RC-17-0035, (Vcsns), Unit 1 - Relief Request RR-4-12, Turbine Driven Emergency Feedwater Pump Inservice Testing Requirements
| ML17088A256 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 03/28/2017 |
| From: | Lippard G South Carolina Electric & Gas Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| RC-17-0035, RR-4-12 | |
| Download: ML17088A256 (13) | |
Text
George A. Lippard Vice President, Nuclear Operations 803.345.4810 A SCANA COMPANY March 28,2017 RC-17-0035 Document Control Desk U. S. Nuclear Regulatory Commission Washington, DC 20555
Dear Sir / Madam:
Subject:
VIRGIL C. SUMMER NUCLEAR STATION (VCSNS) UNIT 1 DOCKET NO. 50-395 OPERATING LICENSE NO. NPF-12 RELIEF REQUEST RR-4-12, TURBINE DRIVEN EMERGENCY FEEDWATER PUMP INSERVICE TESTING REQUIREMENTS South Carolina Electric & Gas Company (SCE&G), acting for itself and as an agent for South Carolina Public Service Authority (Santee Cooper) hereby submits the attached request for using an alternative to the inservice testing requirements of the ASME code.
SCE&G has determined that the requirements would cause a hardship or unusual difficulty without a compensating increase in the level of quality or safety.
A detailed description of the proposed alternative, including basis for relief, is included as attachments to this letter. SCE&G requests NRC review and approval of this request by May 14, 2017, in order to support startup after refueling outage (RF-23) which is schedule to start on April 8, 2017.
SCE&G is submitting the attached relief request in accordance with 10CFR50.55a(z)(2).
V. C. Summer Nuclear Station
- P. 0. Box 88
- Jenkinsville, South Carolina
- 29065
- F (803) 941-9776
- www.sceg.com
Document Control Desk CR-17-01001 RC-17-0035 Page 2 of 2 Commitments made in this letter are established in Attachment 2.
Should you have any questions, please call Bruce L. Thompson at 803-931-5042.
Very truly yours, BB/GAL/wk Enclosure : VCSNS Relief Request RR-4-12 : Pump Curve and Test History : Commitments c:
K. B. Marsh S.M. Shealy K. M. Sutton S. A. Byrne W. M. Cherry NSRC J. B. Archie C. Haney RTS (CR-17-01001)
N. S. Cams S. A. Williams File (810.19-2)
J. H. Hamilton NRC Resident Inspector PRSF (RC-17-0035)
Document Control Desk Enclosure 1 CR-17-01001 RC-17-0035 Page 1 of 6 South Carolina Electric & Gas Co. (SCE&G)
Virgil C. Summer Nuclear Station Unit 1 (VCSNS)
Relief Request RR-4-12
- 1. Subject VCSNS Unit 1 is proposing an alternative to the requirements of ASME OM Code 2004, ISTB-3310 for testing of the Turbine Driven Emergency Feedwater (TDEFW) pump.
Modifications are scheduled for RF-23 (April 2017) to increase margin of the Emergency Feedwater System. The scope of the modifications include increasing the TDEFW pump speed, installing automatic recirculation-flow control (ARC) valves in the Motor Driven Emergency Feedwater (MDEFW) pump recirculation lines, and installing flow limiting Venturis in the common emergency feedwater lines to each steam generator. In addition, the TDEFW pump will be disassembled and inspected in accordance with preventative maintenance program requirements. The code requires a comprehensive test to be performed after pump disassembly, prior to declaring the pump operable.
Conducting a comprehensive test in Mode 3 causes excessive plant cooldown and could result in a safety injection actuation. Compliance with the code requirement would cause a hardship or unusual difficulty without a compensating increase in the level of quality or safety; therefore, SCE&G submits this relief request in accordance with 10CFR50.55a(z)(2). As an alternative SCE&G proposes to conduct a group B test as specified in Table ISTB-3000-1 that includes vibration data per ISTB-3540.
- 2. ASME Code Component(s) Affected Component: XPP0008, Turbine Driven Emergency Feedwater Pump Pump Model: Bingham-Willamette Co. model 3 x 6 x 9C - MSD Pump Type: Centrifugal Pump ASME Code Class: ASME B&PV Code,Section III, Class 3. Safety Class 2b Component: TPP0008, Emergency Feedwater Pump Turbine Model: Terry Turbine Co. model GS-2 single stage, solid wheel type Codes and Standards: ASME B&PV Code,Section III, NEMA SM-22 Applicable FSAR Section: FSAR Section 10.4.9 and Figure 10.4-16.
