ML19310F679
| ML19310F679 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 11/13/2019 |
| From: | Jennifer Dixon-Herrity Plant Licensing Branch IV |
| To: | Bement R Arizona Public Service Co |
| Lingam S,, NRR/DORL/LPLIV 301-415-1564 | |
| References | |
| EPID L-2019-LLR-0093 | |
| Download: ML19310F679 (8) | |
Text
November 13, 2019 Mr. Robert S. Bement Executive Vice President Nuclear/
Chief Nuclear Officer Mail Station 7602 Arizona Public Service Company P.O. Box 52034 Phoenix, AZ 85072-2034
SUBJECT:
PALO VERDE NUCLEAR GENERATING STATION, UNITS 1, 2, AND 3 -
RELIEF REQUEST VRR-01 FOR USE OF THE PROPOSED ALTERNATIVE IN LIEU OF THE INSERVICE TESTING REQUIREMENTS OF THE AMERICAN SOCIETY OF MECHNAICAL ENGINEERS CODE OF OPERATIONS AND MAINTENANCE OF NUCLEAR POWER PLANTS (EPID L-2019-LLR-0093)
Dear Mr. Bement:
By letter dated September 20, 2019, Arizona Public Service Company (the licensee) submitted an alternative request to the U.S. Nuclear Regulatory Commission (NRC). The licensee requested an alternative test plan in lieu of certain inservice testing (IST) requirements of the American Society of Mechanical Engineers (ASME) Code for Operation and Maintenance of Nuclear Power Plants (OM Code) for the IST programs at Palo Verde Nuclear Generating Station (Palo Verde) Units 1, 2, and 3.
Specifically, pursuant to Title 10 of the Code of Federal Regulations (10 CFR) paragraph 50.55a(z)(1), the licensee requested to use proposed alternative VRR-01 for certain isolation valves on the basis that the alternative provides an acceptable level of quality and safety.
The NRC staff reviewed the licensees submittal and determined that the proposed alternative by the licensee in Relief Request VRR-01 provides an acceptable level of quality and safety.
Accordingly, the NRC staff concludes that the licensee has adequately addressed all of the regulatory requirements set forth in 10 CFR 50.55a(z)(1). Therefore, the NRC staff authorizes the use of the proposed alternative in Relief Request VRR-01 for the fourth 10-year IST program interval at Palo Verde, Units 1, 2, and 3, which began on January 15, 2018, and is currently scheduled to end on January 14, 2028.
All other ASME OM Code requirements for which relief was not specifically requested and authorized in the subject relief request remain applicable.
R. Bement If you have any questions, please contact the Project Manager, Siva P. Lingam, at 301-415-1564 or by e-mail to Siva.Lingam@nrc.gov.
Sincerely,
/RA/
Jennifer L. Dixon-Herrity, Chief Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. STN 50-528, STN 50-529, and STN 50-530
Enclosure:
Safety Evaluation cc: Listserv
- by e-mail OFFICE NRR/DORL/LPL4/PM NRR/DORL/LPL4/LA NRR/DEX/EMIB/BC*
NAME SLingam PBlechman SBailey DATE 11/13/19 11/13/19 11/4/19 OFFICE NRR/DORL/LPL4/BC NAME JDixon-Herrity DATE 11/13/19
Enclosure SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELIEF REQUEST VRR-01 FOR THE FOURTH 10-YEAR INTERVAL VALVE INSERVICE TESTING PROGRAM ARIZONA PUBLIC SERVICE COMPANY PALO VERDE NUCLEAR GENERATING STATION, UNITS 1, 2, AND 3 DOCKET NOS. STN 50-528, 50-529, AND 50-530
1.0 INTRODUCTION
By letter dated September 20, 2019 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML19263F875), Arizona Public Service Company (APS, the licensee) submitted Relief Request VRR-01 for Palo Verde Nuclear Generating Station (Palo Verde),
Units 1, 2, and 3. In this relief request, the licensee requests approval for the use of an alternative in lieu of certain inservice testing (IST) requirements of the American Society of Mechanical Engineers (ASME) Code for Operation and Maintenance of Nuclear Power Plants (OM Code) at Palo Verde Units 1, 2, and 3 during the fourth 10-year IST program intervals.
Pursuant to Title 10 of the Code of Federal Regulations (10 CFR) paragraph 50.55a(z)(1),
Acceptable level of quality and safety, Relief Request VRR-01 proposes an alternative to the requirements of the ASME OM Code to perform supplemental indication closure testing that satisfies 10 CFR 50.55a(b)(3)(xi), OM condition: Valve Position Indication, at test frequencies required by 10 CFR Part 50, Appendix J, Primary Reactor Containment Leakage Testing for Water-Cooled Power Reactors, for the valves listed in Table 1 of this safety evaluation (SE). The applicable ASME OM Code edition for the Palo Verde Units 1, 2, and 3 fourth 10-year IST program interval is the 2012 Edition. Currently, APS utilizes procedures developed for the containment local leak-rate test (LLRT) program per 10 CFR Part 50, Appendix J, to satisfy the supplemental indication of valve closure. The licensee is performing these activities to meet Subsection ISTC-3700, Position Verification Testing, of the ASME OM Code test frequency requirement. Subsection ISTC-3700 of the ASME OM Code requires obturator testing more frequent than the individual LLRT tests required by 10 CFR Part 50, Appendix J.
