CNL-21-041, Response to RAI Re Application to Modify the Watts Bar Nuclear Plant Technical Specifications 5.7.2.19, Containment Leakage Rate Testing Program (WBN-TS-19-01)

Response to RAI Re Application to Modify the Watts Bar Nuclear Plant Technical Specifications 5.7.2.19, Containment Leakage Rate Testing Program (WBN-TS-19-01)

ML21119A248
Person / Time
Site:	Watts Bar
Issue date:	04/29/2021
From:	Polickoski J Tennessee Valley Authority
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
CNL-21-041, EPID L-2020-LLA-0223
Download: ML21119A248 (9)

Text

1101 Market Street, Chattanooga, Tennessee 37402 CNL-21-041 April 29, 2021 10 CFR 50.90 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Watts Bar Nuclear Plant, Units 1 and 2 Facility Operating Licenses Nos. NPF-90 and NPF-96 NRC Docket Nos. 50-390 and 50-391

Subject:

Response to Request for Additional Information Regarding Application to Modify the Watts Bar Nuclear Plant Unit 1 and Unit 2 Technical Specifications 5.7.2.19 Containment Leakage Rate Testing Program (WBN-TS-19-01) (EPID L-2020-LLA-0223)

References:

1. TVA letter to NRC, CNL-20-006, Application to Modify the W atts Bar Nuclear Plant Unit 1 and Unit 2 Technical Specifications 5.7.2.19 Containment Leakage Rate Testing Program (WBN-TS-19-01), dated October 2, 2020 (ML20276A092 and ML20276A093)

2. TVA letter to NRC, CNL-20-093, Supplement to Application to Modify the Watts Bar Nuclear Plant Unit 1 and Unit 2 Technical Specifications 5.7.2.19 Containment Leakage Rate Testing Program (WBN-TS-19-01)

(EPID L-2020-LLA-0223), dated December 15, 2020 (ML20350B799)

3. NRC Electronic Mail to TVA, Request for Additional Information Regarding TVA's Request to Revise Technical Specification 5.7.2.19, Containment Leakage Rate Testing Program (EPID L2020LLA0223), dated April 1, 2021 (ML21091A077)

In Reference 1, Tennessee Valley Authority (TVA) submitted a request for an am endment to Facility Operating License Nos. NPF-90 and NPF-96 for the W atts Bar Nuclear Plant (WBN),

Units 1 and 2, respectively. The proposed change revises the WBN Units 1 and 2, Technical Specifications (TS) 5.7.2.19, "Containment Leakage Rate Testing Program," by adopting Nuclear Energy Institute (NEI) 94-01, Revision 3-A, "Industry Guideline for Implementing Performance-Based Option of 10 CFR Part 50, Appendix J," as the implem entation document for the performance-based Option B of 10 CFR Part 50, Appendix J. The proposed change also extends the Type A containm ent integrated leak rate testing (CILRT)

U.S. Nuclear Regulatory Commission CNL-21-041 Page 2 April 29, 2021 interval from 10 years to 15 years and the Type C local leakage rate testing intervals from 60 m onths to 75 months. In Reference 2, TVA submitted a supplement to Reference 1, which, in part, provided the Nuclear Regulatory Commission (NRC) the results of the confirmatory test as recommended in the Kalsi Engineering report that was included in Reference 1.

In Reference 3, the NRC issued a request for additional information (RAI) and requested TVA respond by April 30, 2021. The enclosure to this letter provides the TVA response to the RAI.

This letter does not change the no significant hazard considerations nor the environmental considerations contained in Reference 1. Additionally, in accordance with 10 CFR 50.91(b)(1), TVA is sending a copy of this letter and the enclosure to the Tennessee Department of Environment and Conservation.

There are no new regulatory commitments associated with this submittal. Please address any questions regarding this request to Kimberly D. Hulvey at (423) 751-3275.

I declare under penalty of perjury that the foregoing is true and correct. Executed on this 29th day of April 2021.

