ML24339B882

LRA - Requests for Additional Information

ML24339B882
Person / Time
Site:	Diablo Canyon
Issue date:	12/04/2024
From:	Harris B Office of Nuclear Reactor Regulation
To:
Shared Package
ML24339B881	List: ML24339B882 ML24339B883
References
Download: ML24339B882 (1)

Text

1 REQUEST FOR ADDITIONAL INFORMATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION DIABLO CANYON LRA SAFETY REVIEW PACIFIC GAS AND ELECTRIC COMPANY DIABLO CANYON, UNITS 1, 2 DOCKET NO. 05000275, 05000323 ISSUE DATE: December 4, 2024 Set 2 RAI B.2.3.24 Regulatory Basis Section 54.21(a)(3) of Title 10 of the Code of Federal Regulations (10 CFR) requires an applicant to demonstrate that the effects of aging for structures and components will be adequately managed so that the intended function(s) will be maintained consistent with the current licensing basis for the period of extended operation. One of the findings that the U.S.

Nuclear Regulatory Commission (NRC) staff must make to issue a renewed license (10 CFR 54.29(a)) is that actions have been identified and have been or will be taken with respect to managing the effects of aging during the period of extended operation on the functionality of structures and components that have been identified to require review under 10 CFR 54.21, such that there is reasonable assurance that the activities authorized by the renewed license will continue to be conducted in accordance with the current licensing basis. In order to complete its review and enable making a finding under 10 CFR 54.29(a), the staff requires additional information in regard to the matters described below.

Background

Program Element 3, Parameters Monitored or Inspected in the GALL-SLR Report AMP XI.M38 states, in part:

Periodic surface examinations are conducted if this program is being used to manage cracking in SS or aluminum components. Visual inspections for leakage or surface cracks are an acceptable alternative to conducting surface examinations to detect cracking if it has been determined that cracks will be detected prior to challenging the structural integrity or intended function of the component. [emphasis added]

Program Element 4, Detection of Aging Effects in the GALL-SLR Report AMP XI.M38 states, in part:

Periodic visual inspections or surface examinations are conducted on SS and aluminum to manage cracking every 10 years during the subsequent period of extended operation when applicable (e.g., see SRP-SLR Sections 3.2.2.2.4 and 3.2.2.2.8). One or more of the following three options may be used to implement the periodic visual inspections or surface examinations:

Surface examination conducted in accordance with plant-specific procedures.

ASME Code Section XI VT-1 inspections (including those inspections conducted on non-ASME Code components).

Visual inspections are conducted where it has been analytically demonstrated that surface cracks can be detected by leakage prior to a crack challenging the structural integrity or intended function of the component. The SLRA includes an overview of the analytical

2 method, input variables, assumptions, basis for use of bounding analyses, and results.

[emphasis added]

When using this option, cracks can be detected in gas-filled systems by methods such as, but not limited to: (a) for diesel exhaust piping, detecting staining on external surfaces of components; (b) for accumulators and piping connecting the accumulators to components, monitoring and trending accumulator pressures or refill frequency; and (c) soap bubble testing when systems are pressurized. The SLRA includes the specific methods used. [emphasis added]

In LRA Section B.2.3.24, Inspection of Internal Surfaces in Miscellaneous Piping and Ducting Components the justification for exception 2 states, in part:

Visual inspections for leakage or surface cracks are an acceptable alternative to conducting surface examination to detect cracking if it has been determined that cracks will be detected prior to challenging the structural integrity or intended function of the component. In addition, the NRC previously found these methods acceptable for managing cracking of copper alloy (>15%

Zn or >8% Al) components (Reference ML22054A108).

The NRC staff notes that:

1. The initial SLRA submission referenced in ML22054A108 was revised by a supplement (ML21111A155) to clarify that only surface examinations or ASME Code Section XI VT-1 inspections would be used to detect cracking and loss of material of stainless steel, copper alloy (>15 percent zinc), and aluminum components.

