ML101340829

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License Renewal - Summary of Conference Calls on Metal Fatigue
ML101340829
Person / Time
Site: Palo Verde  Arizona Public Service icon.png
Issue date: 07/14/2010
From: Lisa Regner
License Renewal Projects Branch 2
To:
Regner L M, NRR/DLR, 415-1906
References
TAC ME0254, TAC ME0255, TAC ME0256
Download: ML101340829 (55)
v • d • e


Text

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") ****... ~o July 14, 2010 LICENSEE: Arizona Public Service Company FACILITY: Palo Verde Nuclear Generating Station, Units 1,2, and 3

SUBJECT:

SUNlIVIARY OF TELEPHONE CONFERENCE CALLS BETWEEN THE U.S.

NUCLEAR REGULATORY COMMISSION AND ARIZONA PUBLIC SERVICE COMPANY CONCERNING METAL FATIGUE DRAFT REQUESTS FOR ADDITIONAL INFORMATION PERTAINING TO THE PALO VERDE NUCLEAR GENERATING STATION, UNITS 1,2, AND 3, LICENSE RENEWAL APPLICATION (ME0254, ME0255, AND ME0256)

The U.S. Nuclear Regulatory Commission (the staff) and representatives of Arizona Public Service Company (the applicant) held telephone conference calls on March 29, and April 1, 13, and 29, 2010, to discuss and clarify the staff's draft requests for additional information (RAI) concerning the Palo Verde Nuclear Generating Station, Units 1, 2, and 3, license renewal application. The telephone conference calls were useful in clarifying the intent of the staff's draft RAls specifically associated with Section 4.3 Metal Fatigue Analysis of the license renewal application. The April 1, 2010, conference call utilized a webinar format; the applicant's presentation slides are included in Enclosure 4.

By letter dated April2B, 2010, the applicant submitted Amendment No. 14 to the license renewal application which revised the introduction of Section 4.3 and Section 4.3.1 Fatigue Aging Management Program. Conforming changes to the remaining affected LRA sections were submitted on May 27,2010.

A public meeting was held on May 6,2010, to facilitate resolution of metal fatigue related issues that the staff identified during the review. The meeting summary can be found at Agencywide Document Access and Management System accession number ML 101340B01.

Enclosure 1 provides a listing of the participants for the calls. Enclosure 2 contains a listing of the draft RAls discussed with the applicant, including a brief description on the status of the items. Many draft RAls were resolved by the submittal of Amendment No. 14, as discussed in Enclosure 2. Enclosure 3 contains a listing of inconsistencies and discussion topics concerning

-2 the metal fatigue review which were also resolved by Amendment No. 14. The applicant had an opportunity to comment on this summary.

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Lisa M. Regner, Sr. Project Manager Projects Branch 2 Division of License Renewal Office of Nuclear Reactor Regulation Docket Nos. 50-528, 50-529, and 50-530

Enclosures:

As stated cc w/encls: Distribution via Listserv

TELEPHONE CONFERENCE CALLS PALO VERDE NUCLEAR GENERATING STATION, UNITS 1, 2, AND 3 LICENSE RENEWAL APPLICATION SECTION 4.3 METAL FATIGUE ANALYSIS LIST OF PARTICIPANTS March 29, 2010 April 1, 2010 April 13, 2010 April 29, 2010 PARTICIPANTS AFFILIATIONS Lisa Regner U.S. Nuclear Regulatory Commission (NRC)

Allen Hiser NRC Ja mes Medoff NRC OnYee NRC Girija Shukla NRC Angela Krainik Arizona Public Service Company (APS)

Glenn Michael APS George Pilicy APS Winston Borrero APS Eugene Montgomery APS Doug Berg APS Michael Hooshmand APS (April 13 call only)

Michael Powlikosky APS (April 13 call only)

Shaun Bernat APS (April 13 call only)

Mark Radspinner APS (April 29 call only)

Rex Meeden APS (April 29 call only)

Eric Blocher Strategic Teaming and Resource Sharing (STARS) Alliance Don Stevens STARS Kathleen Fix STARS (April 1 call only)

Richard Schaller Utilities Service Alliance David Gerber Structural Integrity Associates (SIA)

Curt Carney SIA ENCLOSURE 1

DRAFT REQUESTS FOR ADDITIONAL INFORMATION PALO VERDE NUCLEAR GENERATING STATION, UNITS 1, 2, AND 3 LICENSE RENEWAL APPLICATION The U.S. Nuclear Regulatory Commission (the staff) and representatives of Arizona Public Service Company (the applicant or APS) held several telephone conference calls, to discuss and clarify the following draft request for additional information (RAI) concerning the Palo Verde Nuclear Generating Station, Units 1, 2, and 3, license renewal application (LRA).

Cycle Counting Questions DRAFT RAI 4.3-1 Issue LRA Table 4.3-3 indicated the projected 40-year number of cycles exceeded the design basis number of events for seven transients: (1) unbolting/bolting of RC pump casing studs, (2) tensioning/dimensioning of RV head studs, (3) reactor trip, (4) loss of load, (5) turbine trip without reactor trip, (6) initiation of safety injection, and (7) depressurization by MSSV at 100%

power. However, LRA Section 4.3 does not provide sufficient information to determine (a) whether cumulative usage factor (CUF) calculations that are based on any of these seven transients have been updated, (b) whether these seven transient significantly contribute to CUF of any components, and (c) whether any components for which CUF calculations are based on these seven transients utilize global fatigue monitoring method to manage effects of aging.

Request a) Clarify whether CUF calculations that are based on any of these seven transients have been updated.

b) Clarify whether these seven transients significantly contribute to CUF of any components.

c) Clarify whether any components for which CUF calculations are based on these seven transients utilize Global fatigue monitoring method to manage effects of aging.

Discussion: this question was resolved by Amendment 14, submitted by letter dated April 28, 2010.

DRAFT RAI 4.3-2

Background

In Table 4.3-4 of the LRA, the staff noted that the RPV instrumentation nozzle and RPV fuel alignment plate components are monitored because of "High CUF" and that the "Global" fatigue management method is used.

Issue Page 4.3-22 of the LRA states "the 'global' method will only be used for components with low calculated design basis fatigue usage values, for which the fatigue management program does not periodically calculate accumulated fatigue usage to date." LRA Table 4.3-4 provides the "Reason for Monitoring" and the "Fatigue Management Method" for several Class 1 components. There is an apparent discrepancy between the text on LRA Page 4.3-22 and the information in LRA Table 4.3-4 ENCLOSURE 2

-2 Request Resolve the apparent discrepancy between the statement made on LRA Page 4.3-22 and the information provided in LRA Table 4.3-4. If the information in LRA Table 4.3-4 is accurate, justify the use of the "global" monitoring method for these "High CUF" locations.

Discussion: this question was resolved by Amendment 14, submitted by letter dated April 28, 2010.

DRAFT RAI 4.3-3 Issue LRA Section 4.3.1 states that the Cycle-based fatigue with partial cycles ("CBF-PC") monitoring method assigns a fractional severity to a cycle, as compared to a full design cycle, based upon significant characteristics of that event. However, LRA does not provide sufficient information that demonstrates whether "CBF-PC" monitoring method meets ASME B&PV Code,Section III methodology.

Request a) Clarify the methodology used for the "CBF-PC" monitoring method.

b) Justify how this methodology meetsSection III of the ASME B&PV Code.

