NL-25-0008, Request for Alternative for Inservice Testing of the 2A and 2B Charging Pumps in Accordance with 10 CFR 50.55a(z)(2)

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Request for Alternative for Inservice Testing of the 2A and 2B Charging Pumps in Accordance with 10 CFR 50.55a(z)(2)
ML25007A244
Person / Time
Site: Vogtle 
Issue date: 01/07/2025
From: Coleman J
Southern Nuclear Operating Co
To:
Office of Nuclear Reactor Regulation, Document Control Desk
References
NL-25-0008
Download: ML25007A244 (1)
v • d • e


Text

A Southern Nuclear January 7, 2025 Docket No:

50-425 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Regulatory Affairs Vogtle Electric Generating Plant - Unit 2 3535 Colonnade Parkway Birmingham, AL 35243 205 992 5000 NL-25-0008 Request for Alternative for lnservice Testing of the 2A and 2B Charging Pumps in Accordance with 10 CFR 50.55a(z)(2)

Ladies and Gentlemen:

In accordance with 10 CFR 50.55a, "Codes and standards," Southern Nuclear Operating Company (SNC) requests NRC approval of a proposed alternative associated with the lnservice Testing (1ST) Program for Vogtle Electric Generating Plant Unit 2. The proposed alternative requests to defer the requirements to perform Group A quarterly pump tests as required by ISTB-3400, for the 2A and 2B charging pumps until the end of the spring 2025 refueling outage.

The next Group A centrifugal charging pump performance test is due January 30, 2025. This will allow performance of a comprehensive pump test (CPT) for the 2A and 2B charging pumps during the upcoming spring of 2025 refueling outage.

The next scheduled performance of the Group A test for the 2A charging pump is due January 30, 2025 (92 days plus grace from the last test performed on October 7, 2024 ). The next scheduled performance of the Group A test for the 2B charging pump is due February 20, 2025 (92 days plus grace from the last test performed on October 28, 2024 ). A rising trend in the Unit 2 Reactor Coolant pump seals leak off was recently determined to be caused by degraded RCP seals. Performance of the charging pump testing before the damaged RCP seals can be repaired during the spring 2025 outage could introduce additional damage to the degraded seals and undue stress on the backup RCP seals. Performance of these tests as scheduled would constitute a hardship without a compensating increase in the level of quality and safety.

The proposed alternative in the attached enclosure provides reasonable assurance of pump operational readiness and provides an acceptable level of quality and safety. SNC requests NRC approval of this alternative by January 29, 2025. This request, upon approval, will be applied until the end of the spring 2025 refueling outage.

This letter contains no NRC commitments. If you have any questions, please contact Ryan Joyce at 205.992.6468.

