NMP1L3146, Response to Request for Additional Information to Relief to Perform Pressure Isolation Valve Leakage Testing at Frequencies Consistent with 10 CFR 50, Appendix J

Response to Request for Additional Information to Relief to Perform Pressure Isolation Valve Leakage Testing at Frequencies Consistent with 10 CFR 50, Appendix J

ML17096A553
Person / Time
Site:	Nine Mile Point
Issue date:	04/06/2017
From:	Jim Barstow Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NMP1L3146, RR-GVRR-3
Download: ML17096A553 (17)

Text

Exelon Generation 200 Exelon Way Kennett Square. PA 19348 www.exeloncorp.com 10 CFR 50.55a NMP1L3146 April 6, 2017 U.S. Nuclear Regulatory Commission ATIN: Document Control Desk Washington, DC 20555-0001 Nine Mile Point Nuclear Station, Units 1 and 2 Renewed Facility Operating License Nos. DPR-63 and NPF-69 NRC Docket Nos. 50-220 and 50-41 O

Subject:

Request for Relief to Perform Pressure Isolation Valve Leakage Testing at Frequencies Consistent with 10 CFR 50, Appendix J

References:

1) Lerter from J. Barstow (Exelon Generation Company, LLC) to U.::>. NucleC:t1 Regulatory Commission, "Request for Relief to Perform Pressure Isolation Valve Leakage Testing at Frequencies Consistent with 10 CFR 50, Appendix J," dated December 27, 2016

2) Letter from M. Marshall (U.S. Nuclear Regulatory Commission) to 8.

Hanson (Exelon Generation Company, LLC), "Nine Mile Point Nuclear Station, Units 1 and 2 - Request for Additional Information Regarding Proposed Alternative Request Number GVRR-3 to Perform Pressure Isolation Valve Leakage Testing at Frequencies Consistent with Title 1O of the Code of Federal Regulations, Part 50, Appendix J (CAC Nos. MF9073 and MF9074)," dated March 14, 2017 In the Reference 1 letter, Exelon Generation Company, LLC (Exelon) submitted for your review Relief Request No. GVRR-3 associated with the fourth lnservice Testing (IST) interval for Nine Mile Point Nuclear Station, Unit 1 (NMP1) and the third IST interval for Nine Mile Point Nuclear Station, Unit 2 (NMP2}. In the Reference 2 letter, the U.S. Nuclear Regulatory Commission requested additional information. Attached is our response.

There are no regulatory commitments in this letter. If you have any questions concerning this letter, please contact Tom Loomis at (61 O) 765-551 o.

Respectfully, Af, _., J T ,4_, Jf1r- LY'-

James Barstow Director - Licensing & Regulatory Affairs Exelon Generation Company, LLC

U.S. Nuclear Regulatory Commission Nine Mile Point Nuclear Station, Units 1 and 2 Proposed Relief Request Associated with Pressure Isolation Valve Leakage Testing April 6, 2017 Page2 Attachments: 1) Response to Request for Additional Information

2) Revised Relief Request No. GVRR-3 cc: USNRC Region I, Regional Administrator USNRC Senior Resident Inspector, NMP USNRC Project Manager, NMP

Attachment 1 Response to Request for Additional Information

Response to Request for Additional Information Proposed Relief Request Associated with Pressure Isolation Valve Leakage Testing Page 1 Request for Additional Information:

By letter dated December 27, 2017 (Agencywide Documents Access and Management System Accession No. ML17003A096), Exelon Generation Company, LLC (Exelon, the licensee) submitted a request in accordance with Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(z)(1) for a proposed alternative to the requirements of 10 CFR 50.55a and the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code for Nine Mile Point Nuclear Station, Units 1 and 2 (NMP1 and NMP2). The Proposed Alternative Request Number GVRR-3 would allow the licensee to perform pressure isolation valve (PIV) leakage testing at frequencies consistent with the 10 CFR Part 50, Appendix J, "Primary Reactor Containment Leakage Testing for Water-Cooled Power Reactors," reactor containment leakage testing performance-based requirements. The licensee has proposed an alternative test in lieu of the requirements found in the 2004 Edition of the ASME Operation and Maintenance (OM) Code Section ISTC-3630(a) for 35 PIVs.