Discussion: this question was resolved by Amendment 14, submitted by letter dated April 28, 2010.

DRAFT RAI 4.3-4 Issue LRA Section 4.3.1 states that action limits are set below the cycle count to ensure that appropriate evaluation or other corrective action is initiated before the design basis number of events is exceeded. However, LRA does not provide sufficient information for the staff to determine the margin between an action limit and a design basis limit.

Request Provide additional information for the margin between an action limit and a design basis limit.

Discussion: this question was resolved by Amendment 14, submitted by letter dated April 28, 2010.

DRAFT RAI 4.3-5 Issue LRA Table 4.3-2 provides information on the number of transient monitored under the fatigue management program. However, for some transients, the information provided in LRA Table 4.3-2 does not agree with information provided in UFSAR Table 3.9.1-1 (e.g., reactor trip, loss of reactor coolant flow, and turbine trip).

-3 Request Explain the apparent discrepancies in LRA Table 4.3-2 and the UFSAR. Explain any similar discrepancies for Table 4.3-3.

Discussion: this question was resolved by Amendment 14, submitted by letter dated April 28, 2010.

DRAFT RAI 4.3-6 Issue Section 4.3.1.4 of the LRA states that the 1995 record of the revised procedure assumed the accumulation for all transient events not counted to date was 25 percent of the limiting value for the 40-year design. However, the LRA does not provide sufficient information that this assumption is representative of the accumulated number of cycles for first 10 years of plant operation. For example, Section 4.3.1.4 of the LRA states that the yearly accumulation rate was calculated by dividing the composite-unit accumulation from 1985 through 2005 by the least number of years of operation up to 2005 (Unit 3, operating period of 18 years), and this resulted in the worst-case accumulation of cycles over the least amount of time. However, information presented in LRA Table 4.3-3 demonstrates that for some transients (e.g., plant heatup and cooldown) the accumulated number of cycles for the period from 1985 to 1995 was less than for the period from 1995 to 2005 (e.g., for plant heatup, these values are 21 and 43 cycles, respectively).

Request Explain the basis for the 25 percent assumption for the accumulated number of cycles for the first 10 years of plant operation.

Discussion: following discussion with the applicant, the question has been revised as follows and will be issued as a formal RAI:

DRAFT RAI 4.3.1 Issue In the public meeting between APS and the NRC held on Thursday, May 6, 2010, APS indicated that it had updated the design basis transients for the metal fatigue time limited aging analysis (TLAA) to be consistent with those listed in the updated final safety analysis (UFSAR) for the facility. Further, APS stated and that the updated transient projection basis is based on the applicant's updated transient recount activities for the TLAA. The applicant clarified that the 25 percent assumed transient occurrence basis used in the original TLAA was only being applied to five or six transients for which recount data could not be found.

Request Clarify which of the transients in LRA Tables 4.3-2 and 4.3-3 (as modified by Amendment 14) the 25 percent assumed transient occurrence basis remains applicable to and justify why the application of this assumption is considered to yield a conservative 60-year cycle occurrence basis for these transients.

-4 DRAFT RAJ 4.3-7 Issue Table 4.3-3 of the LRA, note 9 states that transients marked as "NC" are not counted in the fatigue cycle count verification. Further, some of these transient (e.g., plant heatup and cooldown) are listed as design basis transients in LRA Table 4.3-2 and the UFSAR. However, the LRA does not provide sufficient information on the basis for not counting these transients in the fatigue cycle count verification.

Request Provide the basis for not counting the bolded transients marked as "NC" in Table 4.3-3 of the LRA for the fatigue cycle count verification, particularly if these were required to be counted by the Technical Specifications and UFSAR.

Discussion: this question was resolved by Amendment 14, submitted by letter dated April 28, 2010.

DRAFT RAI 4.3-8 Issue LRA Table 4.3-3, Note 14 states that some transient events do not contribute significantly to fatigue and are not counted by the fatigue management program. However, in LRA Table 4.3-3, the 50-year projections for some of these transients (e.g., Reactor Coolant Pump Starting and Stopping) approach the design basis limits.

Request Clarify the basis for the bolded transient marked with note 14 in LRA Table 4.3-3.

Discussion: this question was resolved by Amendment 14, submitted by letter dated April 28, 2010.

DRAFT RAI 4.3-9 Issue In LRA Table 4.3-3 some transients (e.g., cold feedwater following hot standby) are marked as ones that contribute significantly to fatigue. However, some of these transient are not included into UFSAR.

Request Explain why all transients that contribute significantly to fatigue are not included in the UFSAR.

Discussion: this question was resolved by Amendment 14, submitted by letter dated April 28, 2010.

- 5 CUF Calculation Questions DRAFT RAI4.3-10 Issue Section 4.3.2.1 of the LRA states that for the Unit 1 instrument nozzles, the calculated CUF of 0.68 is based on 15,000 load following cycles. Section 4.3.2.1 of the LRA further states that because PVNGS units do not operate in the load following mode, nor is the load following mode expected to occur during the period of extended operation, the analyses for instrument nozzles have been projected to the end of the period of extended operation, in accordance with 10 CFR 54.21 (c)(1 )(ii).

Request Describe the conservative assumptions for Unit 1 and why there is a factor of five difference between the Unit 1 and Units 2 and 3 CUFs. Clarify why these transients do not need to be tracked or counted per TS 5.5.5 and LI FSAR Section 3.9.1.1.1. Relate your explanation to the components for which these transients apply in UFSAR Tables 3.9-1 or 3.9.1-1.

Discussion: following discussion with the applicant, the question has been revised as follows and will be issued as a formal RAI:

DRAFT RAI 4.3-2 Issue Table 4.3-3 in Amendment 14 of the LRA provides an adequate technical basis that PVNGS operates as base load plant and that Transient No.3, "5 percent per minute power ramp increase, from 15 percent to 100 percent power," and Transient No.4, "5 percent per minute power ramp decrease, from 15 percent to 100 percent power," do not need to be counted relative to the 15,000 cycle limits for these transients. However, it appears that technical; specification (TS) 5.5.5 and UFSAR Section 3.9.1.1 may still require these transients to be counted, specifically because these transients are currently listed as transients in Section I and II of UFSAR Table 3.9-1.

LRA Section 4.3.2.1 of the LRA states that for the Unit 1 instrument nozzles, the calculated cumulative usage factor(CUF) of 0.68 is based on this 15,000 load following cycle limit.

However, there is a factor of five difference in the CU F that is reported for these components for Unit 1 and those that are reports for the instrument nozzles at Units 2 and 3.

Request

1. Clarify (with a justification) whether these transients are required to be counted per TS 5.5.5 and UFSAR Section 3.9.1.1. If these transients are required to be counted per TS 5.5.5 and UFSAR Section 3.9.1.1, clarify the actions that will be taken to resolve the inconsistency if it is determined there is a valid technical basis for not counting these transients.

- 6

2. Clarify whether or not either Transient NO.3 or Transient No.4 has occurred at the PVNGS site to date. If either transient has occurred, clarify how this is consistent with the plant being operated as a base loaded plant and justify not counting these transients.
3. Clarify why there is a factor of five difference between the CUFs reported for the instrument nozzles at Unit 1 from those that are reported for the corresponding nozzles at Units 2 and 3.