2. The Diablo Canyon LRA did not include an analytical demonstration that surface cracks can be detected by leakage prior to a crack challenging the structural integrity or intended function of the component. Also, the LRA did not include a description of the specific methods that would be used when implementing visual inspections instead of surface examinations or ASME Code Section XI VT-1 inspections.

Issue The NRC staff is unclear on whether the applicant intends to use visual inspections in lieu of surface examinations or ASME Code Section XI VT-1 inspections to detect cracking and loss of material of stainless steel, copper alloy (>15% Zn or >8% Al), and aluminum components.

Request Please discuss whether visual inspections in lieu of surface examinations or ASME Code Section XI VT-1 inspections will be used to detect cracking and loss of material in stainless steel, copper alloy (>15% Zn or >8% Al), and aluminum components. If that is the intention of exception 2, please provide the specific methods that will be used and an overview of the analytical method(s), input variables, assumptions, basis for use of the bounding analyses, and the results.

3 RAI 4.3.2-1 Regulatory Basis Pursuant to 10 CFR 54.21(c), the LRA must include an evaluation of time-limited aging analyses (TLAAs). The applicant must demonstrate that (i) the analyses remain valid for the period of extended operation, (ii) the analyses have been projected to the end of the period of extended operation, or (iii) the effects of aging on the intended function(s) will be adequately managed for the period of extended operation.

Background

LRA Section 4.3.2.12 addresses the TLAA for the primary loop piping in relation to the leak-before-break (LBB) analysis. The LRA indicates that the effects of thermal aging in cast austenitic stainless steel (CASS) materials depend on time (i.e., after a prolonged exposure to high temperatures, the thermal aging effects achieve a saturation level, after which further exposure to high temperatures do not affect the material properties of CASS).

LRA Section 4.3.2.12 also explains that, since the LBB analysis documented in the WCAP-13039 report relied on fully aged reference material (i.e., with the properties at the saturation levels), the analyses do not have a material property time-dependency that would require further evaluation for license renewal and, therefore, the fracture mechanics analysis is not a TLAA in accordance with 10 CFR 54.3(a)(3) (

Reference:

WCAP-13039, Technical Justification for Eliminating Large Primary Loop Pipe Rupture as the Structural Design Basis for the Diablo Canyon Units 1 and 2 Nuclear Power Plants, November 1991).

Issue The staff noted that Table 4-7 of WCAP-13039 describes the fracture toughness values (e.g., J Ic and T mat values) used in the existing LBB analysis for various material heats. In contrast to the statement in LRA Section 4.3.2.12, the fracture toughness values in WCAP-13039, Table 4-7 are equivalent to the 40-year fracture toughness values listed in WCAP-13039, Appendix B, Tables B-1 and B-2 (DCPP Units 1 and 2, respectively) rather than saturated fracture toughness values.

In addition, the staff noted that for location 10 in the cross-over leg (elbow fabricated with CF8M material, heat number 13930-5), the fracture toughness values (e.g., J Ic and T mat values) used in WCAP-13039, Table 4-7 and related fracture mechanics analysis are greater than the saturated facture toughness values estimated in accordance with NUREG/CR-4513, Revision

2.

Request

1. Resolve the apparent inconsistency regarding the use of saturated fracture toughness values between LRA Section 4.3.2.12 and WCAP-13039, Table 4-7. As part of the response, clarify why LRA Section 4.3.2.12 indicates that the existing LBB analysis uses the saturated fracture toughness values in contrast with WCAP-13039, Tables 4-7, B-1 and B-2 that indicate that the LBB analysis uses the 40-year fracture toughness values.

2. If the inconsistency discussed in Request 1 above cannot be resolved, revise LRA Section 4.3.2.12 and related FSAR supplement as needed to discuss a TLAA addressing the time-dependency of the fracture toughness of CASS materials and the TLAA disposition.

3. Given that the fracture toughness values for location 10 used in WCAP-13039, Table 4-7 and related fracture mechanics analysis are greater than the saturated fracture toughness values per NUREG/CR-4513, Revision 2, provide justification for why the fracture toughness

4 values used in WCAP-13039 is adequate for the fracture mechanics analysis for the location. If such justification cannot be made, provide additional information to demonstrate that the fracture mechanics analysis for location 10 based on the saturated fracture toughness values per NUREG/CR-4513, Revision 2 is acceptable.

