NRC-23-0031, Response to NRC Request from Audit of License Amendment Request to Revise Technical Specification 3.8.1, AC Sources -Operating,' Emergency Diesel Generator Voltage and Frequency Surveillance Requirements

Response to NRC Request from Audit of License Amendment Request to Revise Technical Specification 3.8.1, AC Sources -Operating,' Emergency Diesel Generator Voltage and Frequency Surveillance Requirements

ML23136A548
Person / Time
Site:	Fermi
Issue date:	05/16/2023
From:	Frank E DTE Electric Company
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
NRC-23-0031
Download: ML23136A548 (1)

Text

DTE Electric Company 6400 N. Dixie Highway, Newport, MI 48166 Tel: 734.586.6515 Email: eric.frank@dteenergy.com DTE May 16, 2023 NRC-23-0031 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555-0001 Fermi 2 Power Plant NRC Docket No. 50-341 NRC License No. NPF-43

Subject:

Response to NRC Request from Audit of License Amendment Request to Revise Technical Specification 3.8.1, "AC Sources-Operating." Emergency Diesel Generator Voltage and Frequency Surveillance Requirements.

References:

1) DTE Electric letter to NRC-"License Amendment Request to Revise Technical Specification 3.8.1, "AC Sources-Operating," Emergency Diesel Generator Voltage and Frequency Surveillance Requirements",

NRC-22-0026, dated December 16, 2022. (ML22350A504)

2) NRC Letter to DTE Electric "Fermi 2-Audit Plan in Support of Review of License Amendment Request to Revise Technical Specification Surveillance Requirements Relating to Emergency Diesel Generator Voltage and Frequency (EPID L-2022-LLA-0188)," dated February 24, 2023. (ML22325A299) )

In Reference 1, DTE Electric Company (DTE) submitted a license amendment request (LAR) to revise Technical Specification 3.8.1, "AC Sources-Operating," Emergency Diesel Generator Voltage and Frequency Surveillance Requirements". The NRC performed an audit in support of review of the LAR, per the audit plan in Reference 2. In an email from Mr. Surinder Arora to Mr. Eric Frank dated April 25, 2023 (ML23115Al 45), the NRC sent DTE a request for specific pages from four DTE design calculations.

RAI-1 (EEEB) requested pages 1, 9, 10, 11, 26 and 29 from DTE's DC-6538 and pages 1, 58, 59, 61 & 62 from DC-6447.

RAI-2 (EMIB) requested pages 1, 22, 26 & 27 from DTE's DC-0182 and pages 1, 16, 19 & 24 from DC-0758.

The requested pages are included in the three enclosures to this letter. provides pages 1, 9, 10, 11, 26 and 29 from DTE's DC-6538. provides pages 1, 58, 59, 61 & 62 from DC-6447 and a DTE verification memo. provides pages 1, 22, 26 & 27 from DC-0182 and pages 1, 16, 19 & 24 from DC-0758.

USNRC NRC-23-0031 Page 2 This letter and enclosures do not contain any proprietary information. The cover page of DTE calculation DC-6447 in Enclosure 2 has a "PROPRIETARY CONFIDENTIAL" stamp but the pages submitted from that calculation have been verified to not contain any proprietary information so that stamp has been lined out. This is verified by DTE memo TMPE-23-0050 which is also included in Enclosure 2.

DTE has reviewed the information supporting a finding of No Significant Hazards Consideration and the Environmental Consideration provided to the NRC in Sections 4.3 and 5.0 of Enclosure 1 of the Reference 1 LAR. The reference information provided in this letter does not affect the bases for concluding that the proposed license amendment does not involve a significant hazards consideration. In addition, the reference information provided in this letter does not affect the bases for concluding that neither an environmental impact statement nor an environmental assessment needs to be prepared in connection with the proposed amendment.

No new commitments are being made in this submittal.

Should you have any questions or require additional information, please contact me at (734) 586-4772.

Sincerely,

{vJk Eric Frank Manager - Nuclear Licensing

Enclosures:

1) Response to RAI-1 (EEEB) requesting pages from DTE's DC-6538.

2) Response to RAI-1 (EEEB) requesting pages from DTE's DC-6447 and related DTE Verification Memo.