Respectfully, James T. Polickoski Director, Nuclear Regulatory Affairs

Enclosure:

Response to NRC Request for Additional Information cc (Enclosure):

NRC Regional Administrator - Region II NRC Senior Resident Inspector - Watts Bar Nuclear Plant NRC Project Manager - W atts Bar Nuclear Plant Director, Division of Radiological Health - Tennessee State Departm ent of Environm ent and Conservation

Enclosure Response to NRC Request for Additional Information NRC INTRODUCTION By letter dated October 2, 2020 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML20276A092), the Tennessee Valley Authority (TVA, licensee) submitted a license amendment request (LAR) to the U.S. Nuclear Regulatory Commission (NRC) for an amendment to the operating licenses for the Watts Bar Nuclear Plant (Watts Bar), Units 1 and 2. The proposed change would revise the Watts Bar, Units 1 and 2, Technical Specifications (TS) 5.7.2.19, Containment Leakage Rate Testing Program, by adopting Nuclear Energy Institute (NEI) 94-01, Revision 3-A, Industry Guideline for Implementing Performance-Based Option of 10 CFR Part 50, Appendix J, as the implementation document for the performance-based Option B of 10 CFR Part 50, Appendix J. The proposed change would also extend the Type A containment integrated leak rate testing (CILRT) interval from 10 years to 15 years and the Type C local leak rate testing intervals from 60 months to 75 months. Additionally, TVA requested to use a bounding value of 15.0 pounds per square inch gauge (psig) for Pa instead of the calculated Pa value as defined 10 CFR 50, Appendix J, Option B,Section II.

In a letter dated December 15, 2020 (ADAMS Accession No. ML20350B799), TVA submitted a supplement to its LAR to provide the results of confirmatory tests recommended in Kalsi Engineering Report No. 3960C (Revision 0), Evaluation of Higher Test Pressure on Leakage for Watts Bar.

REGULATORY BASIS Option B, Performance-Based Requirements of Appendix J, Primary Containment Leakage Testing for Water-Cooled Power Reactors, to Part 50 of Title 10 of the Code of Federal Regulations (10 CFR), requires, in part, for Type B and C tests, that The performance-based testing program must containwhen establishing test intervalscomparison to previous test results to examine the performance history of the overall containment system to limit leakage.

INFORMATION REQUESTED The Kalsi Engineering report includes Type B and C LLRT history tables for valves in various groups at Watts Bar, Units 1 and 2. These tables are:

• Table 1-2, "Unit 1 and 2 LLRT Leakage History," in Attachment 1, "Local Leak Rate Test Leakage Evaluation at Watts Bar for MOV Gate Valves;"

• Table 1-2, "Leakage History," in Attachment 2, "Local Leak Rate Test Leakage Evaluation at Watts Bar for MOV/AOV Plug Valves;"

• Table 1-2, Unit 1 and Unit 2 LLRT Leakage History, in Attachment 3, Local Leak Rate Test Leakage Evaluation at Watts Bar for Swing Check Valves;

• Table 1-2, Leakage History of Valves in Unit 1 and 2, in Attachment 4, Local Leak Rate Test Leakage Evaluation at Watts Bar for Lift/Piston Check Valves; and

• Table 1-2, Unit 1 and Unit 2 LLRT Leakage History, in Attachment 5, Local Leak Rate Test Leakage Evaluation at Watts Bar for AOV Globe Valves.

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Enclosure In these tables, several valves were reported to have unfavorable leakage history.

Section 4.2, Leakage History Summary, of the main body of the Kalsi Engineering report states that Some valves show unacceptable leakage history, but it is assumed that corrective actions are performed to restore leakage to acceptable levels (see Assumption 5.2). Assumption 5.2 states, For all valves it is assumed that the tested leakage at normal LLRT DP is acceptable. This assumption is reasonable since corrective actions are required if leakage exceeds acceptance criteria and does not require verification. However, there was no discussion of the evaluation or resolution of unfavorable or unacceptable leakage history in the LAR that supports the Kalsi Engineering report assumption that corrective actions were taken to address leakage history. Briefly describe the activities performed to address the unfavorable or unacceptable LLRT leakage history with respect to the tables above.

TVA Response At the W atts Bar Nuclear Plant (WBN), each local leak rate test (LLRT) performance where the m easured leakage rate exceeds the specified administrative limit is entered into the TVA corrective action program. In addition, when a measured leakage rate exceeds the administrative limit, the LLRT crew will perform basic troubleshooting to determine the source of the leakage. For example, the testers will check for external leakage of the test rig and connecting tubing/fittings, verify adequate closure of test boundary valves, and check for air flowing from the vent on the low pressure side of the containment isolation valve. This troubleshooting is important for those LLRTs where multiple valves are tested in parallel and it is necessary to determine which of those containm ent isolation valves needs corrective action.

In cases where an LLRT with unacceptable results involved two valves in parallel, the Kalsi Engineering report provided in the LAR identified both valves with unfavorable history. This is because TVA had provided only the raw LLRT results to Kalsi as input for their evaluation, without distinguishing which of the two valves was determined to be cause of the high leakage rate. Additional information for such situations is included in the discussion in the following tables.

