ML24026A011
| ML24026A011 | |
| Person / Time | |
|---|---|
| Site: | Ginna  |
| Issue date: | 01/26/2024 |
| From: | David Gudger Constellation Energy Generation |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| Download: ML24026A011 (1) | |
Text
200 Exelon Way Kennett Square, PA 19348 www.ConstellationEnergy.com 10 CFR 50.55a January 26, 2024 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 R. E. Ginna Nuclear Power Plant Renewed Facility Operating License No. DPR-18 NRC Docket No. 50-244
Subject:
Relief Request Associated with Inservice Testing of B Auxiliary Feedwater Pump In accordance with 10 CFR 50.55a, Codes and standards,, Constellation Energy Generation, LLC (CEG) requests NRC approval of a proposed relief request associated with the Inservice Testing (IST) Program for the R. E. Ginna Nuclear Power Plant (Ginna). The IST Program for the sixth 10-year interval began on January 1, 2020, and adopted the 2012 Edition of the American Society of Mechanical Engineers (ASME) Code for Operation and Maintenance of Nuclear Power Plants (OM Code). This edition of the OM Code includes a biennial requirement to perform a Comprehensive [Pump] Test (CPT) for Group A pumps and a Pump Periodic Verification Test (PPVT) at the pumps highest design basis accident flow rate.
The next performance of the CPT and PPVT for the B Auxiliary Feedwater (AFW) Pump (PAF01B) is due August 27, 2024, which is 24 months plus grace from the last test performed on March 1, 2022. Currently, degradation of a Condensate Heater 4B Outlet Check Valve is resulting in partial flow blockage. In this condition, performing the CPT and PPVT for the B AFW Pump as scheduled would constitute a hardship without a compensating increase in the level of quality and safety. The Attachment to this request provides a relief request for the B AFW Pump CPT and PPVT. The Relief Request proposes an alternative that provides reasonable assurance of pump operational readiness and provides an acceptable level of quality and safety. CEG requests NRC approval of this relief request by August 27, 2024. This request, upon approval, will be applied until November 30, 2024.
Relief Request Associated with Inservice Testing of B Auxiliary Feedwater Pump January 26, 2024 Page 2 There are no regulatory commitments contained in this letter.
If you have any questions concerning this submittal, please contact Ms. Wendi E. Para at (267) 533-5208.
Respectfully, David T. Gudger Sr. Manager - Licensing Constellation Energy Generation, LLC Attachments: Relief Request PR Inservice Testing of the B Auxiliary Feedwater Pump cc:
USNRC Region I, Regional Administrator USNRC Senior Resident Inspector, Ginna Nuclear Power Plant USNRC Project Manager, NRR - Ginna Nuclear Power Plant
Attachment Relief Request PR Inservice Testing of B Auxiliary Feedwater Pump
10 CFR 50.55a Relief Request PR-03, Revision 0 Page 1 of 6 Request for Relief PR-03 Inservice Testing of B Auxiliary Feedwater Pump In Accordance with 10 CFR 50.55a(z)(2)
- 1. ASME Code Component(s) Affected Component ID Description Code Class Pump Group PAF01B Auxiliary Feedwater Pump B 3
A Each of the two preferred motor-driven, centrifugal Auxiliary Feedwater (AFW) pumps are required to be capable of individually supplying 100% of the AFW flow to the steam generators during a loss of normal feedwater flow or a steam line break in conjunction with a loss of offsite power. This function maintains steam generator water level to provide a secondary heat sink for residual heat removal of the reactor coolant system. Each motor-driven AFW pump is designed to develop a discharge flow of 200 gpm at a pressure equal to or greater than the lowest main steam safety valve setpoint plus accumulation (1085 psig).
2. Applicable Code Edition and Addenda
American Society of Mechanical Engineers (ASME) Code for Operation and Maintenance of Nuclear Power Plants (OM Code) 2012 Edition with no Addenda.
