DCL-10-076, Response to NRC Letter Dated June 29, 2010, Request for Additional Information (Set 6) for License Renewal Application

Response to NRC Letter Dated June 29, 2010, Request for Additional Information (Set 6) for License Renewal Application

ML101970085
Person / Time
Site:	Diablo Canyon
Issue date:	07/15/2010
From:	Becker J Pacific Gas & Electric Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
DCL-10-076, OL-DPR-80, OL-DPR-82
Download: ML101970085 (26)

Text

Pacific Gas and e Electric Companv ; James R. Beeller Diablo Canyon Power Plant Site Vice President Mail Code 104/5/601

p. O. Box 56 Avila Beach, CA 93424 805.545.3462 July 15, 2010 Internal: 691.3462 Fax: 805.545.6445 PG&E Letter DCL-10-076 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20852 Docket No. 50-275, OL-DPR-80 Docket No. 50-323, OL-DPR-82 Diablo Canyon Units 1 and 2 Response to NRC Letter dated June 29.2010. Request for Additional Information (Set 6) for the Diablo Canyon License Renewal Application

Dear Commissioners and Staff:

By letter dated November 23,2009, Pacific Gas and Electric Company (PG&E) submitted an application to the U. S. Nuclear Regulatory Commission (NRC) for the renewal of Facility Operating Licenses DPR-80 and DPR-82, for Diablo Canyon Power Plant (DCPP) Units 1 and 2, respectively. The application included the license renewal application (LRA), and Applicant's Environmental Report-Operating License Renewal Stage.

By letter dated June 29, 2010, the NRC staff requested additional information needed to continue their review of the Diablo Canyon LRA.

PG&E's response to the request for additional information is included in . LRA Amendment 4 resulting from the responses is included in showing the changed pages with line-in/line-out annotations.

PG&E makes the following commitment in Table A4-1: The plant procedure on work control will be revised to require that whenever an in-scope pullbox is going to be opened the Structural Monitoring Aging Management Aging Management program personnel be notified to allow them to determine whether an opportunistic inspection of the pull box should be performed.

If you have any questions regarding this response, please contact Mr. Terence L. Grebel, License Renewal Project Manager, at (805) 545-4160.

A member of the STARS (Strategic Teaming and Resource Sharing) Alliance Callaway

• Comanche Peak

• Diablo Canyon

• Palo Verde

• San Onofre

• South Texas Project

• Wolf Creek

Document Control Desk PG&E Letter DCL-10-076 July 15, 2010 Page 2 I declare under penalty of perjury that the foregoing is true and correct.

Executed on July 15, 2010.

c..

cker Site Vice President pns/50324705 Enclosures cc: Diablo Distribution cc/enc: Elmo E. Collins, NRC Region IV Regional Administrator Nathanial B. Ferrer, NRC Project Manager, License Renewal Kimberly J. Green, NRC Project Manager, License Renewal Michael S. Peck, NRC Senior Resident Inspector Alan B. Wang, NRC A member of the STARS (Strategic Teaming and Resource Sharing) Alliance Callaway

• Comanche Peak

• Diablo Canyon

• Palo Verde

• San Onofre

• South Texas Project 0 Wolf Creek

Enclosure 1 PG&E Letter DCL-1 0-076 Sheet 1 of 13 PG&E Response to NRC Letter dated June 29, 2010 Request for Additional Information (Set 6) for the Diablo Canyon License Renewal Application RAI 82.1.7-1 The Generic Lessons Learned (GALL) Aging Management Program (AMP) XI.M1B "Scope of Program" element states that it "covers bolting within the scope of license renewal, including: 1) safety-related bolting, 2) bolting for nuclear steam supply system (NSSS) component supports, 3) bolting for other pressure retaining components, including nonsafety-related bolting, and 4) structural bolting (actual measured yield strength 150;::: ksi)."

The license renewal application (LRA) description of bolting in the applicant's program for both the "program description" and "scope of program," differs from that in GALL AMP XI.M1B:

a) The applicant's description includes "ASME component support bolting" and "ASME Class bolting" - terms not included in the GALL Report - and excludes "bolting for NSSS component supports" and "structural bolting" that are included in the GALL Report.

b) It is not clear from the applicant's description and scope of program whether "the bolting for other pressure retaining components, including "nonsafety-related bolting" and the "structural bolting" classifications, are included in the LRA.

Reconcile the differences in description and scope of program elements by clarifying where each of the four classifications of the GALL AMP XI.M1B bolting is described in the LRA. If any changes to the program description are needed, revise the Final Safety Analysis Report (FSAR) Supplement, Section A. 1.7 of the LRA accordingly.

PG&E Response to RAI B2.1. 7-1 License Renewal Application (LRA) Sections A1.7 and B2.1.7 have been revised to clarify where each of the four GALL Aging Management Program XI.M 18 bolting classifications are addressed. See revised LRA Sections A 1.7 and B2.1.7 in .