Document Control Desk Enclosure 1 CR-17-01001 RC-17-0035 Page 2 of 6
- 3. Applicable Code Edition and Addenda ASME OM Code-2004 Edition, "Operation and Maintenance of Nuclear Power Plants,"
with Addenda through OMb-2006 Subsection ISTB, "Inservice Testing of Pumps in Light-Water Reactor Nuclear Power Plants" ASME B&PV Code,Section XI IWP (Inservice Testing of Pumps in Nuclear Power Plants)
The station is in its fourth 10 year interval effective from January 1, 2014, through and including December 31, 2023.
- 4. Applicable Code Requirement ISTB-3310, Effect of Pump Replacement, Repair, and Maintenance on Reference Values. This section addresses the establishment of new reference values or the reconfirmation of existing reference values following pump replacement, repair, or maintenance by the performance of a Comprehensive Pump test before declaring the pump Operable. The Comprehensive Pump Test is required to be performed within
+/- 20% of the pump design flow rate per ISTB-3300(e)(1).
- 5. Reason for Request SCE&G is submitting this relief request in accordance with 10CFR50.55a(z)(2) where the requirements would cause a hardship or unusual difficulty without a compensating increase in the level of quality or safety. The station has conducted the comprehensive test in Mode 3 during low decay heat conditions. Stable test conditions have been difficult to establish due to decreasing steam generator pressures and the plant cooldown initiated by the emergency feedwater high flows required to meet ISTB-3300(e)(1). The high cooldown also introduces the risk of an inadvertent safety injection. ISTB-3310 requires the establishment of new reference values or the reconfirmation of existing reference values following pump replacement, repair, or maintenance by the performance of a Comprehensive Pump test before declaring the pump Operable.
The station will be conducting modifications that will enhance emergency feedwater system and improve the TDEFW pump head margin. Modifications are scheduled for RF-23 (April 2017). In addition the pump will be disassembled and inspected in accordance with preventative maintenance program requirements.
Document Control Desk Enclosure 1 CR-17-01001 RC-17-0035 Page 3 of 6 The emergency feedwater system planned activities include:
- 1. Increase TDEFW pump speed.
- 3. TDEFW pump recirculation line modifications due to speed increase.
- 4. Install flow limiting Venturis in the common emergency feedwater lines to each steam generator.
- 5. Disassemble and inspect the TDEFW pump.
- 6. Proposed Alternative and Basis for Use As an alternative VCSNS proposes to perform a group B test that includes vibration data at the higher pump speed in Mode 3 to determine operability. The comprehensive full flow test would then be conducted in Mode 1. Conducting the comprehensive test in stable plant conditions provided by Mode 1 would resolve the risk of an inadvertent safety injection. A safety injection could occur in Mode 3 with low decay heat conditions due to the decreasing steam generator pressures and the plant cooldown that is initiated by the emergency feedwater high flows required by ISTB-3300(e)(1).
Maintenance History The Emergency Feedwater Pump Turbine is the driver for the Pump. The turbine is powered by saturated steam supplied by the Main Steam System from the "B" and "C" Steam Generators. The Turbine is a Terry Turbine Company model GS-2 single stage, solid wheel type turbine. The original nominal design point is 990 hp at 4600 rpm with 37 Ib/hp-hr steam flow at 1169 psig inlet. The pre-modification operating speed is 4150 (+/- 50) rpm with an overspeed trip of 5060 rpm. The turbine was hydrostatically tested in accordance with ASME B&PV Section III, but was designed and constructed in accordance with NEMA SM-22 "Single Stage Steam Turbine for Mechanical Drive Service".
The TDEFW pump is a Bingham-Willamette Company model 3 x 6 x 9C - MSD, horizontally split centrifugal type pump. The pump is double volute with seven stages.
The pump is ANS Safety Class 2b supplied in accordance with the ASME B&PV Code,Section III, Class 3. The original nominal design point is 900 gpm at 3400 ft TDH at 79.9% efficiency at 4600 rpm with 27 ft NPSHR. The pre-modification operating speed is 4150 (+/- 50) rpm.
The original pump curve drawing 1MS-17-0153-00 and Full Flow Test Pump Data Sheets are provided in Attachment 1. The TDEFW pump rotating assembly was last replaced in November of 2000. The post maintenance pump Comprehensive Pump
Document Control Desk Enclosure 1 CR-17-01001 RC-17-0035 Page 4 of 6 Test differential pressure was recorded as 1268 psid at 4174 rpm on March 2, 2001 (STTS #9912841). During RF-22, a differential pressure of 1274 psid was recorded at 4162 rpm on November 2, 2015 during the Comprehensive Test (STTS #1411937).