DRAFT RAI4.3-11 LRA Section 4.3.2.2 states that analyses of Control Element Drive Mechanism (CEDM) nozzle pressure housings were reexamined for the power uprate and steam generator replacement modifications and calculated CUFs were significantly less than the code limit of 1.0. Therefore, the applicant concludes that the design fatigue analyses of CEDM nozzle pressure housings remain valid for the period of extended operation, in accordance with 10 CFR 54.21 (c){1)(i).

LRA Table 4.3-3 indicated the projected 40-year number of cycles exceeded the design basis number of events for seven transients. UFSAR Table 3.9.1-1 indicated that some of these transients (e.g., reactor trip) are used in CUF calculations for Class 1 components. However, LRA Section 4.3.2.2 does not provide sufficient information to confirm whether CEDM nozzle pressure housings calculations have been updated to incorporate the projected 60-year number of cycles.

Request a) Explain which transients are used in the CUF calculations for these components.

b) For those transients, state whether the number of projected cycles for 60 years are bounded by those used for 40 years. If not, update the CUF calculations for projected 60-year cycles as required by 10 CFR 54.21 (c)(1)(ii).

Discussion: this question was resolved by Amendment 14, submitted by letter dated April 28, 2010.

DRAFT RAI4.3-12

Background

LRA Section 4.3.2.5 states that Unit 2 steam generator (SG) tube to tubesheet welds, tubesheet, and feedwater distribution box have a high calculated CUF. Also, LRA Section 4.3.2.5 states that the economizer and downcomer feedwater nozzles are more sensitive to plant operational behavior and, therefore, CUFs for these components bound CUFs for the tubesheet welds, tubesheet, and feedwater distribution box. Therefore, the applicant concluded that because fatigue usage in the economizer and downcomer feedwater nozzles is tracked by the stress-based fatigue monitoring method, this would insure that the effects of aging on Unit 2 tube to tubesheet welds, tubesheet, and feedwater distribution box will be also managed for the period of extended operation.

-7 Issue The LRA does not provide a sufficient description or basis for using this type of bounding SBF monitoring methodology for Class 1 components with high values CUF values (pages 4.3-3 and 4.3-4). The TLAA does not provide sufficient information to demonstrate that the CUF calculations for the economizer and downcomer feedwater nozzles are bounding for monitoring CUF calculations for the tubesheet welds, tubesheet, and feedwater distribution box. The TLAA does not clearly define what type of corrective actions would be taken for the non-SBF monitored components with high CUF values if an action limit is reached for the SBF-monitored components. In addition, the staff is uncertain whether this type of bounding analysis would comply with the cycle counting requirements of TS 5.5.5 if the transients affecting the CUF calculations for the non-SBF-monitored components are required to be tracked.

Request a) Clarify which transients are applicable to the CUF calculations for the SG hot and colds sides of the tubesheets, tubesheet welds, feedwater distribution box, economizer nozzles, and downcomer nozzles.

b) Clarify whether the transients used for the CUF calculations for these components are required to be tracked pursuant to TS 5.5.5.

c) If the transients are required to be tracked by the TS, justify why this type of bounding SBF monitoring methodology can be used for the non-SBF monitored components.

d) Clarify the corrective actions required for the non-SBF-monitored components if an action limit is reached for a SBF-monitored component.

e) Explain whether this methodology has been included into the Metal Fatigue of Reactor Coolant Pressure Boundary Program (LRA AMP B3.1). If not, provide revised AMP that incorporates this SBF methodology.

Discussion: this question was resolved by Amendment 14, submitted by letter dated April 28, 2010.

DRAFT RAI4.3-13

Background

Pursuant to 10 CFR 54.21(c)(1 )(i) - (iii), an applicant must demonstrate one of the following:

(i) the analyses remain valid for the period of extended operation, (ii) the analyses have been projected to the end of the extended period of operation, or (iii) the effects of aging on the intended function{s) will be adequately managed for the period of extended operation.

Issue LRA Section 4.3.2.6 states that 2-inch isolation valves for the charging line are subject to similar but less-severe cyclic effects than the charging nozzles. Therefore, the applicant concluded that because fatigue us~ge in the charging nozzles is tracked by the stress-based fatigue monitOring method, this monitoring would insure that the effects of aging on 2-inch isolation valves for the charging line intended functions will be also managed for the period of extended operation. However, LRA did not provide a description of and the basis for the bounding methodology used. Also, LRA did not provide sufficient information for the staff to conclude that

- 8 the CUF calculations for the charging nozzles bound CUF calculations for 2-inch isolation valves for the charging line.

Reguest a) Clarify which transients are applicable to the CUF calculations for the 2- inch isolation valves for the charging line.

b) Clarify whether the transients used for the CUF calculations for these components are required to be tracked pursuant to TS 5.5.5.

c) If the transients are required to be tracked by the TS, justify why this type of bounding SBF monitoring methodology can be used for the non-SBF monitored components.

d) Clarify the corrective actions required for the non-SBF-monitored components if an action limit is reached for a SBF-monitored component.

e) Explain whether this methodology has been included into the Metal Fatigue of Reactor Coolant Pressure Boundary Program (LRA AMP B3.1). If not, provide revised AMP that incorporates this SBF methodology.

Discussion: this question was resolved by Amendment 14, submitted by letter dated April 28, 2010.

DRAFT RAJ 4.3-14

Background

Pursuant to 10 CFR 54.21 (c)(1 )(i) - (iii), an applicant must demonstrate one of the following:

(i) the analyses remain valid for the period of extended operation, (ii) the analyses have been projected to the end of the extended period of operation, or (iii) the effects of aging on the intended function(s) will be adequately managed for the period of extended operation.

Issue LRA Section 4.3.2.6 states that design basis fatigue analyses of the 16-inch shutdown cooling suction containment isolation valves, the 14-inch safety injection tank injection discharge isolation gate valves, the 14-inch safety injection tank injection discharge check valves, the 12 inch HPSIILPSI check valves, the %-inch safety injection line thermal relief valves, the pressurizer safety valves, and the 2-inch isolation valves for the auxiliary spray indicate that the calculated CUFs are lot smaller than the code limit of 1.0. LRA Section 4.3.2.6 further states that these valves would be able to withstand fatigue effects for at least 1.5 times the original design lifetime. Therefore, the applicant concludes that the design fatigue analyses for these valves remain valid for the period of extended operation, in accordance with 10 CFR 54.21(c)(1)(i). LRA Table 4.3-3 indicated the projected 40-year number of cycles exceeded the design basis number of events for seven transients. UFSAR Table 3.9.1-1 indicated that some of these transients (e.g., reactor trip) are used in CUF calculations for Class 1 components.

However, LRA Section 4.3.2.6 does not provide sufficient information to confirm whether the fatigue analyses of the 16-inch shutdown cooling suction containment isolation valves, the 14 inch safety injection tank injection discharge isolation gate valves, the 14-inch safety injection tank injection discharge check valves, the 12-inch HPSIILPSI check valves, the %-inch safety injection line thermal relief valves, the pressurizer safety valves, and the 2-inch isolation valves for the auxiliary spray have been updated to incorporate the projected 40-year number of cycles.