Enclosure 1 PG&E Letter DCL-1 0-076 Sheet 2 of 13 RAI B2.1. 7-2 The GALL Report program element "parameters monitored or inspected" for AMP XI.M18 states that "bolting for safety-related pressure retaining components is inspected for leakage, loss of material, cracking, and loss of preload/loss of prestress." The applicant, in LRA Appendix B, Section B2. 1. 7, takes exception to the GALL Report and does not include the inspection for loss of preload/prestress.

The applicant's information in the exception to the GALL Report for "parameters monitored or inspected" in LRA Section B2. 1.7 appears to suggest that loss of preload is managed through the control of certain values of the installation torque that are assured procedurally. However, there is no clear statement for this exception as to what is done in lieu of the GALL Report recommended inspection for preload, and what steps are followed to assure proper installation torques and to confirm if the preload is maintained as expected.

Request 1:

Provide a clear statement of (a) what proposed alternative in the Diablo Canyon Nuclear Power Plant (OCPP) Bolting Integrity program is in lieu of the preload inspections and (b) what steps are taken to assure that proper torques are installed and preloads are maintained.

The applicant appears to include as part of its justification for the exception that EPRI NP-5769, Vol. 2, Section 10 "suggests that inspection of preload is usually unnecessary if the installation method has been carefully followed." The quoted suggestion in the LRA does not appear to be from the Section 10, but is a quotation from a paper referenced in that appendix, which has several limitations including that the scope does not include the safety-related pressure retaining bolting.

Request 2:

Provide a correct reference to the quoted suggestion from EPRI NP-5769, Section 10 cited as support for the exception, and provide relevant justification or a basis for the OCPP alternative to the preload inspections of the safety-related pressure retaining bolting.

PG&E Response to RAI B2.1. 7-2 NUREG 1801,Section XI.M18, specifies bolting for safety-related pressure retaining components is inspected for loss of preload/prestress. The Diablo Canyon Power Plant (DCPP) Bolting Integrity Program does not inspect for loss of preload/prestress.

Installation torque values are provided in plant procedures. Bolting is installed to torque values provided in plant procedures by qualified personnel. The installation torque values provided in plant procedures are based on industry and DCPP operating

Enclosure 1 PG&E Letter DCL-10-076 Sheet 3 of 13 experience, which includes the consideration of the expected relaxation of the fasteners over the life of the joint and gasket stress in the application of pressure closure bolting.

Loss of preload would be detected as visible leakage during routine observation or system walkdowns. The DCPP plant operating experience demonstrates these plant procedures have been effective in maintaining bolting integrity.

License Renewal Application (LRA) Section B2.1.7 has been revised to provide further clarification and basis and to remove the reference to EPRI NP-5769 for the GALL exception. See revised LRA Section B2.1.7 in Enclosure 2.

Enclosure 1 PG&E Letter DCL-1 0-076 Sheet 4 of 13 RAI B2.1. 7-3 The "operating experience" program element of the applicant's AMP summarizes an occurrence of bolting failures in 2001 attributed to unanticipated high temperature embrittlement and elevated stress, due to overtorquing, in the presence of a corro dan t.

As a result, OCPP identified components with susceptible bolting material and evaluated for replacement based on service temperature, service life, fastener stress intensity, and chemical composition. The operating experience summary also notes that since the 2001 incident, there have been no aging-related bolting failures and no unique plant-specific experience was identified at OCPP.

Based on a review of available information, the staff could not confirm adequacy of the replacement program with regard to the aging management of the 17-4 PH bolting for the period of extended operation. Also, a review of the industry experience summarized by the applicant did not reveal any similar bolting failures under similar application/conditions in other operating plants.

Provide details on how the integrity of any remaining 17-4 PH fasteners described in the LRA is assured through the inspectionlreplacement plan for the period of extended operation. How does the plan check or confirm that the embrittJement is adequately controlled to provide sufficient margin against any recurrence of this type of bolting failure?

Provide data that supports the OCPP conclusion that no unique plant-specific operating experience was identified. If the type of 2001 bolting failure has not been reported in other plants, then what plant-specific conditions made this a unique experience, and how are these addressed in the long-term aging management of this issue.

PG&E Response to Question 82.1.7-3 The cause of the bolting failure was identified as overload stress. The failed bolts were more highly stressed than the balance of the bolt population, potentially in excess of the procedural limits due to inadequate maintenance practices. Circumstantial evidence supports the conclusion that the bolts were overstressed but remained below the yield stress of the material. PG&E concluded that this higher stress was the most likely explanation for the failure of all eight bolts on PCV-21.

The thermal embrittlement of 17-4PH (Grade 630) material in the H1100 condition causes material to fail via stress corrosion cracking. The PCV-21 fasteners, which failed, were the only failures among a larger population of identical fasteners (i.e., same heat number) installed at the Diablo Canyon Power Plant subjected to identical service time and temperature conditions. The overstressing, which led to these failures, is an event-caused failure and as such is not an aging induced failure. As discussed in License Renewal Application (LRA) Section 82.1.7, components with susceptible bolting material were identified and evaluated for replacement based on service temperature,

Enclosure 1 PG&E Letter DCL-1 0-076 Sheet 5 of 13 service life, and chemical composition. Corrective actions included revising maintenance procedures to require an engineering evaluation to determine service life when similar bolting material is used at elevated temperatures.

