NOC-AE-16003394, Additional Information for the Review of the South Texas Project, Units 1 and 2, License Renewal Application - Aluminum Bronze AMP (TAC Nos. ME4936 and ME4937)

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Additional Information for the Review of the South Texas Project, Units 1 and 2, License Renewal Application - Aluminum Bronze AMP (TAC Nos. ME4936 and ME4937)
ML16221A391
Person / Time
Site: South Texas  STP Nuclear Operating Company icon.png
Issue date: 07/28/2016
From: Connolly J
South Texas
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
NOC-AE-16003394, TAC ME4936, TAC ME4937
Download: ML16221A391 (53)
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Text

South Texas Project Electric Generating Station P.O. Box 2851 Wadsworth, Texas 77483 July 28, 2016 NOC-AE-16003394 10 CFR 54 File No. G25 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555-0001 South Texas Project Units 1 and 2 Docket Nos. STN 50-498, STN 50-499 Additional Information for the Review of the South Texas Project, Units 1 and 2, License Renewal Applicatlbn - Aluminum Bronze AMP (TAC Nos. ME4936 and ME4937)

References:

1. Letter; G. T. Powell to the NRC Document Control Desk; "License Renewal Application",

NOC-AE-10002607; dated October 25, 2010. (ML103010257)

2. Public Meeting "Discussion between South Texas Project, Units 1 and 2, and NRC staff regarding the revised Aluminum Bronze Selective Leaching Aging Management Program for All Potentially Susceptible Welds throughout the Facility", dated June 21, 2016. (ML16180A014)
3. Summary of telecon held on July 5, 2016 between the U.S. Nuclear Regulatory Commission and STP Nuclear Operating Company, concerning additional information pertaining to the South Texas Project, Units 1 and 2, License Renewal Application (TAC.

NOS. ME4936, ME4937)

By Reference 1, STP Nuclear Operating Company (STPNOC) submitted a License Renewal Application (LRA). A public meeting was held with the NRC on June 21, 2016 (Reference 2) followed by a telephone conference on July 5, 2016 (Reference 3) to discuss STPNOC's Aging Management Program (AMP) for selective leaching of Aluminum Bronze. STPNOC is providing supplemental information and an update to the License Renewal Application (LRA) Appendices A and B, in Enclosures 1 and 2 respectively.

Regulatory commitment items 39 and 44 in LRA Table A4-1 have been revised as provided in Enclosure .3. There are no other commitments in this letter.

  • provides a replacement copy of Appendix A and B with no line-in/line-out indicated.

STl:34345483

NOC-AE-16003394 Page 2 of 3 If there are any questions regarding this submittal, please contact Arden Aldridge, STP License Renewal Project Lead, at (361) 972-8243 or Rafael Gonzales, STP License Renewal Project regulatory point-of-contact, at (361) 972-4779.

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

Executed on James Connolly Site Vice President rjg

Enclosures:

1. STPNOC Supplemental Information
2. STPNOC LRA Appendix A and B Lined in/out Sections
3. STPNOC Regulatory Commitments Replacement of Commitments 39 and 44 line in/out
4. STPNOC LRA Replacement Copy

NOC-AE-16003394 Page 3 of 3 cc:

(paper copy) (electronic copy)

Regional Administrator, Region IV Morgan. Lewis & Beckius LLP U.S. Nuclear Regulatory Commission Steve Frantz 1600 East Lamar Boulevard Arlington, TX 76011-4511 U.S. Nuclear Regulatory Commission Lisa M. Regner Lisa M. Regner Lois James Senior Project Manager U.S. Nuclear Regulatory Commission NRG South Texas LP One White Flint North (MS 8 G9A) Chris O'Hara 11555 Rockville Pike Jim von Suskil Rockville, MD 20852 Skip Zahn NRC Resident Inspector CPS Energy U.S. Nuclear Regulatory Commission Kevin Pollo P. 0. Box 289, Mail Code: MN116 Cris Eugster Wadsworth, TX 77 483 L. D. Blaylock Lois James Crain Caton & James. P.C.

License Renewal Project Manager (Safety) Peter Nemeth One White Flint North (MS 011-F1)

U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 City of Austin Elaina Ball John Wester Tam Tran License Renewal Project Manager (Environmental) *Texas Dept. of State Health Services One White Flint North (MS 011 F01) Helen Watkins U.S. Nuclear Regulatory Commission Robert Free Washington, DC 20555-0001

NOC-AE-16003394 Enclosure 1 STPNOC Supplemental Information

(

NOC-AE-16003394 Enclosure 1 Page 1 of 12 The following supplemental information addresses clarifications between South Texas Project, Units 1 and 2, and the NRC staff regarding the revised Aluminum Bronze Selective Leaching Aging Management Program (AMP) for "Susceptible Welds" throughout the facility presented at the Public Meeting (Reference 2) held on June 21, 2016. Specifically, A1.37 and B2.1.37, Selective Leaching of Aluminum Bronze, is the primary scope of this submittal.

NRC Issue:

1. Scope of Program The AMP states that extruded tees with weld repairs will be replaced if it is determined that "the repair size is such that failure of the repair would affect structural integrity of the component." However, during the audit in_ March 2016, the applicant stated that weld repair size was not known for all of the affected tees.

The NRC staff stated it needs to understand how the structural determination will be made in the absence of detailed information about weld repair size was not known for all of the affected tees.

The applicant stated that it had found old tests and results that can be used to do structural analyses. If an analysis cannot be performed, the extruded tees would be replaced. The applicant stated that it will provide a description of the types of information it used and how the size was extrapolated from this information when it forwards the revised AMP.

STP Clarification:

The weld repair sizes are characterized utilizing the following techniques.

1. The vendor Record of Nonconformance is evaluated.
2. Where insufficient information is available then past radiography film is utilized to determine the limiting size of the weld repair by measuring the size of the area of interest on the film.
3. Where past radiography film is not available radiography will be performed to characterize the weld repair.

Extrapolation during sizing of the weld repair is not performed. Below is an example of how characterization is applied.

The weld repair radiographs for Unit 2 underground Tees T7017 and T7008. The area of weld repair isn't marked or directly obtainable from the film, but the area of interest is clearly marked. Both repair welds used two films, marked Oto 1 and 1 to 2. For T7017, the

_;distance between O to 1 is 3 inches and the distance between 1 to 2 is 2 5/8 inches. So the total circumferential distance of the weld repair is less than 5 5/8 inches. Likewise, for T7008, the distance between 0 to 1 is 2 inches and the distance between 1 to 2 is 1 3/4 inches. So the total circumferential distance of the weld repair had to be less than 3 3/4 inches.

Based on the above characterizing techniques, STP can characterize weld repairs on extruded tees.

NOC-AE-16003394 Enclosure 1 Page 2of12 NRC Issue

2. Preventive Actions NUREG-1800 states that activities for prevention ahd mitigation programs should be described. These actions should mitigate or prevent aging degradation. In this light, the NRC staff stated that the AMP should document which portions of the buried essential cooling water system are coated and cite the coating as a pr~ventive action.

The applicant stated that the external surfaces of all buried piping are coated with coal tar, which makes the exterior surface not susceptible to selective leaching. Further, the applicant stated that above ground piping is not coated. The applicant stated that it will update the AMP accordingly.

STP Clarification:

LRA Appendix 82.1.37, Preventive Actions (Element 2) is updated to document that the buried essential cooling water system is coated. The repeated statements on aluminum bronze castings and extruded piping tees are deleted.

Enclosure 2 provides the line-in/line-out revision to LRA Appendix 82.1.37.

Enclosure 3 provides the line-in/line-out revision to LRA Table A4-1.

NRC Issue

3. Parameters Monitored or Inspected The NRC staff expressed two concerns.

What is being monitored or inspected - The AMP should consistently cite the following the appropriate parameters to be monitored or inspected:

Loss of material, which is sometimes referred to as selective leaching in the applicant's AMP, is an aging effect that is a result of dealloying. It will be monitored via system walkdowns and destructive examiriations.

  • Cracking is an aging effect that is associated with dealloying in certain weld configurations. It will be monitored via volumetric examination.
  • Phase distribution is a key factor in the basis for the AMP and is an indirect measure of the potential for continuous dealloying. It will be monitored via destructive examination.

The applicant agreed that it will address these considerations in its update to the AMP.

What operating experience demonstrates - The AMP states that operating experience has shown that certain welds are "not susceptible to cracking caused by selective leaching."

The NRC staff stated that operating experience is not that definitive. Rather, the operating experience only demonstrates that there are no through-wall indications.

The applicant stated that they understood the two concerns and will address them in the revised AMP and background basis

NOC-AE-16003394 Enclosure 1 Page 3 of 12 STP Clarification:

LRA Appendix A 1.37 and B2.1.37, Parameters Monitored or Inspected (Element 3) is updated to use loss of material, cracking and phase distribution, and removed the operating experience sentence.

Enclosure 2 provides the line-in/line-out revision to LRA Appendix A1 .37 and B2:1.37.

Enclosure 3 provides the line-in/line-out revision to LRA Table A4-1.

NRC Issue:

4. Detection of Aging Effects NUREG-1800 states that detection of aging effects should occur before there is a loss of the structure- and component-intended function(s).

The NRC staff asked, when buried pipe are exposed, what is the method of inspection and is the inspection conducted on internal, external, or both surfaces?

The applicant stated that the method of inspection would be visual inspection of the outside coating. If degradation if found near a weld, volumetric examination would be used.

The applicant stated that they understood the question and will address them in the revised AMP and background basis.

Welds with No Backing Rings The NRC staff notes that the AMP indicates that the purpose of the volumetric inspection is to identify cracks. The staff questioned whether crack identification was appropriate. This AMP is specifically for aluminum-bronze selective leaching. Therefore, the parameter to be monitored should be cracks with indication of dealloying. The applicant agreed.

The NRC staff questioned whether a sample size of 3% of the welds with a maximum of 10 welds was sufficient or consistent with the GALL Report recommendations. The staff pointed to AMP Xl.M32, "One-Time Inspection," which recommends 20% with a maximum of 25 prior to period of extended operation (PEO). The applicant agreed to increase the sample size to 20% with a maximum of 25 prior to PEO.

The NRC staff questioned how many rejectable weld flaws can be identified during the one-time inspection to transition to periodic monitoring? The applicant stated that if one rejectable weld flaw is found, the scope of the one-time inspection will be increased by five and if one more rejectable weld flaw is found, the AMP will transition to periodic monitoring.

Welds with Backing Rings Similar to Weld with No Backing Rings, the NRC notes that the AMP indicates that the purpose of ttie volumetric inspection is to identify cracks. The staff questioned whether crack identification was appropriate. This AMP is specifically for aluminum-bronze selective leaching. Therefore, the parameter to be monitored should be cracks with indication of dealloying. The applicant agreed and will update the AMP.

NOC-AE-16003394 Enclosure 1 Page 4of12 The NRC staff noted that the periodic inspection of these welds begin with a scope of 20%

of the welds with a maximum of 25 welds and, "if no weld defects are found," the number of inspections will be reduced to 3% with a maximum of 10 welds. The staff questioned the criteria for reducing the number of welds inspected. The application stated that if one weld flaws is found, the number of welds inspected will not decrease. The staff requested that the basis for reducing the number of welds inspected be strengthened. The applicant agreed to provide a stronger basis for the reduction.

Destructive Examinations The NRC staff first questioned whether the AMP actually dealt with two distinct populations -

welds without backing ring~ and welds with backing rings because the applicant's proposed susceptibility is different for each group.

Backing rings - results in crevice that can result in a greater potential for weld cracks and selective leaching Without backing rings - there is less dilution and a longer cooling period in root pass which creates a more susceptible microstructure for selective leaching The applicant confirmed that they have two distinct populations and will update the AMP.