These test results are essentially identical, indicating no appreciable hydraulic degradation has occurred after fourteen years of service. Review of the 2000 rotating assembly post-maintenance data indicates pump hydraulic performance of this seven stage pump closely follows the manufacturers curve, and as noted above no appreciable degradation has been seen at the Comprehensive Pump Test point.
Machine vibration is and has been low and steady with no real spectral content change since the Predictive Maintenance Program was established. Assuming disassembly finds no conditions requiring rotating assembly replacement, hydraulic characteristics should be comparable to post reassembly.
Pre-Modification Testing A test of the rotational speed (rpm) change will be conducted prior to the station outage RF-23 in accordance with 10CFR50.65a(4) and ISTB-5110 "Preservice Testing" of the ASME OM Code, 2004 Edition with Addenda through 2006. This test collects performance data after manually increasing the speed of Emergency Feedwater Pump Steam Turbine, from the current nominal operating speed of 4150 to 4500 rpm. This test is intended to:
- 1. Verify proper operation of the Terry Turbine Lube Oil System at the operating speed of 4500 rpm.
- 2. Collect Flow Rate and Differential Pressure (dp) Data at a minimum of five points at the speed of 4500 rpm.
- 3. Record Vibration Data for the Pump and Driver at various flow rates to verify ASME OM Code overall vibration velocity caps are not exceeded at the operating speed of 4500 rpm.
- 4. Establish new reference values for dp and vibration at the Comprehensive test flow rates of 670 gpm at the operating speed of 4500 rpm.
- 5. Establish new reference values for dp and vibration for Group B testing at the nominal flow rate of 290 gpm and operating speed of 4500 RPM for use on the modified recirculation lines.
- 6. Collect Flow Rate and Differential Pressure Data (five points) for comparison to vendors Pump Curve and post Rotating Assembly Inservice Test Data to quantify Flydraulic Flead Degradation.
Post Maintenance and Modification Testing of TDEFW Pump The Group B test is scheduled to be performed in Mode 3 after the secondary steam supply pressure is greater than 865 psig. The station proposes to apply a Group B test as specified in Table ISTB-3000-1 and vibration per ISTB-3540. Post Maintenance testing after turbine and pump maintenance is needed in accordance with ISTB-3310. All
Document Control Desk Enclosure 1 CR-17-01001 RC-17-0035 Page 5 of 6 deviations from the reference values shall be compared with the ranges of Table ISTB-5121-1 and corrective action taken as specified in ISTB-6200. Under ISTB-5100(b)(2) "Centrifugal Pumps (Except Vertical Line Shaft Centrifugal Pumps)," a bypass test loop may be used for a Group B test, provided it is designed to meet the pump manufacturer's operating specifications for minimum flow operation. The modified system's addition of a second recirculation line will allow testing the pumps hydraulic capacity at a nominal flowrate of 290 gpm during Group B testing. The hydraulic characteristics should be comparable to the data obtained prior to the outage provided that no rotating assembly replacement is required. Vibration data will also be obtained in accordance with ISTB-3540. The TDEFW pump rotating assembly was last replaced in November of 2000 and historical test results (see Attachment 1) are essentially identical.
Therefore, after fourteen years of service, no appreciable hydraulic degradation has occurred. A projection of pump hydraulic characteristics at 670 gpm will provide reasonable assurance of pump operability and allow the station to safely defer the comprehensive test to Mode 1.
Comprehensive Test The Comprehensive test will be performed per ISTB-5123, "Comprehensive Test Procedure" in Mode 1 at approximately 30% power or within 10 days of entering Mode 3.
Otherwise the action statement of Technical Specification 3.7.1.2 apply:
a) With one emergency feedwater pump inoperable, restore the required emergency feedwater pumps to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in HOT SHUTDOWN within the following 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.
Mode 1 at approximately 30% power will provide the steady state conditions with sufficient core power available to safely perform the test. The comprehensive tests shall be conducted with the pump operating at a specified reference point. The test parameters shown in Table ISTB-3000-1 shall be determined and recorded as required by this paragraph. All deviations from the reference values shall be compared with the ranges of Table ISTB-5121-1 and corrective action taken as specified in ISTB-6200. The vibration measurements shall be compared to both the relative and absolute criteria shown in the alert and required action ranges of Table ISTB-5121-1.