- 9 Request Clarify whether CUF calculations for the 16-inch shutdown cooling suction containment isolation valves, the 14-inch safety injection tank injection discharge isolation gate valves, the 14-inch safety injection tank injection discharge check valves, the 12-inch HPSI/LPSI check valves, the o/-i-inch safety injection line thermal relief valves, the pressurizer safety valves, and the 2-inch isolation valves for the auxiliary spray have been updated to incorporate the projected 60-year number of cycles. If not, justify disposition of this TLAA in accordance with 10 CFR 54.21(c)(1 )(i).

Discussion: this question was resolved by Amendment 14, submitted by letter dated April 28, 2010.

DRAFT RAI 4.3-15 Backqround Pursuant to 10 CFR 54.21(c)(1)(i) - (iii), an applicant must demonstrate one of the following:

(i) the analyses remain valid for the period of extended operation, (ii) the analyses have been projected to the end of the extended period of operation, or (iii) the effects of aging on the intended function(s) will be adequately managed for the period of extended operation.

Issue LRA Section 4.3.2.7 states that the CVCS charging nozzles are the limiting components for Class 1 charging paths. Therefore, the applicant concluded that because fatigue usage in the charging nozzles is tracked by the stress-based fatigue monitoring method, this monitoring would insure that the effects of aging on Class 1 charging paths intended functions will be also managed for the period of extended operation. However, LRA did not provide a description of and the basis for the bounding methodology used. Also, LRA did not provide sufficient information for the staff to conclude that the CUF calculations for the CVCS charging nozzles bound CUF calculations for the Class 1 charging paths.

Request a) Clarify which transients are applicable to the CUF calculations for the Class 1 charging paths b) Clarify whether the transients used for the CUF calculations for these components are required to be tracked pursuant to TS 5.5.5.

c) If the transients are required to be tracked by the TS, justify why this type of bounding SBF monitoring methodology can be used for the non-SBF monitored components.

d) Clarify the corrective actions required for the non-SBF-monitored components if an action limit is reached for a SBF-monitored component.

e) Explain whether this methodology has been included into the Metal Fatigue of Reactor Coolant Pressure Boundary Program (LRA AMP B3.1). If not, provide revised AMP that incorporates this SBF methodology.

Discussion: this question was resolved by Amendment 14, submitted by letter dated April 28, 2010.

- 10 DRAFT RAI4.3-16 Issue Section 4.3.5 of the LRA states in the revised design analyses for the reactor coolant hot leg sample lines piping and the SG downcomer and feedwater recirculation lines piping, that the calculated stresses in limiting locations were less than allowable. However, LRA Section 4.3.5 does not provide sufficient information for the staff to confirm these assertions.

Request a) Provide the code allowable stress limits and the stress ranges obtained in the revised design analyses for the reactor coolant hot leg sample lines piping and the SG downcomer and feedwater recirculation lines piping.

b) Provide the ASME Code edition and specific subsection used for the revised design analyses for these piping components.

Discussion: following discussion with the applicant, the question has been revised as follows and will be issued as a formal RAI:

DRAFT RAI 4.3-3 Issue Section 4.3.5 of the LRA states in the revised design analyses for the reactor coolant hot leg sample lines piping and the SG downcomer and feedwater recirculation lines piping, that the calculated stresses in limiting locations were less than allowable. However, LRA Section 4.3.5 does not provide sufficient information for the staff to confirm these assertions.

Request Provide the code allowable stress limits and the stress ranges obtained in the revised design analyses for the reactor coolant hot leg sample lines piping and the SG downcomer and feedwater recirculation lines piping. Also, provide the American Society of Mechanical Engineers (ASME) Code edition and specific subsection used for the revised design analyses for these piping components.

DRAFT RAI4.3-17 Issue LRA Section 4.3.4 states that for RPV shell and lower head, RPV inlet and outlet nozzles, surge line hot leg elbow, safety injection nozzle, shutdown cooling line, and pressurizer heater penetrations the maximum applicable environmental factors (Fen) for a given material were used and were determined following NUREG/CR-6583 for carbon and low-alloy steels and NUREG/CR-5704 for stainless steel. However, LRA Section 4.3.4 does not provide sufficient information to confirm this assertion.

Request Demonstrate that environmental factors (Fen) used for assessment of the reactor coolant environment impact on RPV shell and lower head, RPV inlet and outlet nozzles, surge line hot leg elbow, safety injection nozzle, shutdown cooling line, and pressurizer heater penetrations

- 11 are maximum applicable for a given material. Provide a basis and justification for any assumptions that were made for the parameters in the assessment.

Discussion: following discussion with the applicant, the question has been revised as follows and will be issued as a formal RAI:

RAI4.3-4 Issue Section 4.3.4 of the LRA states that for reactor pressure vessel (RPV) shell and lower head, RPV inlet and outlet nozzles, safety injection nozzle (forging knuckle) the maximum applicable environmental factors (Fen) for low alloy steel was used and was determined following NUREG/CR-6583 "Effects of LWR Coolant Environments on Fatigue Design Curves of Carbon and Low-Alloy Steels". However, LRA Section 4.3.4 does not provide sufficient information to confirm this statement.

Request Demonstrate that environmental factors (Fen) used for assessment of the reactor coolant environment impact on the RPV shell and lower head, RPV inlet and outlet nozzles, safety injection nozzle (forging knuckle) are the maximum applicable for a given material. Provide a basis and justification for any assumptions that were made for the parameters, such as strain rate, dissolved oxygen, temperature and sulfur content, in the assessment.

DRAFT RAI 4.3-18 Issue Based on the information in Section 4.3.4 of the LRA, the staff noted that the environmental fatigue analyses for the RPV shell and lower head can be projected to the end of the period of extended operation in accordance with 10 CFR 54.21 (c)(1)(ii). However, the applicant concluded that the environmental fatigue analyses of RPV shell and lower head remain valid for the period of extended operation, in accordance with 10 CFR 54.21(c)(1)(i).

Request Provide the technical basis for stating that the design fatigue analyses of RPV shell and lower head remain valid for the period of extended operation in accordance with 10 CFR 54.21 (c)(1)(i) even though the fatigue analyses for these components were projected to the end of 60-years in accordance with 10 CFR 54.21 (c)(1)(ii).

Discussion: this question was resolved by Amendment 14, submitted by letter dated April 28, 2010.

DRAFT RAI4.3-19 Issue Section 4.3.4 of the LRA states that the pressurizer surge line elbow will remain as the bounding location for the environmental fatigue evaluation of the pressurizer surge line. The LRA

- 12 indicates that the non-environmental CUF for the pressurizer surge line hot leg elbow was re evaluated using the design basis number of transient cycles and the ASME Code,Section III, Subsection NB, six-component stress tensor methodology. The re-evaluated non environmental CUF was higher than the previously calculated non-environmental CUF.

However, later in this section of the LRA, it states that because the fatigue usage in the pressurizer surge line elbow is tracked by the stress based fatigue (SBF) monitoring method, this will be used as the bounding method for the pressurizer surge line hot leg elbow, and that this will ensure that the effects of aging (including environmental effects) on the intended functions of the pressurizer surge line elbow and pressurizer surge line hot leg elbow will be also managed for the period of extended operation. As a result, SBF monitoring of the pressurizer surge line elbow will be used as a bounding monitoring method for the pressurizer surge line hot leg nozzle.

The LRA does not provide any basis for how this bounding SBF-monitoring methodology would be applied to the evaluation of other non-SBF-monitored. high-valued-CUF components. The LRA did not provide sufficient information for the staff to conclude that the EAF CUF calculations for the pressurizer surge line nozzle bound calculations for the pressurizer surge line hot leg elbow. It is unclear to the staff if this methodology is being used as bounding for other Class 1 components.