The corrective actions to this event included providing specific torque values and prohibiting the use of impact or slugging tightening techniques. Additional corrective actions specify the replacement of all potentially-embrittled Grade 630 fasteners.

Enclosure 1 PG&E Letter DCL-1 0-076 Sheet 6 of 13 RAI 82.1.7-4 The applicant has taken an exception to the GALL Report for the "monitoring and trending" program element of the GALL AMP XI.M1B. This relates to the use of DCPP Corrective Action Program (CAP) with detailed evaluation of any non-ASME, pressure-retaining bolting leakage to determine the monitoring frequency, instead of the GALL AMP prescribed frequency.

Provide the technical basis and justification for the CAP based determination of the monitoring frequency. Include in your discussion, an explanation of why the alternative method will be adequate in ensuring proper monitoring frequency during the period of extended operation.

PG&E Response to RAI 82.1.7-4 NUREG 1801,Section XI.M18 specifies that if a bolting connection for pressure retaining components (not covered by ASME Section XI) is reported to be leaking, then it may be inspected daily. If the leak rate does not increase, the inspection frequency may be decreased to biweekly or weekly. Diablo Canyon Power Plant (DCPP) procedures require that when a leak is found it is entered into the Corrective Action Program (CAP) and evaluated based on the fluid, leak rate, leak location, potential impact on personnel safety, potential impact on other components, and radiation protection concerns, to determine the appropriate corrective actions and frequency of monitoring. The leakage monitoring will verify that the leak rate has not changed.

Identified leaks may have their action level changed. DCPP operating experience has not indicated the need for a set frequency for leakage inspections involving bolting.

LRA Section 82.1.7 has been revised to provide justification for CAP-based determination of monitoring frequency. See revised LRA section 82.1.7 in Enclosure 2.

Enclosure 1 PG&E Letter DCL-1 0-076 Sheet 7 of 13 RAI B2.1. 7-5 GALL AMP XI.M18, "Bolting Integrity" states that GALL AMP XI.S3, "ASME Section XI Subsection IWF" also manages inspection of safety-related bolting. This includes high strength bolting for which EPRI NP-5769 and EPRI TR-104213 recommend inspections for stress corrosion cracking (SCC) to prevent or mitigate degradation and failure of structural bolting with actual yield strength greater than or equal to 150 ksi.

Provide confirmation that high strength bolting with yield strength greater than or equal to 150 ksi are employed as structural bolting, ASME component and piping supports bolting, NSSS support bolting, safety-related AMPs. Provide confirmation that the determination for high strength of structural bolting is based on the actual measured yield strength.

Also, explain how the GALL Report recommendations to prevent or mitigate the degradation and failure of these bolts are implemented in the applicant's program to confirm that the aging effects of high strength bolting are adequately managed so that their intended function will be maintained consistent with the current licensing basis for the period of extended operation, as required by 10 CFR 54.21 (a)(3).

PG&E Response to RAI B2.1. 7-5 High strength bolting is found in nuclear steam supply sample component supports and reactor vessel closure studs. A sampling review of Certified Material Test Reports for all steam generator manway bolting, one set of reactor coolant pump flange bolting, and one set of pressurizer manway bolting did not identify any bolting in the sampled population that had actual yields greater than 150 ksi. However, reactor closure studs had some heats with yields greater than 150 ksi. In addition, structural bolting used in support applications, with a minimum specified yield of 130 ksi, has the potential for actual yields being greater than 150 ksi. Given that the bolting used could have actual yields greater than 150 ksi in the properly heated condition (meeting the material specifications), managing aging by visually identifying and correcting corrosive environments removes one component necessary for stress corrosion cracking to initiate.

The aging of high-strength bolting, with the potential of having actual yield strengths greater than 150ksi, used in safety-related pressure boundary and structural applications is managed by visually identifying and correcting corrosion or conditions indicative of corrosion that could contribute to stress corrosion cracking. In accordance with B2.1.1 (XLM1), B2.1.20 (XLM36), and B2.1.29 (XLS3), periodic visual examinations per ASME Section XI and system engineering walkdowns provide the means for early detection of adverse conditions. As stated in B2.1.7 (XLM18), bolting procedures specify use of lubricants/sealants consistent with EPRI good bolting practices. The early identification of corrosion and compatible lubricants removes one component necessary for stress corrosion cracking.

Enclosure 1 PG&E Letter DCL-1 0-076 Sheet 8 of 13 The visual identification of conditions of corrosion or indicative of corrosion will cause appropriate corrective action under the Corrective Action Program. Corrective actions may include volumetric examination, hammering or other appropriate actions for the identified condition.

The GALL recommendations to prevent or mitigate the degradation and failure of high strength bolts, is described in revised LRA Section 82.1.7. See revised LRA Section 82.1.7 in Enclosure 2.