The licensee proposes to functionally test and verify the leakage rate of these PIVs using 10 CFR Part 50, Appendix J, Option B, performance-based schedule. Valves would initially be tested at the required interval schedule, which is currently every refueling outage (RFO), or 2 years, as specified by ASME OM Code, Section ISTC-3630(a). Valves that have demonstrated good performance for two consecutive cycles may have their test interval extended. Any PIV leakage test failure would require the component to return to the initial interval of every RFO, or 2 years, until good performance can again be established.

In its proposed alternative, Exelon states that the extension of test frequencies will be consistent with the guidance provided for Appendix J, Type C, leak rate tests as detailed in NEI 94-01, Revision 2-A, "Industry Guidelines for Implementing Performance-Based Option of 10 CFR Part 50, Appendix J," paragraph 10.2.3.2, "Extended Test Interval" (ADAMS Accession No. ML100620847), which states that, "Intervals for Type C testing may be increased to a specific value in a range of frequencies from 30 months up to a maximum of 60 months" (see page 1O of proposed alternative).

Also, the licensee states that it proposes to perform PIV testing at intervals ranging from every refueling outage to every third refueling outage (see page 3 of proposed alternative).

The U.S. Nuclear Regulatory Commission (NRC) staff understands that NMP1 and NMP2 have a refueling cycle of 24 months. The proposed testing interval from every refueling outage to every third refueling outage would exceed the maximum 60-month test interval described in NEI 94-01, Revision 2-A.

NEI 94-01 has been updated and is currently on its third version that has been accepted by the NRC staff. For NMP1, the Type C test interval is in accordance with NEI 94-01, Revision O (ADAMS Accession No. ML11327A025), which is endorsed by Regulatory Guide 1.163, "Performance-Based Containment Leak-Test Program" (ADAMS Accession No. ML003740058). Type C tests intervals are set to 60 months. For NMP2, the Type C test interval is in accordance with NEI 94-01, Revision 2-A which has been accepted with limitations by letter dated June 25, 2008 (ADAMS Accession No. ML081140105). Type C test intervals are set to 60 months with a 9-month grace period. The third version of NEI

Response to Request for Additional Information Proposed Relief Request Associated with Pressure Isolation Valve Leakage Testing Page2 94-01, Revision 3-A (ADAMS Accession No. ML12221A202), has been approved with conditions by NRC staff. Type C test intervals can be extended to 75 months with a 9-month grace period with conditions.

The NRC staff has determined that the following additional information is required to complete its review:

(1) Explain which version of NEI 94-01 NMP1 and NMP2 wants to apply to the extension of PIV test frequencies.

(2) Clarify whether the extension of the PIV test frequencies will be consistent with NEI 94-01, paragraph 10.2.3.2, or up to every third refueling outage.

Response

Nine Mile Point, Unit 1 and Nine Mile Point, Unit 2 propose to perform Pressure Isolation Valve (PIV) testing at intervals ranging from every refueling outage to every third refueling outage as discussed in Section 5 ("Proposed Alternative and Basis for Use").

Additionally, Section 5 of the relief request (Attachment 2) has been revised to clarify that:

The extension of test frequencies will be consistent with the guidance provided for Appendix J, Type C leak rate tests as detailed in NEI 94-01, Revision 3-A, Paragraph 10.2.3.2, "Extended Test Interval," (as approved by letter dated June 8, 2012 (ADAMS Accession No. ML121030286) which states:

Test intervals for Type C valves may be increased based upon completion of two consecutive periodic as-found Type C tests where the result of each test is within a licensee's allowable administrative limits. Elapsed time between the first and last tests in a series of consecutive passing tests used to determine performance shall be 24 months or the nominal test interval (e.g., refueling cycle) for the valve prior to implementing Option B to Appendix J. Intervals for Type C testing may be increased to a specific value in a range of frequencies from 30 months up to a maximum of 75 months. Test intervals for Type C valves should be determined by a licensee in accordance with Section 11.0.