3. Applicable Code Requirement
ISTB-3400, Frequency of Inservice Tests, states that an inservice test shall be run on each pump as specified in Table ISTB-3400-1, Inservice Test Frequency. Table ISTB-3400-1 specifies that a Comprehensive [Pump] Test (CPT) and Pump Periodic Verification Test be performed biennially for Group A pumps.
Mandatory Appendix V, Pump Periodic Verification Test Program,(b) requires that a PPVT is performed at least once every two years.
Mandatory Appendix V, V-2000, Definitions, defines the Pump Periodic Verification Test (PPVT) as a test that verifies a pump can meet the required (differential or discharge) pressure as applicable, at its highest design basis accident flow rate.
4. Reason for Request
Pursuant to 10 CFR 50.55a, Codes and standards, paragraph (z)(2), an alternative is proposed to the CPT and PPVT requirements of the ASME OM-2012 Code. The basis of the request is that compliance with the specified requirements results in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
A disc separation of the Condensate Heater 4B Outlet Check Valve has resulted in partial flow blockage, which has caused secondary plant transients during inservice testing of AFW pumps with forward flow to the Steam Generators (September 20, 2023 full flow testing of the Turbine Driven AFW Pump (PAF03) and November 13, 2023 full flow testing of the Standby AFW Pump C (PSF01A)). These transients resulted in a rapid reduction in heater
10 CFR 50.55a Relief Request PR-03, Revision 0 Page 2 of 6 drain tank (HDT) level below 40% which necessitates manual operation of the HDT level controller. In this condition, if the HDT pump tripped on low level it would necessitate rapid downpower to 50% reactor power to prevent a thermal power transient, which places unnecessary thermal and pressure cycles on plant equipment thereby reducing overall safety and reliability. In addition, in this condition there is an increased probability of a loss of Main Feedwater transient. A loss of Main Feedwater transient would result in a reactor trip which is an unplanned reactivity management event.
Repairs to address the disc separation of the Condensate Heater 4B Outlet Check Valve are scheduled for the upcoming refueling outage in the fall of 2024. As a contingency, the repair scope is included on the forced outage worklist and would be performed if a forced outage of sufficient duration and scope were necessary prior to the planned refueling outage.
Repairs online would require a significant downpower of the unit which, as stated above, places unnecessary thermal and pressure cycles on plant equipment thereby reducing overall safety and reliability. In addition, online repairs would require an exceptional tagout due to single valve isolation of a high energy line, which does not provide complete conventional isolation of hazardous energy for the work in accordance with 29 CFR 1910.269(d)(6)(v) through (vii).
The next performance of the CPT and PPVT for the B AFW Pump (PAF01B) is due August 27, 2024, which is 24 months plus grace from the last test performed on March 1, 2022.
Constellation Energy Generation, LLC (CEG) is requesting NRC approval of this relief request by August 27, 2024, prior to the expiration of the testing frequency window.
5. Proposed Alternative and Basis for Use
The proposed alternative to the requirements to perform CPT and PPVT every two years on the B AFW Pump as required by ISTB-3400, Frequency of Inservice Tests, and Mandatory Appendix V, Pump Periodic Verification Test Program, is to defer the CPT and PPVT until no later than November 30, 2024. A quarterly Group A test will still be performed as scheduled to provide continued monitoring and assurance of the B AFW Pumps operational readiness.
As provided in ISTB-5120, Inservice Testing, Group A tests and CPTs are both conducted with the pump operating as close as practical to each tests specified reference point and testing verified the same test parameters as outlined in OM Code Table ISTB-3000-1, Centrifugal Pump Test Acceptance Criteria. However, Group A tests and CPTs differ in their acceptance criteria ranges, with the CPT ranges being more restrictive. As defined in Mandatory Appendix V, Pump Periodic Verification Test Program, the PPVT verifies a pump can meet the required (differential or discharge) pressure at its highest design basis accident flow.
