ML19263F875

Relief Request VRR-01: Request for Alternative Frequency to Supplemental Indication Requirements of 10 CFR 50.55a(b)C3)(xi)

ML19263F875
Person / Time
Site:	Palo Verde
Issue date:	09/20/2019
From:	Lacal M Arizona Public Service Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
102-07983-MLL/MDD
Download: ML19263F875 (9)

Text

10 CFR 50.55a Oaps 102-07983-MLL/MDD MARIA L. LACAL Senior Vice President, Nuclear Regulatory & Oversight Palo Verde September 20, 2019 Nuclear Generating Station P.O. Box 52034 U. S. Nuclear Regulatory Commission Phoenix, AZ 85072 ATTN: Document Control Desk Mail Station 705 Washington, DC 20555-0001 Tel 623.393.6491

Subject:

Palo Verde Nuclear Generating Station Units 1, 2, and 3 Docket Nos. STN 50-528, 50-529, and 50-530 Renewed Operating License Numbers NPF-41, NPF-51, and NPF-74 Relief Request VRR Request for Alternative Frequency to Supplemental Indication Requirements of 10 CFR 50.55a(b)C3)(xi)

Pursuant to 10 CFR 50.55a(z)(l), Arizona Public Service Company (APS) requests Nuclear Regulatory Commission (NRC) approval of the enclosed request for an alternative frequency to perform supplemental indication closure testing per 10 CFR 50.55a(b)(3)(xi). The alternative frequency would be consistent with the test frequencies in 10 CFR 50 Appendix J, Primary Reactor Containment Leakage Testing for Water-Cooled Power Reactors.

The enclosure identifies the affected components, applicable American Society of Mechanical Engineers (ASME) Code requirements, reason for request, proposed alternative and basis for use. A pre-submittal phone call was held between NRC and APS on August 27, 2019, to discuss the request for alternative frequency to supplemental indication requirements of 10 CFR 50.55a(b)(3)(xi). APS requests approval of the proposed alternative by March 1, 2020, to support the next Unit 2 refueling outage in the Spring of 2020.

No new commitments are being made in this submittal.

If you have any questions about this request, please contact Michael D. DiLorenzo, Department Leader, Nuclear Regulatory Affairs, at (623) 393-3495.

Sincerely, MLL/MDD

Enclosure:

Relief Request VRR Request for Alternative Frequency to Supplemental Indication Requirements of 10 CFR 50.55a(b)(3)(xi) cc: S. A. Morris NRC Region IV Regional Administrator S. P. Lingam NRC NRR Project Manager for PVNGS C. A. Peabody NRC Senior Resident Inspector for PVNGS A member of the STARS Alliance LLC Callaway

• Diablo Canyon

• Palo Verde

• Wolf Creek

Enclosure Relief Request VRR-01 Request for Alternative Frequency to Supplemental Indication Requirements of 10 CFR 50.55a(b)(3)(xi)

Enclosure Relief Request VRR-01 Arizona Public Service Company (APS) is requesting an alternative per 10 CFR 50.55a(z)(l) to perform supplemental indication closure testing that satisfies 10 CFR 50.55a(b)(3)(xi) at 10 CFR 50 Appendix J-driven test frequencies for the valves in Table 1 for Palo Verde Nuclear Generating Station (PVNGS) Units 1, 2, and 3. Supplemental indication of valve opening is not within the scope of the request. Table 1 provides a brief description of when open indication is performed.

1. ASME Code Component(s) Affected The American Society of Mechanical Engineers (ASME) code components affected by this relief request are listed in Table 1, Scope of Valves.

Table 1 - Scope of Valves ASME Valve ID / OM Valve Valve Description Code Open Indication Operator Category Class Reactor drain tank outlet inboard Valves are verified open when CHAUV0560 containment isolation valve 2 A reactor drain tank is pumped Pneumatic (penetration no. 44) down every 18 months during Reactor drain tank outboard refueling outages. This is not a CHBUV0561 containment isolation valve 2 A normal flow path during the Pneumatic (penetration no. 44) operating cycle.

Valve is verified open when Reactor makeup water to reactor reactor drain tank is filled every CHAUV0580 drain tank outboard containment 2 A 18 months during refueling Pneumatic isolation valve (penetration no. 45) outages. This is not a normal flow path during the operating cycle.