It should be noted that if for some unforeseen reason the station needs to shutdown and cooldown below Mode 3 before completing the comprehensive test, the 10 day period will restart upon reentering mode 3 ascending.
Document Control Desk CR-17-01001 RC-17-0035 Page 6 of 6
- 7. Duration of Proposed Alternative:
The proposed alternative is for the duration of the station's fourth 10 year interval which is effective from January 1, 2014, through and including December 31, 2023.
- 8. Precedents:
None.
- 9.
References:
- 2. NUREG-1482, Rev. 2, Guidelines for Inservice Testing at Nuclear Power Plants
- 3. V.C. Summer Unit 1 FSAR Section 10.4.9 and Figure 10.4-16.
Document Control Desk CR-17-01001 RC-17-0035 Page 1 of 4 VIRGIL C. SUMMER NUCLEAR STATION (VCSNS) UNIT 1 ATTACHMENT 1 Pump Curve and Tests History
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Document Control Desk CR-17-01001 RC-17-0035 Page 3 of 4 Table 1: Full Flow Test Pump Data Circa March 2001
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- 0) 73 o ATTACHMENT III CQ 01 i o PAGE 1 OF 4 0 -vj c i I 3 REVISION 8 o 0 STTS# /*///*?37 O oo 13 00 o on o o XPP0008 Comprehensive Full Flow Pump Test and Valve Data Sheet o 3
DATA RANGES OF 1ST QUANTITIES INSTALLED PLANT TEST QUANTITY INSTRUMENTS MEASURED REFERENCE ACCEPTABLE ALERT RANGE REQUIRED ACTION o
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7T LOW HIGH ID NO. CALDUE Main Steam Line Pressure (PSIG) 1080 2:865 PI-485 Q - FLOW (GPM) W. rto (14.178 to 14.549 mA) 664 - 676 i
N- SPEED(RPM) 4157-4167 £4200 >4200 Pd - Pump Disch Press (PSIG)
I2 1300 Pi - Pump Inlet Press (PSIG)
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- dP - Differential Press (PSID) ' r
XPP0008-7V. (PIV) o.(o ( 0.079 £0.189 >0.189 to 0.455 >0.455 XPP0008 - 8H, (PIH)
OrOCffc 0.088 £0.211 >0.211 to 0.506 >0.506 XPP0008 - 10V. (POV)
- o. 1 0.106 £0.254 >0.254 to 0.610 >0.610 XPP0008 - 11H. (POH)
Ot loz 0.111 £0.266 >0.266 to 0.639 >0.639 XPP0008- 12A, (POA) 0.072 £0.172 >0.172 to 0.414 >0.414 Note 1: Utilize Table 1 (page 4) to determine the minimum acceptable dP for the measured suction pipe temperature of Step 6.1.20.1 to develop a 2910 Ft. (TDH).
Document Control Desk CR-17-01001 RC-17-0035 Page 1 of 1 VIRGIL C. SUMMER NUCLEAR STATION (VCSNS) UNIT 1 ATTACHMENT 2 LIST OF REGULATORY COMMITMENTS There are three regulatory commitments created due to this Relief Request. Any other statements in this submittal are provided for information purposes and are not considered to be regulatory commitments. Please direct questions regarding these commitments to Mr. Bruce L. Thompson at (803) 931-5042.
Commitment Completion Time Perform ISTB-5122, Group B Test Procedure as Group B Test Procedure specified and test parameter values identified in initiated in Mode 3 with the Table ISTB-3000-1. All deviations from the secondary steam supply reference values shall be compared with the ranges pressure greater than 865 psig.
of Table ISTB-5121-1 and corrective action taken All deviations from the reference as specified in ISTB-6200. values addressed under the station corrective action program.
Perform vibration test as specified in ISTB-3540. Vibration test initiated in Mode 3 The vibration measurements shall be compared to with the secondary steam both the relative and absolute criteria shown in the supply pressure being greater alert and required action ranges of Table ISTB- than 865 psig. All deviations 5121-1. from the reference values addressed under the station corrective action program.
The Comprehensive test will be performed as Comprehensive test initiated at specified in ISTB-5123, "Comprehensive Test approximately 30% power or Procedure." All deviations from the reference within 10 days of entering Mode values shall be compared with the ranges of Table 3. All deviations from the ISTB-5121-1 and corrective action taken as reference values addressed specified in ISTB-6200. The vibration under the station corrective measurements shall be compared to both the action program.
relative and absolute criteria shown in the alert and required action ranges of Table ISTB-5121-1.