Next, the NRC staff questioned the number of destructive examinations to be conducted and the population to be inspected. Two welds with backing rings only is not consistent with the GALL Report recommendation and does not address both populations. Regarding the number of welds, AMP Xl.M32, for example, recommends 20% with a maximum of 25. The staff indicated that both populations should be inspected. The applicant agreed and will update the AMP.

The NRC staff then discussed the purpose of the destructive examinations:

for welds without backing rings, destructive examinations demonstrate:

- - no loss of material due to dealloying (layer -like, plug-like),

- a phase distribution that supports the basis document,

- and no cracking accompanied with dealloying for welds with backing rings, destructive examinations demonstrate:

- no loss of material due to dealloying,

- a phase distribution that supports the basis document,

- and the frequency of occurrence of cracking accompanied with dealloying The applicant agreed that it will address these considerations in its update to the AMP.

Inspection Locations The NRC staff noted that the AMP states that inspection locations will be randomly selected.

The staff indicated that the inspections should be representative of a random range of weld sizes and other consider pertinent factors. The applicant agreed and will update the AMP.

NOC-AE-16003394 Enclosure 1 Page 5 of 12 Inspection Timing The NRC staff asked for clarification on when one-time inspections occur prior to PEO and how often the periodic inspection will be. The staff recognized that the phase distribution in the weld metal is not time dependent. The applicant stated that the one-time inspection will be performed in the 10 years prior to PEO. The applicant further stated that the initial periodic inspections will be performed in the 1O years prior to PEO and then on a 10-year basis. The staff noted that some editorial changes may be required in the AMP for consistent wording.

STP Clarification:

Detection of Aging Effects:

Method of inspection of buried ECW piping is visual inspection of the outside coating.

If degradation is found near a weld, a volumetric examination will be used.

Weld with No Backing Rings Parameter to be monitored is cracking.

Sample size is increased to 20% with a maximum of 25 prior to PEO.

If acceptance criteria are not met on one weld, the scope of the one-time inspection will be increased by five and the AMP will transition to periodic monitoring.

Welds with Backing Rings Parameter to be monitored is cracking.

- ,If acceptance criteria are not met on one weld, the scope of the one-time inspection will be increased by five.

Reduction to 3% or maximum of 10 welds for subsequent inspections was removed.

Destructive Examinations Welds with no backing rings andmelds with backing rings are maintained as two separate weld categories.

Both populations (i.e. welds with and without backing rings) will be destructively examined at 20% or maximum of 25 welds per category.

Purpose of destructive examinations is to demonstrate:

  • Identify loss of material due to selective leaching.

Identify the phase distribution supports the basis document.

  • Validate cracking is not accompanied with selective leaching.

The terms layer or plug-like were discussed as part of casting component selective leaching characteristics. In describing selective leaching associated with welds the focus is selective leaching associated with cracking. If selective leaching is identified the destructive examination will characterize the extent of selective leaching.

Inspection Locations Randomly selected based on a representative sample of pipe sizes.

Other factors like heat input and weld orientation are controlled by the established weld procedures assuring consistency and are not called out as specific inspection location criteria.

NOC-AE-16003394 Enclosure 1 Page 6of12 Inspection Timing STP will perform the initial periodic inspections within the last 10 years of initial license and every 10 years thereafter. This wording assures the inspections would be performed within the 30-40 year, 40-50 year, and 50-60 year periods. No additional clarification is proposed.

LRA Appendix A 1.37 and 82.1.37, Detection of Aging Effects (Element 4) is updated to:

Reference AMP 82.1.18, Buried Piping and Tanks Inspection Aging Management Program, to address the buried piping coating inspections.

Increase the one-time volumetric examination sample populations for welds without backing rings to 20%, maximum of 25 welds prior to PEO.

Require periodic volumetric examination every 10 years of 20%, maximum of 25 welds if one weld without backing ring is found not to meet the acceptance criteria.

Delete the reduction to 3% or maximum of 10 welds for subsequent inspections for welds with backing rings.

Increase destructive examination sample population of welds with and without backing rings to 20%, maximum of 25 welds per category.

Add size distribution when selecting the samples for volumetric examination Enclosure 2 provides the line-in/line-out revision to LRA Appendix A1 .37 and 82.1.37.

Enclosure 3 pr9vides the line-in/line-out revision to LRA Table A4-1.

NRC Issue:

5. Monitoring and Trending The NRC staff recognizes that qualitative results will not be obtained by the planned volumetric and destructive inspections/examinations. However, without planned trending, inspection results would be "buried" in the corrective action program. The staff questioned why the results of the volumetric and destructive inspections would not be compiled (trended) and evaluated, and why the results of the walk downs would not be compiled (trended) and evaluated. The applicant agreed to include compilation of results and evaluation as trending into the AMP.

'-

STP Clarification:

LRA Appendix 82.1.37, Monito~ing and Trending (Element 5) is updated to add compilation and evaluation of results.

Enclosure 2 provides the line-in/line-out revision to LRA Appendix 82.1.37.

Enclosure 3 provides the line-in/line-out revision to LRA Table A4-1.

NOC-AE-16003394 Enclosure 1 Page 7of12 NRC Issue:

6. Acceptance Criteria The NRC staff and the applicant discussed what the acceptance criteria should be for the inspections and examinations.

Volumetric Examinations The NRC staff noted that the AMP states the acceptance criteria for welds is no defects.

However, the staff was unsure of what "no defects" mean. The applicant agreed to provide specific, detailed criteria for determining what indicates a rejectable weld indication.

Destructive Examinations The NRC staff noted that the AMP does not provide acceptance criteria for the destructive examinations. The applicant agreed to provide specific, detailed criteria for determining acceptance criteria, including cracking, loss of material, and phase distribution.

Buried Pipe Coatings The NRC staff noted that the AMP does not provide acceptance criteria for buried pipe coatings.

The applicant agreed to revise the AMP to reference criteria cited in its Buried Piping and Tanks Inspection program during direct visual inspections of buried pipe coatings.

STP Clarification:

Based on removed aluminum bronze welds, the microstructure reviews identified the average root pass region of the weld to be approximately 0.094 inches. The acceptance criteria of 80% (approximately 0.076 inches) was chosen to allow detection of indication using volumetric examination and allow for a 20% margin against crack propagation due to potential selective leaching that could penetrate beyond the protective microstructure of the root pass region.

Volumetric Examinations Replaced the term defect with "a weld indication that does not meet the acceptance criteria". Added specific weld indication acceptance criteria.

Destructive Examinations Added specific destructive examination acceptance criteria, added loss of material, cracking and added phase distribution to parameters monitored.

Buried Pipe Coatings Acceptance criteria for buried pipe coatings are referenced in AMP B2.1.18, Buried Piping and Tanks Inspection Aging Management Program.

Acceptance Criteria The acceptance criteria is revised to add measurable criteria for loss of material due to selective leaching regardless of the type i.e. plug-like or layer-like selective leaching.

Selective leaching is characterized through destructive examination and the structural integrity evaluation is performed based on the size and amount of selective leaching

NOC-AE-16003394 Enclosure 1 Page 8 of 12 regardless of the type. The acceptance criteria applied assures selective leaching is contained and non-propagating.

LRA Appendix A 1.37 and 82.1.37, Acceptance Criteria (Element 6) is updated to:

Reference AMP 82.1.18, to address the buried piping coating inspection acceptance criteria.

Replaced the term defect with "a weld indication that does not meet the acceptance criteria".

Added measureable acceptance criteria for the volumetric and destructive examinations.

Added acceptance criteria for the destructive examinations.

Enclosure 2 provides the line-in/line-out revision to LRA Appendix A 1.37 and 82.1.37.

Enclosure 3 provides the line-in/line-out revision to LRA Table A4-1.

NRC Issue:

7. Corrective Actions Expansion of Examinations The NRC staff acknowledges that STP does not expect leaks associated with aluminum-bronze selective leaching once the casting components have been replaced. However, corrective action is a key element of an AMP. The following items were discussed during the audit:
  • What type of inspections will be conducted if aboveground leaks are detected?

What type of inspections will be conducted if buried pipe welds leak?

  • What type of expanded inspection will be conducted if leaks are detected (e.g.,

volumetric, destructive).

  • For welds without backing rings, what corrective actions will occur if dealloying is detected?

For welds with backing rings, what corrective actions will occur depending on the frequency of occurrence of cracking accompanied with dealloying?

  • Will expansion of destructive examinations be conducted if acceptance criteria for destructive examinations is not met?
  • What corrective actions will be taken for the detection of plug-like or uniform dealloying?
  • What corrective actions will be taken for buried pipe coating defects?

The applicant agreed to expand the corrective action element of the AMP.

STP Clarification:

STP site QA procedures, review and approval process, and administrative controls are implemented in accordance with the requirements of 10 CFR 50 Appendix B and are acceptable in addressing corrective actions. The QA program includes elements of corrective action and is applicable to the safety-related and nonsafety-related systems, structures and components that are subject to aging management review.

If an unanticipated condition is identified that challenges the ability of the system or component's design bases or structural integrity, operability and/or reportability evaluations

NOC-AE-16003394 Enclosure 1 Page 9of12 will be performed in accordance with 10 CFR 50 Appendix 8. Casual analysis, extent of condition, compensatory measures are considered during these evaluations.

  • Type of inspections to be conducted if above ground leaks are detected.

Additional volumetric inspections Structural Integrity Evaluation Repair/replacement of leaking component Evaluation of extent of condition and cause AMP effectiveness evaluation

  • Type of inspections to be conducted if buried pipe welds leak.

Additional volumetric inspections Structural Integrity Evaluation Repair/replacement of leaking component Evaluation of extent of condition and cause AMP effectiveness evaluation

  • Expanded inspection to be conducted if a leak is detected (e.g. volumetric, destructive).

5 additional volumetric inspections Destructive examination of leaking weld

  • Corrective actions if unacceptable selective leaching is detected for welds with or without backing rings include:

Structural integrity evaluation assessing acceptability through PEO Scope expansion of 5 additional destructive examinations

  • Corrective actions if unacceptable cracking is accompanied with selective leaching for welds with or without backing rings include:

Structural integrity evaluation assessing acceptability through PEO Scope expansion of 5 additional welds volumetrically and destructively examined

  • Additional corrective actions that must be taken if STP finds unanticipated selective leaching.

Additional destructive examinations Structural Integrity Evaluation Repair or replacement weld Evaluation of extent of condition and cause AMP effectiveness evaluation

  • There are no specific acceptance criteria for the detection of plug-like or uniform selective leaching as it relates to welds. The characterization of the selective leaching is performed as part of the destructive examination.
  • Corrective actions for buried pipe coating defects are described in AMP 82.1.18. Added reference to 82.1.18 for corrective actions when buried piping coating degradation is identified.

NOC-AE-16003394 Enclosure 1 Page 10of12 LRA Appendix A 1.37 and 82.1.37, Corrective Actions (Element 7) is updated to include:

Add reference to B2.1.18 for corrective actions when buried piping coating degradation is identified.

Revised corrective actions Element 7 to describe specific corrective actions when the acceptance criteria are not met.

Enclosure 2 provides the line-in/line-out revision to LRA Appendix A 1.37 and B2.1.37.

Enclosure 3 provides the line-in/line-out revision to LRA Table A4-1.

NRC Issue:

Basis Document The staff discussed a few questions on the Basis document. The staff noted that the margin between the detectable limit and the allowed flaw size for one set of buried pipe fittings was very low (i.e., 1.01 ). The applicant agreed to provide a stronger basis for the acceptability of these fittings.

STP Clarification:

The original analysis (design basis) was reviewed in support of this leak rate assessment to identify the conservatisms in the Bechtel design analysis and where margins on stress can be reduced. It was concluded that one area of conservatism exists with the assumed value for the coefficient of subgrade reaction.