When an individual component LLRT exceeds the specified administrative limit during two consecutive periodic perform ances, the performance criteria for unreliability of containment isolation valves (established for the 10 CFR 50.65 maintenance rule program at WBN) are exceeded. Such components are entered in the Maintenance Rule Program for Cause Determination and Evaluation (CDE). This was done for the valves identified in the Kalsi Engineering report with an unfavorable LLRT history, except for 1-CKV-67-575D. This one exception was a case where the as-found LLRT for the valve had been missed and, as a result, the as-found leakage rate had been recorded as a gross leak rate for the purposes of calculating the as-found minimum pathway leakage of the total containment leakage to comply with WBN TS 5.7.2.19. The missed as-found LLRT was entered into the WBN corrective action program.

A brief description of activities performed or planned for each valve identified in the Kalsi Engineering report with an unfavorable history is provided in the table below. The valves are listed in the order they appear in the report.

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Enclosure Valves identified in Attachment 1, Table 1-2, of the Kalsi Engineering report Valve Containment Penetration / Description of Actions Taken / Planned Boundary 1-FCV-62-61 X-44 / Inboard The unfavorable leakage was attributed to valve 1-CKV-62-639.

Note: This valve is leak rate See the description of actions taken for 1-CKV-62-639 in the table of this tested in parallel with enclosure regarding Attachm ent 4, Table 1-2 of the Kalsi Engineering 1-CKV-62-639 Report.

(listed in Attachment 4, Table 1-2 of the Kalsi Engineering report) 1-FCV-70-134 X-50B / Outboard In the WBN Unit 1 Cycle 14 refueling outage (U1R14) (spring 2017), the as-found LLRT exceeded the administrative limit. The valve disc was cut to fit the seat properly. The as-left LLRT was 0.00 standard cubic feet per hour (scfh).

The as-found LLRTs in U1R15 (fall 2018) and U1R16 (spring 2020) were acceptable.

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Enclosure Valves identified in Attachment 2, Table 1-2, of the Kalsi Engineering report Valve Containment Penetration / Description of Actions Taken / Planned Boundary 2-FCV-31-327 X-66 / Inboard The unfavorable leakage was attributed to 2-CKV-31-3392. See the Note: This valve is leak rate description of actions taken for 2-CKV-31-3392 in the table of this enclosure tested in parallel with regarding Attachment 4, Table 1-2 of the Kalsi Engineering Report.

2-CKV-31-3392 (listed in Attachment 4, Table 1-2 of the Kalsi Engineering report) 2-FCV-31-329 X-67 / Inboard The unfavorable leakage was attributed to 2-CKV-31-3378. See the Note: This valve is leak rate description of actions taken for 2-CKV-31-3378 in the table of this enclosure tested in parallel with regarding Attachment 4, Table 1-2 of the Kalsi Engineering Report.

2-CKV-31-3378 (listed in Attachment 4, Table 1-2 of the Kalsi Engineering report) 2-FCV-67-130 X-69 / Outboard In U2R2 (spring 2019), the as-found LLRT exceeded the administrative limit. Several unsuccessful attempts at making adjustments to the actuator and plug vertical position were made during U2R2 without success. The as-left LLRT also exceeded the administrative limit. An evaluation was performed to accept the leakage rate above the administrative limit based on total containment leakage rate margin in accordance with site procedures, which ensures that the overall containment acceptance criteria is not exceeded.

In U2R3 (fall 2020), the as-found LLRT was less than the administrative limit and no maintenance was performed on the valve.

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Enclosure Valves identified in Attachment 3, Table 1-2, of the Kalsi Engineering report Valve Containment Penetration Description of Actions Taken / Planned

/ Boundary 1-CKV-26-1260 X-78 / Inboard In U1R15 (fall 2018), the as-found LLRT exceeded the administrative limit.

The valve was disassembled, cleaned, inspected, and reassembled. The as-left LLRT was less than the administrative limit. In U1R16 (spring 2020),

the as-found LLRT was less than the administrative limit.

Due to poor LLRT history, this valve has been placed in a 10 CFR 50.65 Maintenance Rule (a)(1) plan intended to drive further corrective action.

1-CKV-26-1296 X-31 / Inboard The as-found LLRT during U1R12 (spring 2014) exceeded the administrative limit. The valve was disassembled, cleaned, inspected, and reassembled. The as-left LLRT was below the administrative limit. The as-found LLRTs during U1R13 (fall 2015), U1R14 (spring 2017), and U1R16 (spring 2020) were less than the administrative limit. The valve was not tested in U1R15.