U. S. Nuclear Regulatory Commission NL-25-0008 Page 2 Respectfully submitted,

~~~

Jamie M. Coleman Regulatory Affairs Director JMC/jdj/cbg

Enclosure:

Request for Alternative RR-PR-04 cc:

Regional Administrator NRR Project Manager - Vogtle 1 & 2 Senior Resident Inspector - Vogtle 1 & 2 RType: CVC?000 2

Enclosure to NL-25-0008 Request for Alternative lnservice Testing of 2A and 2B Charging Pumps Vogtle Electric Generating Plant - Unit 2 Request for Alternative RR-PR-04 lnservice Testing of the 2A and 2B Charging Pumps in Accordance with 10 CFR 50.55a(z)(2)

Enclosure to NL-25-0008 Request for Alternative lnservice Testing of 2A and 2B Charging Pumps Request for Alternative RR-PR-04 lnservice Testing of the 2A and 2B Centrifugal Charging Pumps in Accordance with 10 CFR 50.55a(z)(2)

1.

ASME Code Components Affected Component Number Component Title Code Class Pump Group or Category 21208P6002 eves eePA Pump 2

Group A Pump 21208P6003 eves eeP B Pump 2

Group A Pump The chemical and volume control system (CVCS) serves as part of the emergency core cooling system (ECCS) by providing high head injection (HHI) capability. As part of the ECCS, the HHI pumps provide core cooling and negative reactivity to ensure that the reactor core is protected after any of the following accidents:

  • Loss of coolant accident (LOCA), coolant leakage greater than the capability of the normal charging system
  • Loss of secondary coolant accident, including uncontrolled steam release or feedwater line rupture
2.

Applicable Code Edition and Addenda

American Society of Mechanical Engineers (ASME) Code for Operation and Maintenance of Nuclear Power Plants (OM Code) 2004 Edition with Addenda through OMb-2006.

3.

Applicable Code Requirement

ISTB-3400, Frequency of lnservice Tests, states "An inservice test shall be run on each pump as specified in Table ISTB-3400-1". Table ISTB-3400-1, lnservice Test Frequency, specifies that for Group A pumps, a 'Comprehensive [Pump] Test' (CPT) be performed biennially and a

'Group A Test' be performed quarterly.

4.

Reason for Request

Pursuant to 10 CFR 50.55a, Codes and standards, paragraph (z)(2), an alternative is proposed to the quarterly pump test requirements of the ASME OM-2004 Code with Addenda through OMb-2006. 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 rising trend in Unit 2 RCP #1 Seal Leak-off on all RCPs was identified on December 26, 2024. The increased leakage is due to degradation of the #1 seals causing increased seal leak-off. While the source of the #1 seal degradation cannot be formally concluded before inspection during reactor shutdown, the most probable cause is believed to be increased iron oxide deposition on the faceplates.

Based on this condition, any centrifugal charging pump test could cause perturbations to the #1 seals based on the required changes to seal injection flow, charging flow, Volume Control Tank pressure, and pressure changes to the #1 seal return flow path during the test. Damage or degradation of the #1 seals could cause loss of coolant through the seal package which challenges plant safety and reliability.

E-1

Enclosure to NL-25-0008 Request for Alternative lnservice Testing of 2A and 2B Charging Pumps Damage or degradation of the #1 seals (due to perturbations caused by the Group A pump test) could cause seal leak-off flow rates to exceed procedural operating limits and require a shutdown of Unit 2 in order to prevent the potential small break loss of coolant accident. The system operating procedure provides direction for monitoring operational parameters and taking appropriate action. Procedures direct the operators to manually trip the reactor then secure the affected RCP if the total seal leak off exceeds the operational limit defined in procedures (currently 6 gpm).