An additional conservatism exists with the peak ground acceleration. Following the accident at the Fukushima Daiichi nuclear power plant, the NRC issued a 50.54(f) letter that requested information including reevaluating the seismic hazards for each site and comparing the new results against the design basis. Results of the seismic reevaluation yielded an approximate 40% reduction in stress levels. The seismic reevaluation is not part of the design basis for the plant. This data can only be used to show how much conservatism exits in the current design basis with respect to seismic.

The cumulative impact of using more realistic values for these input parameters reduced

  • the faulted bending stress by about 51.3%. Therefore a multiplying factor of 0.513 was applied to the original code Equation 90 (faulted) bending stresses.

The resultant sensitivity change in the ratio of the allowable length Lanowlleak length LLeak lowest margin below ground lowest margin Tee is:

10 gpm original: 30" discharge Tee@ 1.01 1O gpm optimized: 30" discharge Tee @ 1.54

NOC-AE-16003394 Enclosure 1 Page 11of12 NRC Issue:

Editorial Comments The staff discussed several editorial comments on the AMP. The staff classified these as editorial changes because they believed that the applicant's intent was to include the information. The applicant agreed to address the editorial comments in its AMP update.

STP Clarification:

1. LRA Appendix 82.1.37 is updated to include walkdowns of aboveground weld locations in the "parameters monitored or inspected" program Element 3.
2. LRA Appendix 82.1.37 is updated to include walkdowns in the "parameters monitored or inspected" program Element 3, to address the detection of buried pipe leaks.
3. LRA Appendix 82.1.37 is updated to credit the buried aluminum bronze piping coatings as a preventive action to prevent selective leaching of the exterior surface of the aluminum bronze welds. Coatings are addressed by the Buried Piping and Tanks Inspection Aging Management Program 82.1.18.
4. .The enhancement is revised to state the replacement material will not be susceptible to selective leaching.
5. The corrective action Element 7 is revised to clearly address the actions required if a through wall leak of the above or below ground weld is identified. The revised corrective action is required for all leaking weld.

Enclosure 2 provides the line-in/line-out revision to LRA 82.1.37.

Enclosure 3 provides the line-in/line-out revision to LRA Table A4-1.

NRC Issue:

At the audit on June 22, 2016, the applicant mentioned that its buried piping is coated with coal tar, which makes the exterior surface not susceptible to selective leaching. The coating would also impede detection of leaks originating from the inside of the pipe. The openings of the cracks of concern are only around 0.01 inches. Could this kind of crack/leak breach the coating? Even if it did, it might restrict the leak exit area to a degree, thus the leak rate calculations could be non-conservative.

The U.S. Nuclear Regulatory Commission (NRC or the staff) and representatives of STP Nuclear Operating Company held a telephone conference call on July 5, 2016, to discuss and clarify the following identification of additional information concerning the license renewal application.

Based on the discussion with the applicant, the staff indicated that the topic should be addressed when the revised AMP is submitted to the staff for review.

How is the margin between the detectible leak size necessary to reveal leaks at the surface within 30 days and the allowable flaw size affected by the presence of external coatings, such as coal tar epoxy and tape?

NOC-AE-16003394 Enclosure 1 Page 12of12 The applicant agreed to supplement their license renewal application to address this topic.

STP Clarification:

Essential water buried piping is coated with Cold Tar Epoxy coating and the weld joints are protected utilizing a Tape-Coat CT tape wrap. Discussions with the coatings development engineer at Chase Corporation concluded that Tape-coat CT will not be able to resist the operating pressure if there is a leak. Water from a small leak could get trapped under the coating, *but since is the component is only coated on the weld joints it would quickly work its way out to the edge of the coating. If there were any delay from seeing a leak at the surface, it is reasonable to conclude that it would be much less than a day, maybe a couple hours at most. Key considerations in this conclusion include:

- The coating is not designed to be a pressure boundary.

- Elongation of the backing and adhesive is 800% providing a very pliable coating that would present an ever increasing area to .the initial through wall crack pressure allowing for rapid propagation of the outside diameter leakage to the tape joint and soil.

- Adhesive thickness is greater than 3 times the backing thickness and only has 1O lb/in adhesion strength. This low adhesive strength provides for tape alignment and maintenance of placement during soil movement only.

- A crack length associated with a 10 gpm leak provides sufficient pressure and flow that resistance to the flow rate from a through wall leak is considered to be negligible.

- The optimized margin increase identified in the below ground leakage rate assessment provides confidence that any delay of a through wall leak penetrating the coating and reaching the surface will not significantly affect the ratio of the allowable length Lanowlleak length LLeak margins.

NOC-AE-16003394 Enclosure 2 STPNOC LRA Appendix A and B Line in/out Sections Affected LRA Section A1.37 82.1.37

NOC-AE-16003394 Enclosure 2 Page 1 of 14 A1.37 SELECTIVE LEACHING OF ALUMINUM BRONZE The Selective Leaching of Aluminum Bronze program manages loss of material and cracking due to selective leaching of aluminum bronze (copper alloy with greater than 8 percent aluminum) components and welds exposed to raw water within the scope oflicense renewal.

The program also validates phase distribution characteristics of the microstructure.

All aluminum bronze castings susceptible to selective leaching, including attachment welds related to the castings, and aluminum bronze root valves with adapter socket welds will be replaced prior to the period of extended operation with material that is not susceptible to selective leaching. Extruded piping tees with aluminum bronze weld repairs, where the repair size is such that failure of the repair would affect the structural integrity of the component, will be replaced prior to the period of extended operation.

STP uses copper alloy piping with less than 8 percent aluminum content, which is not susceptible to selective leaching. However, there are welds in which the filler metal is copper alloy with greater than 8 percent aluminum. The final composition of welds and process used to fabricate the welds results in a reduction in the susceptibility of the root pass filler materiaJ to selective leaching.

The Selective Leaching of Aluminum Bronze program directs that prior to the period of extended operation ~20 percent with a maximum of 4-025 welds of the above ground weld population with no backing rings are examined one-time volumetrically to manage cracking. validate *.veld integrity If.§ rejectable weld flmvs (weld defects) indication that does not meet the acceptance criteria per ASME Section IX requirements are is found during the one-time inspection of welds with no backing rings, periodic volumetric examinations of 20 percent with a maximum of 25 welds will be performed every 10 years thereafter.

The Selective Leaching of Aluminum Bronze program directs that 20 percent with a maximum of 25 welds of the above ground weld population with backing rings are examined volumetrically to manage cracking validate weld integrity prior to the period of extended operation and every 10 years thereafter. If no weld defects are found during the 20 percent inspection performed prior to the period of extended operation, the 10 year follow up volumetric examinations will be reduced to 3 percent with a maximum of 10 welds.

Discovery of.§ weld indication that does not meet the acceptance criteria defects requires expansion of the volumetric examination sample population. Each weld found with a defect weld indication that does not meet the acceptance criteria requires five additional volumetric examinations to be performed until no additional weld indication that does not meet the acceptance criteria defects are is found.

The Selective Leaching of Aluminum Bronze program directs that prior to the period of extended operation 20 percent with a maximum of 25 welds of the above ground weld population with no backing rings and 20 percent with a maximum of 25 welds of the above ground weld population with backing rings be examined one-time destructively to detect loss of material due to selective leaching and verify microstructure phase distribution. If selective leaching that does not meet the acceptance criteria is found. periodic destructive examinations of 20 percent with a maximum of 25 welds of the above ground weld population with no backing rings and 20 percent with a maximum of 25 welds of the above ground weld population with backing rings will be performed every 1O years thereafter.

NOC-AE-16003394 Enclosure 2 Page 2of14 Discovery of unacceptable selective leaching requires five additional destructive examinations to be performed until no unacceptable selective leaching is found.

Additionally, the aging management program directs that P.vo *JVelds with backing rings are destructively examined prior to the period of extended operation to verify the absence of selective leaching.

Yard walkdowns are performed in the areas above the buried piping with aluminum bronze welds to look for changes in ground conditions that would indicate leakage. If a leak from a buried pipe weld is discovered by surface water monitoring or during a buried ECW piping inspection, a section of each leaking piping weld will be removed for destructive examination.

Visual inspections are performed every six months (not to exceed nine months) of the external surfaces of the above ground welds for evidence of through wall leakage.

The Buried and Underground Piping and Tank program. 82.1.18, includes the visual inspection of the buried aluminum bronze exterior pipe coatings for visible breaks. gaps, and discontinuities which could indicate cracking of the welds and defines the acceptance criterion for buried pipe coatings.

The acceptance criterion for volumetric examination of aluminum bronze welds is no defects. detected planar indication that is surface connected (exposed to the ECW environment) unless the depth of the indication is contained within the 80% of the weld root pass region. An indication not connected to the surface (not exposed to the ECW environment) is acceptable.

The acceptance criterion for visual inspection of the aluminum bronze welds and adjacent copper alloy piping during the walkdowns is no through wall leakage.

The acceptance criterion for destructive examinations is no loss of material due to selective leaching penetrating 80% of the root-pass region and non-propagating (surrounded by a resistant phase distribution). The microstructure of the weld root region exhibits a non-continuous phase distribution consistent with the metallurgical technical basis report.

An A~luminum-bronze welds found to have an indication that does not meet the acceptance criteria defects or has through wall leakage ara-is removed and destructively examined to determine the extent of cracks and/or selective leaching. The condition is documented in the corrective action program and a structural integrity analysis is performed to confirm that the load carrying capacity of the installed welds remain adequate to support the intended function of the ECW system through the period of extended operation.

NOC-AE-16003394 Enclosure 2 Page 3of14 82.1.37 Selective Leaching of Aluminum Bronze Program Description The Selective Leaching of Aluminum Bronze program manages loss of material and cracking due to selective leaching for aluminum bronze (copper alloy with greater than eight percent aluminum) components and welds exposed to raw water within the scope of license renewal.

The program also validates phase distribution characteristics of the microstructure. The selective leaching of aluminum bronze is applied in addition to the Open-Cycle Cooling Water program (B2.1.9).

All aluminum bronze castings susceptible to selective leaching, including attachment welds related to the castings and aluminum bronze root valve adapter socket welds, will be replaced prior to the period of extended operation with material that is not susceptible to selective leaching. Extruded piping tees with aluminum bronze weld repairs, where the repair size is such that failure of the repair would affect the structural integrity of the c0mponent, will be replaced prior to the period of extended operation.

STP uses copper alloy piping with less than 8 percent aluminum content, which is not susceptible to selective leaching. However, there are welds in which the filler metal is copper alloy with greater than 8 percent aluminum. The final composition of welds and process used to fabricate the welds results in a reduction in the susceptibility of the root pass filler material to

  • selective leaching.

The Selective Leaching of Aluminum Bronze program directs that prior to the period of extended operation ~20 percent with a maximum of .:t-Q25 welds of the above ground weld population with no backing rings are examined one-time volumetrically to manage cracking validate weld integrity. If.§ rejectable weld flaws (weld defects) indication that does not meet the acceptance .

criteria per ASME Section IX requirements 3f8-is found during the one-time inspection of welds with no backing rings, periodic volumetric examinations of 20 percent with a maximum of 25 welds will be performed every 10 years thereafter.

The Selective Leaching of Aluminum Bronze program directs that 20 percent with a maximum of 25 welds of the above ground weld population with backing rings are examined volumetrically to manage cracking validate weld integrity prior to the period of extended operation and every 1O years thereafter. If no weld defects are found during the 20 percent inspection performed prior to the period of extended operation, the 10 year follow up volumetric examinations will be reduced to 3 percent v:ith a maximum of 10 welds.

Discovery of§ weld indication that does not meet the acceptance criteria defects requires expansion of the volumetric examination sample population. Each weld found with a defect weld indication that does not meet the acceptance criteria requires five additional volumetric examinations to be performed until no additional weld indication that does not meet the acceptance criteria defects areis found.