In addition, the issues discussed in DRAFT RAI 4.3-12 also apply to this RAI.

Request a) Clarify which transients are applicable to the CUF calculations for the pressurizer surge line b) Clarify whether the transients used for the CUF calculations for this component is required to be tracked pursuant to TS 5.5.5.

c) If the transients are required to be tracked by the TS, justify why this type of bounding SBF monitoring methodology can be used for the non-SBF monitored components.

d) Clarify the corrective actions required for the non-SBF-monitored components if an action limit is reached for a SBF-monitored component.

e) Explain whether this methodology has been included into the Metal Fatigue of Reactor Coolant Pressure Boundary Program (LRA AMP B3.1). If not, provide revised AMP that incorporates this SBF methodology.

Discussion: this question was resolved by Amendment 14, submitted by letter dated April 28, 2010.

DRAFT RAI 4.3-20

Background

GSI-190 recommends assessment of the reactor coolant environment impact on fatigue life of critical components sample listed in NUREG/CD-6260.

Issue The conclusion of calculations PV-30Q-314 "Surge Line Hot Leg Elbow Fatigue Usage Analysis" and PV-30Q-315 "Environmentally-Assisted Fatigue Analysis of the Surge Line Elbow" do not agree with the conclusions of calculations PV-30Q-317 "Fatigue Usage Evaluation of Charging

-13 Nozzles, Safety Injection Nozzles and Surge Line Hot Leg Elbow using Assumed Plant Cycles" and PV-30Q-318 "Environmentally-Assisted Fatigue Evaluation of Charging Nozzles, Safety Injection Nozzles and Surge Line Hot Leg Elbow using Assumed Plant Cycles." However, the conclusions of calculations PV-30Q-314 and PV-30Q-315 were relied on in Table 4.3-11 of the LRA.

Request Clarify and justify whether calculations PV-30Q-314 and PV-30Q-315 or calculations PV-30Q 317 and PV-30Q-318 are relied upon for the environmental fatigue assessments for the pressurizer surge line hot leg elbow, when the conclusions between the calculations are not consistent.

Discussion: this question was resolved by Amendment 14, submitted by letter dated April 28, 2010.

DRAFT RAI 4.3-21 Issue Section 4.3.4 of the LRA does not contain sufficient information on the assumptions that have been used for the environmental Fen factor calculations of the charging system nozzle-to-safe end location and the safety injection nozzle.

Request Describe in detail the methodology that has been used for the environmental Fen factor calculation of the charging system nozzle-to-safe end location and the safety injection nozzle.

Provide a basis and justification for any assumptions that were made for the parameters in the assessment.

Discussion: following discussion with the applicant, the question has been revised as follows and will be issued as a formal RAt:

DRAFT RAI 4.3-5 Issue Note 7 and 9 of LRA Table 4.3-11 states the reanalysis computed Fen values for load set pairs with a significant fatigue contribution, for the charging system nozzle (safe end) and the safety injection nozzle (safe end), respectively. LRA Section 4.3.4 of the LRA does not contain sufficient information on the assumptions that have been used for the environmental Fen factor calculations of the charging system nozzle (safe end) and the safety injection nozzle (safe end).

Request

1. Describe in detail the methodology that has been used for the environmental Fen factor calculation of the charging system nozzle (safe end) and the safety injection nozzle (safe end).

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2. Provide a basis and justification for any assumptions that were made for the parameters.

such as strain rate, dissolved oxygen, and temperature, in the assessment of a computed Fen value for the load set pairs with a significant fatigue contribution.

3. Confirm the value of the maximum Fen factor used for all remaining load set pairs.

New Question (discussed during the May 6,2010 Public Meeting):

DRAFT RAI 4.3-6

Background

LRA Section 4.3.4 states that a bounding Fen factor of 1.49 was used for the Alloy 600 component (pressurizer heater penetrations). NUREG/CR-6335 provides the statistical characterizations used to derive this Fen factor of 1.49 for Alloy 600, which states the fatigue S-N database for Alloy 600 is extremely limited and does not cover an adequate range of material and loading variables that might influence fatigue life. It further states that the data was obtained from relatively few heats of material and are inadequate to establish the effect of strain rate on fatigue life in air or of temperature in a water environment. NUREG/CR-6909 incorporates more recent fatigue data using a larger database for determining the Fen factor of nickel alloys.

Issue The Fen factor of 1.49 for nickel alloys may be non-conservative. The Fen for nickel alloys based on NUREG/CR-6909 varies based on temperature, strain rate and dissolved oxygen. Based on actual plant operating conditions the Fen factor can vary from a value of 1.0 to 4.52 based on this methodology. Therefore, the cumulative usage factor (CUF) value for the pressurizer heater penetrations may be as high as 2.86 using the CUF presented in the LRA and the maximum Fen derived from NUREG/CR-6909 which would exceed the design limit of 1.0 when considering environmental effects of reactor coolant during the period of extended operation.

Request

1. Since the Fen for nickel alloys can vary from 1.0 to 4.52 based on NUREG/CR-6909 and the CUF value may exceed the design limit of 1.0 for the pressurizer heater penetrations when considering environmental effects, justify using a value of 1.49 for the Fen factor for this nickel alloy component.
2. Describe the current or future planned actions to update the CUF calculation with Fen factor for the Alloy 600 component only, consistent with the methodology in NUREG/CR 6909. If there are no current or future planned actions to update the CUF calculation with Fen factor for the Alloy 600 component consistent with the methodology in NUREG/CR-6909, provide a justification for not performing the update.

Discussion: the applicant stated that the question is clear; it will be sent as a formal RAI.

Palo Verde LRA Section 4.3 TLAA Information

1. Design Basis Information Inconsistencies:

A. Transients listed in UFSAR Table 3.9-1 as one type of transient but listed in LRA Tables 4.3-2 and 4.3-3 as a different type of transient:

  • Transient #50, "Depressurization by MSSV at 100% Power" -listed in the LRA Cycle tables as an upset condition transient, but is listed as an emergency event transient in USAR Table 3.9-1 (Item I.C.3.a)
  • Transient #14, "Low-Low Volume Control Tank/Charging Pump Suction Diversion to RWT" - listed in the LRA Cycle tables as a normal operating condition transient, but is listed as an upset condition transient in UFSAR Table 3.9-1 (Item I.D.2.d)
  • Transient #15, "Pressure Level Control, Failure to Open" -listed in the LRA Cycle tables as a normal operating condition transient, but is listed as an upset condition transient in UFSAR Table 3.9-1 (Item I.D.2.e)

B. Normal Operating Condition Transients, Upset Condition, or Test Condition Transients listed in UFSAR Table 3.9-1 which appear to be tracked per TS 5.5.5 but that are not included as transients for monitoring in LRA Tables 4.3-2 or 4.3-3.

  • Upset Transient I.A.2.f, "Pressurization by Spurious Actuation of All Pressurizer Heaters at 100% Power"
  • SI Test Transient 1I1.A.5.b, "Standby to Inservice Hydrostatic Test to Standby" C. Transients Listed in LRA Table 4.3-3 That Were Not Tracked Initially by the Counting Procedure, but That Are Required to be Tracked by TS 5.5.5 and one or more of the Transient Tables in UFSAR Section 3.9.1.1 (UFSAR Table 3.9.1-1 or UFSAR Table 3.9-1, Sections I, II, or III).