Due to poor LLRT history, this valve has been placed in a Maintenance Rule (a)(1) plan intended to drive further corrective action.

2-CKV-26-1260 X-78 / Inboard In U2R3 (fall 2020), the as-found LLRT exceeded the administrative limit.

The valve was disassembled, cleaned, inspected, and reassembled. The as-left LLRT was less than the administrative limit.

Due to poor LLRT history, this valve has been placed in a Maintenance Rule (a)(1) plan intended to drive further corrective action.

1-CKV-70-679 X-50B / Inboard In U1R12 (spring 2014), the as-found LLRT exceeded the administrative limit. The valve was disassembled, cleaned, inspected, and reassembled.

During this process it was discovered that the disc was misaligned. The valve disc, hinge pin, and hinge assembly were replaced. The as-left LLRT was less than the administrative limit.

The as-found LLRTs have been less than the administrative limit in subsequent periodic tests.

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Enclosure Valves identified in Attachment 4, Table 1-2, of the Kalsi Engineering report Valve Containment Penetration Description of Actions Taken / Planned

/ Boundary 2-CKV-31-3378 X-67 / Inboard The as-found LLRTs during U2R1 (fall 2017), U2R2 (spring 2019), and Note: This valve is leak rate U2R3 (fall 2020) exceeded the administrative limit. After corrective tested in parallel with maintenance, the as-left LLRTs for each outage were below administrative 2-FCV-31-329 limits.

(listed in Attachment 2, Table 1-2 of the Kalsi Due to poor LLRT history, this valve has been placed in a Maintenance Engineering report) Rule (a)(1) plan intended to drive further corrective action.

2-CKV-31-3392 X-66 / Inboard The as-found LLRTs during U2R1 (fall 2017), U2R2 (spring 2019), and Note: This valve is leak rate U2R3 (fall 2020) exceeded the administrative limit. Each time the valve was tested in parallel with disassembled, cleaned, inspected, and reassembled. As-left LLRTs for 2-FCV-31-327 each outage were below administrative limits.

(listed in Attachment 2, Table 1-2 of the Kalsi Due to poor LLRT history, this valve has been placed in a Maintenance Engineering report) Rule (a)(1) plan intended to drive further corrective action.

1-CKV-62-639 X-44 / Inboard In U1R15 (fall 2018), the as-found LLRT exceeded the administrative limit.

Note: This valve is leak rate A disc to seat contact check (blue check) of the seating surfaces of tested in parallel with 1-CKV-62-639 was perform ed and found to be inadequate. The valve was 1-FCV-62-61 lapped until the blue check was satisfactory. The as-left leak rate was 0.00 (listed in Attachment 1, scfh.

Table 1-2 of the Kalsi Engineering report) In U1R16 (spring 2020), the as-found LLRT was 0.00 scfh.

1-CKV-67-575D X-57A / Inboard In U1R15 (fall 2018), the as-found LLRT was missed as noted in the RAI response. The missed test was entered into the corrective action program and a gross leak rate was assigned for the as-found test for calculation of the minimum pathway total containment leakage rate.

The as-found LLRTs for all other periodic tests (before and after the missed test) have been less than the administrative limit.

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Enclosure Valves identified in Attachment 5, Table 1-2, of the Kalsi Engineering report Valve Containment Penetration / Description of Actions Taken / Planned Boundary 2-FCV-32-111 X-34 / Outboard The as-found LLRTs during U2R1 (fall 2017), U2R2 (spring 2019), and U2R3 (fall 2020) exceeded the administrative limit. An evaluation was performed to accept the U2R3 leakage rate above the administrative limit based on valve service conditions, total containment leakage rate margin, and relatively consistent leakage rates m easured in each outage.

Due to poor LLRT history, this valve has been placed in a Maintenance Rule (a)(1) plan intended to drive further corrective action.

1-FCV-63-23 / X-30 / Outboard The as-found LLRTs during U1R15 (fall 2018) and U1R16 (spring 2020) 1-FCV-63-84 Note: These valves are leak exceeded the administrative limit. An evaluation was performed to accept rate tested in parallel the leakage rate above the administrative limit based on the relatively low leakage rate, total containment leakage rate margin, and consistent leakage rates in each outage. Troubleshooting determined that 1-FCV-63-23 is the valve that is leaking and not 1-FCV-63-84.

Due to poor LLRT history, this valve has been placed in a Maintenance Rule (a)(1) plan intended to drive further corrective action.

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