Enclosure 1 PG&E Letter DCL-1 0-076 Sheet 9 of 13 RAI82.1.26-1 GALL Report AMP XI.E3, "Inaccessible Medium Voltage Cables Not Subject to 10 CFR 50.49 Environmental Qualification Requirements," program Element 1, "scope of program," provides definitions for significant moisture and significant voltage. SPR-LR Table 3.6-2, Final Safety Analysis Report (FSAR) Supplement for Aging Management of Electrical and Instrumentation and Control System also includes definitions for significant moisture and significant voltage. In addition, GALL Report AMP XI.E3 states that the specific type of test performed will be determined prior to the initial test, and is to be a proven test for detecting deterioration of the insulation system due to wetting, such as power factor, partial discharge, or polarization index as described in EPRI TR-103834-P1-2.

LRA FSAR Supplement Section A 1.26 does not include definitions of significant moisture or significant voltage consistent with SRP-LR Table 3.6-2 or GALL AMP XI.E3.

The lack of these definitions in combination with the applicant's stated objective of using inspection to ensure that cables are infrequently submerged may not provide consistency with GALL AMP XI.E3. Additionally, Section A 1.26 does not specify that other testing is to be a proven test for detecting deterioration of the insulation system due to wetting as stated by SRP-LR Table 3.6-2 and GALL AMP XI.E3.

Explain why LRA FSAR Supplement Section A1.26 for LRA AMP 82.1.26 does not include the definitions of significant voltage and significant moisture or specify that other testing is to be a proven test consistent with GALL Report AMP XI.E3 and SRP-LR Table 3.6-2.

PG&E Response to RAI B2.1.26-1 The Inaccessible Medium Voltage Cables Not Subject to 10 CFR 50.49 Environmental Qualification Requirements Program manages localized damage and breakdown of insulation leading to electrical failure in inaccessible medium voltage cables exposed to adverse localized environments caused by significant moisture (moisture that lasts more than a few days) simultaneously with significant voltage (energized greater than 25 percent ofthe time) to ensure that inaccessible medium voltage cables not subject to the environmental qualification requirements of 10 CFR 50.49 and within the scope of license renewal are capable of performing their intended function.

License Renewal Application (LRA) Sections A 1.26 and B2.1.26 have been revised to include the definition of significant voltage and moisture.

NUREG 1800, Table 3.6-2, states that the specific type of test performed will be determined prior to the initial test, and is to be a proven test for detecting deterioration of the insulation system due to wetting, such as power factor, partial discharge, or polarization index, as described in EPRI TR -103834-P1-2, or other testing that is state-of-the-art at the time the test is performed.

Enclosure 1 PG&E Letter DCL-1 0-076 Sheet 10 of 13 LRA Sections A 1.26 and B2.1.26 have been revised to show conformance with NUREG-1800, Table 3.6-2 guidance regarding cable testing. See revised LRA Sections A 1.26 and B2.1.26 in Enclosure 2.

Enclosure 1 PG&E Letter DCL-1 0-076 Sheet 11 of 13 RAI82.1.26-2 GALL AMP XI.E3, states that the program applies to inaccessible medium voltage cables that are exposed to significant moisture simultaneously with significant voltage.

Significant moisture is defined as periodic exposures to moisture that lasts for more than a few days. GALL AMP XI.E3 also states that periodic actions are taken to prevent cables from being exposed to significant moisture. GALL AMP XI.E3 further states that inspection for water collection should be performed based on actual plant experience with water accumulation in the manhole with an inspection frequency of at least every two years.

The applicant identified operating experience, and the staff confirmed through operating experience review, cases of in-scope inaccessible medium voltage cables exposed to significant moisture (cable submergence) and cable support structural degradation inconsistent with GALL AMP XI.E3 (i.e., periodic actions are taken to prevent cables from being exposed to significant moisture). Cables submerged for an extended period of time may be degraded and may not be able to perform their intended function for the period of extended operation.

Discuss how LRA AMP 82.1.26, described as consistent with the GALL Report, will be an effective AMP during the period of extended operation based on DCPP operating experience that shows in-scope inaccessible medium voltage cables exposed to significant moisture (i.e. exposure lasting more than a few days). Specifically,

1. Describe how plant operating experience has been or will be assessed and applicable changes incorporated into AMP 82.1.26 to minimize exposure of in-scope inaccessible medium voltage cables and cable splices to significant moisture and minimize cable support structure degradation during the period of extended operation.

2. Discuss manhole/vault inspection procedures for in-scope cable testing and inspection. The discussion should include any periodic and event-driven (such as rain/flood) inspections as applicable to minimize inaccessible medium voltage cable exposure to significant moisture. In the discussion, provide your assessment of cable insulation including splices, and efforts to minimize cable support structure degradation during the period of extended operation. The discussion should also include accommodation for future adjustments/modifications to inspection methods and frequency based on operating experience (industry and plant specific).

3. Describe corrective actions taken or planned to minimize in-scope medium voltage submergence and cable support structure degradation.