Attachment 2 Revised Relief Request No. GVRR-3

10 CFR 50.55a Request Number GVRR-3 Proposed Alternative In Accordance with 10 CFR 50.55a(z){1)

Alternative Provides Acceptable Level of Quality and Safety (Page 1 of 11)

1. ASME Code Component(s) Affected UNIT 1 Component Number System Code Class Category CKV-40-03 cs 1 A/C CKV-40-13 cs 1 A/C CKV-40-20 cs 2 A/C CKV-40-21 cs 1 A/C CKV-40-22 cs 1 A/C CKV-40-23 cs 2 A/C CKV-38-165 soc 2 A/C CKV-38-166 soc 2 A/C CKV-38-167 soc 2 A/C CKV-38-168 soc 2 A/C CKV-38-169 soc 1 A/C CKV-38-170 soc 1 A/C CKV-38-171 soc 1 A/C CKV-38-172 soc 1 A/C UNIT2 Component Number System Code Class Category 2CSH*V108 CSH 1 A/C 2CSH*MOV107 CSH 1 A 2CSL*V101 CSL 1 A/C 2CSL *MOV104 CSL 1 A 21CS*V156 ICS 1 A/C 21CS*V157 ICS 1 A/C 2RHS*V16A RHS 1 A/C 2RHS*V168 RHS 1 A/C 2RHS*V16C RHS 1 A/C 2RHS*V39A RHS 1 A/C 2RHS*V398 RHS 1 A/C 2RHS*MOV104 RHS 1 A 2RHS*MOV112 RHS 1 A 2RHS*MOV113 RHS 1 A 2RHS*MOV24A RHS 1 A 2RHS*MOV248 RHS 1 A 2RHS*MOV24C RHS 1 A 2RHS*MOV40A RHS 1 A 2RHS*MOV408 RHS 1 A 2RHS*MOV67 A RHS 1 A 2RHS*MOV678 RHS 1 A

10 CFR 50.55a Request Number GVRR-3 Proposed Alternative In Accordance with 10 CFR 50.55a(z)(1)

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2. Applicable Code Edition and Addenda

ASME OM Code 2004 Edition with no Addenda

3. Applicable Code Requirement

ISTC-3630, "Leakage Rate for Other Than Containment Isolation Valves," states that Category A valves with a leakage requirement not based on an Owner's 10 CFR 50, Appendix J program, shall be tested to verify their seat leakages are within acceptable limits. Valve closure before seat leakage testing shall be by using the valve operator with no additional closing force applied.

ISTC-3630(a), "Frequency," requires licensees to conduct these leakage rate tests at least once every two years.

4. Reason for Request

Pursuant to 10 CFR 50.55a, "Codes and Standards," paragraph (z)(1 ), relief is requested from the requirement of ASME OM Code ISTC-3630(a). The basis of the relief request is that the proposed alternative would provide an acceptable level of quality and safety.

ISTC-3630 requires that leakage rate testing for Pressure Isolation Valves (PIVs) be performed at least once every two years. PIVs are not specifically included in the scope for performance-based testing as provided for in 10 CFR 50 Appendix J, "Primary Reactor Containment Leakage Testing for Water-Cooled Power Reactors," Option B, "Performance-Based Requirements." These motor-operated and check valve PIVs are, in some cases, Containment Isolation Valves (CIVs), but are not within the Appendix J scope since the Reactor Shutdown Cooling System valves are considered water-sealed.

The Nine Mile Point, Unit 1 (NMP1) leakage rate testing program is in accordance with NEI 94-01, "Industry Guideline for Implementing Performance-Based Option of 10 CFR 50, Appendix J," Revision 0, dated July 21, 1995.

