ML20034C819
| ML20034C819 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs, Peach Bottom, Nine Mile Point, Braidwood, Limerick, Ginna, Clinton  |
| Issue date: | 01/31/2020 |
| From: | Rafferty-Czincila S Exelon Generation Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| Download: ML20034C819 (10) | |
Text
Exelon Generation@
200 Exelon Way Kennett Square, PA 19348 www.exeloncorp.com January 31, 2020 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001
Subject:
Braidwood Station, Units 1 and 2 Renewed Facility Operating License Nos. NPF-72 and NPF-77 NRC Docket Nos. STN 50-456 and STN 50-457 Calvert Cliffs Nuclear Power Plant, Units 1 and 2 Renewed Facility Operating License Nos. DPR-53 and DPR-69 NRC Docket Nos. 50-317 and 50-318 Clinton Power Station, Unit 1 Facility Operating License No. NPF-62 NRC Docket No. 50-461 RE. Ginna Nuclear Power Plant Renewed Facility Operating License No. DPR-18 NRC Docket No. 50-244 Limerick Generating Station, Units 1 and 2 Renewed Facility Operating License Nos. NPF-39 and NPF-85 NRC Docket Nos. 50-352 and 50-353 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 50-410 Peach Bottom Atomic Power Station, Units 2 and 3 Renewed Facility Operating License Nos. DPR-44 and DPR-56 NRC Docket Nos. 50-277 and 50-278 Proposed Alternative to Utilize Code Case OMN-26 10 CFR 50.55a In accordance with 10 CFR 50.55a, "Codes and standards," paragraph (z)(1), Exelon Generation Company, LLC (Exelon), hereby requests NRC approval of a proposed relief request associated with the lnservice Testing (IST) Programs for the cited Exelon Nuclear Power Plants (NPPs). This request proposes to implement the American Society of Mechanical Engineers (ASME) Code Case OMN-26, "Alternate Risk-Informed and Margin Based Rules for lnservice Testing of Motor Operated Valves," that has been approved by the ASME Board of Nuclear Codes and Standards for use under the 2012 edition of the ASME OM Code. Each of the IST Programs for the cited Exelon NPPs either complies with the 2012 edition of the ASME OM Code or will so by July 2020. The basis for this relief request is that the proposed
Proposed Alternative to Utilize Code Case OMN-26 January 31, 2020 Page 2 alternative rules for safety related Motor Operated Valves provide an acceptable level of quality and safety, equivalent to compliance with ASME Section Ill requirements.
Exelon requests your review and approval of this fleet request by July 31, 2020.
There are no regulatory commitments contained in this letter.
If you have any questions, please contact Mr. David Neff at (267) 533-1132.
Respectfully,
Attachment:
Relief Request to Utilize Code Case OMN-26 cc:
Regional Administrator - NRC Region I Regional Administrator-NRC Region Ill NRC Senior Resident Inspector - Braidwood Station NRC Senior Resident Inspector - Calvert Cliffs Nuclear Power Plant NRC Senior Resident Inspector - Clinton Power Station NRC Senior Resident Inspector - R.E Ginna Nuclear Power Plant NRC Senior Resident Inspector - Limerick Generating Station NRC Senior Resident Inspector - Nine Mile Point Nuclear Station NRC Senior Resident Inspector - Peach Bottom Atomic Power Station NRC Project Manager - Braidwood Station NRC Project Manager - Calvert Cliffs Nuclear Power Plant NRC Project Manager - Clinton Power Station NRC Project Manager-R.E. Ginna Nuclear Power Plant NRC Project Manager - Limerick Generating Station NRC Project Manager - Nine Mile Point Nuclear Station NRC Project Manager - Peach Bottom Atomic Power Station Illinois Emergency Management Agency - Department of Nuclear Safety R. R. Janati - Bureau of Radiation Protection, Commonwealth of Pennsylvania D. A. Tancabel - State of Maryland A. L. Peterson - NYSERDA
ATTACHMENT Relief Request to Utilize Code Case OMN-26
EXELON GENERATION COMPANY, LLC IST PROGRAM - RELIEF REQUEST Proposed Alternative in Accordance with 10 CFR 50.55a(z)(1)
Relief Request to Utilize Code Case OMN-26
- 1. ASME Code Component(s) Affected:
Active safety related motor operated valves (MOVs) that are required by Subsection ISTC of the 2012 Edition of the American Society of Mechanical Engineers (ASME)
Operation and Maintenance (OM) Code to be tested in accordance with ASME OM Code Mandatory Appendix Ill.