ENCLOSURE 3

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  • Transients 3,4,5,6,7,8,9, 13, 14, 15, 18, 19,20,21, 22, 23, 24, 25, 26. 28. 29, 30,31,32,33,34,35,36,37,38,39,41,42,45,46,47,48,49(53),50,51,52, 54, 56, 58, 59, 60, and 61 D. Normal Operating Condition Transients, Upset Condition, or Test Condition Transients listed multiple times in USAR Section 3.9.1.1 (Le., in USAR Table 3.9.1-1 or in Table 3.9-1,Section I. II, or III) Each With a Different Design Basis Allowable, but for Which the "Limiting Number of Events" column in LRA Tables 4.3-2 and 4.3-3 list a Single Value.
  • Upset Condition Transient 24, "Reactor Trip" - The design basis values listed for this event are 480 in USAR Table 3.9.1-1 for NSSS Class 1 components; 50 in USAR Table 3.9-1 Item 1.A.2.h for Class RCS piping components; and 240 in USAR Table 3.9-1 Item II.B.2.b for Class 1 CVCS piping components. However, "Limiting Number of Events" column in LRA Tables 4.3-2 and 4.3-3 list the number as 50 (Are we making a design basis change here? Also Table 4.3-2 only listed the 480 and the 50 values in the "USAR" column - 240 was missing).
  • Upset Condition Transient 25, "Loss Reactor Coolant Flow" - The design basis values listed for this event are 480 in USAR Table 3.9.1-1 for NSSS Class 1 components; 40 in USAR Table 3.9-1 Item II.B.2.a for Class 1 CVCS piping components. However, "Limiting Number of Events" column in LRA Tables 4.3-2 and 4.3-3 list the number as 40. .
  • Upset Condition Transient 36, "Turbine Trip Without a Reactor Trip" - The design basis values listed for this event are 40 in USAR Table 3.9-1 Item I.C.2.d for Class 1 RCS piping components; and 120 in USAR Table 3.9-1 Item II.D.2.b for Class 1 CVCS piping components. However, "Limiting Number of Events" column in LRA Tables 4.3-2 and 4.3-3 list the number as 40. Also Table 4.3-2 failed to list the applicable 120 design basis value in the "USAR" column).
  • Upset Condition Transient 37, "Inadvertent Actuation of Main Steam Isolation Valve" - The" Limiting Number of Events" column in LRA Table 4.3-3 list the number as 5/40. Footnote 21 to LRA Table 4.3-3 attempts to explain this up by stating that the values are 5 from 100% power and 40 from an unspecified power level. This could be different from the design basis, which appears represent this one event. one as applied to the Class 1 RCS piping components in USAR Table 3.9-1 Item I.C.2.b (for which the value is listed as 5) and one as applied to the Class 1 CVCS interfacing piping components in USAR Table 3.9-1 Item II.D.2.c (for which the value is listed as 40).

E. Transients Required to be Counted per Tech Spec 5.5.5 and USAR Section 3.9.1.1 but for which Footnote 11 of LRA Table 4.3-3 indicates that the transients not accounted for (indicated by "NR" entry in the "1985-1995 25% Assumed" column) in the cycle count Procedure #73ST-9RC02.

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  • Transient 3, "Plant Loading, 5%/min": This is required to be monitored by TS 5.5.5 because it is listed as a normal operating condition transient for Class 1 NSSS (vessel) components in USAR Table 3.9.1-1, and for Class 1 RCS components in USAR Table 3.9-1 Item 1.A.1.b.
  • Transient 4, "Plant Unloading, 5%/min": This is required to be monitored by TS 5.5.5 because it is listed as a normal operating condition transient for Class 1 NSSS (vessel) components in USAR Table 3.9.1-1, and for Class 1 RCS components in USAR Table 3.9-1 Item 1.A.1.c.
  • Transient 6, "10% Step Load Increase": This is required to be monitored by TS 5.5.5 because it is listed as a normal operating condition transient for Class 1 RCS piping components in USAR Table 3.9-1 Item I.C.1.a.
  • Transient 7, "Normal Plant Variation": This is required to be monitored by TS 5.5.5 because it is listed as a normal operating condition transient for Class 1 RCS piping components in USAR Table 3.9-1 Item I.C.1.c.
  • Transient 18, "Safety Injection Check Valve Test": This is required to be monitored by TS 5.5.5 because it is listed as a test condition transient for Class 1 RCS piping components in USAR Table 3.9-1 Item 1.E.1.a and a normal operating condition transient for Class 1 SI interfacing components in USAR Table 3.9-1 Item 1I1.A.1.e.
  • Transient 19, "High Pressure Safety Injection Header Check Valve Test": This is required to be monitored by TS 5.5.5 because it is listed as a normal operating condition transient for Class 1 CVCS interfacing piping components in USAR Table 3.9-1 Item 11.A.1.b.
  • Transient 20, "Turbine Roll Test at Hot Standby": This is required to be monitored by TS 5.5.5 because it is listed as a normal operating condition transient for Class 1 RCS piping components in USAR Table 3.9-1 Item I.C.1.e.
  • Transient 21, "Auxiliary Spray During Cooldown": This is required to be monitored by TS 5.5.5 because it is listed as a normal operating condition transient for Class 1 CVCS interfacing piping components in USAR Table 3.9-1 Item 11.A.1.c.
  • Transient 23, "RCP Coastdown at 100% Power": This is required to be monitored by TS 5.5.5 because it is listed as an upset condition transient for Class 1 RCS piping components in USAR Table 3.9-1 Item 11.A.2.a.
  • Transient 32, "Extended Loss of Letdown": This is required to be monitored by TS 5.5.5 because it is listed as an upset condition transient for Class 1 RCS components in USAR Table 3.9-1 Item I.D.2.f and for Class 1 CVCS interfacing piping components in USAR Table 3.9-1 Item 11.A.2.e.

-4

  • Transient 53, "Inadvertent Closure of All MSIVs at 100% Power": This is required to be monitored by TS 5.5.5 because it is listed as an upset condition transient for Class 1 RCS components in USAR Table 3.9-1 Item I.B.2.f.

F. Transients Required to be Tracked by TS 5.5.5 and USAR Section 3.9.1.1 That Were Not Include in the Cycle Recount Verification Basis (Transients with "NC" input values not Including those transients tracked since initial startups of Units).

  • Transients 3, 4, 7, 23, 39, 51, and 53 listed in LRA Table 4.3-3.
2. Inconsistencies Between Different Subsections of LRA Section 4.3:

A. Apparent Inconsistencies Between LRA Section 4.3 Cycle Tables (Le., Information in LRA Table 4.3-2 vs. Information in LRA Table 4.3-3)

B. Apparent Inconsistencies Between Text Provided in Section 4.3.1.4 and Data Provided in Either LRA Table 4.3-2 or Table 4.3-3

  • Transients Counted Since Day One of Plant Operation (Footnote 2 in LRA Table 4.3-3 is applicable): Transients 1, 2, 11, 12, 27, 40, 55, and 57.
  • Transients Listed in LRA Tables 4.3-2 and 4.3-3 Which Do Not Appear to Be Within the Scope of TS 5.5.5 or USAR Section 3.9.1.1 But For Which LRA Section 4.3.1.4, Subsection "Transients Not Included in the FSAR" Indicates Are Important To Track Per the Fatigue Monitoring Program: (1) Transient 10, "Cold Feedwater Following Hot Standby"; (2) Transient 16, "Unbolting/Bolting of RC Pump Casing Studs"; (3) Transient 17, Tensioning/Detensioning, of RV Head Studs"; (4) Transient 43, "Loss of RCP Seal Coolant"; and (5) Transient 44, "Loss of RCP Seal Injection."