Enclosure 1 PG&E Letter DCL-1 0-076 Sheet 12 of 13

4. Discuss inspections and tests performed that demonstrate in-scope medium voltage cable will continue to perform its intended function during the period of extended operation having previously been exposed to significant moisture (cable submergence).

PG&E Response to RAI B2.1.26-2

1. Plant operating experience is summarized in License Renewal Application (LRA)

Section B2.1.26, including water accumulation in pull boxes and conduits and corrective actions taken. The evaluation of plant operating experience during the period of extended operation is performed as part of the Corrective Action Program (CAP) described in LRA Section B2.1.26. The CAP will evaluate exposure of in-scope inaccessible medium cables and cable splices to significant moisture and cable support structure degradation and ensure appropriate corrective actions are taken.

2. Diablo Canyon Power Plant (DCPP) utilizes cable pull boxes instead of manholes and vaults. LRA Section B2.1.26 indicates that cable pull boxes with a potential for water intrusion that contain inaccessible medium voltage cables are inspected for water collection and that the inspection frequency is at least once every 2 years. The inspection frequency will be adjusted based on plant operating experience. DCPP is currently performing these inspections more frequently than every 2 years. Based on the corrective actions taken to previous water accumulation in the cable pull boxes and recent inspections, these inspections have been effective in minimizing inaccessible medium voltage cable exposure to significant moisture. These inspections are being performed using work orders as part of the plant maintenance program. As discussed in LRA Section B2.1.26, these inspections will be formalized in a plant procedure prior to the period of extended operation.

Testing of in-scope cables will be performed in accordance with the Standard Review Plan for License Renewal, NUREG-1800 Revision 1, Table 3.6-2, which indicates that the specific type of test performed will be determined prior to the initial test, and is to be a proven test for detecting deterioration of the insulation system due to wetting, such as power factor, partial discharge, or polarization index, as described in EPRI TR-1 03834-P1-2, or other testing that is state-of-the-art at the time the test is performed.

3. As discussed in LRA Section B2.1.26, corrective actions taken to minimize in-scope medium voltage cable submergence include inspection of pull boxes for water accumulation, removal of water as required, maintenance of sump pumps, and removal of conduit seals. Corrective actions taken to minimize cable support structure degradation are evaluated as part of the Structural Monitoring Program (LRA Section B2.1.32). The plant procedure on work control will be revised to require that whenever an in-scope pullbox is going to be opened the Structural

Enclosure 1 PG&E Letter DCL-1 0-076 Sheet 13 of 13 Monitoring Aging Management Aging Management Program personnel be notified to allow them to determine whether an opportunistic inspection of the pull box should be performed. LRA Table A4-1 has been revised to track this commitment.

4. As discussed in LRA Section B2.1.26, DCPP has experienced failures of medium voltage in-scope cables. , Routine cable testing identified additional medium voltage cable that did not pass testing acceptance criteria. In response to these cable failures, DCPP has completed corrective actions to replace all in-scope inaccessible medium voltage cable with cable that is more moisture-resistant.

Based on DCPP operating experience, which is derived from frequent pull box inspections, the new cables have not been exposed to significant moisture. The completed corrective actions, continued pull box inspections and routine cable testing provide assurance that medium voltage, inaccessible, cable will perform its intended function during the period of extended operation.

See revised LRA Table A4-1 in Enclosure 2.

PG&E Letter DCL-1 0-076 Page 1 of 11 LRA Amendment 4 LRA Section RAI Section A 1.7 B2.1.7-1 Section A 1.26 B2.1.26-1 Table A4-1 B2.1.26-2 B2.1.7-1, B2.1.7-2, Section B2.1.7 B2.1.7-4, B2.1.7-5 Section B2.1.26 B2.1.26-1 Appendix A PG&E Letter DCL-10-076 Final Safety Analysis Report Supplement Page 2 of 11 A1.7 BOLTING INTEGRITY The Bolting Integrity program manages cracking, loss of material, and loss of preload for pressure retaining bolting, including non safety related bolting, and ASME component support bolting, including NSSS component support bolting which includes high strength bolting. Aging management of the bolting associated with structural steels and non-ASME component structural support (non-pressure boundary) is evaluated in XI. S6, "Structures Monitoring Program. " The program includes preload control, selection of bolting material, use of lubricants/sealants consistent with EPRI good bolting practices, and performance of periodic inspections for indication of aging effects. The program also includes the inservice inspection requirements established in accordance with ASME Section XI, Subsections IWB, IWC, IWD, and IWF for ASME Class pressure retaining bolting and ASME component support bolting.

DCPP procedures include requirements for proper disassembling, inspecting, and assembling of connections with threaded fasteners. The general practices that are established in this program are consistent with EPRI NP-5067, Good Bolting Practices, Volume 1 and Volume 2 and the recommendations delineated in NUREG-1339, Resolution of Generic Safety Issue 29: Bolting Oegradation or Failure in Nuclear Power Plants, and EPRI TR-1 04213, Bolted Joint Maintenance & Applications Guide.