The Nine Mile Point, Unit 2 (NMP2) Technical Specifications contain a requirement to establish the leakage rate testing program in accordance with the guidelines contained in NEI 94-01, Revision 2-A, "Industry Guideline for Implementing Performance-Based Option of 10 CFR Part 50, Appendix J," dated October 2008.

The concept behind the Option B alternative for CIVs is that licensees should be allowed to adopt cost effective methods for complying with regulatory requirements. Additionally, NEI 94-01 describes the risk-informed basis for the extended test intervals under Option B. That justification shows that for CIVs which have demonstrated good performance by the successful completion of two consecutive leakage rate tests over two consecutive cycles may increase their test frequencies. Further, it states that if the component does not fail

10 CFR 50.55a Request Number GVRR-3 Proposed Alternative In Accordance with 10 CFR 50.55a(z)(1)

Alternative Provides Acceptable Level of Quality and Safety (Page 3 of 11) within two operating cycles, further failures appear to be governed by the random failure rate of the component. NEI 94-01 also presents the results of a comprehensive risk analysis, including the conclusion that "the risk impact associated with increasing [leak rate] test intervals is negligible (i.e., less than 0.1 percent of total risk)."

The valves identified in this relief request are all in water applications. Testing is performed with water pressurized to pressures lower than function maximum pressure differential; however, the observed leakage is adjusted to the function maximum pressure differential value in accordance with ISTC 3630(b)(4). This relief request is intended to provide for a performance-based scheduling of PIV tests at NMP1 and NMP2. The reason for requesting this relief is dose reduction to conform with NRC and industry As Low As Reasonably Achievable (ALARA) radiation dose principles. The nominal fuel cycle lengths at NMP1 and NMP2 are 24 months. However, since refueling outages may be scheduled slightly beyond 24 months, a 4-1/2 year period is used to provide a bounding timeframe to encompass two refueling outages. The review of recent historical data identified that PIV testing each refueling outage results in a total personnel dose of approximately 1 Rem, assuming all of the PIVs remain classified as good performers. The proposed extended test intervals would provide for a savings of approximately 1 Rem over an approximate 4 year period (two refuel outages).

NUREG-0933, "Resolution of Generic Safety Issues," Issue 105, "Interfacing Systems LOCA at LWRs," discussed the need for PIV leak rate testing based primarily on three pre-1985 historical failures of applicable valves industry-wide. These failures all involved human errors in either operations or maintenance. None of these failures involved inservice equipment degradation. The performance of PIV leak rate testing provides assurance of acceptable seat leakage with the valve in a closed condition. Typical PIV testing does not identify functional problems which may inhibit the valves ability to reposition from open to closed. For check valves, functional testing is accomplished in accordance with ASME OM Code Section ISTC-3520, "Exercising Requirements," and Section ISTC-3522, "Category C Check Valves." For power-operated valves, testing is full stroke testing in accordance with the ASME OM Code to ensure their functional capabilities. Performance of the separate two-year PIV leak rate testing does not contribute any additional assurance of functional capability; it only determines the seat tightness of the closed valves.

5. Proposed Alternative and Basis for Use NMP1 and NMP2 propose to perform PIV testing at intervals ranging from every refueling outage to every third refueling outage. The specific interval for each valve would be a function of its performance and would be established in a manner consistent with the CIV process under 10 CFR 50 Appendix J, Option B. A conservative control will be established such that if any valve fails either PIV test, the test interval for both tests will be reduced consistent with Appendix J, Option B requirements until good performance is reestablished.

The primary basis for this relief request is the historically good performance of the PIVs.

The functional capability of the check valves is demonstrated by the open and close exercising. This testing is separate and distinct from PIV testing and is performed at a refuel outage frequency in accordance with ASME OM Code, Section ISTC-3522.