C. Inconsistencies With Use of Fatigue Monitoring Program methods used to disposition individual TLAA CUF values for Code Class 1 components Under 10 CFR 54.21(c)(1)(iii)

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  • Multiple occurrences with use of "Global" monitoring method or any of the CBF monitoring methods to disposition under (iii) for components with high CUF components.
  • Use of SBF monitoring of one highly valued CUF component as a bounding basis for other components with high valued CUF values. Same issue with using bounding CBF monitoring bases.
  • Validity of scaling basis for Partial CBF-monitoring bases (CBF-PC).
  • Inconsistencies on cycle counting and CUF monitoring action limits and corrective actions when these action limits are not met.
  • Conflicting information within the scope of LRA Table 4.3-4.
3. Other Metal Fatigue Disposition Issues:
  • Page 4.3 CUF Corrective Action 2, "Enhance fatigue monitoring to confirm continued performance to the code limit" - Staff seeks clarification on what this means.
  • Section 4.3.2.1 basis on page 4.3-33 for support lugs - Staff seeks additional clarification on using monitoring of the RV closure head studs as a bounding method for the RV bottom head support lugs, which have a higher CUF that the RV closure head studs.
  • Section 4.3.2.1 basis on page 4.3-33 for RV instrument nozzles. The applicant is required to track Transients 3 and 4 in LRA Tables 4.3-2 and 4.3-3 by TS 5.5.5 and their USAR basis. The staff seeks justification why the applicant would not count Transients 3 and 4 for these nozzles when TS 5.5.5 would require them to do this.
  • Section 4.3.2.1 basis and revised basis for Unit 2 RV closure head vent pipe (LRA page 4.3-34) - The staff seeks justification why future plans for replacing the head vent pipe are valid to use a basis for dispositioning the TLAA for these components in accordance with 10 CFR 54.21(c)(1)(ii).
  • Section 4.3.2.3 basis for RCP casings closure bolts - The reduction of design limit from 500 cycles to 475 cycles for plant heatups and cooldowns for the CUF calculations of the components appears to be a design basis change for the facility.

The staff seeks justification why it is valid to use the Fatigue Monitoring Program as the basis for documenting the change in design basis limit for heatups and cooldowns applied to these bolts without a design change process.

  • Section 4.3.2.4 basis for pressurizer components, including pressurizer half nozzles and MNSA repairs?

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  • Section 4.3.2.5 basis (LRA pages 4.3-48 and -49) that SG tube CUF analysis for replaced SG tubes is not a TLAA - The Technical Specification inservice inspection requirements are not a valid replacement for meeting applicable design requirements.

Thus, the staff seeks justification why it is valid to use these TS requirements to claim that the CUF calculations are not a TLAA.

  • Section 4.3.2.5 bounding SBF monitoring basis for SG feedwater distribution box, tube-to-tubesheet welds, and tubesheets. The staff seeks additional clarification why the bounding methodology can be used for these components and justification on why the applicant can use SBF-monitoril1g of the FW economizer and downcomer nozzles as bounding locations for these components, particularly when the coldside of the tubesheet-to-shell junction appears to be a slightly more limiting component that these nozzles.

ML101520388(Package)ML101340829(Letter&EncI1-3)ML101380215(Encl 4)

OFFICE LA:RPOB:DLR PM:RPB2:DLR BC:RPB2:DLR PM:RPB2:DLR NAME SFigueroa LRegner DWrona LRegner DATE 07/14/10 06/28/10 07/14/10 07/14/10

Memorandum to Arizona Public Service Company from Lisa M. Regner dated July 14,2010

SUBJECT:

SUMMARY

OF TELEPHONE CONFERENCE CALLS BETWEEN THE U.S.

NUCLEAR REGULATORY COMMISSION AND ARIZONA PUBLIC SERVICE COMPANY CONCERNING METAL FATIGUE DRAFT REQUESTS FOR ADDITIONAL INFORMATION PERTAINING TO THE PALO VERDE NUCLEAR GENERATING STATION, UNITS 1,2, AND 3, LICENSE RENEWAL APPLICATION (ME0254, ME0255, AND ME0256)

DISTRIBUTION:

HARDCOPY:

DLR RF E-MAIL:

PUBLIC RidsNrrDlr Resource RidsNrrDlrRpb1 Resource RidsNrrDlrRpb2 Resource RidsNrrDlrRarb Resource RidsNrrDlrRasb Resource RidsNrrDlrRapb Resource RidsNrrDlrRpob Resource RidsNrrDciCvib Resource RidsNrrDciCpnb Resource RidsNrrDciCsgb Resource RidsNrrDraAfpb Resource RidsNrrDraApla Resource RidsNrrDeEmcb Resource RidsNrrDeEeeb Resource RidsNrrDssSrxb Resource RidsNrrDssSbpb Resource RidsNrrDssScvb Resource RidsOgcMailCenter Resource RidsOpaMaii Resource L. Regner D. Drucker R. Hall B. Mizuno, OGC R. Treadway, RIV G. Pick, RIV

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Discussion Topics

  • Historical and general background
  • Metal Fatigue Monitoring Program
  • Cycle Counting Questions
  • Class 1 Fatigue TLAA Evaluation Process
  • Future actions
  • NRC staff questions

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Initial development of PVNGS metal fatigue monitoring program

  • Program required by PVNGS Technical Specificatron 5.5.5
  • SYS80-PE-DE "Compilation of NSSS Responses to Design Bases Dynamic Events for the System 80 Standard Design" established applicable design cycles and their 40-year expected accumulation
  • Class I metal fatigue analyses incorporated the SYS80-PE-DE limits and in some cases identified additional items of concern

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Initial development of PVNGS metal fatigue monitoring program

  • The initial Technical Specification program did not require all UFSAR transients to be monitored
  • The UFSAR does not incorporate all of the additional limits (e.g. Rep stud tensioning/de-tensioning) - to be discussed later in this presentation

Program Review - 1995

  • Implemented expanded list of transients in January 1996
  • ITS upgrade in 1998 established current requirements
  • Not counted data between '85 and '95 was assumed to be an accumulation of 25% of the design allowed transients in all but a few cases

Performance of cycle counting since January 1996

  • Actual event counting has been in place since January 1996
  • Unit 1, 2 and 3 records have now been reviewed for LRA support

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Current PVNGS Metal Fatigue Monitoring Program

  • Current methodology:

- Cycle counting to ensure design assumptions are not exceeded

- Specific component locations are not specified

- Exception: Partial cycle (CBF-PC) methodology is used to track spray nozzle usage

Addressing Cycle Count Assumptions

  • LRA development prompted PVNGS staff to revisit the assumptions for 1985 - 1995
  • Recounts of all three units were reported in the response to RAI 83.1-4 (see RAI response Table 3.1-4)

- Recount Methodology

  • Best source selected (logs, MORs, LERs, WOs, interviews)
  • Validated assumptions

Cycle Recou nt

  • Recount Methodology

- Best source selected (logs, MORs, LERs, WOs, interviews)

- Reviewed assumption of 25% accumulated cycles

.