Reactor coolant pump seal injection CHBHV0255 outboard containment isolation valve 2 A Motor Flow is verified when reactor (penetration no. 72) coolant pump seal injection is Reactor coolant seal bleed-off initiated every 18 months during CHAUV0506 inboard containment isolation valve 2 A refueling outages. Flow is Pneumatic (penetration no. 43) continuous through these valves Reactor coolant seal bleed-off throughout the operating cycle.

CHBUV0505 outboard containment isolation valve 2 A Pneumatic (penetration no. 43)

CHBUV0515 Letdown isolation valve 1 B Pneumatic Flow is verified when letdown line CHAUV0516 Letdown inboard containment is placed in service every 18 1 A months during refueling outages.

Pneumatic isolation valve (penetration no. 40)

Flow is continuous through these Letdown from regenerative heat valves throughout the operating CHBUV0523 cycle.

exchanger outboard containment 2 A Pneumatic isolation valve (penetration no. 40)

Valve is verified open during Containment isolation between GRAUVOOOl reactor coolant system reactor drain tank and gas surge 2 A Motor depressurization every 18 months header (penetration no. 52) during refueling outages.

Valve is verified open every 18 Containment radwaste sump outlet RDBUV0024 months during refueling outages outboard containment isolation valve 2 A Pneumatic via radwaste sump level (penetration no. 9) decreases.

Enclosure Relief Request VRR-01

2. Applicable Code Edition and Addenda

ASME Operation and Maintenance of Nuclear Power Plants (OM Code), 2012 Edition, No Addenda (Reference 1)

3. Applicable Code Requirement

The alternative applies to:

• The two-year frequency established for supplemental indication per 10 CFR 50.55a(b)(3)(xi) and ASME OM Code, 2012 Edition, subsection ISTC-3700 (Reference 1).

• The three-year frequency established for supplemental indication of motor operated valves (MOVs) tested per 10 CFR 50.55a(b)(3)(xi) and ASME OM Code, 2012 Edition, subparagraphs III-3300(e) and III-3310(b) (Reference 1).

10 CFR 50.55a(b)(3)(xi) states:

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.

Subsection ISTC-3700 of ASME OM Code, 2012 Edition, states:

Valves with remote position indicators shall be observed locally at least once every 2 yr 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 shall be tested in accordance with Mandatory Appendix III of this Division.

Mandatory Appendix III, subparagraph III-3300(e), states:

Remote position indication shall be verified iocally during inservice testing or maintenance activities.

Mandatory Appendix III, subparagraph III-3310(b), states:

If insufficient data exist to determine the inservice test interval in accordance with para. 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.

4. Reason for Request

Currently, APS utilizes procedures developed for containment local leak rate (LLRT) program testing per 10 CFR 50, Appendix J (Reference 2), to satisfy the supplemental indication of valve closure. APS is performing these activities to meet the Subsection ISTC-3700 of ASME OM Code (Reference 1) 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 50, Appendix 2

Enclosure Relief Request VRR-01 J. APS desires to have the LLRT test frequency requirement satisfy both the obturator testing and LLRT individual valve testing.

5. Proposed Alternative and Basis for Use Obtaining supplemental indication at frequencies controlled by the 10 CFR 50, Appendix J (Reference 2), program provides an acceptable level of quality and safety for the valves in Table

1. Regulation 10 CFR 50, Appendix J, describes an NRC required testing program. The testing required by 10 CFR 50, Appendix J, is more rigorous than that applied for supplemental indication, since 10 CFR 50, Appendix J, also applies leak rate requirements to valves. The ASME OM Code, 2012 Edition (Reference 1), describes another NRC-required testing program. This testing program has different position indication frequency requirements based on valve operator type. PVNGS valve performance history shows the stem-disc connection is reliable. Therefore, obtaining supplemental indication at a test interval longer (less frequent) than the frequencies specified in ASME OM Code, 2012 Edition, and controlled by 10 CFR 50, Appendix J, requirements provides an acceptable level of quality and safety.

10 CFR 50, Appendix J, states:

The purposes of the tests are to assure that (a) leakage through the primary reactor containment and systems and components penetrating primary containment shall not exceed allowable leakage rate values as specified in the technical specifications or associated bases; and (b) periodic surveillance of reactor containment penetrations and isolation valves is performed so that proper maintenance and repairs are made during the service life of the containment, and systems and components penetrating primary containment.