Appendix A PG&E Letter DCL-10-076 Final Safety Analysis Report Supplement Page 3 of 11 A1.26 INACCESSIBLE MEDIUM VOLTAGE CABLES NOT SUBJECT TO 10 CFR 50.49 ENVIRONMENTAL QUALIFICATION REQUIREMENTS The Inaccessible Medium Voltage Cables Not Subject to 10 CFR 50.49 Environmental Qualification Requirements program manages the aging effects of inaccessible medium voltage cables within the scope of license renewal located in conduit, duct banks, and pull boxes exposed to adverse localized environments caused by significant moisture simultaneously with significant voltage. Significant moisture is defined as periodic exposures to moisture that last more than a few days (e.g., cable in standing water) .

Periodic exposures to moisture that last less than a few days (i.e. , normal rain and drain) are not significant. Significant voltage exposure is defined as being subjected to system voltage for more than twenty-five percent of the time.

Cable pull boxes with a potential for water intrusion that contain in-scope non-EQ inaccessible medium voltage cables are inspected for water collection. Collected water is removed as required. This inspection and water removal is performed based on actual plant experience with an inspection frequency of at least every two years.

Inspection for water collection within the cable pull boxes is performed based on plant experience with water accumulation.

The program provides for testing of in scope non EQ inaccessible medium voltage cables to p,rovide an indication of the conductor insulation condition. At least once every 10 years, a polarization index test as described in ErRI TR 103834 r1 2, Effects of Moisture on the Life of Power P.Jant Cab/es or other testing that is state of the art at the time of the testing is performed. Testing of in-scope cables will be performed in accordance with Standard Review Plan for License Renewal, NUREG-1800 Revision 1, Table 3.6-2 which indicates that the specific type of test performed will be determined prior to the initial test, and is to be a proven test for detecting deterioration of the insulation system due to wetting, such as power factor, partial discharge, or polarization index, as described in EPRI TR - 103834-P1-2, or other testing that is state-of-the-art at the time the test is performed. The first test will be completed prior to the period of extended operation.

Appendix A PG&E Letter DCL-1 0-076 Final Safety Analysis Report Supplement Page 4 of 14 Table A4-1 License Renewal Commitments Item # Commitment LRA Implementation Section Schedule 33 The plant procedure on work control will be revised to 82.1.32 Prior to the period require that whenever an in-scope pullbox is going to be of extended opened the Structural Monitoring Aging Management operation Aging Management program personnel be notified to allow them to determine whether a opportunistic inspection of the pull box should be performed.

Appendix B PG&E Letter DCL-1 0-076 AGING MANAGEMENT PROGRAMS Page 5 of 11 B2.1.7 Bolting Integrity Program Description The Bolting Integrity program manages cracking, loss of material, and loss of preload for pressure retaining bolting and ASME component support bolting including NSSS component support bolting which includes high strength bolting. Aging management of the bolting associated with structural steels and non-ASME component structural support (non-pressure boundary) is evaluated in XI. S6, "Structures Monitoring Program. " The program includes preload control, selection of bolting material, use of lubricants/sealants consistent with EPRI good bolting practices, and performance of periodic inspections for indication of aging effects including leakage. The program also includes in-service inspection requirements established in accordance with ASME Section XI, Subsections IWB, IWC, IWD, and IWF for ASME pressure retaining bolting and ASME component supportGass bolting.

DCPP procedures include requirements for proper disassembling, inspecting, and assembling of connections with threaded fasteners. These procedures are consistent with EPRI NP-5067, Good Bolting Practices, Volume 1 and Volume 2 and EPRI TR-1 04213, Bolted Joint Maintenance and Applications Guide.

Following the review of the recommendations provided in NRC Generic Letter 91-17, Generic Safety Issue 29, Bolting Degradation or Failure in Nuclear Power Plants; NUREG-1339, Resolution of Generic Safety Issue 29: Bolting Degradation or Failure in Nuclear Power Plants; and the EPRI reports, NP-5769, Degradation and Failure of Bolting in Nuclear Power Plants; and NP-5067, DCPP identified and implemented the actions related to bolting degradation or failure . The DCPP program references EPRI Good Bolting Practices, Vol. 1 and 2 to ensure the integrity of the subject bolting connections.

The following DCPP aging management programs supplement the Bolting Integrity program with management of cracking, loss of material, and loss of preload:

(a) ASME Section XI In-service Inspection , Subsections IWB, IWC and IWD program (B2 .1.1), provides the requirements for in-service inspection of ASME Class 1, 2, and 3 safety-related pressure retaining bolting.

(b) ASME Section XI, Subsection IWF program (B2.1.29), provides the requirements for in-service inspection of safety-related component support bolting .

(c) External Surfaces Monitoring Program (B2 .1.20) provides the requirements for inspection of pressure boundary closure bolting, including non safety related bolting, within the scope of license renewal.

Appendix B PG&E Letter DCL-10-076 AGING MANAGEMENT PROGRAMS Page 6 of 11 NUREG-1801 Consistency The Bolting Integrity program is an existing program that is consistent with exception to NUREG-1801,Section XI.M18, Bolting Integrity.