10 CFR 50.SSa Request Number GVRR-3 Proposed Alternative In Accordance with 10 CFR 50.55a(z){1)

Alternative Provides Acceptable Level of Quality and Safety (Page 4 of 11)

Note that NEI 94-01 is not the sole basis for this relief request, given NEI 94-01 does not address seat leakage testing with water. This document was cited as an approach similar to the requested alternative method.

If the proposed alternative is authorized and the valves exhibit good performance, there is the possibility that the PIV test frequency could be extended so that the test would not be required each refueling outage.

Tables 1 through 6 below present historical test data that demonstrates acceptable PIV performance for all the related systems:

10 CFR 50.SSa Request Number GVRR-3 Proposed Alternative In Accordance with 10 CFR 50.55a(z)(1)

Alternative Provides Acceptable Level of Quality and Safety (Page 5of11)

Table 1: Unit 1 Historical Leak Rate Test Performance for Core Spray (System 40) PIVs Component Date of Test Measured Value Required Action Comments (aom} Limit (gpm)

CKV-40-03 3/23/2011 <1 5 CKV-40-03 4/17/2013 <1 5 CKV-40-03 3/27/2015 <1 5 CKV-40-13 12/16/2012 <1 5 CKV-40-13 4/17/2013 <1 5 CKV-40-13 3/27/2015 <1 5 CKV-40-20 12/18/2012 <1 5 CKV-40-20 5/1/2013 <1 5 CKV-40-20 3/27/2015 <1 5 CKV-40-21 12/18/2012 <1 5 CKV-40-21 5/1/2013 <1 5 CKV-40-21 3/27/2015 <1 5 CKV-40-22 3/23/2011 <1 5 CKV-40-22 4/25/2013 <1 5 CKV-40-22 3/27/2015 <1 5 CKV-40-23 3/23/2011 <1 5 CKV-40-23 4/25/2013 <1 5 CKV-40-23 3/27/2015 <1 5

1o CFR 50.55a Request Number GVRR-3 Proposed Alternative In Accordance with 10 CFR 50.55a(z)(1)

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Table 2: Unit 1 Historical Leak Rate Test Performance for Reactor Shutdown Cooling (System 38) Check Valve PIVs Component Date of Test Measured Value Required Action Comments (gpm) Limit Caom)

CKV-38-165 3/27/2011 <1 5 CKV-38-165 5/1/2013 <1 5 CKV-38-165 3/27/2015 <1 5 CKV-38-166 3/27/2011 <1 5 CKV-38-166 5/1/2013 <1 5 CKV-38-166 3/27/2015 <1 5 CKV-38-167 3/27/2011 <1 5 CKV-38-167 5/1/2013 <1 5 CKV-38-167 3/27/2015 <1 5 CKV-38-168 3/27/2011 <1 5 CKV-38-168 5/1/2013 <1 5 CKV-38-168 3/27/2015 <1 5 CKV-38-169 3/27/2011 <1 5 CKV-38-169 5/1/2013 <1 5 CKV-38-169 3/27/2015 <1 5 CKV-38-170 3/27/2011 <1 5 CKV-38-170 5/1/2013 <1 5 CKV-38-170 3/27/2015 <1 5 CKV-38-171 3/27/2011 <1 5 CKV-38-171 5/1/2013 <1 5 CKV-38-171 3/27/2015 <1 5 CKV-38-172 3/27/2011 <1 5 CKV-38-172 5/1/2013 <1 5 CKV-38-172 3/27/2015 <1 5