This statement documents the 10 CFR 50, Appendix J, role in validating a component's ability to perform as designed. Valves are subject to strict leakage requirements to assure performance of the overall containment structure. Valves that do not perform acceptably receive maintenance to restore performance. Performance is validated with follow-up leakage testing to provide assurance that maintenance is effective and valve performance is satisfactory. These requirements drive licensees to demonstrate they are effectively protecting the public health and safety by maintaining plant equipment to the specifications established by plant design and the technical specifications. PVNGS conforms to the requirements of 10 CFR 50, Appendix J, as described in PVNGS Procedure 73DP-9CL02, Containment Leakage Rate Testing Program (Reference 3). The procedure documents PVNGS conformance with Option B, Performance-Based Requirements, of 10 CFR 50, Appendix J and NEI 94-01, Industry Guideline for Implementing Performance-Based Option of 10 CFR Part 50, Appendix J (Reference 4). NRC has endorsed NEI 94-01 as providing an acceptable level of quality and safety under Regulatory Guide 1.163, Performance-Based Containment Leak-Test Program (Reference 5).

Regulation 10 CFR 50, Appendix J, requires more rigorous acceptance criteria than 10 CFR 50.55a(b)(3)(xi). PVNGS procedure 73ST-9CL01, Containment Leakage Type B and C Testing (Reference 6), implements containment leak rate program requirements. The procedure shows valve acceptance criteria measured in standard cubic centimeters per minute (SCCM), ranging from 500 SCCM to 1500 SCCM for valves in Table 1. These values are assigned to support overall containment leakage requirements that satisfy technical specifications (TS) 3.6.1, Containment, and TS 5.5.16, Containment Leakage Rate Testing Program. Regulation 10 CFR 50.55a(b)(3)(xi) requires verification of indications that "provide assurance of proper obturator position." The quantitative requirements of 73ST-9CL01 are specific to individual valves and measurable. In contrast, 10 CFR 50.55a(b)(3)(xi) drives licensees to obtain evidence of gross flow or closure. A valve could provide indication of proper obturator position yet leak without detection. This condition is precluded by 10 CFR 50, Appendix J, test requirements of 73ST-9CL01, which

Enclosure Relief Request VRR-01 specifically quantifies valve leakage. The requirements of 73ST-9CL01 are rigorous and, therefore, satisfy closed verifications meeting 10 CFR 50.55a(b)(3)(xi).

Regulation 10 CFR 50, Appendix J (Reference 2), test periods are performance-based. Valves with consistent, acceptable performance qualify for period extension up to 60 months. Valves must pass two successful as-found leakage tests to qualify for a 60-month test period. A valve passes its test when it exhibits leakage below the assigned administrative limit. Current test intervals for containment isolation valves are shown in Table 2. All but two valves have met the performance standard for extension to a 60-month period. The PVNGS operating cycles are 18-months, therefore, valves on a 60-month period are tested every three refueling cycles (54 months) to meet the 60-month period. Currently, MOVs GRAUVOOOl in Unit 1 and CHBHV0255 in Unit 3 are tested every 18 months during each refueling outage due to valve replacement or test results that exceeded procedural limits. The 18-month 10 CFR 50, Appendix J, test period applied to these valves is more frequent than the most limiting period requirement for supplemental indication: three years for MOVs and two years for all other valves.

Table 2 - Test Interval for Containment Isolation Valves 10 CFR 50, Appendix 3 Test 10 CFR 50, Appendix J Interval (months)

Valve ID Operator Test Type Unit 1 Unit 2 Units CHAUV0560 Pneumatic CHBUV0561 Pneumatic CHAUV0580 Pneumatic CHBHV0255 Motor CHAUV0506 Pneumatic CHBUV0505 Pneumatic CHAUV0516 Pneumatic CHBUV0523 Pneumatic GRAUVOOOl Motor RDBUV0024 Pneumatic The NRC has endorsed ASME OM Code, 2012 Edition (Reference 1), as providing an acceptable level of quality and safety. Regulation 10 CFR 50.55a(a)(l)(iv), ASME Operation and Maintenance Code, identifies ASME OM Code, 2012 Edition, as an acceptable test methodology, subject to conditions in 10 CFR 50.55a(b), Use and conditions on the use of standards. ASME OM Code, 2012 Edition, paragraph ISTA-1100, Scope, states:

Section 1ST establishes the requirements for preservice and inservice testing and examination of certain components to assess their operational readiness in light-water reactor nuclear power plants. It identifies the components subject to test or examination, responsibilities, methods, intervals, parameters to be measured and evaluated, criteria for evaluating the results, corrective action, personnel qualification, and record keeping.