  • Actual data
  • Comparison to '95 - '05 operating history

Enhanced Metal Fatigue Monitoring Program

  • Required by 10 CFRS4.21 (c)(1 )(iii)
  • Scope - All Class I components
  • Methodology:

- Based on component locations

- Adds SBF for high usage locations (not discussed in this presentation)

- Continues cycle counting for "Global" monitoring

  • Used for low 40-year design CUF
  • No new industry issues since original design
  • Industry experience indicates not a problem location

- Expands CUF monitoring

  • CBF-C (CUF based on design cycle)
  • CBF-PC (CUF based on partial cycle)
  • CBF-EP (CUF based on event pairing)

- Establishes appropriate action limits and corrective actions

Enhanced Program Status

  • SBF methodology (to be determined)
  • FatiguePro is under evaluation for cycle counting and CBF monitoring
  • Current manual cycle counting will continue until a suitable software program has been validated
  • Enhanced program will be implemented no later than two years prior to the PEO (LRA commitment #39 as revised in Amendment 9)

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Cycle Counting RAls and Amendments

  • Amendment 3 (annual update)

- Added Unit 3 record review results and revised one transient total to replace an estimate with data

- Revised current program action limit discussion to avoid confusion with the enhanced program limits

- Minor clarifications were included in the AMP DE discussion

Cycle Counting RAls and Amendments (continued)

  • Amendment 9 (result of RAI 83.1-1 thru 8)

- RAI 83.1-4 response provided the individual unit cycle totals from best available sources

- Corrected typographical errors

- Included enhanced monitoring implementation schedule

- Committed to selection of a suitable S8F methodology

- Clarified cycle projection methodology

Cycle Counting RAls and Amendments (continued)

Most recent cycle count related DRAI set (DRAI 4.3 1 thru 9

- DRAI 4.3-1 Transients projected to exceed 40-year limits

  • Projections are conservative and may not be reached
  • NUREG 1801 Vol 2 AMP X.M1 allows use of this program to manage aging and recommends "no further evaluation" if this program is selected to satisfy 10CFRS4.21 (c)(1 )(iii)
  • PVNGS took no exceptions to X.M1 and concludes fatigue reanalyses are not required based on projections. Corrective action will be initiated if needed based on program action limits

Cycle Counting RAls and Amendments (continued)

- Presented for information only

- Concept of a worst case bounding unit

- Conservative Assumptions

  • Highest unit total was used for '85-'95 and for '95-'05
  • Lowest operating years was used for accumulation rate
  • 42 years were used for projecting and added to above
  • 'Zero accumulation' assumed to be linear times 22/40

- If not expected still assumed 1 event

Cycle Counting RAls and Amendments (continued)

  • ORAl 4.3-2 Global monitoring criteria does not seem consistent

- Exceptions are explained in LRA table notes

  • ORAl 4.3-3 Clarify the CBF-PC method
  • ORAl 4.3-4 Program action limits (see commitment #39)
  • ORAl 4.3-5 Some cycles do not agree with the UFSAR

- Some are derived from UFSAR sections other than 3.9.1

- Some come from specific analyses (e.g. RCP studs)

- Addition of cycles to the UFSAR is under consideration

Cycle Counting RAls and Amendments (continued)

  • ORAl 4.3-6 25% cycle assumption

- Review of best source data was presented in the response to RAI 83.1-4

- Compared assumption to actual data from recount efforts or data from '95-'05

- Result:

  • Four assumptions of 25% cycle accumulation are being reviewed: Rx Trip, Load Reject, Turbine Trip wlo Rx Trip and Depressurization by MSSV at 100 % power
  • Remaining 25 % assumptions are conservative

' - - - - -_ _ _ _ _ _ _ _ _ _ _ _ 1

Cycle Counting RAls and Amendments (continued)

  • DRAI 4.3-7 Not all cycles were recounted

- Some had accurate data and did not require recount

- Some were not significant (e.g. plant loading at 5%/min)

- Some could not be recovered so the 25%

assumption was used and validated from '95

'05 data I

Cycle Counting RAls and Amendments (continued)

  • ORAl 4.3-8 Questioned an incorrect table note (had been corrected in Amendment 9)
  • ORAl 4.3-9 Some cycles are not included in the UFSAR (similar to ORAl 4.3-5)

- Some come from specific analyses (e.g. Rep studs)

- Addition of cycles to the UFSAR is under consideration I

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Class 1 Fatigue TLAA Evaluation Process

  • Identify TLAAs and Affected Components

- SRP Guidance, Industry Experience, CLB Search

  • Retrieve Component Current Licensing and Design Basis Documents (CLB and COB)

- Analysis Results - Analyzed Locations, CUFs, etc.

- Effects of Modification, Analysis, and Op. History

- Effects of Differences in Analysis Methods

- Identify Disposition

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Identify TLAAs and Affected Components

- NUREG-1800 Sect. 4.3 and Tables for Class 1

- Based on ASME III Subsection NB and NG and Industry Experience

  • Industry Experience - Examples:

- Other LRAs

- NRC and NSSS vendor Bulletins, Notices, etc.

- Word Search of CLB (FSAR, Docketed Reports, Letters, etc.)

- Confirm applicability to Palo Verde

- Identify other plant-specific TLMs

Retrieve Component Current Licensing and Design Basis Documents (CLB and COB)

  • Research and Summarize History of CLB

- Confirm Current Licensing Basis

  • Research Design and Analysis History

- Confirm Current Design Basis

- TLAAs are analyses, are therefore part of the COB

- TLAAs are usually bases of the CLB

("incorporated by reference") rather than included verbatim

Evaluate and Summarize COB TLAAs

  • Analysis Results

- All TLM Results (e.g., all reported fatigue summaries)

- All Analyzed Locations

- Tabulated for Complex Components

  • Effects of Modification, Analysis, and Operating History - Examples:

- Instrument Nozzle Half-Nozzle and MNSA Repairs (Several LRA Sections)

- Pressurizer Surge Line Thermal Stratification (LRA Section 4.3.2.9)

- Unit 2 Head Vent Repair - high part-life CUF, head replaced Fall 2009 (LRAp.4.3-34)

Evaluate and Summarize COB TLAAs (Continued)

  • Identify Disposition

- Based on Analysis History, Results, and Methods

confirm adequate margin at 60 years

- Requires Aging Management

Evaluate and Summarize COB TLAAs (Continued)

  • Identify Disposition (Continued)

- 10 CFR 54.21 (c)(1)(iii) monitoring methods are described in LRA 4.3.1, summarized by monitored location in Table 4.3-4

- Details of 10 CFR 54.21(c)(1)(iii) monitoring methods are location and analysis-specific. Examples:

  • Cycle-based fatigue (CBF) - monitor transients, possible CUF impacts
  • Stress-based fatigue (SBF) - impact of transients require reevaluation of CUF

NRC Staff Questions

  • Have we answered the questions and issues stated in this presentation?
  • Does the staff have additional questions with respect to cycle counting or the PVNGS approach to metal fatigue?
  • Review action items
  • Future topics Thank you for your participation
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