Repairs to address the RCP #1 seal leakages are scheduled for the upcoming refueling outage in the spring of 2025. 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. Repair of the RCP seals requires the pump and motor to be decoupled which would require shutdown of the Unit 2 reactor and reduce plant reliability.

The next performance of the Group A test for the 2A centrifugal charging pump is due January 30, 2025, which is 92 days plus grace from the last test performed on October 7, 2024, and the next performance of the Group A test for the 2B centrifugal charging pump is due February 20, 2025, which is 92 days plus grace from the last test performed on October 28, 2024. Southern Nuclear Operating Company is requesting NRC approval of this relief request by January 29, 2025, prior to the expiration of the testing frequency window.

5.

Proposed Alternative and Basis for Use The proposed alternative requests to defer the requirements to perform Group A quarterly pump tests as required by ISTB-3400 for the 2A and 2B centrifugal charging pumps until the end of the spring 2025 refueling outage. This will allow performance of a comprehensive pump test (CPT) for the 2A and 2B centrifugal charging pumps during the upcoming spring of 2025 refueling outage. The Group A quarterly pump tests will resume as scheduled following the spring of 2025 refueling outage and repair of the #1 RCP seals.

Previous trends for the 2A and 2B charging pumps are in Attachment 1 (Tables 1 - 8) and show the operational readiness of the pumps to perform their intended safety function. The last two years of data from the quarterly Group A testing and the last 10 years of data from the CPT for the 2A and 2B Centrifugal Charging Pumps indicate there is no current pump degradation. All recorded values for pump vibration, flow, and differential pressure during the review period were within ASME OM code and design limits. Therefore, it is unlikely that the upcoming quarterly pump tests would produce a failing value for any test parameter. Additionally, no significant maintenance has been performed or is planned for the 2A and 2B centrifugal charging pumps that would alter the pump test parameters.

Repairs to the #1 seals are planned for the upcoming spring of 2025 refueling outage because repair of the seals requires the pump and motor to be decoupled which would require shutdown of the Unit 2 reactor. In the current conditions, performing the Group A quarterly test for the 2A and 2B centrifugal charging pumps would constitute a hardship without a compensating increase in the level of quality and safety. The proposed alternative to ISTB-3400, Frequency of lnservice Tests, provides reasonable assurance of pump operational readiness and provides an acceptable level of quality and safety.

E-2

Enclosure to NL-25-0008 Request for Alternative lnservice Testing of 2A and 2B Charging Pumps Relief is requested pursuant to 10 CFR 50.55a(z)(2) based on the determination that compliance with the ASME OM Code required quarterly charging pump test requirements cannot be achieved without considerable plant safety and reliability risks prior to significant repairs to address the #1 RCP seal degradation. Performance of the Group A quarterly charging pump test could cause perturbations to the #1 seals that could challenge the ability of the RCP seal package to prevent loss of coolant which challenges plant safety and reliability.

6.

Duration of Proposed Alternative This request, upon approval, will be applied until the end of the spring 2025 refueling outage.