The passage captures the ASME OM Code, 2012 Edition, intent. The document provides instructions for the assurance of operational readiness of safety-related components, such as valves, through periodic performance testing. Operational readiness is a component's ability to perform its function as described by plant design and technical specification. ASME OM Code, 4

Enclosure Relief Request VRR-01 2012 Edition (Reference 1), also contains instructions for resolving issues identified via testing; the corrective action provisions detail the role of analysis and maintenance in restoring components to meeting design requirements. ASME OM Code serves a similar function to 10 CFR 50, Appendix J (Reference 2). ASME OM Code components are assessed on a periodic basis to assure performance capability. When performance criteria are not met, analysis is performed to verify operational readiness or maintenance is performed to restore performance and verified with follow-up testing. These requirements drive licensees to demonstrate they are effectively protecting the public health and safety by maintaining plant equipment to the specifications established by the plant design and technical specifications. PVNGS conforms to ASME OM Code, 2012 Edition requirements as described in PVNGS procedure 73DP-9XI01, Pump and Valve Inservice Testing Program (Reference 7).

The NRC finds it acceptable to obtain position indication verification at frequencies longer than two years in specific cases. ASME OM Code, 2012 Edition, requires position indication verification for MOVs at the Inservice Test (1ST) frequency as described in III-3300(e). The frequencies are controlled by ASME OM Code, 2012 Edition, and the APS commitments under Generic Letter 89-10, Safety-Related Motor-Operated Valve Testing and Surveillance (Reference 8). The maximum test periods are six years for high-risk valves and ten years for low-risk valves. These exceed the two-year position indication verification applicable to non-motor-operated valves per ISTC-3700.

The longest period between 10 CFR 50, Appendix J, tests at PVNGS is four and a half years or 54 months, equal to three 18-month operating cycles.

PVNGS safety-related valves have been reliable. The station has no history of stem-disc separation in safety-related valves. This was confirmed by an INPO Consolidated Events Database (ICES) search for "stem-disc separation." The search returned 71 results, none of which were from PVNGS. Table 2 shows containment isolation valves in the scope of this request are exhibiting optimal leakage performance as demonstrated by qualifying for the 60-month Appendix J test period. Valves tested at periods less the maximum are tested more frequently than that required by the supplemental indication condition of 10 CFR 50.55a(b)(3)(xi).

Regulation 10 CFR 50, Appendix J-driven test periods also apply an acceptable level of quality and safety for a non-containment isolation valve relied upon to perform valve-specific leak rate testing. PVNGS design and the 10 CFR 50, Appendix J, requirement to test valves in the accident direction requires letdown isolation valve CHBUV0515 to perform an essential function in leak-rate testing containment isolation valve CHAUV0516. PVNGS procedure 73ST-9CL01, Appendix R (Reference 6), shows CHBUV0515 is the boundary valve for testing CHAUV0516. The valve arrangement is illustrated in Figure 1. PVNGS piping and instrumentation diagrams show CHBUV0515 is the only valve that isolates CHAUV0516 from the reactor coolant system. To test CHAUV0516, technicians port air through CHEV853, letdown line drain valve, to pressurize the void space between CHBUV0515 and CHAUV0516, measure leakage and compare the result to an acceptance criterion for CHAUV0516. Valve CHBUV0515 must be closed to achieve the test pressure and obtain a leak rate for CHAUV0516. The test conservatively assumes all leakage is through CHAUV0516. Test equipment cannot distinguish between leakage through CHBUV0515 and CHAUV0516. The total leakage is compared to the CHAUV0516 acceptance criterion in 73ST-9CL01 (Reference 6). Successful performance of the CHAUV0516 leak test provides supplemental indication that CHBUV0515 is accurately indicated in the closed position. Additional testing to meet the two-year frequency requirement for CHBUV0515 requires additional resource expenditure without a compensating increase in quality and safety; the valve is verified closed during each leak test of CHAUV0516 to meet 10 CFR 50, Appendix J, requirements.