PLANT INTERVAL OM EDITION START END Braidwood Station Fourth 2012 Edition July 29, 2018 July 28, 2028 Units 1and2 Calvert Cliffs Nuclear Power Fifth 2012 Edition July 1, 2018 June 30, 2028 Plant, Units 1 and 2 Nine Mile Point Nuclear Fifth - U1 2012 Edition January 1, 2019 December 31, 2028 Station, Unit 1 and 2 Fourth-U2 Peach Bottom Atomic Power Fifth 2012 Edition November 16, 2018 August 14, 2028 Station, Unit 2 and 3 R.E. Ginna Nuclear Power Sixth 2012 Edition January 1, 2020 December 31, 2029 Plant Unit 1 Limerick Generating Station, Fourth 2012 Edition January 8, 2020 January 7, 2030 Units 1 and 2 Clinton Power Station, Unit 1 Fourth 2012 Edition July 1, 2020 June 30, 2030
3. Applicable Code Requirements
The ASME OM Code Mandatory Appendix 111, Preservice and lnservice testing of Active Electric Motor-Operated Valve Assemblies in Water Cooled Reactor Nuclear Power Plants.
The following Appendix Ill Paragraphs are affected by this Relief Request to adopt Code Case OMN-26, "Alternate Risk-Informed and Margin Based Rules for lnservice Testing of Motor Operated Valves."
111-3310 (c).
111-3700 Risk-Informed MOV lnservice Testing.
111-3722 (d).
For each of these paragraphs, relief is being sought for alternative treatments described in Section 5 of this relief request based on the ASME Board of Nuclear Codes and Standards (BNCS) approved Code Case OMN-26.
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EXELON GENERATION COMPANY, LLC IST PROGRAM - RELIEF REQUEST Proposed Alternative in Accordance with 10 CFR 50.55a(z)(1)
Relief Request to Utilize Code Case OMN-26
4. Reason for Request
In accordance with 10 CFR 50.55a(z)(1), Exelon Generation Company, LLC (Exelon) is requesting approval to adopt ASME OM Code Case OMN-26 in conjunction with implementing Mandatory Appendix Ill for all Exelon plants identified in Section 2.
Code Case OMN-26 better aligns OM Code Mandatory Appendix Ill to the Risk and Margin Based Licensee Motor Operated Valve (MOV) Programs developed in response to NRC Generic Letter 96-05, "Periodic Verification of Design-Basis Capability of Safety-Related Motor-Operated Valves," that have been in effect since 1998. The Appendix Ill ten-year maximum inservice test interval was originally established to align with the maximum test interval allowed under the Generic Letter 96-05 MOV Programs that, for most Licensees, was established by the Joint Owners Group (JOG) MOV Periodic Verification Program. There is no formal technical basis for the current Appendix Ill ten-year maximum interval that applies to all MOVs regardless of Risk and Margin. Over the past twenty years, Exelon MOV Programs have demonstrated many margin stable MOVs that can be readily justified to extend from their current MOV Program maximum inservice test intervals of six years (for High Risk) and ten years (for Low Risk).
5. Proposed Alternative and Basis for Use
Proposed Alternative:
Exelon proposes to implement the ASME OM Code Case OMN-26 alternative risk and margin informed rules for inservice testing of MOVs in its entirety as described below:
Proposed Alternative to 111-331 O (c) The maximum inservice test interval shall not exceed 10 years unless Risk Informed lnservice Testing applies under the provisions of para. 111-3700. MOV inservice tests conducted per para. 111-3400 may be used to satisfy this requirement.