10 CFR 50.55a Request Number GVRR-3 Proposed Alternative In Accordance with 10 CFR 50.55a(z)(1)

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Table 3: Unit 2 Historical Leak Rate Test Performance for Core Spray High (CSH) PIVs Component Date of Test Measured Value Required Action Comments laom) Limit lapm) 2CSH*V108 4/20/2012 <1 5 2CSH*V108 4/23/2014 <1 5 2CSH*V108 4/28/2016 <1 5 2CSH*MOV107 4/20/2012 <1 5 2CSH*MOV107 4/23/2014 <1 5 2CSH*MOV107 4/28/2016 <1 5 Table 4: Unit 2 Historical Leak Rate Test Performance for Core Spray Low (CSL) PIVs Component Date of Test Measured Value Required Action Comments (apm) Limit Caom) 2CSL*V101 4/14/2012 <1 5 2CSL*V101 4/15/2014 <1 5 2CSL*V101 4/21/2016 <1 5 2CSL*MOV104 4/14/2012 <1 5 2CSL*MOV104 4/15/2014 <1 5 2CSL*MOV104 4/21/2016 <1 5 Table 5: Unit 2 Historical Leak Rate Test Performance for Reactor Core Isolation Cooling (ICS) PIVs Component Date of Test Measured Value Required Action Comments (apm) Limit (apm) 21CS*V156 5/1/2012 <1 5 21CS*V156 4/4/2014 <1 5 21CS*V156 4/14/2016 <1 5 21CS*V157 5/7/2012 <1 5 21CS*V157 4/4/2014 <1 5 21CS*V157 4/27/2016 <1 5

10 CFR 50.55a Request Number GVRR-3 Proposed Alternative In Accordance with 10 CFR 50.55a(z)(1)

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Table 6: Unit 2 Historical Leak Rate Test Performance for Residual Heat Removal (RHS) PIVs Component Date of Test Measured Value Required Action Comments Cacm) Limit (gpm) 2RHS*V16A 4/14/2012 <1 5 2RHS*V16A 4/9/2014 <1 5 2RHS*V16A 4/22/2016 <1 5 2RHS*V16B 5/12/2012 <1 5 2RHS*V16B 3/31/2014 <1 5 2RHS*V16B 4/26/2016 <1 5 2RHS*V16C 4/30/2012 <1 5 2RHS*V16C 3/30/2014 <1 5 2RHS*V16C 4/29/2016 <1 5 2RHS*V39A 4/26/2012 <1 5 2RHS*V39A 4/9/2014 <1 5 2RHS*V39A 4/22/2016 <1 5 2RHS*V398 5/12/2012 <1 5 2RHS*V398 3/31/2014 <1 5 2RHS*V398 4/26/2016 <1 5 2RHS*MOV104 5/1/2012 <1 5 2RHS*MOV104 3/31/2014 <1 5 2RHS*MOV104 4/26/2016 <1 5 2RHS*MOV112 5/14/2012 <1 5 2RHS*MOV112 4/13/2014 <1 5 2RHS*MOV112 4/24/2016 <1 5 2RHS*MOV113 5/14/2012 <1 5 2RHS*MOV113 4/13/2014 <1 5 2RHS*MOV113 4/24/2016 <1 5 2RHS*MOV24A 4/14/2012 <1 5 2RHS*MOV24A 4/09/2014 <1 5 2RHS*MOV24A 4/22/2016 <1 5 2RHS*MOV24B 5/12/2012 <1 5 2RHS*MOV24B 3/31/2014 <1 5 2RHS*MOV24B 4/26/2016 <1 5

10 CFR 50.55a Request Number GVRR-3 Proposed Alternative In Accordance with 10 CFR 50.55a(z)(1)

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Component Date of Test Measured Value Required Action Comments laom) Limit (apm) 2RHS*MOV24C 4/30/2012 <1 5 2RHS*MOV24C 3/30/2014 <1 5 2RHS*MOV24C 4/29/2016 <1 5 2RHS*MOV40A 4/14/2012 <1 5 2RHS*MOV40A 4/10/2014 <1 5 2RHS*MOV40A 4/22/2016 <1 5 2RHS*MOV40B 5/12/2012 <1 5 2RHS*MOV40B 3/31/2014 <1 5 2RHS*MOV40B 4/26/2016 <1 5 2RHS*MOV67A 4/26/2012 <1 5 2RHS*MOV67A 4/09/2014 <1 5 2RHS*MOV67A 4/22/2016 <1 5 2RHS*MOV67B 5/12/2012 <1 5 2RHS*MOV67B 3/31/2014 <1 5 2RHS*MOV67B 4/26/2016 <1 5