4. Given that the fracture toughness estimation in accordance with NUREG/CR-4513, Revision 2 considers the effects of the casting method (i.e., static or centrifugal casting), clarify whether the elbows evaluated in the LBB analysis are static or centrifugal cast elbows.

RAI B.2.3.41-1 Regulatory Basis 10 CFR 54.21(a)(3) requires an applicant to demonstrate that the effects of aging for structures and components will be adequately managed so that the intended function(s) will be maintained consistent with the current licensing basis for the period of extended operation. One of the findings that the staff must make to issue a renewed license (10 CFR 54.29(a)) is that actions have been identified and have been or will be taken with respect to managing the effects of aging during the period of extended operation on the functionality of structures and components that have been identified to require review under 10 CFR 54.21, such that there is reasonable assurance that the activities authorized by the renewed license will continue to be conducted in accordance with the current licensing basis. In order to complete its review and enable making a finding under 10 CFR 54.29(a), the staff requires additional information in regard to the matters described below.

Background

LRA Section B.2.3.41 describes the new Periodic Inspections for Selective Leaching program as plant-specific. The applicant identified two populations (i.e., materials and environment combinations) where selective leaching is occurring and provided the Periodic Inspections for Selective Leaching program to manage loss of material due to selective leaching for these populations. The two populations being managed using this plant-specific AMP are: (a) gray cast iron components exposed to soil; and (b) aluminum-bronze components exposed to raw water. With the issuance of GALL-SLR Report AMP XI.M33, Selective Leaching, the staff provided a framework to manage loss of material due to selective leaching through periodic inspections, as opposed to the GALL-LR Report AMP XI.M33 framework which recommends one-time inspections to demonstrate that this aging effect is not occurring. In addition, the staff noted the applicant developed the Periodic Inspections for Selective Leaching program based on the guidance provided in GALL-SLR Report AMP XI.M33. Therefore, the staff compared the program elements included in LRA Section B.2.3.41 to the corresponding program elements of GALL-SLR Report AMP XI.M33.

As amended by letter dated October 14, 2024 (ML24289A118), the detection of aging effects program element in LRA Section B.2.3.41 states the following (in part):

[t]here are less than 35 valves and associated gray cast iron piping for each Unit that are in a soil environment (applies to the Fire Protection System and Makeup Water System). In accordance with the recommendations set forth by NUREG-2191, for sample populations with less than 35 components, DCPP will perform one destructive examination for this population during each inspection period at each Unit GALL-SLR Report AMP XI.M33 recommends two destructive examinations are performed in each 10-year period at each unit for sample populations with greater than 35 susceptible

5 components. When inspections are conducted on piping, a 1-foot axial length section is considered as one inspection.

Issue It is the staffs understanding that there are greater than 35 gray cast iron components exposed to soil, when considering that a 1-foot axial length section of piping is considered one component. Based on this, the staff seeks clarification with respect to why two destructive examinations will not be performed for this population.

Request Clarify if there are greater than 35 gray cast iron components exposed to soil, when considering that a 1-foot axial length section of piping is considered one component. If there is, state the basis for performing one destructive examination for this population during each inspection period at each unit. Alternatively, revise the LRA (as appropriate) to reflect that two destructive examinations will be performed for this population during each inspection period at each unit.

RAI B.2.3.26-1 Regulatory Basis 10 CFR 54.21(a)(3) requires an applicant to demonstrate that the effects of aging for structures and components will be adequately managed so that the intended function(s) will be maintained consistent with the current licensing basis for the period of extended operation. One of the findings that the staff must make to issue a renewed license (10 CFR 54.29(a)) is that actions have been identified and have been or will be taken with respect to managing the effects of aging during the period of extended operation on the functionality of structures and components that have been identified to require review under 10 CFR 54.21, such that there is reasonable assurance that the activities authorized by the renewed license will continue to be conducted in accordance with the current licensing basis. In order to complete its review and enable making a finding under 10 CFR 54.29(a), the staff requires additional information in regard to the matters described below.