At Ginna, the B AFW pump CPT and PPVT are performed concurrently at the PPVT full flow rate value of 200 gpm on a line that terminates at a steam generator, there is not an alternative flow path to utilize to achieve the required flow parameters. In the current condition, with a disc separation of a Condensate Heater 4B Outlet Check Valve which has resulted in a partial flow blockage, the 200 gpm forward flow to the Steam Generators has been shown to initiate a series of secondary system oscillations and responses that ultimately cause a secondary flow imbalance which increases plant risk. Conversely, the quarterly Group A test is conducted on a recirculation line that does not flow into the steam
10 CFR 50.55a Relief Request PR-03, Revision 0 Page 3 of 6 generator and therefore, can be performed without causing the secondary transients in the same conditions. The Group A test is conducted when the pump is operated in recirculation mode with an installed flow orifice that establishes a 40 gpm flow rate. It should be noted that flow is not directly measured during the quarterly Group A test per NRC approved Relief Request PR-02, Ginna sixth 10-Year Interval IST Program Plan. The Group A test flow rate is considerably lower than the 200 gpm reference used for the CPT and PPVT, however, despite the flow differences, the Group A test produces test results that are commensurate to the CPT and PPVT vibration and differential pressure results (see Tables 1 through 4, Figures 1 and 2).
Past data and trends from the quarterly Group A testing, the CPT, and the PPVT for the B AFW Pump show no negative trending for any inservice test parameter which indicates there is no current pump degradation. Therefore, it is unlikely that the upcoming CPT or PPVT would produce a failing value for any test parameter. However, should there be a change in the pump performance during the period covered by this relief request, the quarterly Group A pump test that will still be performed would detect any failures or declining trends. Additionally, no significant maintenance has been performed or is planned for the B AFW pump that would alter the flow or pressure parameters.
Relief is requested pursuant to 10 CFR 50.55a(z)(2) based on the determination that compliance with the Code required CPT and PPVT pump test requirements cannot be achieved without considerable plant safety and reliability risks prior to significant repairs to address the disc separation of a Condensate Heater 4B Outlet Check Valve. Recent inservice testing of the AFW pumps with forward flow to the Steam Generators has caused secondary plant transients that had the potential to result in a rapid reactor downpower and increased the probability of a loss of Main Feedwater transient and a subsequent unplanned reactivity management event (reactor trip). Repairs to the valve are planned for the upcoming refueling outage in the fall of 2024 because repairs online present personnel safety and plant reliability risks. In the current conditions, performing the CPT and PPVT for the B AFW pump would constitute a hardship without a compensating increase in the level of quality and safety. The proposed alternative provides reasonable assurance of pump operational readiness and provides an acceptable level of quality and safety.
6. Duration of Proposed Alternative
This request, upon approval, will be applied until November 30, 2024. This date provides an adequate window of opportunity to perform the CPT and PPVT at full power following Ginnas scheduled fall 2024 refueling outage, when repairs will be made to the Condensate Heater 4B Outlet Check Valve. The biennial test frequency for the B AFW Pump will restart from the date of performance of the CPT and PPVT in the fall of 2024.
10 CFR 50.55a Relief Request PR-03, Revision 0 Page 4 of 6
- 7. Precedent The NRC authorized Monticello Nuclear Generating Plant Alternative Request PR-08 to defer the quarterly testing of certain components in the HPCI system due to a degraded component in a connected system until the scheduled 2023 spring RFO as documented in the citation below.