The Selective Leaching of Aluminum Bronze program directs that prior to the period of extended operation 20 percent with a maximum of 25 welds of the above ground weld population with no backing rings and 20 percent with a maximum of 25 welds of the above ground weld population with backing rings be examined one-time destructively to detect loss of material due to selective leaching and verify microstructure phase distribution. If selective leaching that does not meet

NOC-AE-16003394 Enclosure 2 Page 4of14 the acceptance criteria is found, periodic destructive examinations of 20 percent with a maximum of 25 welds of the above ground weld population with no backing rings and 20 percent with a maximum of 25 welds of the above ground weld population with backing rings will be performed every 10 years thereafter.

Discovery of unacceptable selective leaching requires five additional destructive examinations to be performed until no unacceptable selective leaching is found .

. Additionally, the aging management program directs that t\vo welds with backing rings are destructively examined prior to the period of extended operation to verify the absence of selective leaching.

Yard walkdowns are performed in the areas above the buried piping with aluminum bronze welds to look for changes in ground conditions that would indicate leakage. If a leak from a buried pipe weld is discovered by surface water monitoring or during a buried ECW piping inspection, a section of each leaking piping weld will be removed for destructive examination.

Visual inspections are performed every six months (not to exceed nine months) of the external surfaces of the above ground welds for evidence of through wall leakage.

The Buried and Underground Piping and Tank program. 82.1.18, includes the visual inspection of the buried aluminum bronze exterior pipe coatings for visible breaks. gaps, and discontinuities which could indicate cracking of the welds.

The acceptance criterion for volumetric examination of aluminum bronze welds is nodefects detected planar indication that is surface connected (exposed to the ECW environment) unless the depth of the indication is contained within the 80% of the weld root pass region. An indication not connected to the surface (not exposed to the ECW environment) is acceptable.

The acceptance criterion for visual inspection of the aluminum bronze welds and adjacent copper alloy piping during the walkdowns is no through wall leakage.

The acceptance criterion for destructive examinations is no loss of material due to selective leaching penetrating 80% of the root-pass region and non-propagating (surrounded by a resistant phase distribution). The microstructure of the weld root region exhibits a non- h continuous phase distribution consistent with the metallurgical technical basis report.

An A.§luminum bronze welds found to have an indication that does not meet the acceptance criteria defects or has through wall leakage are-is removed and destructively examined to determine the extent of cracks and/or selective leaching. The condition is documented in the corrective action program and a structural integrity analysis is performed to confirm that the load carrying capacity of the installed welds remain adequate to support the intended function of the ECW system through the period of extended operation.

Aging Management Program Elements An evaluation of each element of the Aging Management Program against the 10 elements described in Appendix A of NUREG-1800, Standard Review Plan for Review of License Renewal Applications for Nuclear Power Plants, is provided below.

NOC-AE-16003394 Enclosure 2 Page 5 of 14 Scope of Program (Element 1)

The Selective Leaching of Aluminum Bronze program manages loss of material and cracking due to selective leaching for aluminum bronze (copper alloy with greater than 8 percent aluminum) components and welds exposed to raw water within the scope of license renewal.

Prior to the period of extended operation, all aluminum bronze castings susceptible to loss of material due to selective leaching, including attachment welds related to the castings and aluminum bronze root valves with adapter socket welds, will be replaced with material that is not susceptible to selective leaching.

Extruded piping tees with.aluminum bronze weld repairs where the repair size is such that failure of the repair would affect the structural integrity of the component will be replaced prior to the period of extended operation.

STP uses copper alloy piping with less than 8 percent aluminum, which is not susceptible to selective leaching. However, welds in which the filler metal is copper alloy with greater than 8 percent aluminum may be susceptible to loss of material and cracking due to selective leaching.

The final composition of welds and process used to fabricate the welds results in a reduction in the susceptibility of the root pass filler material to selective leaching.

The following weld material is used.

  • ERCuAl-A2 with no backing ring,
  • ERCuNiAI with no backing ring,
  • ERCuAl-A2 with backing ring, and
  • ERCuAl-A2 non-cast component weld repairs.

Preventive Actions (Element 2)

The Selective Leaching of Aluminum Bronze program does not prevent degradation due to aging effects but provides for component replacement and inspections to detect aging degradation prior to the loss of intended functions.

Prior to the period of extended operation, all aluminum bronze castings susceptible to selective leaching, including attachment welds related to the castings and aluminum bronze root valves i.vith adapter socket welds, will be replaced *.vith material that is not susceptible to selective leaching.

Extruded piping tees *.vith aluminum bronze weld repairs where the repair size is such that failure of the repair would affect the structural integrity of the component *.viii be replaced prior to the period of extended operation.

External surfaces of the buried aluminum bronze piping are coated to prevent selective leaching of the exterior surface of the aluminum bronze welds. The above ground piping is not coated.

Parameters Monitored or Inspected (Element 3)

The susceptibility of aluminum bronze welds is related to the integrity of the weld, the weld material composition, and the welding temperature controls.

Loss of material due to selective leaching is monitored through system walkdowns and destructive examinations.

NOC-AE-16003394 Enclosure 2 Page 6of14 Cracking associated with selective leaching is monitored through volumetric examination and destructive examination.

Phase distribution to verify the potential for continuous selective leaching is monitored through destructive examination.

Welds without backing rings are either original ERCuAl-A2 material or replacement ERCuNiAI material. The original ERCuAl-A2 welds without backing rings were radiographed at time of installation to detect the presence of weld flaws. The replacement ERCuNiAI welds without backing rings were examined visually and by liquid penetrant method at time of installation. The ERCuNiAI weld material is less susceptible to selective leaching than the ERCuAl-A2 weld material due to the addition of nickel.

Welds with backing rings are original ERCuAl-A2 material. The original ERCuAl-A2 welds with backing rings were examined visually and by use of liquid penetrant method at time of installation.

Operating experience has sho*.vn that ERCuAI l\2 *.velds without weld 'flaws, v1elds using ERCuNiAI *.veld material, and *.velds without backing rings are not susceptible to cracking caused by selective leaching.

The aging management program will manage cracking verify the weld integrity of the above ground weld population with no backing rings by performing a one-time volumetric examination on J20 percent with a maximum of 4-025 welds prior to the period of extended operation. If§.

rejectable weld flaws (i.veld defects) indication that does not meet the acceptance criteria fIBf l\SME Section IX requirements are .1§._found during the one-time inspection of welds with no backing rings, periodic volumetric examinations of 20 percent with a maximum of 25 welds will be performed every 10 years thereafter.

The aging management program will manage cracking verify the weld integrity of the above ground weld population with backing rings by performing periodic volumetric examinations on 20 percent with a maximum of 25 welds prior to the period of extended operation anq every 10 _

years thereafter. If no weld defects !§.are found during the inspection performed prior to the period of extended operation of *.veld with backing rings, the follow up volumetric examinations will be reduced to 3 percent with a maximum of 10 welds.

Since the population of welds use similar material and are exposed to the same environment, the samples for volumetric examination will be randomly selected from the total population of welds. considering construction and size distributions. The above ground welds are used as the bounding condition to represent both the above and below ground welds when performing the volumetric examination.

T\vo welds *.vith backing rings will be destructively examined prior to the period of extended operation to verify the absence of selective leaching.*

The aging management program will manage loss of material due to selective leaching and verify microstructure phase distribution of the above ground weld population with and without backing rings by performing a one-time destructive examination on 20 percent with a maximum of 25 welds with backing rings and 20 percent with a maximum of 25 welds without backing rings prior to the period of extended operation. If selective leaching that does not meet the

NOC-AE-16003394 Enclosure 2 Page 7 of 14 acceptance criteria is found. periodic destructive examinations of 20 percent with a maximum of 25 welds will be performed every 10 years thereafter.

Since destructive examinations is used to verify the susceptibility of the weld to selective leaching the sample population will be randomly selected from the total population of welds with and without backing rings.

Periodic walkdowns of the above ground piping, components and welds is performed to verify no through wall leakage.

Periodic walkdowns of the yard areas over the buried ECW piping and welds is performed to verify no evidence of through wall leakage.

An A.§.luminum bronze welds found to have an indication that does not meet the acceptance criteria or has through wall leakage aFe-i.§ removed and destructively examined to determine extent of cracks and/or selective leaching. The condition is documented in the corrective action program and a structural integrity analysis is performed to confirm that the load carrying capacity of the installed welds remain adequate to support the intended function of the ECW system through the period of extended operation.

The Buried and Underground Piping and Tank program. B2.1.18. includes the visual inspection of the buried aluminum bronze exterior pipe coatings for visible breaks. gaps, and discontinuities which could indicate possible cracking of the welds.

  • Detection of Aging Effects (Element 4)

The Selective Leaching of Aluminum Bronze program includes a-one-time and periodic volumetric and destructive examination§ of above ground aluminum bronze welds to determine if loss of material and cracking due to selective leaching or cracl<ing is occurring.

The Selective Leaching of Aluminum Bronze program includes visual inspections every six months (not to exceed nine months) of the external surfaces of the above ground components and welds for evidence of through wall leakage.

Every six months, a walkdown is performed in the areas above the buried ECW piping containing copper alloy welds with aluminum content greater than 8 percent. During the walkdown, the ground is observed for conditions that would indicate leakage. If a leak from a below-grade piping weld is discovered by surface water monitoring, a section of each leaking piping weld will be removed for destructive examination.

The Buried and Underground Piping and Tank program. B2.1.18. specifies that Wwhenever aluminum bronze materials are exposed during inspection of the buried ECW piping, the exterior pipe coating is inspected for degradation. If degradation is identified near a weld a volumetric examination will be performed to determine if cracking of the weld is occurring components are examined for indications of selective leaching.

If leaking below-grade welds are discovered during a buried ECW piping inspection, a section of each leaking weld will be removed for destructive examination.

NOC-AE-16003394 Enclosure 2 Page 8 of 14 An Ag_luminum bronze welds found to have an indication that does not meet the acceptance criteria or has through wall leakage aFS-is removed and destructively examined to determine extent of loss of material and/or cracks cracking due to selective leaching or selective leaching.

Monitoring and Trending (Element 5)

This is an inspection program to determine if selective leaching is occurring and the degree of.

the selective leaching. No trending is performed ..

STP will maintain the history of the volumetric and destructive examinations results. Following completion of the volumetric and destructive examinations scope, a review is performed to identify potential adverse trends or other indications requiring action.

Acceptance Criteria (Element 6)

The acceptance criterion for volumetric examination of aluminum bronze welds is no defects. detected planar indication that is surface connected (exposed to the ECW environment) unless the depth of the indication is contained within the 80% of the weld root pass region. An indication not connected to the surface (not exposed to the ECW environment) is acceptable.

The acceptance criterion for visual inspection of the aluminum bronze welds and adjacent copper alloy piping during the walkdowns is no through wall leakage.

The acceptance criterion for destructive examinations is no loss of material due to selective leaching penetrating 80% of the root-pass region and non-propagating* (surrounded by a resistant phase distribution). The microstructure of the weld root region exhibits a non-continuous phase distribution consistent with the metallurgical technical basis report.

The acceptance criterion for buried aluminum bronze exterior pipe coating is defined in the Buried Piping and Tanks Inspection Aging Management Program 82.1.18.

If an acceptance criterion is not met, the condition is documented in the corrective action program. and a structural integrity analysis is performed to confirm that the load carrying capacity of the tested material remains adequate to support the intended function of the ECW system through the period of extended operation.

Corrective Actions (Element 7)

The following corrective actions are performed when acceptance criteria are not met:

A through wall leak of the above or below ground weld.

  • Remove weld and destructively examined to determine the extent of cracks or selective leaching.
  • Perform five additional volumetric inspections to assess extent of condition and cause.
  • Perform a structural integrity evaluation to confirm that the load carrying capacity of the installed welds remain adequate to support the intended function of the ECW system through the period of extended operation.
  • Replace leaking weld

NOC-AE-16003394 Enclosure 2 Page 9 of ,14 '---

  • Perform an AMP effectiveness evaluation to determine program changes required to manage the aging.