Background

As amended by letter dated October 14, 2024 (ML24289A118), LRA Table 3.3.2-3 states that hardening, loss of strength, and loss of material for elastomeric expansion joints exposed to a buried environment will be managed by the Buried and Underground Piping and Tanks program.

The AMR items cite generic note J.

As amended by letter dated October 14, 2024, LRA Section B.2.3.26, Buried and Underground Piping and Tanks, states [t]he DCPP Buried and Underground Piping and Tanks AMP is an existing program that manages cracking, loss of material, hardening and loss of strength (for elastomers only), and change in surface conditions of buried and underground components in the auxiliary saltwater (ASW) system, diesel generator fuel transfer system, fire protection system, and the makeup water system[v]isual inspections monitor the condition of protective coatings and wrappings and directly assess the surface condition of components with no protective coatings or wraps.

LR-ISG-2012-02, "Aging Management of Internal Surfaces, Fire Water Systems, Atmospheric Storage Tanks, and Corrosion Under Insulation, provides guidance with respect to managing hardening and loss of strength for elastomeric components using GALL-LR Report AMP XI.M36,

6 External Surfaces Monitoring of Mechanical Components. The guidance specifies that (a) physical manipulation is used to augment visual inspections to confirm the absence of elastomer hardening and loss of strength; and (b) that the sample size for physical manipulation should be at least 10 percent of available surface area.

Issue It is unclear to the staff why physical manipulation (i.e., pressing, flexing and bending) of at least 10 percent of available surface area is not used to augment visual inspections of the buried elastomeric expansion joints.

Request State the basis for why physical manipulation of at least 10 percent of available surface area is not used to augment visual inspections of the buried elastomeric expansion joints. Alternatively, revise the LRA (as appropriate) to reflect that physical manipulation of at least 10 percent of available surface area will be used to augment visual inspections of the buried elastomeric expansion joints.

RAI B.2.3.36 Regulatory Basis 10 CFR 54.21(a)(3) requires an applicant to demonstrate that the effects of aging for structures and components will be adequately managed so that the intended function(s) will be maintained FRQVLVWHQWZLWKWKHFXUUHQWOLFHQVLQJEDVLVIRUWKHSHULRGRIH[WHQGHGRSHUDWLRQ2QHRIWKH

findings that the staff must make to issue a renewed license (10 CFR 54.29(a)) is that actions have been identified and have been or will be taken with respect to managing the effects of aging during the period of extended operation on the functionality of structures and components that have been identified to reTXLUHUHYLHZXQGHU&)5VXFKWKDWWKHUHLVUHDVRQDEOH

assurance that the activities authorized by the renewed license will continue to be conducted in DFFRUGDQFHZLWKWKHFXUUHQWOLFHQVLQJEDVLV,QRUGHUWRFRPSOHWHLWVUHYLHZDQGHQDEOHPDNLQJD finding under 10 CFR 54.29(a), the staff requires additional information in regard to the matters described below.

Background

As amended by letter dated October 14, 2024 (ML24289A118), the applicant included a proposed revision to aging management program (AMP) B.2.3.36, Insulation Material for Electric Cables and Connections Not Subject to 10 CFR 50.49 Environmental Qualification Requirements. The proposed revision resulted from an observation made during the NRC staffs onsite audit at DCPP. Specifically, during the onsite audit, the applicants staff identified the presence of and showed the NRC staff an adverse localized environment (ALE) that involved oil mist residue on in-scope cables located in the auxiliary building.

The proposed aging management revision is contrary to existing guidance noted in EPRI Report 3002010641, Low Voltage and Instrumentation and Control Cable Aging Management Guide.

Revision 1 which provides guidance for instances when low voltage and instrumentation and controls cables that are unintentionally exposed to chemicals, including oil. Unlike the actual condition at DCPP, the EPRI report guidance assumes that the oil exposure was because of a one-time event/spill (i.e., assumes that once the cables are cleaned that they will no longer be exposed to chemicals/oil, thereby removing a potential degradation mechanism). The cables were not designed to be protected against constant exposure to oil.