The licensee desires to have the LLRT test frequency requirement satisfy both the obturator testing and LLRT individual valve testing.
Specifically, pursuant to 10 CFR 50.55a(z)(1), the licensee requested to use proposed alternative VRR-01 for certain isolation valves on the basis that the alternative provides an acceptable level of quality and safety.
2.0 REGULATORY EVALUATION
Paragraph 50.55a(f), Preservice and inservice testing requirements, of 10 CFR requires, in part, that IST of certain ASME Code Class 1, 2, and 3 components must meet the requirements of the ASME OM Code and applicable addenda, except where alternatives have been authorized pursuant to 10 CFR 50.55a(z)(1) or 10 CFR 50.55a(z)(2).
In proposing alternatives, a licensee must demonstrate that the proposed alternatives provide an acceptable level of quality and safety (10 CFR 50.55a(z)(1)) or compliance would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety (10 CFR 50.55a(z)(2)).
Based on the above, and subject to the following technical evaluation, the U.S. Nuclear Regulatory Commission (NRC) staff finds that regulatory authority exists for the licensee to request, and the NRC to authorize, the proposed alternative requested by the licensee.
3.0 TECHNICAL EVALUATION
3.1 Applicable ASME OM Code The following request is an alternative test plan in lieu of certain IST requirements of the 2012 Edition of the ASME OM Code and the requirement 10 CFR 50.55a(b)(3)(xi) for the IST program at Palo Verde Units 1, 2, and 3 for the fourth interval, which began on January 15, 2018, and is currently scheduled to end on January 14, 2028.
3.2 Licensees Alternative Request VRR-01 ASME OM Code Requirements:
Subsection ISTC-3530 Valve Obturator Movement, states that The necessary valve obturator movement shall be determined by exercising the valve while observing an appropriate indicator, such as indicating lights that signal the required changes of obturator position, or by observing other evidence, such as changes in system pressure, flow rate, level, or temperature, that reflects change of obturator position.
Subsection ISTC-3700 states that Valves with remote position indicators shall be observed locally at least once every 2 yr [years] to verify that valve operation is accurately indicated.
Where practicable, this local observation should be supplemented by other indications such as use of flow meters or other suitable instrumentation to verify obturator position. These observations need not be concurrent. Where local observation is not possible, other indications shall be used for verification of valve operation. Position verification for active MOVs[
motor-operated valves] shall be tested in accordance with Mandatory Appendix III of this Division.
Mandatory Appendix III-3300 Inservice Test, Item (e), states that Remote position indication shall be verified locally during inservice testing or maintenance activities.
Mandatory Appendix III-3310 Inservice Test Interval, Item (b), states that If insufficient data exist to determine the inservice test interval in accordance with para. [paragraph] III-6400, then MOV inservice testing shall be conducted every two refueling cycles or 3 yr (whichever is longer) until sufficient data exist, from an applicable MOV or MOV group, to justify a longer inservice test interval.
Paragraph 50.55a(b)(3)(xi) of 10 CFR Requirement:
OM condition: Valve Position Indication. When implementing ASME OM Code, 2012 Edition, Subsection ISTC-3700, Position Verification Testing, licensees shall verify that valve operation is accurately indicated by supplementing valve position indicating lights with other indications, such as flow meters or other suitable instrumentation, to provide assurance of proper obturator position.
Alternative testing is requested for the following valves:
Table 1 Valve ID/Operator Valve Description ASME Code Class OM Valve Category CHAUV0560 Pneumatic Reactor drain tank outlet inboard containment isolation valve (CIV)
(penetration no. 44) 2 A
CHBUV0561 Pneumatic Reactor drain tank outboard CIV (penetration no. 44) 2 A
CHAUV0580 Pneumatic Reactor makeup water to reactor drain tank outboard CIV (penetration no. 45) 2 A
CHBHV0255 Motor Reactor coolant pump seal injection outboard CIV (penetration no. 72) 2 A
CHAUV0506 Pneumatic Reactor coolant seal bleed-off inboard CIV (penetration no. 43) 2 A
CHBUV0505 Pneumatic Reactor coolant seal bleed-off outboard CIV (penetration no. 43) 2 A
CHBUV0515 Pneumatic Letdown isolation valve 1
B CHAUV0516 Pneumatic Letdown inboard CIV (penetration no. 40) 1 A
CHBUV0523 Pneumatic Letdown from regenerative heat exchanger outboard CIV (penetration no. 40) 2 A
GRAUV0001 Motor Containment isolation between reactor drain tank and gas surge header (penetration no. 52) 2 A
RDBUV0024 Pneumatic Containment radwaste sump outlet outboard CIV (penetration no. 9) 2 A
=
Reason for Request===
All valves listed in Table 1 of this SE are classified in the Palo Verde IST program plan to have a close safety function. Valves CHAUV0560, CHBUV0561, and CHAUV0580 are normally closed and the remaining valves are normally open. Flow is verified through all valves every 18 months. Currently APS utilizes procedures developed for containment LLRT to satisfy the supplemental indication requirement of 10 CFR 50.55a(b)(3)(xi) when testing valves with remote position indicators per ASME OM Code Subsection ISTC-3700 or Mandatory Appendix III.