Proposed Alternative to 111-3700 Risk-informed MOV inservice testing that incorporate risk insights in conjunction with MOV Functional Margin to establish MOV grouping, acceptance criteria, exercising requirements and test interval may be implemented.
Proposed Alternative to 111-3721 111-3721 HSSC MOVs. HSSC MOVs shall be tested in accordance with para. 111-3300 and exercised in accordance with para. 111-3600 while applying the following HSSC MOV Risk insights and limitations:
(a) HSSC MOVs that can be operated during plant operation shall be exercised quarterly, unless the potential increase in core damage frequency (CDF) and large early release (LER) associated with a longer exercise interval is small.
(b) For HSSC MOVs, the maximum inservice test interval shall be established in accordance with Table 1 of OMN-26 (see below)
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EXELON GENERATION COMPANY, LLC IST PROGRAM - RELIEF REQUEST Proposed Alternative in Accordance with 10 CFR 50.55a(z)(1)
Relief Request to Utilize Code Case OMN-26 OMN-26 Table 1 HSSC MOV - Margin Based Maximum lnservice Test Intervals HSSC MOV Functional Maximum lnservice If MOV is routinely(AJ operated Marginl0l Test Interval at Design Basis Pressure (Years)
Conditions - Max lnservice Test Interval (Years) (BJ Low(< 5%)
2 4
Medium (2: 5% and <
4 9
10%)
High (2: 10% and< 20%)
9 9
Very High (2: 20%)
9 12 OMN-26 Table 1 - Notes (A) Occurs at a periodicity no less frequent than once a refueling outage.
(B) To utilize these intervals, test strokes at or exceeding design basis system conditions must be in the applicable safety function direction(s) and have no applicable operating experience, degradation or diagnostic test anomaly with the potential for adverse impact on MOV functional margin or the capability of the MOV to perform its design basis function.
(D) For the purpose of this code case, the MOV functional margin limits apply to the As-lett MOV condition at the start of the inservice test interval and include applicable test uncertainties and allowance for service-related degradation.
Proposed Alternative to 111-3722 (d)
(d) For LSSC MOVs, the maximum inservice test interval shall be established in accordance with Table 2 of OMN-26 (see below)
OMN-26 Table 2 LSSC MOV - Margin Based Maximum lnservice Test Intervals LSSC MOV Functional Maximum lnservice If MOV is routinely(AJ operated Margin<0J Test Interval at Design Basis Pressure (Years)
Conditions - Max lnservice Test Interval (Years) (BJ Low(< 5%)
4 9
Medium (2: 5% and< 10%)
9 12 High (2: 10% and< 20%)
12 12 Very High (2: 20%)
12 16(C)
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EXELON GENERATION COMPANY, LLC IST PROGRAM - RELIEF REQUEST Proposed Alternative in Accordance with 10 CFR 50.55a(z)(1)
Relief Request to Utilize Code Case OMN-26 OMN-26 Table 2 Notes:
(A) Occurs at a periodicity no less frequent than once a refueling outage.
(8) To utilize these intervals, test strokes at or exceeding design basis system conditions must be in the applicable safety function direction(s) and have no applicable operating experience, degradation or diagnostic test anomaly with the potential for adverse impact on MOV functional margin or the capability of the MOV to perform its design basis function.
(C) Operating plants that have acquired the requisite test data to satisfy Appendix Ill, paragraphs 111-331 O(b) or lll-3722(c) must complete one cycle of collecting diagnostic test data at an extended test interval, minimum 9 and maximum 12 years, before extending the test interval by engineering evaluation to the maximum 16-year test interval.
(D) For the purpose of this code case, the MOV functional margin limits apply to the As-lett MOV condition at the start of the inservice test interval and include applicable test uncertainties and allowance for service-related degradation.