7 The proposed aging management revision consisted of visual inspection of the accessible portions of the cable trays from the ground level and the wiping of the cables. The NRC staff is not aware of any additional inspections or tests that the applicant performed on the impacted cables to assess the current condition or the effects of the oil on the cables. The proposed aging management for in-scope cables subject to this ALE may lead to degradation going undetected.

Therefore, consistent with EPRI Report 3002010641, more precise testing, such as indenter modulus, in combination with full visible and tactile inspections appears to be more appropriate to fully ascertain whether in-scope cables are showing signs of degradation (i.e., softening or swelling) during the period of extended operation.

The NRC staff needs additional information to reach a conclusion of reasonable assurance that the applicants proposed AMP B.2.3.36, Insulation Material for Electric Cables and Connections Not Subject to 10 CFR 50.49 Environmental Qualification Requirements, as modified in Amendment 1, will adequately manage the degradation mechanisms caused by the aforementioned ALE to ensure that in-scope cables will continue to perform their design function(s) consistent with the CLB during the period of extended operation.

Request Provide additional information supporting the proposed aging management of in-scope cables subjected to the ALE (chemicals/oil mist) and/or additional aging management actions to provide reasonable assurance that the impacted cables will perform their design function(s) during the period of extended operation including corrective actions to prevent oil mist residue from contacting the impacted cables.

RAI B.2.3.33-1 Regulatory Basis Title 10 of the Code of Federal Regulations Section 54.21(a)(3) requires the applicant to demonstrate that the effects of aging for structures and components will be adequately managed so that the intended function will be maintained consistent with the current licensing basis (CLB) for the period of extended operation. As described in the SRP-LR, an applicant may demonstrate compliance with 10 CFR 54.21(a)(3) by referencing the GALL-LR Report when evaluation of the matter in the GALL-LR Report applies to the plant.

Background

LRA Section B.2.3.33, as modified by LRA Amendment 1 (ML24289A118), provides an enhancement to the parameters monitored or inspected program element, which relates to monitoring/inspecting structural sealants (including weatherproofing boots) for parameters specified in ACI 349.3R and/or ANSI/ASCE 11, and it also provides an enhancement to the acceptance criteria program element, which relates to specifying that structural sealants (including weatherproofing boots) are acceptable if the observed loss of material, cracking, and hardening will not result in loss of sealing.

LRA Section A.2.2.33 states that the DCPP Structures Monitoring AMP utilizes acceptance criteria for structural components and structural features in accordance with ACI 349.3R-02 and ASCE 11-90.

GALL-LR XI.S6 AMP states in the parameters monitored or inspected program element that elastomeric vibration isolators and structural sealants are monitored for cracking, loss of material, and hardening.

8 Issue LRA does not specify the version of ACI 349.3R and ANSI/ASCE 11 in the enhancement. The staff reviewed ACI 349.3R-02 and ANSI/ASCE 11-90 and did not find parameters monitored or inspected for structural sealants (including weatherproofing boots).

Request

1. Clarify the parameters monitored or inspected for structural sealants (including weatherproofing boots).

2. Clarify the version of ACI 349.3R and ANSI/ASCE 11 in this enhancement and clarify which code provisions specify the parameters monitored or inspected for structural sealants (including weatherproofing boots).

3. Revise the enhancement accordingly based on the responses above.

B.2.3.33-2 Regulatory Basis Title 10 of the Code of Federal Regulations Section 54.21(a)(3) requires the applicant to demonstrate that the effects of aging for structures and components will be adequately managed so that the intended function will be maintained consistent with the current licensing basis (CLB) for the period of extended operation. As described in the SRP-LR, an applicant may demonstrate compliance with 10 CFR 54.21(a)(3) by referencing the GALL-LR Report when evaluation of the matter in the GALL-LR Report applies to the plant.