Enclosure Relief Request VRR-01 Figure 1: Diagram in 73ST-9CL01, Appendix R, used fortesting CHAUV0516

___________________ (labeied UV516)_____________

100 ft Behind Elevator I ^ Behinc^

. Elevator Regen HX O C O Cl UV515 O

UV516 II r U40 O

o II o"XI oil For MOVs in Table 1, it is requested that supplemental indication closure testing be allowed at the 10 CFR 50, Appendix J (Reference 2), test frequency. This is requested because MOV inservice test periods can vary based on maintenance. Mandatory Appendix III, subparagraph III-3310(b) requires a three-year test frequency for MOVs after intrusive maintenance that could affect actuator or valve performance. The three-year frequency exists to ensure valve performance trends are understood prior to assigning longer test periods. Valves CHBHV0255 and GRAUVOOOl are globe valves and MOV diagnostic testing provides no insight to the stem-disc connection to supplement position indication verification. Supplemental indication of the open position of the valves is verified each refueling outage when flow is passed through the valves and documented in surveillance test procedures.

Obtaining supplemental indication of valve closure at the 10 CFR 50, Appendix 1, test frequency provides an acceptable level of quality and safety regardless of the MOV test period because the MOV diagnostic test provides no supplemental indication for globe valves. Table 3 shows current diagnostic test intervals for each MOV in the scope of this request. Both valves are in the scope of ASME OM Code, 2012 Edition (Reference 1), and Generic Letter 89-10 (Reference 8). Valve CHBHV0255 was replaced and is tested per the three-year frequency requirement of subparagraph III-3310(b). Valve GRAUVOOOl is tested to meet the six-year requirement of the Joint Owners' Group (JOG) Program and Generic Letter 89-10, which also meets the requirements of ASME OM Code, 2012 Edition.

Table 3: MOV Risk Rankings and Diagnostic Test Frequencies Valve ID Risk Rank Unit 1 Unit 2 Unit 3 CHBHV0255 Low 3 years 3 years 3 years GRAUVOOOl High 6 years 6 years 6 years Verifying supplemental indication for position-indicated containment isolation valves at a frequency controlled by the 10 CFR 50, Appendix J program, and valves that support 10 CFR 50, Appendix J testing, provides an acceptable level of quality and safety in meeting 10 CFR 6

Enclosure Relief Request VRR-01 50.55a(b)(3)(xi) because it applies more rigorous acceptance criteria at a period that is less than other valves as described in their approved testing process. Regulation 10 CFR 50, Appendix J (Reference 2), was written by the NRC to provide assurance of containment integrity through testing and maintenance. Regulation 10 CFR 50, Appendix J, testing quantifies leakage through containment isolation valves, a more rigorous standard than the supplemental indication requirements of 10 CFR 50.55a(b)(3)(xi).

NRC endorses ASME OM Code, 2012 Edition (Reference 1) as an acceptable testing program by incorporation into 10 CFR 50.55a(a)(l)(iv). ASME OM Code, 2012 Edition requires position indication verification for valves in scope of the testing program, applying different frequencies based on valve operator type. MOVs have the longest period between required position indication verifications. Position-indicated valves supporting 10 CFR 50, Appendix J, testing of containment isolation valves need not be additionally tested for supplemental indication because 10 CFR 50, Appendix J, testing satisfies the requirement at the required frequency of an NRC-endorsed testing program. Therefore, verifying supplemental indication of valves specified in Table 1 at the 10 CFR 50, Appendix J, test frequency provides an acceptable alternative to the two-year frequency required by ISTC-3700 and the three-year frequency required by III-3310(b).

6. Duration of Proposed Alternative The proposed alternative is requested for the current ten-year 1ST interval. PVNGS is in its fourth ten-year 1ST interval, which began January 15, 2018, and ends January 14, 2028, for all three PVNGS Units.

7. Precedents None

8. References

1. ASME OM-2012, Operation and Maintenance of Nuclear Power Plants, April 8, 2013

2. 10 CFR 50, Appendix J, Primary Reactor Containment Leakage Testing for Water-Cooled Power Reactors

3. PVNGS Procedure 73DP-9CL02, Containment Leakage Rate Testing Program, Revision 35

4. NEI 94-01, Revision 0, Industry Guideline for Implementing Performance-Based Option of 10 CFR Part 50, Appendix J, dated July 26, 1995

5. Regulatory Guide 1.163, Performance-Based Containment Leak-Test Program, September 1995

6. PVNGS Procedure 73ST-9CL01, Containment Leakage Type B and C Testing, Revision 47

7. PVNGS Procedure 73DP-9XI01, Pump and Valve Inservice Testing Program, Revision 39

8. NRC Generic Letter 89-10, Safety-Related Motor-Operated Valve Testing and Surveillance