Basis for Use:
The requested relief to adopt OMN-26 is in line with the current JOG MOV Periodic Verification Test Program that Exelon has implemented since the late 1990's in response to NRC Generic Letter 96-05. Both the JOG MOV PV Program and Code Case OMN-26 provide a Risk-Margin based methodology that establishes limitations for maximum inservice test intervals for MOVs. Code Case OMN-26 simply provides a reasonable extension of this Risk-Informed philosophy based on the lessons learned and accumulated MOV performance data gathered over more than 25 years of MOV Performance Verification Testing. Appendix Ill alone, in isolation from OMN-26, provides no such methodology other than a maximum limit for the inservice test interval regardless of Risk or Margin.
The requested allowed maximum inservice test intervals are modest extensions with many of the Low Risk MOVs extending from 10 to 12 years (20% increase). This test interval change can be readily adopted with no loss of MOV performance and/or safety system reliability provided that no adverse performance trends are indicated. Exelon's MOV Performance Trending Governance will ensure that only MOV's with good performance history, high stable margins and no adverse diagnostic trends would be candidates for the OMN-26 based inservice test interval extensions.
The requested High Margin Maximum interval changes afforded by OMN-26 align with Exelon's desire to adopt a divisional MOV outage testing strategy that reduces the implementation burden of MOV lnservice Testing and allows greater flexibility in optimizing safety system availability. The current six and ten-year JOG Program based High-Margin Maximum Intervals do not support this strategy.
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EXELON GENERATION COMPANY, LLC IST PROGRAM - RELIEF REQUEST Proposed Alternative in Accordance with 10 CFR 50.55a(z)(1)
Relief Request to Utilize Code Case OMN-26 The requested relief reduces the maximum test interval for High Safety Significant Component (HSSC) MOVs allowed by Appendix Ill from ten years to nine years commensurate with Risk Informed Methodology. Further under this relief request, Exelon will treat MOVs currently classified as Medium Risk by the 3-Tier JOG Risk Ranking as High Risk (HSSC) thereby providing more rigorous periodic verification requirements for the applicable valves especially those with less than high margin.
The requested relief takes credit for routine design basis differential pressure testing (DBDPT) of MOVs to justify extending the maximum lnservice test interval to 12 Years for Very High Margin HSSC MOVs and 16 years for Very High Margin low Safety Significant Component (lSSC) MOVs.
With the exception of low Risk MOVs routinely operated at design basis differential pressure (D-P) conditions, Code Case OMN-26 does not allow maximum MOV lnservice Test intervals to exceed ten years unless the associated MOVs are classified as High Margin. Most High Risk MOVs are limited to four years or less for low/Medium Margins and most low Risk MOVs are limited to nine years or less for low/Medium Margins. Code Case OMN-26 provides more rigorous requirements targeted specifically to low/Medium Margin MOVs than currently allowed under Appendix Ill. This Risk/Margin approach is in line with accepted Risk-Informed Strategies such as the JOG MOV Periodic Verification Program.
Use of the proposed alternative is expected to result in improved MOV Margins at each Exelon station in order to attain higher margin status to allow use of the extended maximum inservice test intervals permitted by the OMN-26 Code Case.
For the majority of applicable MOVs (i.e., those MOVs not subject to periodic stroking under design basis D-P conditions), the Code Case limited the scope to only High Margin Valves for extending test intervals incrementally beyond current limits:
Test intervals for High Risk MOVs go from six to nine years (Note: Nine years is aligned to Pressurized Water Reactor nuclear power plants (PWRs) on 18-month refueling cycles)
Test intervals for Low Risk MOVs go from ten to 12 years (Note: 12 years is aligned for all Boiling Water Reactor nuclear power plants (BWRs) and PWRs with either 18-or 24-month refueling cycles)
The Table below provides a detailed comparison of the Maximum MOV Test Intervals for the JOG MOV Program, Mandatory Appendix Ill and Code Case OMN-26 that Exelon seeks to adopt via this relief request. MOVs identified with Bold type have maximum MOV inservice test intervals exceeding the current Appendix Ill ten-year limit.