Background

EPRI 3002007358, 2016 technical report, provides guidance for aging management of leaking spent fuel pools (SFPs) for pressurized water reactors (PWRs) with a focus on boric acid attack of concrete (BAAC). The Appendix A of EPRI report provides a generic aging management program (AMP) template for managing effects of BAAC in a spent fuel pool (SFP) structure that has been exposed to leakage.

LRA Section B.2.3.33, as modified by LRA Amendment 1 (ML24289A118), provides enhancements to the Elements 1 to 7, which relate to including but not limited to the following: (1) Develop or revise procedures to manage the SFP and Transfer Canal (TC) surveillance and maintenance activities consistent with Elements 1 through 7 of EPRI 3002007348; and (2) Evaluate NUREG/CR-7111, EPRI 3002007348 enhancement recommendations, industry OE, and DCPP OE pertaining to reactor cavity and refueling canal liner leaks to determine appropriate inspection and maintenance activities for the reactor cavity and refueling canal. The staff noted that no enhancement to the preventative actions program element is needed for aging management of BAAC based on review of EPRI 3002007358 report.

During the audit (ML24311A123), the staff noted that the applicant made an evaluation of the DCPP Structures Monitoring program elements 1 through 7 for the SFP and TC to identify the level of consistency with the Appendix A AMP template for aging management of boric acid attack on reinforced concrete structures in EPRI 3002007348 report and provided the detailed enhancements to the Structures Monitoring program for each program element. The staff reviewed these enhancements to the Structures Monitoring program (file name: SFP & Transfer Canal Element 1-7 Evaluations.pdf) and identified the following issues:

9 (1) All Elements: Enhancements to the Structures Monitoring program do not make clear whether they are applicable to the TC, reactor cavity and refueling canal since only SFP is mentioned; (2) Element 3, Parameters monitored or inspected: Monitoring of leak chase system discharge: The enhancement lacks information for determining flow (drip) rate from the leak chase system discharge, it also miss some parameters (e.g. pH, Boron, Iron) from the chemical analyses; (3) Element 4, Detection of aging effects: Monitoring of leak chase system discharge:

Sample collection and analyses lack other parameters such as pH, boron, and iron. Inspection of telltale: Subsequent periodic tell-tale drain internal inspection frequency is not specified; (4) Element 6, Acceptance criteria: Inspection of telltales: The enhancement is inconsistent with EPRI 3002007348 report recommendations on no indications of blockage development; (5) Element 7, Corrective actions: The applicant does not provide the justification why the enhancement to the corrective actions program element is not needed.

Issue The enhancements to the Structures Monitoring program for aging management of BAAC in LRA Section B.2.3.33, as modified by LRA Amendment 1 (ML24289A118) are too broad. They need to be specific with detailed information based on the plant-specific operating experiences to ensure when they are implemented, they will be consistent with the EPRI 3002007358 report recommendations. In addition, see issues identified by the staff in the background section above.

Request

1. Evaluate Elements 1, and 3 through 7 in the EPRI 3002007348 report AMP template to determine which elements need to be enhanced in the DCPP Structures Monitoring program for managing aging effects of BAAC in the SFP, TC, reactor cavity and refueling canal, and provide detailed enhancements to each program element if necessary to ensure the consistency with EPRI 3002007348 report recommendations.

2. Provide the justification for why certain enhancements described in EPRI 3002007348 report AMP template are not necessary.

3. Address the issues from 1 to 5 identified by the staff in the background section.

4. Revise the LRA accordingly based on the responses above.

RAI 3.5.2 Regulatory Basis Title 10 of the Code of Federal Regulations Section 54.21(a)(3) requires the applicant to demonstrate that the effects of aging for structures and components will be adequately managed so that the intended function will be maintained consistent with the current licensing basis (CLB) for the period of extended operation. As described in the SRP-LR, an applicant may demonstrate compliance with 10 CFR 54.21(a)(3) by referencing the GALL-LR Report when evaluation of the matter in the GALL-LR Report applies to the plant.