Exceptions to NUREG-1801 Program Elements Affected Scope of Program - Element 1 NUREG-1801,Section XI.M18 specifies the use of ASME Section XI 1995 edition with addenda 1996. The lSI program is required to comply with the latest edition and addenda of the Code incorporated by reference in 10 CFR 50.55a one year prior to the start of an inspection interval. Accordingly, the ASME Section XI 2001 Edition through 2003 addenda is the Code that DCPP must meet for the third interval lSI Program. Use

• of the 2001 Code through 2003 addenda does not change the requirements regarding inspections, evaluations and corrective actions for safety-related bolting to ensure the integrity of the intended functions . In addition, for the period of extended operation, DCPP is required to update its Code of Record to the Edition and Addenda as referenced in 10 CFR 50.55a(b) 12 months prior to the start of each 120-month interval.

Parameters Monitored or Inspected - Element 3 NUREG-1801,Section XI.M18 specifies bolting for safety related pressure retaining components is inspected for loss of preload/prestress. The DCPP Bolting Integrity Program does not inspect for loss of preload/prestress. Installation torque values are provided in plant procedures if not provided by the vendor instructions, design documents or specifications . Bolting is installed to torque values provided in plant procedures by qualified personnel. The installation torque values provided in plant procedures are based on industry and DCPP operating experience which the industrial experience that includes the consideration of the expected relaxation of the fasteners over the life of the joint and gasket stress in the application of pressure closure bolting.

Loss of preload would be detected as visible leakage during routine observation or system walkdowns. The DCPP plant operating experience demonstrates these plant procedures have been effective in maintaining bolting integrity. The discussion of bolt preload in EPRI NP 5769, Vol. 2, Section 10, indicates that job inspection torque is non conservative since for a given fastener tension more torque is required to restart the installed bolts. EPRI NP 5769, Vol. 2, Section 10 suggests that inspection of preload is usually unnecessary if the installation method has been carefully followed.

Monitoring and Trending - Element 5 NUREG-1801,Section XI.M18 specifies that if a bolting connection for pressure retaining components (not covered by ASME Section XI) is reported to be leaking, then it may be inspected daily. If the leak rate does not increase, the inspection frequency may be decreased to biweekly or weekly. DCPP procedures require that when a leak is found it is entered into the Corrective Action Program and evaluated based on the fluid, Appendix B PG&E Letter DCL-10-076 AGING MANAGEMENT PROGRAMS Page 7 of 11 leak rate, leak location, potential impact on personnel safety, potential impact on other components, and radiation protection concerns, to determine the appropriate corrective actions and frequency of monitoring. The leakage monitoring will verify that the leak rate has not changed. Identified leaks may have their action level changed. OCPP operating experience has not indicated the need for a set frequency for leakage inspections involving bolting.

Enhancements None Operating Experience Based on a review of DCPP operating experience, the Bolting Integrity program has effectively identified and addressed issues relating to bolting integrity. The following is a discussion of bolting failure that occurred in 2001 .

An occurrence of a bolting failure caused by a combination of unanticipated high temperature embrittlement and elevated stress, due to overtorquing, in the presence of a corrodant occurred at DCPP in 2001 . Laboratory tests on the failed fasteners showed that these fasteners had become embrittled after 10 years at elevated temperature and were therefore much more susceptible to stress corrosion cracking . Corrective actions included revising maintenance procedures to provide specific final torque values and to require an engineering evaluation to determine service life when similar bolting material is used at elevated temperatures. Components with susceptible bolting material were identified and evaluated for replacement based on service temperature, service life, fastener stress intensity, and chemical composition. Since this bolting failure , there have been no aging-related bolting failures at DCPP.

Both the industry and NRC have identified a number of instances of bolting concerns from material control and certification (e.g. NRC IEB 87-02) to bolting practices, use of lubrication and injection sealants and its effect on stress corrosion cracking (SCC) (e.g.,

NRC IEB 82-02, and INPO SOER 84-05). The DCPP Bolting Integrity program incorporates the applicable industry experience on bolting issues into the program.

Actions taken include confirmatory testing/analysis or inspections.

Operating experience at DCPP that pertains to bolting integrity demonstrates that the aging effects of cracking, loss of material, and loss of preload for pressure retaining bolting and ASME component support bolting have been adequately managed. This is accomplished through the use of the corrective action program by promptly identifying, documenting, and correcting conditions or events that could compromise bolting integrity. In addition, industry operating experience provides additional input to ensure that the program is maintained at an acceptable level. The program is continually improved to assure the capability of mechanical bolting to support the safe operation of DCPP throughout the period of extended operation. The DCPP operating experience findings for this program identified no unique plant specific operating experience; therefore DCPP operating experience is consistent with NUREG-1801.

Appendix B PG&E Letter DCL-10-076 AGING MANAGEMENT PROGRAMS Page 8 of 11 Conclusion The continued implementation of Bolting Integrity 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.