Dependent on the type of valve and its requirements, the test intervals for position verification testing can vary.
Proposed Alternative The licensee proposes to perform the supplemental indication test requirement of 10 CFR 50.55a(b(3)(xi) at frequencies controlled by a 10 CFR Part 50, Appendix J, Option B, type program for the valves listed in Table 1 of this SE. The valve open function verification will remain the same, in that flow is verified every 18 months. The valve close function will be determined by a 10 CFR Part 50, Appendix J, Option B type schedule, which is a performance-based program. Valves must pass two successful as-found leakage tests to qualify for a 60 month extension test interval. The longest period between 10 CFR Part 50, Appendix J, Option B tests at Palo Verde is 41/2 years or 54 months, which is equal to three 18-month operating cycles.
3.3
NRC Staff Evaluation
The ASME OM Code requires active and passive valves to be periodically tested in accordance with Subsection ISTC-3500 Valve Testing Requirements. Active valves are exercised at a frequency determined by Subsection ISTC-3510 Exercising Test Frequency. Valves are nominally exercised every 3 months except where the exercise is not practicable when the plant is operating. During the valve exercise, valve obturator movement is verified by Subsection ISTC-3530 Valve Obturator Movement. Subsection ISTC-3530 allows the use of remote position indicating lights that signal the required change of obturator position to complete this test. However, the use of remote position indicating lights does not provide a positive verification that the valve operation is accurately indicated. To address this, the ASME OM Code developed Subsection ISTC-3700, which requires local observation of the valve exercise every 2 years to verify valve operation is accurately indicated. The ASME OM Code is not specific on how this is completed. The NRC staff issued a condition in rulemaking, 10 CFR 50.55a(b)(3)(xi), which requires the position verification test to be supplemented with other indications, such as flow meters or other suitable instrumentation, to provide assurance of proper obturator position.
The licensee has proposed an alternative test in lieu of the requirements of the 2012 Edition of the ASME OM Code Subsection ISTC-3700, Mandatory Appendix III, and the rulemaking condition, 10 CFR 50.55a(b)(3)(xi), for valves listed in Table 1 of this SE. Valves would initially be tested at the required interval schedule, which is every refueling outage, 2 years, or interval as specified by the ASME OM Code. The valve open function will be verified by observing flow through each valve once every 18 months during refueling outages. The valve close function will be verified by successful completion of a valve leakage test once every 18 months. The valve open function test interval will remain at the current test schedule. The valve close function test interval will be determined by using a 10 CFR Part 50, Appendix J, Option B performance-based schedule. Valves that have demonstrated good performance for two consecutive cycles may have their test interval extended up to 60 months. Palo Verde operating cycles are 18 months, therefore, valves on a 60-month period are tested every three refueling outages (54 months) to meet the 60-month period. Any leakage test failure would require the component to return to the initial interval until good performance can again be established.
Appendix J, Option B of 10 CFR Part 50 is a performance-based leakage test program.
Guidance for implementation of acceptable leakage rate test methods, procedures, and analyses is provided in Regulatory Guide (RG) 1.163, Performance-Based Containment Leak-Test Program (ADAMS Accession No. ML003740058). RG 1.163 endorses Nuclear Energy Institute [NEI] Topical Report [TR] 94-01, Revision 0, Industry Guideline for Implementing Performance Based Option of 10 CFR 50, Appendix J, dated July 21, 1995, with the limitation that Type C components test interval cannot extend greater than 60 months.
In reviewing the licensees alternative request VRR-01, the NRC staff noted that Palo Verde safety-related valves listed in Table 1 of this SE have been reliable and have no history of stem-disk separations. Verification of the flow through the valves every 18 months coupled with a supplemental leak rate test at a 10 CFR Part 50, Appendix J, Option B test interval represents valve operation is accurately indicated and provides an acceptable alternative to the 2-year frequency required by Subsection ISTC-3700 of the OM Code, and the test intervals determined by Mandatory Appendix III. Extending the valve close function leakage test interval based on good performance is a logical progression to a performance-based program.
4.0 CONCLUSION
As set forth above, the NRC staff finds that the proposed alternative described in Relief Request VRR-01 provides an acceptable level of quality and safety for the components listed in Table 1 of this SE. Accordingly, the NRC staff concludes that the licensee has adequately addressed all of the regulatory requirements set forth in 10 CFR 50.55a(z)(1). Therefore, the NRC staff authorizes the proposed alternative VRR-01 for the Fourth 10-Year IST interval at Palo Verde Units 1, 2, and 3, which began on January 15, 2018 and is currently scheduled to end on January 14, 2028.
All other ASME OM Code requirements for which relief was not specifically requested and approved in the subject requests for relief remain applicable.
Principal Contributor: M. Farnan Date: November 13, 2019