10

Background

LRA Table 3.5.2-14, as modified by LRA Amendment 1 (ML24289A118), lists PVC conduit and supports exposed to a buried environment, there is no aging effect, and no Aging Management Program (AMP) is proposed. The AMR item cites generic note G. The AMR item cites plant-specific note 2, which states that, due to DCPPs location in a negligible weathering region where concrete is rarely exposed to freezing in the presence of moisture, there are no significant seasonal changes on the soil, and no movement over time that would induce loss of material due to wear on the buried PVC conduit. While the staff noted that a freeze/thaw cycle is a potential contributor to movement of deleterious materials on the soil, it is not the only potential contributor to loss of material due to wear on the buried PVC conduit and supports.

Seasonal heavy precipitation and/or variations of groundwater levels throughout the site could potentially cause significant changes to occur on the soil surrounding PVC conduit and supports.

Issue The LRA does not provide adequate technical basis for not managing the aging effect of loss of material due to wear for PVC conduit and supports exposed to a buried environment. In addition, the LRA does not make clear how the definition of a negligible weathering region defined for not impacting concrete due to freeze-thaw is applicable to PVC as these materials are subject to different aging mechanisms and aging effects due to their inherent differences in chemical/physical composition and their interactions with the surrounding soil or groundwater.

Request

1. Provide adequate justification for not managing the aging effect of loss of material due to wear for PVC conduit and supports exposed to a buried environment. Otherwise, identify and assess an appropriate AMP to manage loss of material for PVC in a buried environment to be consistent with the GALL-LR Report.

2. Revise the application accordingly based on the responses above.

RAI 3.6 Regulatory Basis:

Section 54.21(a)(3) of Title 10 of the Code of Federal Regulations (10 CFR) requires an applicant to demonstrate that the effects of aging for structures and components will be adequately managed so that the intended function(s) will be maintained consistent with the current licensing basis for the period of extended operation. One of the findings that the U.S. Nuclear Regulatory Commission (NRC) staff must make to issue a renewed license (10 CFR 54.29(a)) is that actions have been identified and have been or will be taken with respect to managing the effects of aging during the period of extended operation on the functionality of structures and components that have been identified to require review under 10 CFR 54.21, such that there is reasonable assurance that the activities authorized by the renewed license will continue to be conducted in accordance with the current licensing basis. To complete its review and enable making a finding under 10 CFR 54.29(a), the staff requires additional information in regard to the matters described below.

11

Background:

SRP-LR section 3.6.2.2.3, Loss of Material due to Wind-Induced Abrasion, Loss of Conductor Strength due to Corrosion, and Increased Resistance of Connection due to Oxidation or Loss of Pre-load, states that the loss of material due to wind-induced abrasion could occur in switchyard bus and connections.

LRA Table 3.6-1, Summary of Aging Management Evaluations for Electrical Commodities, item 3.6-1, 006 indicates that the aging effects for switchyard bus and connections are loss of material due to wind-induced abrasion and increased resistance of connection due to oxidation or loss of pre-load. LRA Table 3.6-1, Item Number 3.6-1, 006 states that the plant-specific AMP B.2.3.42 is used to manage the aging effects of loss of material - and increased resistance for switchyard bus and connections and further evaluation is provided in LRA section 3.6.2.2.3.

LRA Table 3.6-1, item 3.6-1, 007 indicates that the aging effect of loss of material due to wind-induced abrasion is applicable to transmission conductors, and the plant-specific AMP B.2.3.42 is used to manage this aging effect. LRA Table 3.6-1, item 3.6-1, 007 states that further evaluation is provided in LRA section 3.6.2.2.3.

LRA Table 3.6.2-1, Electrical and Instrument and Controls - Summary of Aging Management Evaluation - Electrical Components, Table 1 item 3.6-1, 006 and Table 1 item 3.6-1, 007 indicate that the aging effect requiring management of loss of material is applicable to the switchyard bus and the transmission conductors, respectively.

LRA section B.2.3.42, element 3, Parameters Monitored or Inspected, states that Aluminum buses are inspected for degradation of the bus due to aging that would be evidenced by corrosion buildup or cracks at joints and connections, and element 5 Monitoring and Trending, discusses monitoring of switchyard buses for corrosion and degraded connections.