This timeframe provides an adequate window of opportunity to perform the Comprehensive Pump Tests (CPTs) during the spring 2025 refueling outage, after repairs have been made to the RCP seals. The performance of the quarterly Group A inservice tests for the components included in this request will resume at the normal frequency following the spring 2025 refueling outage.

7.

Precedent M. Markley (NRC) to J. M. Coleman (Southern Nuclear Operating Company), "JOSEPH M.

FARLEY NUCLEAR PLANT, UNIT NO. 2 - RE: AUTHORIZATION OF PROPOSED ALTERNATIVE RR-PR-04 INSERVICE TESTING OF THE 2A, 2B, AND 2C CHARGING PUMPS AND MINI-FLOW ISOLATION VALVES (EPID L-2024-LLR-0068)," dated December 19, 2024 (ML24351A040)

8.

References None.

E-3

Enclosure to NL-25-0008 Request for Alternative lnservice Testing of 2A and 2B Charging Pumps Table 1 - 2A Centrifugal Charging Pump Quarterly Group A Test - Differential Pressure Trends Date Flow (gpm)* ~p (psid) dP Acceptance Criteria (psid) 10/19/2022 o4.5 12684.0 2420.1 to 2957.9 1/19/2023 p4.3 12658.0 2420.1 to 2957.9 4/19/2023 p4.5

!2684.0 2420.1 to 2957.9 7/19/2023 o4.5 12658.0 2420.1 to 2957.9 10/11/2023 p4.5

!2656.0 2420.1 to 2957.9 1/10/2024 p4.5

!2657.0 2420.1 to 2957.9 4/10/2024 p4.5 12684.0 2420.1 to 2957.9 7/8/2024 p4.5

!2558.0 2420.1 to 2957.9 10/7/2024 o4.5 12658.0 2420.1 to 2957.9

  • Flow is adjusted to the reference point of 64.5 gpm +2%/-1 % (63.9 gpm to 65.7 gpm)

Note: All trends were within acceptance criteria; however, any adverse trend or notable deviation if identified would require engineering input to determine the cause.

Table 2 - 2A Centrifugal Charging Pump Biennial CPT - Differential Pressure Trends Date Flow (gpm)*

dP (psid) dP Acceptance Criteria (psid) 3/25/2013 502.0 1085.0 1021.7 to 1131.6 10/4/2014 500.0 1110.0 1021.7 to 1131.6 3/10/2016 500.0 1104.0 1021.7 to 1131.6 9/20/2017 500.0 1052.0 1021.7 to 1131.6 3/14/2019 506.0 1102.0 1021.7 to 1131.6 8/20/2020 500.0 1106.0 1021.7 to 1131.6 3/10/2022 500.0 1107.0 1021.7 to 1131.6 9/12/2023 500.0 1081.0 1021.7 to 1164.5**

  • Flow is adjusted to the reference point of 499 gpm +2%/-1 % (494 to 508 gpm)
    • OMN-19 was invoked to gain additional margin on the upper limit (1.06) for CPT dP Note: All trends were within acceptance criteria; however, any adverse trend or notable deviation if identified would require engineering input to determine the cause.

Table 3 - 2A Centrifugal Charging Pump Quarterly Group A Test - Vibration Data Date Pump Outboard Pump Outboard Pump Outboard Pump Inboard Pump Inboard Axial (IPS*)

Horizontal (IPS*)

Wertical (IPS*)

Horizontal (IPS*) Vertical (IPS*)

10/19/2022 0.074 0.094 K).131 p.067 0.082 1/19/2023 0.077 0.085 Kl.136 0.068 0.082 4/19/2023 0.078 0.090 Kl.135 P.067 0.091 7/19/2023 0.071 0.092 K).131 p.088 0.087 10/11/2023 0.080 0.087 KJ.126 0.068 0.087 E-4

Enclosure to NL-25-0008 Request for Alternative lnservice Testing of 2A and 2B Charging Pumps 1/10/2024 0.075 0.089 Kl.133 K).068 0.086 4/10/2024 0.075 0.094 KJ.132 P.075 0.087 7/8/2024 0.070 0.099 K).130 P.073 0.092 10/7/2024 0.075 0.085 Kl.127 P.067 0.082 Acceptance

0.178
0.225
0.275 t 0.130
0.188 Criteria
  • Inches per second Note: All trends were within acceptance criteria; however, any adverse trend or notable deviation if identified would require engineering input to determine the cause.

Table 4 - 2A Centrifugal Charging Pump Biennial CPT - Vibration Data Pump Pump Outboard Pump Pump Inboard Pump Inboard Date Outboard Outboard

~ial(IPS*)

Horizontal (IPS* ) Vertical (IPS*) Horizontal (IPS*) Wertical (IPS*)

3/25/2013 0.071 0.136 0.149 0.046 KJ.063 10/4/2014 0.082 0.142 0.147 0.049 K).074 3/10/2016 0.101 0.158 0.141 0.049 K).075 9/20/2017 0.087 0.137 0.178 0.072 KJ.076 3/14/2019 0.081 0.177 0.162 0.078 K).079 8/20/2020 0.078 0.151 0.157 0.056 Kl.072 3/10/2022 0.083 0.132 0.184 0.059 K).073 9/12/2023 0.084 0.127 0.159 0.048 K).071 Acceptance

0.185
0.245
0.325