An aluminum bronze weld found to have an indication that does not meet the acceptance criteria. -

  • Remove weld and destructively examined to determine the extent of cracks or selective leaching.
  • Perform five additional volumetric examinations until no additional weld indication that does not meet the acceptance criteria defects are is found to assess extend of condition and cause.
  • Perform a structural integrity evaluation to confirm that the load carrying capacity of the installed welds remain adequate to support the intended function of the ECW system through the period of extended operation.
  • Perform an AMP effectiveness evaluation to determine program changes required to manage the aging. 'l>
  • Replace weld A destructive examination does not meet acceptance criteria.
  • Perform five additional ,destructive examinations until no unacceptable selective leaching is found to assess extend of condition and cause.
  • Perform a structural integrity evaluation to confirm that the load carrying capacity of the installed welds remain adequate to support the intended function of the ECW system through the period of extended operation.
  • Perform an AMP effectiveness evaluation to determine program changes required to manage the aging.

Aluminum bronze 'Nelds found to have defects or through 1.vall leakage are removed and destructively examined to determine the extent of cracks or selective leaching. The condition is documented in the corrective action program and a structural integrity analysis is performed to confirm that the load carrying capacity of the installed i.velds remain adequate to support the intended function of the ECW system through the period of extended operation.

Discovery of defects requires expansion of the volumetric examination sample population. Each

  • .veld with a defect requires five additional volumetric examinations to be performed until no additional unacceptable cracking weld defects are found.

The Buried Piping and Tanks Inspection Aging Management Program 82.1.18, outlines corrective actions resulting from the identification of degraded buried aluminum bronze exterior pipe coating.

If a leak from a buried pipe weld is discovered by surface *.vater monitoring or during a buried ECW piping inspection, a section of each leaking piping weld will be removed for destructive examination.

When acceptance criteria are not met a determination of operability and an assessment of the extent of condition is performed. - "'

NOC-AE-16003394 Enclosure 2 Page 10of14 and a structural integrity analysis is performed to confirm that the load carrying capacity of the tested material remains adequate to support the intended function of the ECW system through the period of extended operation.

STP QA procedures, review and approval process, and administrative controls are implemented in accordance with the requirements of 10 CFR 50 Appendix B and are acceptable in addressing corrective actions. The QA program includes elements of the corrective action, and is applicable to the safety-related and nonsafety-related systems, structures, and components that are subject to aging management review.

Confirmation Process (Element 8)

STP QA procedures, review and approval process, and administrative controls are implemented in accordance with the requirements of 10 CFR 50 Appendix B and are acceptable in addressing confirmation processes and administrative controls. The QA program includes elements of the corrective action, and is applicable to the safety-related and nonsafety-related systems, structures, and components that are subject to aging management review.

Administrative Controls (Element 9)

See Element 8.

Operating Experience (Element 10)

STP identified through-wall cracks in the ECW system piping which were initiated by pre-existing weld defects and propagated by a selective leaching dealloying phenomenon. The pre-existing weld defects identified appeared in welds with backing rings. The weld population consists of shop and field welds without backing rings, field welds with backing rings, weld repairs to extruded piping tees, and valves with adapter socket welds. Welds that have shown through-wall cracks have been welds with backing rings, weld repairs to extruded piping tees, and valves with adapter socket welds. Laboratory failure analysis data has indicated that in the cases with leaks, a preexisting crack penetrating into the central core of the weld was present.

Poor fit-up may have contributed to such root pass cracking. Crack growth appears to have occurred by a process of the crack tip selective leaching dealloying locally and the crack propagating through the selectively leached dealloyed zone. The affected welds were repaired.

Selective leaching has occurred in susceptible aluminum bronze components. STP will replace all susceptible aluminum bronze components prior to the period of extended operation.

Enhancements Prior to the period of extended operation, the following enhancements will be implemented in the following program elements:

Scope of Program (Element 1) and Preventive Actions (Element 2)

Procedure will be enhanced to:

  • Replace all aluminum bronze castings susceptible to selective leaching, including attachment welds with material that is not susceptible to selective leaching, prior to the period of extended operation.

NOC-AE-16003394 Enclosure 2 Page 11 of 14

  • Replace aluminum bronze root valve adapter socket welds with material that is not susceptible to selective leaching prior to the period of extended operation.
  • Replace extruded piping tees with aluminum bronze weld repairs where the repair size is such that failure of the repair would affect the structural integrity of the component prior to the period of extended operation.
  • Parameters Monitored or Inspected (Element 3)

Procedure will be enhanced to:

  • Specify, loss of material due to selective leaching is monitored through system walkdowns and destructive examinations.
  • Specify, cracking associated with selective leaching is monitored through volumetric examination and destructive examination.
  • Specify, phase distribution to verify the potential for continuous selective leaching is determined through destructive examination.
  • Verify, the \Neid integrity management of cracking of the above ground weld population with no backing rings by performing a one-time volumetric examination on ~.2.Q percent with a maximum of W25 welds prior to the period of extended operation.
  • Specify, if .£..Weld indication that does not meet the acceptance criteria flmvs are i.§__found during the one-time inspection of weld with no backing rings, periodic volumetric examinations of 20 percent with a maximum of 25 _welds will be performed every 10 years thereafter.
  • Verify, the weld integrity management of cracking of the above ground weld population with backing rings by performing periodic volumetric examinations on 20 percent with a maximum of 25 welds prior to the period of extended operation and every 10 years thereafter.
  • Specify, if no weld defects are found during the periodic inspection performed prior to the period of extended operation of weld with backing rings, the follow up volumetric examinations 'Nill be reduced to 3 percent .vith a maximum of 10 welds.

/

1

  • Specify, the samples for volumetric examination be randomly selected from the total population of above ground welds, considering construction and size distributions.
  • Require, two welds with backing rings be destructively examined prior to the period of extended operation to verify the absence of selective leaching.
  • Verify. the management of selective leaching and microstructure phase distribution of the above ground weld population with and without backing rings by performing a one-time destructive examination on 20 percent with a maximum of 25 welds with backing rings and 20 percent with a maximum of 25 welds without backing rings prior to the period of extended operation. *
  • Specify, if selective leaching does not meet the acceptance criteria during the one-time destructive examinations, periodic destructive examinations of 20 percent with a maximum of 25 welds will be performed every 10 years thereafter.
  • Require the sample population for destructive examinations be randomly selected from the total population of welds with and without backing rings.
  • Require f!....Welds which does not meet the acceptance criteria are found to have defects or has through wall leakage, be removed and destructively examined to determine the -

extent of cracks and/or selective leaching.

  • Require,.§ welds which does not meet the acceptance criteria are found to have defects or has through wall leakage, be documented in the corrective action program and a structural integrity analysis be performed to confirm that the load carrying capacity of the installed welds remain adequate to support the intended function of the ECW system through the period of extended operation.

Detection of Aging Effects (Element 4)

Procedure will be enhanced to:

  • Require one-time and periodic volumetric examination of above ground aluminum bronze welds to determine if loss of material due to selective leaching or cracking is occurring.
  • Require one-time and periodic destructive examination of above ground aluminum bronze welds to determine if selective leaching is occurring and verify phase distribution.
  • Require fl....Welds which does not meet the acceptance criteria are found to have. defects or has through wall leakage, be removed and destructively examined to determine extent of cracks and/or selective leaching.
  • Require whenever aluminum bronze materials are exposed during inspection of the buried ECW piping, the exterior aluminum bronze pipe coating is inspected for degradation. If degradation is identified near a weld a volumetric examination will be performed to determine if loss of material or cracking due to selective leaching is occurring.

Monitoring and Trending (Element 5)

Procedure will be enhanced to:

  • Require that the history of the volumetric and destructive examinations results be maintained and a review be performed to identify potential adverse trends or other indications requiring action.

NOC-AE-16003394 Enclosure 2 Page 13of14 Acceptance Criteria (Element 6)

Procedure will be enhanced to:

  • Specify, the acceptance criterion for volumetric examination of aluminum bronze welds is no defects. detected planar indication that is surface connected (exposed to the ECW environment) unless the depth of the indication is contained within the 80% of the weld root pass region. An indication not connected to the surface (not exposed to the ECW environment) is acceptable.
  • Specify, the acceptance criterion for visual inspection of the aluminum bronze welds and
  • adjacent copper alloy piping during the walkdowns is no through wall leakage.
  • Specify, the acceptance criterion for destructive examinations is no loss of material due to selective leaching penetrating 80% of the root-pass region and non-propagating (surrounded by a resistant phase distribution). The microstructure of the weld root region exhibits a non-continuous phase distribution consistent with the metallurgical technical basis report.
  • Require, if an acceptance criterion is not met. the unacceptable_inspections condition be documented in the corrective action program and a structural integrity analysis be performed to confirm that the load carrying capacity of the installed welds remain adequate to support the intended function of the ECW system through the period of extended operation.

Corrective Actions (Element 7)

Procedure will be enhanced to:

  • Require, upon discovery of a weld which does not meet the acceptance criteria found to have unacceptable cracking, loss of material due to selective leaching, weld defects or has through wall leakage, the weld i§_ara-removed and destructively examined to determine extent of cracking and/or selective leaching.
  • Specify, when a weld is found that does not meet the acceptance criteria Require, weJG defects or through wall leakage be documented in the corrective action program and a structural integrity analysis shall be performed to confirm that the load carrying capacity of the installed welds remain adequate to support the intended function of the ECW system through the period of extended operation.
  • Specify, discovery of~ weld indication that does not meet the acceptance criteria defects requires expansion of the volumetric examination sample population. Each weld found with a defect weld indication that does not meet the acceptance criteria requires five additional volumetric examinations to be performed until no additional weld indication that does not meet the acceptance criteria defects ara-is found.
  • Specify, discovery of selective leaching that does not meet the acceptance criteria requires expansion of the destructive examinations sample population. Each destructive examination that does not meet the acceptance criteria requires five additional destructive examination examinations to be performed until no unacceptable selective leaching is found.

NOC-AE-16003394 Enclosure 2 Page 14of14

" Specify, if acceptance criteria are not met a determination of operability and an assessment of the extent of condition is performed. Additionally, perform an AMP effectiveness evaluation to determine program changes required to manage the aging.

Conclusion The continued implementation of the Selective Leaching of Aluminum Bronze program provides reasonable assurance that aging effects will be managed such that the systems and components within the scope of this program will continue to perform their intended functions consistent with the current licensing basis for the period of extended operation.

NOC-AE-16003394 Enclosure 3 STPNOC Regulatory Commitments Replacement of Commitments 39 and 44 line in/out

NOC-AE-16003394 Enclosure 3 Page 1 of 4 Table A4-1 License Renewal Commitments

',,, lrrip~,i!i~~~~

3*,, *,,.,, >"/:::~;

39 Enhance the Selective Leaching of Aluminum Bronze procedures to: 82.1.37 No later than the date the renewed

  • Visually examine aluminum bronze materials exposed during inspection of the operating licenses buried essential cooling water piping for evidence of coating degradation are issued.

leakage, and

  • If degradation is identified near a weld a volumetric examination will be CR 11-28986 performed to determine if cracking of the weld is occurring.
  • If a leak from buried aluminum bronze welds is discovered by surface water monitoring or during a buried ECW piping inspection, a section of each leaking weld will be removed for destructive metallurgical examination.

44 The Selective Leaching of Aluminum Bronze program will: 82.1.37 Replacements and inspections to be

  • Replace all aluminum bronze castings susceptible to selective leaching, complete no later including attachment welds related to the castings with material that is not than six months susceptible to selective leaching. prior to the PEO or
  • Replace aluminum bronze root valve adapter socket welds with material that is the end of the last not susceptible to selective leaching. refueling outage prior to the PEO,
  • Replace extruded piping tees with aluminum bronze weld repairs where the whichever occurs repair size is such that failure of the repair would affect the structural integrity later.

of the component.