SRP-LR Table 3.0-1, FSAR Supplement for Aging Management of Applicable Systems, states that the description of the AMP should contain information associated with the bases for determining that aging effects will be managed during the period of extended operation.

LRA section A.2.2.42, Transmission Conductor and Connections, Switchyard Bus and Connections, and High-Voltage Insulators, provides the following Final Safety Analysis Report (FSAR) Supplement for the aging management program (AMP) B.2.3.42, Transmission Conductor and Connections, Switchyard Bus and Connections, and High-Voltage Insulators:

The DCPP Transmission Conductor and Connections, Switchyard Bus and Connections, and High-Voltage Insulators AMP is an existing AMP that manages the aging effects of the 230 kV and 500 kV components required for SBO recovery which include transmission conductors and connections, insulators, and switchyard bus and connections to ensure that these components are capable of performing their intended functions throughout the PEO.

12 Infrared thermography inspection of transmission and bus connections for indications of loose or degraded connections, inspection of transmission conductors for corrosion and fatigue, and inspection of insulator supports for corrosion and wear will be conducted at a frequency based on plant-specific OE. In addition, inspection of the high-voltage insulators for contamination occurs at a frequency based on plant-specific OE.

The NRC staff notes that:

1. It appears that LRA section 3.6.2.2.3, Loss of Material due to Wind-Induced Abrasion, Loss of Conductor Strength due to Corrosion, and Increased Resistance of Connection due to Oxidation or Loss of Pre-load, and LRA section B.2.3.42 do not discuss the aging effect of loss of material due to wind-abrasion on switchyard bus and transmission conductors.

2. It appears that LRA section A.2.2.42 does not contain information associated with the bases for determining that aging effects on the switchyard bus will be managed during the period of extended operation.

Issue The NRC staff is unclear on whether the loss of material due to wind-abrasion or other cause is an applicable aging effect for DCPP switchyard bus and transmission conductors. The staff is also unclear on how the FSAR supplement in LRA section A.2.2.42 covers the information for determining that aging effects on the switchyard bus will be managed during the period of extended operation.

Request

1. Provide further evaluation for the aging effect of loss of material on switchyard bus in LRA section 3.6.2.2.3 and section B.2.3.42.

2. Provide further evaluation for the aging effect of loss of material on transmission conductors in LRA section 3.6.2.2.3 and section B.2.3.42.

3. Provide the bases for determining that applicable aging effects (corrosion, loss of material) on the switchyard bus will be adequately managed during the period of extended operation in LRA section A.2.2.4 RCI B.2.3.33-1 Regulatory Basis Title 10 of the Code of Federal Regulations Section 54.21(a)(3) requires the applicant to demonstrate that the effects of aging for structures and components will be adequately managed so that the intended function will be maintained consistent with the current licensing basis (CLB) for the period of extended operation. As described in the SRP-LR, an applicant may demonstrate compliance with 10 CFR 54.21(a)(3) by referencing the GALL-LR Report when evaluation of the matter in the GALL-LR Report applies to the plant.

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Background

LRA Section B.2.3.33, as modified by LRA Amendment 1 (ML24289A118), provides new enhancement to the acceptance criteria program element which relates to clarifying that fiberglass roofing is acceptable if there is no evidence of blistering, cracking or loss of material that could cause a loss of function prior to the next scheduled inspection.

LRA Table 3.5.2-4, as modified by LRA Amendment 1 (ML24289A118), lists aging effects of blistering, cracking, loss of material due to exposure to ultraviolet light, ozone, radiation, temperature, or moisture for fiberglass roofing panel, that are managed by the Structures Monitoring program.

Request x Confirm that the fiberglass roofing described in the enhancement above refers to the fiberglass roofing panel.

x Confirm that blistering, cracking, loss of material due to exposure to ultraviolet light, ozone, radiation, temperature, or moisture are aging effects being considered for the fiberglass roofing panel, which will be included in an enhancement to the parameters monitored or inspected program element in LRA Section B.2.3.33.