0.115
0.138 Criteria
  • Inches per second Note: All trends were within acceptance criteria; however, any adverse trend or notable deviation if identified would require engineering input to determine the cause.

Table 5 - 2B Centrifugal Charging Pump Quarterly Group A Test - Differential Pressure Trends Date Flow (gpm)* ~p (psid) dP Acceptance Criteria (psid) 11/4/2022 64.5 12708.0 2438.1 to 2979.9 1/24/2023 p4.5

!2707.0 2438.1 to 2979.9 5/5/2023 64.5 12708.0 2438.1 to 2979.9 7/25/2023 p4.5

!2682.5 2438.1 to 2979.9 10/26/2023 p4.5

!2707.0 2438.1 to 2979.9 1/25/2024 64.5 12708.0 2438.1 to 2979.9 4/25/2024 p4.5 12708.0 2438.1 to 2979.9 7/23/2024 64.2 12707.0 2438.1 to 2979.9 10/28/2024 64.3 12708.0 2438.1 to 2979.9

  • Flow is adjusted to the reference point of 63.5 gpm +2%/-1 % (62.9 gpm to 64.7 gpm)

Note: All trends were within acceptance criteria; however, any adverse trend or notable deviation if identified would require engineering input to determine the cause.

E-5

Enclosure to NL-25-0008 Request for Alternative lnservice Testing of 2A and 2B Charging Pumps Table 6 - 2B Centrifugal Charging Pump Biennial CPT - Differential Pressure Trends Date Flow (gpm)*

dP (psid) dP Acceptance Criteria psid) 3/25/2013 502.0 1008.0 938.2 to 1039.1 10/4/2014 490.0 1035.0 938.2 to 1039.1 3/10/2016 490.0 1029.0 938.2 to 1039.1 9/20/2017 490.0 1039.0 938.2 to 1039.1 3/14/2019 490.0 1056.0 995.1 to 1102.1**

8/20/2020 490.0 1057.0 995.1 to 1102.1 3/10/2022 492.0 1058.0 995.1 to 1102.1 9/12/2023 490.0 1006.0 995.1 to 1134.2***

  • Flow is adjusted to the reference point of 492 gpm +2%/-1 % (487 to 502 gpm)
    • Rebaseline based on pump rotating element replacement
      • OMN-19 was invoked to gain additional margin on the upper limit (1.06) for CPT dP Note: All trends were within acceptance criteria; however, any adverse trend or notable deviation if identified would require engineering input to determine the cause.

T bl 7 2B C t "f a e -

en n uga I Ch argmg p ump ua eriy Q

rt I G roup es -

1 ra 10n aa AT t V"b f D t Date Pump Outboard Pump Outboard Pump Outboard Pump Inboard Pump Inboard Axial (IPS*)

Horizontal (IPS*)

Wertical (IPS*)

Horizontal (IPS*) Vertical (IPS*)

11/4/2022 0.049 0.059 K).089 P.079 0.074 1/24/2023 0.051 0.058 Kl.089 p.o5o 0.074 5/5/2023 0.052 0.066 KJ.096 P.053 0.077 7/25/2023 0.050 0.058 K).093 P.054 0.085 10/26/2023 0.053 0.052 Kl.089 P.054 0.071 1/25/2024 0.051 0.052 K).089 0.051 0.072 4/25/2024 0.059 0.064 K).090 p.056 0.079 7/23/2024 0.053 0.067 KJ.086 P.057 0.076 10/28/2024 0.052 0.055 K).090 0.051 0.071 Acceptance

0.185
0.325
0.325

~0.277

0.222 Criteria
  • Inches per second Note: All trends were within acceptance criteria; however, any adverse trend or notable deviation if identified would require engineering input to determine the cause.

Table 8 - 2B Centrifugal Charging Pump Biennial CPT - Vibration Data Pump Pump Outboard Pump Pump Inboard Pump Inboard Date Outboard Outboard

~ial(IPS*)

Horizontal (IPS*) Vertical (IPS*) Horizontal (IPS*) Wertical (IPS*)

3/25/2013 0.081 0.107 0.183 0.063 K).058 10/4/2014 0.086 0.226 0.182 0.112 Kl.079 3/10/2016 0.127 0.088 0.176 0.051 KJ.058 9/20/2017 0.089 0.205 0.196 0.176 K).065 E-6

Enclosure to NL-25-0008 Request for Alternative lnservice Testing of 2A and 2B Charging Pumps 3/14/2019 0.084 0.116 0.188 0.060 Kl.060 8/20/2020 0.078 0.117 0.183 0.056 K).058 3/10/2022 0.088 0.134 0.171 0.051 Kl.061 9/12/2023 0.077 0.199 0.175 0.072 Kl.069 Acceptance 5:0.203 5:0.325 5:0.325 5:0.325 5:0.183 Criteria

  • Inches per second Note: All trends were within acceptance criteria; however, any adverse trend or notable deviation if identified would require engineering input to determine the cause.

E-7

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