Procedure changes Enhance the Selective Leaching of Aluminum Bronze procedure to: no later than the date the renewed

  • Specify loss of material due to selective leaching is monitored through system operating licenses walkdowns and destructive examinations.

are issued.

  • Specify cracking associated with selective leaching is monitored through CR 12-22150

NOC-AE-16003394 Enclosure 3 Page 2 of 4 Table A4-1 License Renewal Commitments

  • item#
  • Implementation scliedule*--- -

volumetric examination and destructive examination.

  • Specify phase distribution to verify the potential for continuous selective leaching is monitored through destructive examination
  • Verify the \Veld integrity management of cracking of the above ground weld population with no backing rings _by performing a one-time volumetric examination on a20 percent with a maximum of W25 welds prior to the period of extended operation.
  • Specify, if§. weld defects areindication that does not meet the acceptance criteria is found during the one-time inspection of welds with no backing rings, periodic volumetric examinations of 20 percent with a maximum of 25 welds will be performed every 1O years thereafter.
  • Verify, the weld integrity management of cracking of the above ground weld population with backing rings by performing periodic volumetric examinations on 20 percent with a maximum of 25 welds prior to the period of extended operation and every 1O years thereafter.
  • Specify, if no weld defects are found during the periodic inspection performed prior to the period of extended operation of \Velds with backing rings, the follow up volumetric examinations will be reduced to 3 percent with a maximum of 10 welds.
  • Specify, the samples for volumetric examination be randomly selected from the total population of above ground welds, considering construction and size distributions.
  • Require two welds with backing rings be destructively examined prior to the period of extended operation to verify the absence of selective leaching.
  • Verify, the management of loss of material due to selective leaching and microstructure hase distribution of the above round weld o ulation with and

NOC-AE-16003394 Enclosure 3 Page 3 of 4 Table A4-1 License Renewal Commitments without backing rings by performing a one-time destructive examination on 20 percent with a maximum of 25 welds with backing rings and 20 percent with a maximum of 25 welds without backing rings prior to the period of extended operation.

  • Specify. if loss of material due to selective leaching does not meet the acceptance criteria during the one-time destructive examinations. periodic destructive examinations of 20 percent with a maximum of 25 welds will be performed every 10 years thereafter.
  • Require the sample population for destructive examinations be randomly selected from the total population of welds with and without backing rings.
  • Require .§..Welds which does not meet the acceptance criteria are found to Ra-ve.. defects or has through wall leakage, be removed and destructively examined to determine extent of cracking and/or selective leaching.
  • Require .§..Welds which does not meet the acceptance criteria are found to have defects or has through wall leakage, be documented in the corrective action program, and a structural integrity analysis be performed to confirm that the load carrying capacity of the installed welds remain adequate to support the intended function of the ECW system through the period of extended operation.
  • Require that the history of the volumetric and destructive examinations results be maintained and a review be performed to identify potential adverse trends or other indications requiring action.
  • Specify, the acceptance criterion for volumetric examination of aluminum bronze welds is no defects. detected planar indication that is surface connected (exposed to the ECW environment) unless the depth of the indication is contained within the 80% of the weld root ass re ion. An

~--------------------------- - - - - -

NOC-AE-16003394 Enclosure 3 Page 4 of 4 Table A4-1 License Renewal Commitments indication not connected to the surface (not exposed to the ECW environment) is acceptable.

  • Specify, the acceptance criterion for visual inspection of the aluminum bronze welds and adjacent copper alloy piping during the walkdowns is no through wall leakage.
  • Specify, the acceptance criterion for destructive examinations is no loss of material due to selective leaching penetrating 80% of the root-pass region and non-propagating (surrounded by a resistant phase distribution). The microstructure of the weld root region exhibits a non-continuous phase distribution consistent with the metallurgical technical basis report.
  • Specify, discovery of g_weld indication that does not meet the acceptance criteria defects requires expansion of the volumetric examination sample population. Each weld found with a weld indication that does not meet the acceptance criteria defect requires five additional volumetric examinations to be performed until no additional-weld indication that does not meet the acceptance criteria defects are i§_found.
  • Specify, discovery of selective leaching that does not meet the acceptance criteria requires expansion of the destructive examinations sample population.

Each destructive examination that does not meet the acceptance criteria requires five additional destructive examination examinations to be performed until no unacceptable selective leaching is found.

  • Specify, when acceptance criteria are not met a determination of operability and an assessment of the extent of condition is performed. Additionally, perform an AMP effectiveness evaluation to determine program changes required to manage the aging.

NOC-AE-16003394 Enclosure 4 STPNOC LRA Replacement Copy

NOC-AE-16003394 Enclosure 4 Page 1 of 16 A1.37 SELECTIVE LEACHING OF ALUMINUM BRONZE The Selective Leaching of Aluminum Bronze program manages loss of material and cracking due to selective leaching of aluminum bronze (copper alloy with greater than 8 percent aluminum) components and welds.exposed to raw water within the scope of license renewal.

The program also validates phase distribution characteristics of the microstructure.

All aluminum bronze castings susceptible to selective leaching, including attachment welds related to the castings, and aluminum bronze root valves with adapter socket welds will be replaced prior to the period of extended operation with material that is not susceptible to selective leaching. Extruded piping tees with aluminum bronze weld repairs, where the repair size is such that failure of the repair would affect the structural integrity of the component, will be replaced prior to the period of extended operation.

STP uses copper alloy piping with less than 8 percent aluminum content, which is not susceptible to selective leaching. However, there are welds in which the filler metal is copper alloy with greater than 8 percent aluminum. The final composition of welds and process used to fabricate the welds results in a reduction in the susceptibility of the root pass filler material to selective leaching.

The Selective Leaching of Aluminum Bronze program directs that prior to the period of extended operation 20 percent with a maximum of 25 welds of the above ground weld population with no backing rings are examined one-time volumetrically to manage cracking. If a weld indication that does not meet the acceptance criteria is found during the one-time inspection of welds with no backing rings, periodic volumetric examinations of 20 percent with a maximum of 25 welds will be performed every 10 years thereafter.

The Selective Leaching of Aluminum Bronze program directs that 20 percent with* a maximum of 25 welds of the above grouqd weld population with backing rings are examined volumetrically to manage cracking prior to the period of extended operation and every 10 years thereafter.

Discovery of a weld indication that does not meet the acceptance criteria requires expansion of the volumetric examination sample population. Each weld found with a weld indication that does not meet the acceptance criteria requires five additional volumetric examinations to be performed until no additional weld indication that does not meet the acceptance criteria is found.

The Selective Leaching of Aluminum Bronze program directs that prior to the period of extende,d operation 20 percent with a maximum of 25 welds of the above ground weld population with no backing rings and 20 percent with a maximum of 25 welds of the above ground weld population with backing rings be examined one-time destructively to detect verify the management of loss of material due to selective leaching and verify microstructure phase distribution. If selective leaching that does not meet the acceptance criteria is found, periodic destructive examinations of 20 percent with a maximum of 25 welds of the above ground weld population with no backing rings and 20 percent with a maximum of 25 welds of the above ground weld population with backing rings will be performed every 10 years thereafter.

Discovery of unacceptable selective leaching requires five additional destructive examinations to be performed until no unacceptable selective leaching is found.

Yard walkdowns are performed in the areas above the buried piping with aluminum bronze welds to look for changes in ground conditions that would indicate leakage. If a leak from a buried pipe weld is discovered by surface water monitoring or during a buried ECW piping

NOC-AE-16003394 Enclosure 4 Page 2 of 16 inspection, a section of each leaking piping weld will be removed for destructive examination.

Visual inspections are performed every six months (not to exceed nine months) of the external surfaces of the above ground welds for evidence of through wall leakage.

The Buried and Underground Piping and Tank program, B2.1.18, includes the visual inspection of the buried aluminum bronze exterior pipe coatings for visible breaks, gaps, and discontinuities which could indicate cracking of the welds and defines the acceptance criterion for buried pipe coatings.

The acceptance criterion for volumetric examination of aluminum bronze welds is no detected planar indication that is surface connected (exposed to the ECW environment) unless the depth of the indication is contained within the 80% of the weld root pass region. An indication not connected to the surface (not exposed to the ECW environment) is acceptable.

The acceptance criterion for visual inspection of the aluminum bronze welds and adjacent copper alloy piping during the walkdowns is no through wall leakage.

The acceptance criterion for destructive examinations is no loss of material due to selective leaching penetrating 80% of the root-pass region and non-propagating (surrounded by a resistant phase distribution). The microstructure of the weld root region exhibits a non-continuous phase distribution consistent with the metallurgical technical basis report.

The acceptance criterion for buried aluminum bronze exterior pipe coating is defined in the Buried Piping and Tanks Inspection Aging Management Program B2.1.18.

An aluminum-bronze weld found to have an indication that does not meet the acceptance criteria or has through wall leakage is removed and destructively examined to determine the extent of cracks and/or selective leaching. The condition is documented in the corrective action program and a structural integrity analysis is performed to confirm that the load carrying capacity of the installed welds remain adequate to support the intended function of the ECW system through the period of extended operation.

NOC-AE-16003394 Enclosure 4 Page 3 of 16 82.1.37 Selective Leaching of Aluminum Bronze Program Description The Selective Leaching of Aluminum Bronze program manages loss of material and cracking due to selective leaching for aluminum bronze (copper alloy with greater than eight percent aluminum) components and welds exposed to raw water within the scope of license renewal.

The program also validates phase distribution characteristics of the microstructure. The selective leaching of aluminum bronze is applied in addition to the Open-Cycle Cooling Water program (B2.1.9).

All aluminum bronze castings susceptible to selective leaching, including attachment welds related to the castings and aluminum bronze root valve adapter socket welds, will be replaced prior to the period of extended operation vyith material that is not susceptible to selective leaching. Extruded piping tees with aluminum bronze weld repairs, where the repair size is such that failure of the repair would affect the structural integrity of the component, will be replaced prior to the period of extended operation.

STP uses copper alloy piping with less than 8 percent aluminum content, which is not susceptible to selective leaching. However, there are welds in which the filler metal is copper alloy with greater than 8 percent aluminum. The final composition of welds and process used to fabricate the welds results in a reduction in the susceptibility of the root pass filler material to selective leaching.

The Selective Leaching of Aluminum Bronze program directs that prior to the period of extended operation 20 percent with a maximum of 25 welds of the above ground weld population with no a

backing rings are examined one-time volumetrically to manage cracking. If weld indication that does not meet the acceptance criteria is found during the one-time inspection of welds with no backing rings, periodic v0lumetric examinations of 20 percent with a maximum of 25 welds will be performed every 10 years thereafter.

The Selective Leaching of Aluminum Bronze program directs that 20 percent with a maximum of 25 welds of the above ground weld population with backing rings are examined volumetrically to manage cracking prior to the period of extended operation and every 10 years thereafter.

Discovery of a weld indication that does not meet the acceptance criteria requires expansion of the volumetric examination sample population. Each weld found with a weld indication that does not meet the acceptance criteria requires five additional volumetric examinations to be performed until no additional weld indication that does not meet the acceptance criteria is found.

The Selective Leaching of Aluminum Bronze program directs that prior to the period of extended operation 20 percent with a maximum of 25 welds of the above ground weld population with no backing rings and 20 percent with a maximum of 25 welds of the above ground weld population with backing rings be examined one-time destructively to detect loss of material due to selective leaching and verify microstructure phase distribution. If selective leaching that does not meet the acceptance criteria is found, periodic destructive examinations of 20 percent with a maximum of 25 welds of the above ground weld population with no backing rings and 20 percent with a maximum of 25 welds of the above ground weld population with backing rings will be performed every 10 years thereafter.