Appendix B PG&E Letter DCL-10-076 AGING MANAGEMENT PROGRAMS Page 9 of 11 8 2.1.26 Inaccessible Medium Voltage Cables Not Subject to 10 CFR 50.49 Environmental Qualification Requirements Program Description The Inaccessible Medium Voltage Cables Not Subject to 10 CFR 50.49 Environmental Qualification Requirements program manages the aging effects of inaccessible medium-voltage cables located in conduit, duct banks, and pull boxes exposed to adverse localized environments caused by significant moisture simultaneously with significant voltage to ensure that inaccessible medium voltage cables not subject to the environmental qualification (EQ) requirements of 10 CFR 50.49 and within the scope of license renewal are capable of performing their intended function. Significant moisture is defined as periodic exposures to moisture that last more than a few days (e.g., cable in standing water). Periodic exposures to moisture that last less than a few days (i.e. ,

normal rain and drain) are not significant. Significant voltage exposure is defined as being subjected to system voltage for more than twenty-five percent of the time .

This program considers the technical information and guidance provided in NUREG/CR-5643, Insights Gained From Aging Research, IEEE Std. P1205, IEEE Guide for Assessing, Monitoring and Mitigating Aging Effects on Class 1E Equipment Used in Nuclear Power Generating Stations, SAND 96-0344, Aging Management Guideline for Commercial Nuclear Power Plants - Electrical Cable and Terminations, and EPRI TR-1 09619, Guideline for the Management of Adverse Localized Equipment Environments.

Cable pull boxes with a potential for water intrusion that contain in-scope non-EQ inaccessible medium voltage cables are inspected for water collection. The inspection frequency is at least once every two years. Inspection for water collection within the cable pull boxes is performed based on plant experience with water accumulation. If any of the pull boxes are found to contain water, the collected water is removed as required, and the inspection frequency adjusted based on past experience.

In scope non EQ inaccessible medium voltage cables routed through pull boxes will be tested to provide an indication of the conductor insulation condition . A polarization index test as described in EPRI TR 103834 P1 2, Effects of Moisture on the Life of Power Pl-ant CaNes or other testing that is state of the art at the time of the testing will be performed at least once every 10 years .

Testing of in-scope cables will be performed in accordance with Standard Review Plan for License Renewal, NUREG-1800 Revision 1, Table 3.6-2 which indicates that the specific type of test performed will be determined prior to the initial test, and is to be a proven test for detecting deterioration of the insulation system due to wetting, such as power factor, partial discharge, or polarization index, as described in EPRI TR - 103834-P1-2, or other testing that is state-of-the-art at the time the test is performed. The first test will be completed prior to the period of extended operation. The acceptance criteria for each test will be defined for the specific type of test performed and the specific cable tested.

Appendix B PG&E Letter DCL-10-076 AGING MANAGEMENT PROGRAMS Page 10 of 11 Corrective actions for conditions that are adverse to quality are performed in accordance with the Corrective Action Program as part of the QA program. The corrective action process provides reasonable assurance that deficiencies adverse to quality are either promptly corrected or are evaluated to be acceptable.

Trending actions are not included as part of this program because the ability to trend results is dependent on the specific type of method chosen.

NUREG-1801 Consistency The Inaccessible Medium Voltage Cables Not Subject to 10 CFR 50.49 Environmental Qualification Requirements program is an existing program, that following enhancement, will be consistent with NUREG-1801,Section XI.E3, Inaccessible Medium Voltage Cables Not Subject to 10 CFR 50.49 Environmental Qualification Requirements.

Exceptions to NUREG-1801 None Enhancements Prior to the period of extended operation, the following enhancement will be implemented in the following program elements:

Scope of Program - Element 1, Preventive Actions - Element 2, Parameters Monitored/Inspected - Element 3, Detection of Aging Effects - Element 4, Acceptance Criteria - Element 6, and Corrective Actions - Element 7 Procedures will implement the aging management program for testing of the medium voltage cables not subject to 10 CFR 50.49 EQ requirements and enhance the periodic inspections and removal of water from the cable pull boxes containing in scope medium voltage cables not subject to 10 CFR 50.49 EQ requirements.

Operating Experience A review of the plant operating experience indicates that DCPP has experienced seven in-service power cable single phase grounds that required removing components from service to replace conductors. In response to industry and plant operating experience cable testing identified four additional cables did not pass the insulation acceptance criteria. All 11 cables have been replaced. DCPP has replaced all medium voltage cable within the scope of license renewal.

DCPP has experienced water accumulation in pull boxes and underground conduits.

Actions taken to address this water accumulation include inspection of pull boxes for water accumulation, removal of the water as required, maintenance of sump pumps and removal of conduit seals. The DCPP operating experience findings for this program Appendix B PG&E Letter DCL-1 0-076 AGING MANAGEMENT PROGRAMS Page 11 of 11 identify no unique plant specific operating experience; therefore DCPP operating experience is consistent with NUREG-1801.

Conclusion The continued implementation of the Inaccessible Medium Voltage Cables Not Subject to 10 CFR 50.49 Environmental Qualification Requirements program will provide 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.