of TMI Action Plan Requirements, Item I.C.5, Procedures for Feedback of Operating Experience to Plant Staff. The Operating Experience program interfaces with and relies on active participation in the Institute of Nuclear Power Operations operating experience program, as endorsed by the NRC. The Operating Experience program will be enhanced to ensure, through the ongoing review of both internal and external operating experience, that the license renewal aging management programs are effective to manage the aging effects for which they are credited throughout the period of extended operation. The aging management programs are either enhanced or new programs developed when the review of operating experience indicates that the existing programs do not provide reasonable assurance that aging effects are being effectively managed.

Ongoing evaluation of operating experience related to aging management will begin no later than receipt of the renewed operating licenses, and will consider the following aspects, as appropriate:

• Systems, structures, or components that are similar or identical to those involved with the identified operating experience issue.

• Material of construction, operating environment, and aging effects associated with the identified aging issue so that lessons learned can be applied to susceptible SSCs within the scope of license renewal.

• Aging mechanisms associated with the operating experience to confirm that Byron and Braidwood Stations have appropriate AMPs in place to manage aging that could be caused by these mechanisms.

• AMPs associated with this operating experience so that if the AMPs have been demonstrated to be ineffective, similar AMPs in place at Byron and Braidwood Stations can be evaluated to determine if AMP changes are appropriate, or a new AMP is needed. Included in this review is consideration of activities, criteria, and evaluations integral to the elements of the plant AMPs.

The Operating Experience program will be enhanced to:

1. Require the review of internal and external operating experience for aging-related degradation or impacts to aging management activities, to determine if improvements to Byron and Braidwood Units 1 and 2 aging management activities are warranted. NRC and industry guidance documents and standards applicable to aging management are considered part of this information (e.g., License Renewal Interim Staff Guidance (LR-ISG) documents, NUREG-1801 (GALL) revisions,

RS-14-092 Enclosure B Page 3 of 3 etc.) Ensure there are written expectations for identifying and processing these documents as operating experience.

2. Establish criteria to define aging-related degradation. In general, the criteria will be used to identify aging that is in excess of what would be expected, relative to design, previous inspection experience and the inspection intervals.

3. Establish identification coding within the corrective action program for use in identification, trending and communications of aging-related degradation. Provide a definition for the coding. This coding will assist plant personnel in ensuring that, in addition to addressing the specific issue, the adequacy of existing aging management programs is assessed. Station personnel are required to periodically assess the performance of the aging management programs, including insights obtained through operating experience. Adverse trends are entered into the corrective action program for evaluation. This could lead to AMP revisions or the establishment of new AMPs, as appropriate.

4. Require communication of significant internal aging-related degradation, associated with SSCs in the scope of license renewal, to other Exelon plants and to the industry. Criteria will be established for determining when aging-related degradation is significant.

5. Provide training to those responsible for screening, evaluating and communicating operating experience items related to aging management and aging-related degradation. This training will be commensurate with their role in the process, will be provided periodically and include provisions to accommodate personnel turnover.

These enhancements will be implemented no later than the date that the renewed operating licenses are issued and conducted on an ongoing basis throughout the terms of the renewed licenses.