NOC-AE-16003394 Enclosure 4 Page 4of16 Discovery of unacceptable selective leaching requires five additional destructive examinations to be performed until no unacceptable selective leaching is found.

Yard walkdowns are performed in the areas above the buried piping with aluminum bronze welds to look for changes in ground conditions that would indicate leakage. If a leak from a buried pipe weld is discovered by surface water monitoring or during a buried ECW piping inspection, a section of each leaking piping weld will be removed for destructive examination.

Visual inspections are performed every six months of the external surfaces of the above ground welds for. evidence of through wall leakage.

The Buried and Underground Piping and Tank program, B2.1.18, includes the visual inspection of the buried aluminum bronze exterior pipe coatings for visible breaks, gaps, and discontinuities which could indicate cracking of the welds.

The acceptance criterion for volumetric examination of aluminum bronze welds is no detected planar indication that is surface connected (exposed to the ECW environment) unless the depth of the indication is contained within the 80% of the weld root pass region. An indication not connected to the surface (not exposed to the ECW environment) is acceptable.

The acceptance criterion for visual inspection of the aluminum bronze welds and adjacent copper alloy piping during the walkdowns is no through wall leakage.

  • The acceptance criterion for destructive examinations is no loss of material due to selective leaching penetrating 80% of the root-pass region and non-propagating (surrounded by a resistant phase distribution). The microstructure of the weld root region exhibits a non-continuous phase distribution consistent with the metallurgical technical basis report.

An aluminum bronze weld found to have an indication that does not meet the acceptance criteria or has through wall leakage is removed and destructively examined to determine the extent of cracks and/or selective leaching. The condition is documented in the corrective action program and a structural integrity analysis is performed to confirm that the load carrying capacity of the installed welds remain adequate to support the intended function of the ECW system through the period of extended operation.

Aging Management Program Elements

Scope of Program (Element 1)

The Selective Leaching of Aluminum Bronze program manages loss of material and cracking due to selective leaching for aluminum bronze (copper alloy with greater than 8 percent aluminum) components and welds exposed to raw water within the scope of license renewal.

Prior to the period of extended operation, all aluminum bronze castings susceptible to loss of material due to selective leaching, including attachment welds related to the castings and aluminum bronze root valves with adapter socket welds, will be replaced with material that is not susceptible to selective leaching.

NOC-AE-16003394 Enclosure 4 Page 5of16 Extruded piping tees with aluminum bronze weld repairs where the repair size is such that failure of the repair would affect the structural integrity of the component will be replaced prior to the period of extended operation.

STP uses copper alloy piping with less than 8 percent aluminum, which is not susceptible to selective leaching. However, welds in which the filler metal is copper alloy with greater than 8 percent aluminum may be susceptible to loss of material and cracking due to selective leaching.

The final composition of welds and process used to fabricate the welds results in a reduction in the susceptibility of the root pass filler material to selective leaching.

The following weld material is used.

  • ERCuAl-A2 with no backing ring,
  • ERCuNiAI with no backing ring,
  • ERCuAl-A2 with backing ring, and
  • ERCuAl-A2 non-cast component weld repairs.

Preventive Actions (Element 2)

The Selective Leaching of Aluminum Bronze program does not prevent degradation due to aging effects but provides for component replacement and inspections to detect aging degradation prior to the loss of intended functions.

External surfaces of the buried aluminum bronze piping are coated to prevent selective leaching of the exterior surface of the aluminum bronze welds. The above ground piping is not coated.

Parameters Monitored or Inspected (Element 3)

The susceptibility of aluminum bronze welds is related to the integrity of the weld, the weld material composition, and the welding temperature controls.

Loss of material due to selective leaching is monitored through system walkdowns and destructive examinations.

Cracking associated with selective leaching is monitored through volumetric examination and destructive examination.

Phase distribution to verify the potential for continuous selective leaching is monitored through destructive examination.

Welds without backing rings are either original ERCuAl-A2 material or replacement ERCuNiAI material. The original ERCuAl-A2 welds without backing rings were radiographed at time of installation to detect the presence of weld flaws. The replacement ERCuNiAI welds without backing rings were examined visually and by liquid penetrant method at time of installation. The ERCuNiAI weld material is less susceptible to selective leaching than the ERCuAl-A2 weld material due to the addition of nickel.

Welds with backing rings are original ERCuAl-A2 material. The original ERCuAl-A2 welds with backing rings were examined visually and by use of liquid penetrant method at time of installation.

The aging management program will manage cracking of the above ground weld population with no backing rings by performing a one-time volumetric examination on 20 percent with a

NOC-AE-16003394 Enclosure 4 Page 6 of 16 maximum of 25 welds prior to the period of extended operation. If a weld indication that does not meet the acceptance criteria is found during the one-time inspection of welds with no backing rings, periodic volumetric examinations of 20 percent with a maximum of 25 welds will be performed every 10 years thereafter.

The aging management program will manage cracking of the above ground weld population with backing rings by performing periodic volumetric examinations on 20 percent with a maximum of 25 welds prior to the period of extended operation and every 1O years thereafter.

Since the population of welds use similar material and are exposed to the same environment, the samples for volumetric examination will be randomly selected from the total population of welds, considering construction and size distributions. The above ground welds are used as the bounding condition to represent both the above and below ground welds when performing the volumetric examination.

The aging management program will manage loss of material due to selective leaching and verify microstructure phase distribution of the above ground weld population with and without backing rings by performing a one-time destructive examination on 20 percent with a maximum of 25 welds with backing rings and 20 percent with a maximum of 25 welds without backing rings prior to the period of extended operation. If selective leaching that does not meet the acceptance criteria is found, periodic destructive examinations of 20 percent with a maximum of 25 welds will be performed every 10 years thereafter.

Since destructive examinations is used to verify the susceptibility of the weld to selective leaching the sample population will be randomly selected from the total population of welds with and without backing rings.

Periodic walkdowns of the above ground piping, components and welds is performed to verify no through wall leakage.

Periodic walkdowns of the yard areas over the buried ECW piping and welds is performed to verify no evidence of through wall leakage.

An aluminum bronze weld found to have an indication that does not meet the acceptance criteria or has through wall leakage is removed and destructively examined to determine extent of cracks and/or selective leaching. The condition is documented in the corrective action program and a structural integrity analysis is performed to confirm that the load carrying capacity of the installed welds remain adequate to support the intended function of the ECW system through the period of extended operation.

The Buried and Underground Piping and Tank program, B2.1.18, includes the visual inspection of the buried aluminum bronze exterior pipe coatings for visible breaks, gaps, and discontinuities which could indicate possible cracking of the welds.

Detection of Aging Effects (Element 4)

The Selective Leaching of Aluminum Bronze program includes one-time and periodic volumetric and destructive examinations of aluminum bronze welds to determine if loss of material and cracking due to selective leaching is occurring.

NOC-AE-16003394 Enclosure 4 Page 7of16 The Selective Leaching of Aluminum Bronze program includes visual inspections every six months of the external surfaces of the above ground components and welds for _evidence of through wall leakage.

Every six months, a walkdown is performed in the areas above the buried ECW piping containing copper alloy welds with aluminum content greater than 8 percent. During the walkdown, the ground is observed for conditions that would indicate leakage. If a leak from a below-grade piping weld is discovered by surface water monitoring, a section of each leaking piping weld will be removed for destructive examination.

The Buried and Underground Piping and Tank program, B2.1.18, specifies that whenever aluminum bronze materials are exposed during inspection of the buried ECW piping, the exterior pipe coating is inspected for degradation. If degradation is identified near a weld a volumetric examination will be performed to determine if cracking of the weld is occurring.

If leaking below-grade welds are discovered during a buried ECW piping inspection, a section of each leaking weld will be removed for destructive examination.

An aluminum bronze weld found to have an indication that does not meet the acceptance criteria or has through wall leakage is removed and destructively examined to determine extent of loss of material and/or cracking due to selective leaching.

Monitoring and Trending (Element 5)

This is an inspection program to determine if selective leaching is occurring and the degree of the selective leaching.

STP will maintain the history of the volumetric and destructive examinations results. Following completion of the volumetric and destructive examinations scope, a review is performed to identify potential adverse trends or other indications requiring action.

Acceptance Criteria (Element 6)

The acceptance criterion for volumetric examination of aluminum bronze welds is no detected planar indication that is surface connected (exposed to the ECW environment) unless the depth of the indication is contained within the 80% of the weld root pass region. An indication not connected to the surface (not exposed to the ECW environment) is acceptable.

The acceptance criterion for visual inspection of the aluminum bronze welds and adjacent copper alloy piping during the walkdowns is no through wall leakage.

The acceptance criterion for destructive examinations is no loss of material due to selective leaching penetrating 80% of the root-pass region and non-propagating (surrounded by a resistant phase distribution). The microstructure of the weld root region exhibits a non-continuous phase distribution consistent with the metallurgical technical basis report.

The acceptance criterion for buried aluminum bronze exterior pipe coating is defined in the Buried Piping and Tanks Inspection Aging Management Program B2.1.18.

NOC-AE-16003394 Enclosure 4 Page 8 of 16 If an acceptance criterion is not met, the condition is documented in the corrective action program.

Corrective Actions (Element 7)

The following corrective actions are performed when acceptance criteria are not met:

A through wall leak of the above or below ground weld.

  • Remove weld and destructively examined to determine the extent of cracks or selective leaching.
  • Perform five additional volumetric inspections to assess extent of condition and cause.
  • Perform a structural integrity evaluation to confirm that the load carrying capacity of the installed welds remain adequate to support the intended function of the ECW system through the period of extended operation.
  • Replace leaking weld
  • Perform an AMP effectiveness evaluation to determine program changes required to manage the aging.

An aluminum bronze weld found to have an indication that does not meet the acceptance criteria.

  • Remove 'weld and destructively examined to determine the extent of cracks or selective leaching.
  • Perform five additional volumetric examinations until no additional weld indication that does not meet the acceptance criteria defects are is found to assess extend of condition and cause.
  • Perform a structural integrity evaluation to confirm that the load carrying capacity of the installed welds remain adequate to support the intended function of the ECW system through the period of extended operation.
  • Perform an AMP effectiveness evaluation to determine program changes required to manage the aging.
  • Replace weld A destructive examination does not meet acceptance criteria.
  • Perform five additional destructive examinations until no unacceptable selective leaching is found to assess extend of condition and cause.
  • Perform a structural integrity evaluation to confirm that the load carrying capacity of the installed welds remain adequate to support the intended function of the ECW system through the period of extended operation.
  • Perform an AMP effectiveness evaluation to determine program changes required to manage the aging.

The Buried Piping and Tanks Inspection Aging Management Program 82.1.18, outlines corrective actions resulting from the identification of degraded buried aluminum bronze exterior pipe coating.

(

NOC-AE-16003394 Enclosure 4 Page 9 of 16 STP QA procedures, review and approval process, and administrative controls are implemented in accordance with the requirements of 10 CFR 50 Appendix B and are acceptable in addressing corrective actions. The QA program includes elements of corrective action, and is applicable to the safety-related and nonsafety-related systems, structures, and components that are subject to aging management review.

Confirmation Process (Element 8)

STP QA procedures, review and approval process, and administrative controls are implemented in accordance with the requirements of 10 CFR 50 Appendix B and are acceptable in addressing confirmation processes and administrative controls. The QA program includes elements of corrective action, and is applicable to the safety-related and nonsafety-related systems, structures, and components that are subject to aging management review.

Administrative Controls (Element 9)

See Element 8.

Operating Experience (Element 10)

STP identified through-wall cracks in the ECW system piping which were initiated by pre-existing weld defects and propagated by a selective leaching phenomenon. The pre-existing weld defects identified appeared in welds with backing rings. The weld population consists of shop and field welds without backing rings, field welds with backing rings, weld repairs to extruded piping tees, and valves with adapter socket welds. Welds that have shown through-wall cracks have been welds with backing rings, weld repairs to extruded piping tees, and valves with adapter socket welds. Laboratory failure analysis data has indicated that in the cases with leaks, a preexisting crack penetrating into the central core of the weld was present.