V. Sreenivas (NRC) to C. P. Domingos (Northern States Power Company),
Monticello Nuclear Generating Plant - Authorization and Safety Evaluation for Alternative Request PR-08 (EPID L-2022-LLR-0088), dated April 25, 2023 (ML23107A285)
- 8. References None
10 CFR 50.55a Relief Request PR-03, Revision 0 Page 5 of 6 Table 1. Quarterly Group A Test - Differential Pressure (dP)
Date Flow (gpm) dP (psid)
Flow Acceptance Criteria (gpm) dP Acceptance Criteria (psid) 12/1/2023 N/A1 1496.1 N/A1 1342.0 to 1640.2 8/29/2023 N/A1 1492.2 N/A1 1342.0 to 1640.2 6/4/2023 N/A1 1489.3 N/A1 1342.0 to 1640.2 2/27/2023 N/A1 1496.4 N/A1 1342.0 to 1640.2 11/28/2022 N/A1 1491.6 N/A1 1342.0 to 1640.2 8/9/2022 N/A1 1489.0 N/A1 1342.0 to 1640.2 5/26/2022 N/A1 1494.6 N/A1 1342.0 to 1640.2 Table 2. Biennial CPT and PPVT - Differential Pressure and Flow Date Flow (gpm) dP (psid)
Flow Acceptance Criteria (gpm) dP Acceptance Criteria (psid) 3/1/2022 202.5 1305.3 199 to 204 1223.1 to 1394.1 4/30/2020 203.0 1312.7 199 to 204 1223.1 to 1394.1 4/12/2018 200.4 1317.7 200 to 201.1 1223.1 to 1354.6 4/22/2017 200.6 1313.0 200 to 201.1 1223.1 to 1354.6 10/14/2015 200.6 1304.1 200 to 201.1 1223.1 to 1354.6 10/1/2014 200.6 1307.0 200 to 201.1 1223.1 to 1354.6 2/27/2013 200.8 1316.8 200 to 201.1 1223.1 to 1354.6 Table 3. Quarterly Group A Test - Vibration Data Date POA2 (IPS3)
POH4 (IPS)
POV5 (IPS)
PIH6 (IPS)
PIV7 (IPS) 12/1/2023 0.054 0.078 0.074 0.064 0.083 8/29/2023 0.056 0.098 0.088 0.076 0.089 6/4/2023 0.049 0.109 0.087 0.059 0.069 2/27/2023 0.050 0.097 0.096 0.055 0.065 11/28/2022 0.043 0.104 0.090 0.060 0.077 8/9/2022 0.049 0.090 0.080 0.063 0.067 5/26/2022 0.044 0.095 0.082 0.065 0.065 Acceptance Limit 0.292 0.225 0.215 0.195 0.148 1 Tested on a recirculation line without flow meter. See PR-02 in the 6th Interval IST Program Plan.
2 Pump Outboard - Axial 3 Inches Per Second Peak 4 Pump Outboard - Horizontal 5 Pump Outboard - Vertical 6 Pump Inboard - Horizontal 7 Pump Inboard - Vertical
10 CFR 50.55a Relief Request PR-03, Revision 0 Page 6 of 6 Table 4. Biennial CPT - Vibration Data Date POA (IPS)
POH (IPS)
PIH (IPS)
PIV (IPS) 3/1/2022 0.032 0.096 0.051 0.063 0.049 4/30/2020 0.053 0.125 0.063 0.065 0.053 4/12/2018 0.046 0.104 0.050 0.049 0.040 4/22/2017 0.053 0.098 0.052 0.051 0.047 10/14/2015 0.042 0.115 0.048 0.054 0.043 10/1/2014 0.045 0.104 0.049 0.049 0.044 2/27/2013 0.027 0.117 0.045 0.063 0.045 Acceptance Limit 0.063 0.208 0.113 0.153 0.068 Figure 1: Quarterly Group A Test - Differential Pressure Values Figure 2: Biennial CPT and PPVT - Differential Pressure Values 1342 1392 1442 1492 1542 1592 DifferentialPressure(psid)
TestDate 1223.1 1243.1 1263.1 1283.1 1303.1 1323.1 1343.1 1363.1 1383.1 2/1/2013 6/1/2013 10/1/2013 2/1/2014 6/1/2014 10/1/2014 2/1/2015 6/1/2015 10/1/2015 2/1/2016 6/1/2016 10/1/2016 2/1/2017 6/1/2017 10/1/2017 2/1/2018 6/1/2018 10/1/2018 2/1/2019 6/1/2019 10/1/2019 2/1/2020 6/1/2020 10/1/2020 2/1/2021 6/1/2021 10/1/2021 2/1/2022 DifferentialPressure(psid)
TestDate