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MOV Margin Low
. (<5%)
Medium
(;::5% and <10%)
High EXELON GENERATION COMPANY, LLC IST PROGRAM - RELIEF REQUEST Proposed Alternative in Accordance with 10 CFR 50.55a(z)(1)
Relief Request to Utilize Code Case OMN-26 Exelon Maximum MOV Test Intervals Based on Code Case OMN-26 Maximum lnservice Test Intervals (Years)
HSSC MOVs LSSC MOVs JOG Appendix OMN-26 OMN-26 JOG Appendix OMN-26 MOVPV Ill w/DBDPT MOVPV Ill Program (6)
Program 2
10 2 (1,2) 4 (5) 6 10 4 (1,3,5) 4 10 4 (1,2,5) 9 (5) 10 10 9 (1,3,5) 6 10 9 (5) 9 (5) 10 10 12 (4,5)
(;::10% and <20%)
Very High N/A 10 9 (5) 12 (4,5)
N/A 10 12 (4,5)
(;:: 20%)
Existing Existing Relief Relief Existing Existing Relief Description ->
Industry ASME Request Request Standard ASME Request Standard OM Code OM Code Table Notes OMN-26 w/DBDPT (6) 9 (5) 12 (4,5) 12 (4,5) 16 (4,5,7)
Relief Request
- 1. Code Case Maximum lnservice Test Intervals for all Low/Medium Margin MOVs are less than or equal to current ten-year Appendix Ill limit. (i.e., Code Case is more conservative than Appendix Ill for Low/Medium Margin MOVs).
- 2. Code Case Maximum lnservice Test Intervals for Low/Medium Margin HSSC MOVs are equal to the current JOG MOV PV Program limits of two/four years respectively. (Code Case intervals are aligned with JOG MOV).
- 3. Code Case Maximum lnservice Test Intervals for Low/Medium Margin LSSC MOVs (four/nine years) are less than the current JOG MOV PV Program limits of six/ten years respectively.
- 4. The following four categories of MOVs have maximum inservice test intervals that exceed the current ten-year limit:
- b. Very High Margin, HSSC MOVs that are periodically stroked at design basis DP conditions (DBDPT) (12 Years)
- 5. Except for Low Margin HSSC MOVs, the Maximum MOV lnservice Test Intervals are optimized for Divisional Outage Scheduling (i.e., 4, 9, 12, 16 years). Nine years is optimal for PWRs restricted to 18 month refueling outages. 12 years is optimal for both PWRs and BWRs and supports both 18-month and 24-month refueling outages.
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EXELON GENERATION COMPANY, LLC IST PROGRAM - RELIEF REQUEST Proposed Alternative in Accordance with 10 CFR 50.55a(z)(1)
Relief Request to Utilize Code Case OMN-26
- 6. To utilize these intervals, strokes at or exceeding design basis system conditions must be in the applicable safety function direction(s) and have no known applicable operating experience, degradation or diagnostic test anomaly that potentially impacts MOV functional margin or the capability of the MOV to perform its design basis function.
- 7. Operating plants that have acquired the requisite test data to satisfy lll-3310(b) or lll-3722(c) must complete one cycle of collecting diagnostic test data at an extended test interval, minimum 9 and maximum 12 years, before extending the test interval by engineering evaluation to the maximum 16-year test interval.
6. Duration of Proposed Alternative
The proposed alternative is for use of the Code Case for the remainder of each plant's ten-year lnservice Testing interval as specified in Section 2.
- 7. Precedent:
None
- 8.
References:
- 1. ASME OM Code Case OMN-26, Alternative Risk-Informed and Margin Based Rules for lnservice Testing of Motor Operated Valves, approved by ASME Board of Nuclear Codes and Standards (BNCS) December 2019.
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