Poor fit-up may have contributed to such root pass cracking. Crack growth appears to have occurred by a process of the crack tip selective leaching locally and the crack propagating through the selectively leached zone. The affected welds. were repaired.

Selective leaching has occurred in susceptible aluminum bronze components. STP will replace all susceptible aluminum bronze components prior to the period of extended operation.

Enhancements Prior to the period of extended operation, the following enhancements will be implemented in the following program elements:

Scope of Program (Element 1) and Preventive Actions (Element 2)

Procedure will be enhanced to:

  • Replace all aluminum bronze castings susceptible to selective leaching, including attachment welds with material that is not susceptible to selective leaching, prior to the period of extended operation.
  • Replace aluminum bronze root valve adapter socket welds with material that is not susceptible to selective leaching prior to the period of extended operation.

NOC-AE-16003394 Enclosure 4 Page 10of16

  • Replace extruded piping tees with aluminum bronze weld repairs where the repair size is such that failure of the repair would affect the structural integrity of the component prior to the period of extended operation.

Parameters Monitored or Inspected (Element 3)

Procedure will be enhanced to:

  • Specify, loss of material due to selective leaching is monitored through system walkdowns and destructive examinations.

\

  • Specify, cracking associated with selective leaching is monitored through volumetric examination and destructive examination.
  • Specify, phase distribution to verify the potential for continuous selective leaching is determined through destructive examination.
  • Verify, the management of cracking of the above ground weld population with no backing rings by performing a one-time volumetric examination on 20 percent with a maximum of 25 welds prior to the period of extended operation.
  • Specify, if a weld indication that does not meet the acceptance criteria is found during the one-time inspection of weld with no backing rings, periodic volumetric examinations of 20 percent with a maximum of 25 welds will be performed every 10 years thereafter.
  • Verify, the management of cracking of the above ground weld population with backing rings by performing periodic volumetric examinations on 20 percent with a maximum of 25 welds prior to the period of extended operation and every 10 years thereafter.
  • Specify, the samples for volumetric examination be randomly selected from the total population of above ground welds, considering construction and size distributions.
  • Verify, the management of selective leaching and microstructure phase distribution of the above ground weld population with and without backing rings by performing a one-time destructive examination on 20 percent with a maximum of 25 welds with backing rings and 20 percent with a maximum of 25 welds without backing rings prior to the period of extended operation.
  • Specify, if selective leaching does not meet the acceptance criteria during the one-time destructive examinations, periodic destructive examinations of 20 percent with a maximum of 25 welds will be performed every 10 years thereafter.
  • . Require the sample population for destructive examinations be randomly selected from the total population of welds with and without backing rings.

'

  • Require a weld which does not meet the acceptance criteria or has through wall leakage, be removed and destructively examined to determine the extent of cracks or selective leaching.
  • Require a welds which does not meet the acceptance criteria or has through wall leakage be documented in the corrective action program and a structural integrity

NOC-AE-16003394 Enclosure 4 Page 11of16 analysis be performed to confirm that the load carrying capacity of the installed welds remain adequate to support the intended function of the ECW system through the period of extended operation.

Detection of Aging Effects (Element 4)

Procedure will be enhanced to:

  • Require one-time and periodic volumetric examination of above ground aluminum bronze welds to determine if loss of material due to selective leaching or cracking is occurring.
  • Require one-time and periodic destructive examination of above ground aluminum bronze welds to determine if selective leaching is occurring and verify phase distribution.
  • Require a weld which does not meet the acceptance criteria or has through wall leakage be removed and destructively examined to determine extent of cracks and/or selective leaching.
  • Require whenever aluminum bronze materials are exposed during inspection of the buried ECW piping, the exterior aluminum bronze pipe coating is inspected for degradation. If degradation is identified near a weld a volumetric examination will be performed to determine if loss of material or cracking due to selective leaching is occurring.

Monitoring and Trending (Element 5)

Procedure will be enhanced to:

  • Require that the history of the volumetric and destructive examinations results be maintained and a review be performed to identify potential adverse trends or other indications requiring action.

Acceptance Criteria (Element 6)

Procedure will be enhanced to:

  • Specify, the acceptance criterion for volumetric examination of aluminum bronze welds is no detected planar indication that is surface connected (exposed to the ECW environment) unless the depth of the indication is contained within the 80% of the weld root pass region. An indication not connected to the surface (not exposed to the ECW environment) is acceptable.
  • Specify, the acceptance criterion for visual inspection of the aluminum bronze welds and adjacent copper alloy piping during the Walkdowns is no through wall leakage.
  • Specify, the acceptance criterion for destructive examinations is no loss of material due to selective leaching penetrating 80% of the root-pass region and non-propagating (surrounded by a resistant phase distribution). The microstructure of the weld root region exhibits a non-continuous phase distribution consistent with the metallurgical technical basis report.

NOC-AE-16003394 Enclosure 4 Page 12of16

  • Require, if an acceptance criterion is not met, the unacceptable condition be documented in the corrective action program and a structural integrity analysis be performed to confirm that the load carrying capacity of the installed welds remain adequate to support the intended function of the ECW system through the period of extended operation.

Corrective Actions (Element 7)

Procedure will be enhanced to:

  • Require, upon discovery of a weld which does not meet the acceptance criteria or has through wall leakage, the weld is removed and destructively examined to determine extent of cracking and/or selective leaching.
  • Specify, when a weld is found that does not meet the acceptance criteria a structural integrity analysis shall be performed to confirm that the load carrying capacity of the installed welds remain adequate to support the intended function of the ECW system through the period of extended operation.
  • Specify, discovery of a weld indication that does not meet the acceptance criteria requires expansion of the volumetric examination sample population. Each weld found with a weld indication that does not meet the acceptance criteria requires five additional volumetric examinations to be performed until no additional weld indication that does not meet the acceptance criteria is found.
  • Specify, discovery of selective leaching that does not meet the acceptance criteria . I requires expansion of the destructive examinations sample population. Each destructive i I

examination that does not meet the acceptance criteria requires five additional I destructive examination examinations to be performed until no unacceptable selective leaching is found.

  • Specify, if acceptance criteria are not met a determination of operability and an assessment of the extent of condition is performed. Additionally, perform an AMP effectiveness evaluation to determine program changes required to manage the aging.

Conclusion The continued implementation of the Selective Leaching of Aluminum Bronze program provides reasonable assurance that aging effects will be managed such that the systems and components within the scope of this program will continue to perform their intended functions consistent with the current licensing pasis for the period of extended operation.

NOC-AE-16003394 Enclosure 4 Page 13of16 Table A4-1 License Renewal Commitments 39 Enhance the Selective Leaching of Aluminum Bronze procedures to: 82.1.37 No later than the date the renewed

  • Visually examine aluminum bronze materials exposed during inspection of the operating licenses buried essential cooling water piping for evidence of coating degradation and are issued.
  • If degradation is identified near a weld a volumetric examination will be performed to determine if cracking of the weld is occurring. \ CR 11-28986

)

  • If a leak from buried aluminum bronze welds is discovered by surface water monitoring or during a buried ECW piping inspection, a section of each leaking weld will be removed for destructive metallurgical examination.

44 The Selective Leaching of Aluminum Bronze program will: 82.1.37 Replacements and inspections to be

  • Replace all aluminum bronze castings susceptible to selective leaching, complete no later including attachment welds related to the castings with material that is not than six months susceptible to selective leaching. prior to the PEO or
  • Replace aluminum bronze root valve adapter socket welds with material that is the end of the last not susceptible to selective leaching. refueling outage prior to the PEO,
  • Replace extruded piping tees with aluminum bronze weld repairs where the whichever occurs repair size is such that failure of the repair would affect the structural integrity later.

of the component.

Procedure changes Enhance the Selective Leaching of Aluminum Bronze procedure to:

no later than the

  • Specify loss of material due to selective leaching is monitored through system date the renewed walkdowns and destructive examinations. operating licenses are issued.

~ Specify cracking associated with selective leaching is monitored through volumetric examination and destructive examination.

CR 12-22150

NOC-AE-16003394 Enclosure 4 Page 14 of 16 Table A4-1 License Renewal Commitments

  • Specify phase distribution to verify the potential for continuous selective leaching is monitored through destructive examination
  • Verify the management of cracking of the above ground weld population with no backing rings by performing a one-time volumetric examination on 20 percent with a maximum of 25 welds prior to the period of extended operation.
  • Specify, if a weld indication that does not meet the acceptance criteria is found during the one-time inspection of welds with no backing rings, periodic volumetric examinations of 20 percent with a maximum of 25 welds will be performed every 1O years thereafter.
  • Verify, the management of cracking of the above ground weld population with backing rings by performing periodic volumetric examinations on 20 percent with a maximum of 25 welds prior to the period of extended operation and every 10 years thereafter.
  • Specify, the samples for volumetric examination be randomly selected from the total population of above ground welds, considering construction and size distributions.
  • Verify, the management of loss of material due to selective leaching and microstructure phase distribution of the above ground weld population with and without backing rings by performing a one-time destructive examination on 20 percent with a maximum of 25 welds with backing rings and 20 percent with a maximum of 25 welds without backing rings prior to the period of extended operation.
  • Specify, if loss of material due to selective leaching does not meet the acceptance criteria during the one-time destructive examinations, periodic destructive examinations of 20 percent with a maximum of 25 welds will be erformed ever 1O ears thereafter.

NOC-AE-16003394 Enclosure 4 Page 15of16 Table A4-1 License Renewal Commitments

  • Require the sample population for destructive examinations be randomly selected from the total population of welds with and without backing rings.
  • Require a weld which does not meet the acceptance criteria or has through wall leakage, be removed and destructively examined to determine extent of cracking and/or selective leaching.
  • Require a weld which does not meet the acceptance criteria or has through wall leakage, be documented in the corrective action program, and a structural integrity analysis be performed to confirm that the load carrying capacity of the installed welds remain adequate to support the intended function of the ECW system through the period of extended operation.
  • Require that the history of the volumetric and destructive examinations results be maintained and a review be performed to identify potential adverse trends or other indications requiring action.
  • Specify, the acceptance criterion for volumetric examination of aluminum bronze welds is no detected planar indication that is surface connected (exposed to the ECW environment) unless the depth of the indication is contained within the 80% of the weld root pass region. An indication not connected to the surface (not exposed to the ECW environment) is acceptable.
  • Specify, the acceptance criterion for visual inspection of the aluminum bronze welds and adjacent copper alloy piping during the walkdowns is no through wall leakage.
  • Specify, the acceptance criterion for destructive examinations is no loss of material due to selective leaching penetrating 80% of the root-pass region and non-propagating (surrounded by a resistant phase distribution). The microstructure of the weld root region exhibits a non-continuous phase distribution consistent with the metallur ical technical basis re ort.

NOC-AE-16003394 Enclosure 4 Page 16of16 Table A4-1 License Renewal Commitments

  • Specify, discovery of a weld indication that does not meet the acceptance criteria requires expansion of the volumetric examination sample population.

Each weld found with a weld indication that does not meet the acceptance criteria requires five additional volumetric examinations to be performed until no additional-weld indication that does not meet the acceptance criteria is found.

  • Specify, discovery of selective leaching that does not meet the acceptance criteria requires expansion of the destructive examinations sample population.

Each destructive examination that does not meet the acceptance criteria requires five additional destructive examination examinations to be performed until no unacceptable selective leaching is found.

  • Specify, when acceptance criteria are not met a determination of operability and an assessment of the extent of condition is performed. Additionally, perform an AMP effectiveness evaluation to determine program changes required to manage the aging.
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