10 CFR 50.55a Request Number GVRR-3 Proposed Alternative In Accordance with 10 CFR 50.55a(z)(1)

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The extension of test frequencies will be consistent with the guidance provided for Appendix J, Type C leak rate tests as detailed in NEI 94-01, Revision 3-A, Paragraph 10.2.3.2, "Extended Test Interval," (as approved by letter dated June 8, 2012 (ADAMS Accession No. ML121030286)) which states:

Test intervals for Type C valves may be increased based upon completion of two consecutive periodic as-found Type C tests where the result of each test is within a licensee's allowable administrative limits. Elapsed time between the first and last tests in a series of consecutive passing tests used to determine performance shall be 24 months or the nominal test interval (e.g., refueling cycle) for the valve prior to implementing Option B to Appendix J. Intervals for Type C testing may be increased to a specific value in a range of frequencies from 30 months up to a maximum of 75 months. Test intervals for Type C valves should be determined by a licensee in accordance with Section 11.0.

Additional basis for this relief request is provided below:

• Separate functional testing of motor-operated valve (MOV) PIVs and Check Valve PIVs per ASME OM Code will continue.

• The low likelihood of valve mis-positioning during power operations (e.g., procedures, interlocks).

• Relief valves in the low pressure (LP) piping - these relief valves may not provide Inter-System Loss of Coolant Accident (ISLOCA) mitigation for inadvertent PIV mis-positioning but their relief capacity can accommodate conservative PIV seat leakage rates.

• Alarms that identify high pressure (HP) to LP leakage - Operators are highly trained to recognize symptoms of a present ISLOCA and to take appropriate actions.

6. Duration of Proposed Alternative The proposed alternative will be utilized for the remainder of the third and fourth 120 month interval which is currently scheduled to end on December 31, 2018 for NMP1 and NMP2.

7. Precedents

1. A similar relief request was approved for Fermi Power Station for the third IST Interval in a letter from R. J. Pascarelli (NRC) to J. M. Davis (Detroit Edison), "Fermi 2 - Evaluation of In-Service Testing Program Relief Requests VRR-011, VRR-012, and VRR-013 (TAC Nos. ME2558, ME2557, and ME2556)," dated September 28, 2010 (ADAMS Accession No. ML102360570).

2. A similar relief request was approved for Quad Cities Nuclear Power Station, Units 1 and 2 for the fifth IST interval in a letter from J. Wiebe (NRC) to M. J. Pacilio (Exelon), "Quad Cities Nuclear Power Station, Units 1 and 2 - Safety Evaluation in Support of Request for Relief Associated with the Fifth 10 Year Interval lnservice Testing Program (TAC Nos.

ME7981, ME7982, ME7983, ME7984, ME7985, ME7986, ME7987, ME7988, ME7990, ME7991, ME7992, ME7993, ME7994, and ME7995)," dated February 14, 2013 (ADAMS Accession No.ML13042A348).

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3. A similar relief request was approved for Dresden Nuclear Power Station, Units 2 and 3 for the fifth IST interval in a letter from T. L. Tate (NRG) to B. Hanson (Exelon), "Dresden Nuclear Power Station, Units 2 and 3 - Relief Request to Use An Alternative from the American Society of Mechanical Engineers Code Requirements (CAC Nos. MF5089 AND MF5090) dated October 27, 2015 (ADAMS Accession No. ML15174A303).

4. A similar relief request was approved for Peach Bottom Atomic Power Station, Units 2 and 3 for the fourth interval in a letter from D. A. Broaddus (NRG) to B. Hanson (Exelon), "Peach Bottom Atomic Power Station, Units 2 and 3 - Safety Evaluation of Relief Request GVRR-2 Regarding the Fourth 10-Year Interval of the lnservice Testing Program (CAC NOS. MF7630 and MF7631)," dated September 21, 2016 (ADAMS Accession No. ML16235A340).