3) Response to RAI-2 (EMIB) requesting pages from DTE's DC-0182 and DC-0758.

cc: NRC Project Manager NRC Resident Office Regional Administrator, Region III Michigan Department of Environment, Great Lakes, and Energy

Enclosure 1 to NRC-23-0031 Fermi 2 NRC Docket No. 50-341 Operating License No. NPF-43 Response to RAI-1 (EEEB) requesting pages from DTE's DC-6538 to NRC-23-0031 Page 1 DESIGN CALCULATION COVER SHEET Total P s 130 A) Design Calculation Number DC-6538 B) Volume Number IDCDI C) Revision D) PIS Number E) QALevel A R3000 [] Non-Q [X]l [] IM F) ASME Code Classification [X] NA G) Certification Required [] Yes X No H) Lead Discipline l&C I) Incorporation Code F J) Title EDG Voltage and Frequency Tolerances K) Design Change Documents Incorporated (Number and Revision) None.

L) Design Calculations Superseded (Number and Revision)

DC-6538 Vol I DCD 1, Rev. 0 M) Revision Summary Updated calculation to incorporate New Analytical Limits, revised Technical Specification Allowable Values, and corres ondin as-left and as-found settin s for EDG fre uenc and volta e N) Review of Assumptions, Methods, and Inputs Completed (Step 4.3.2)

D Standard review, completed in revision _ _ _ _ _ __

IS] Key calculation review, completed in revision _ _0"-------

0 NIA (Non-Q)

0) Key Calculation Review Incorporated in revision 0 D NIA, Not a Key Calculation P) PPRNs are required: [X] Yes [] No Issuing DCD MIC WO# 50676140 [] NIA Q) Key Calculation: [X] Yes [] No Justification for Yes or No: Determines EDG frequency and voltage tolerances in support of Tech Spec surveillances.

ISFSI Related: r Yes P No DIC: TPMMES DSN: MES15001 Rev. 9 Pl/1 File: 1703.22 Issued: 1-04-11 DTC: TDPCAS r TDPELE r TDPINC p TDPMEC r DSN: DC 6538 Vol I DCD I Rev: A File: 1801 IP: I to NRC-23-0031 Page 2 DTE Energy- DC-6538 VOL I DCD 1 A Page 9 of 44

, Calculation No. Revision Project No. NIA

2. Purpose & Objectives 2.1 . Purpose The purpose of this calculation is to develop Technical Specification Allowable Values and procedural setting values for the safety-related Emergency Diesel Generator (EDG) frequency and voltage. The values developed in this calculation are based on Analytical Limit values identified in other calculations (References 1.5.1 - 1.5.3).

The Allowable Values (AVs) and settings are developed using instrument error computations based on the methodology in the setpoint methodology guidelines in C1 4180 (Reference 1.4.1).

There are two frequency loops. One frequency loop consists of the EDG governor speed controller and the local frequency meter (FM). The other frequency loop consists of the EDG governor speed controller and the control room frequency meter.

There are two voltage loops. The local voltage loop consists of the EDG voltage regulator, two potential transformers (PTa and PTb) and one voltmeter (VM). The control room voltage loop consists of the EDG voltage regulator one potential transformer (PTa) and one voltmeter.

2.2. Objective The objective of this calculation is to:

• Determine the accuracy of the EDG voltage regulator and governor.

• Determine the readability I accuracy of the Control Room and local Frequency and Voltmeter loops.

• Determine Allowable Values for use in the plant Technical Specifications (References 1.7.1 and 1.7.2)

• Determine As-Left and As-Found values for the EDG surveillances and operating procedures.

to NRC-23-0031 Page 3 DTE Energy- DC-6538 VOL I DCD 1 A Page 10 of 44

, Calculation No. Revision Project No. NIA

3. Conclusion, Summary of Results This calculation develops Technical Specification Allowable Values and procedural setting values for EDG frequency and voltage. The values developed in this calculation are based on Analytical Limits identified in input sections 9.6 and 9.7 and calculation section 10.1. The Allowable Values (AVs) and settings are developed using instrument error computations based on the methodology in the setpoint methodology guidelines in C1 4180 (Reference 1.4.1 ).

3.1.1. EDG Frequency The EDG frequency limits and settings are tabulated below:

Calculation Limit Hz Hz Settin~ Section Alim 60.66 9.6 AV 60.6 10.5.3 60.3 As-found 10.5.3 60.2 As-left 10.5.3 60.0 Nominal 10.5.3 59.8 As-left 10.5.3 59.7 As-found 10.5.3 AV 59.4 10.5.3 AL 59.34 9.6 The proposed range of Allowable Values in Technical Specifications section 3.8.1 is 59.5 - 60.5 Hz.

The recommended as-found range for EDG surveillance and operating procedures is 59.7 - 60.3 Hz.

The recommended as-left range for EDG surveillance and operating procedures is 59.8 - 60.2 Hz.

to NRC-23-0031 Page 4 DTE Energy- DC-6538 VOL I DCD 1 A Page 11 of 44

, Calculation No. Revision Project No. NIA 3.1.2. EDG Voltage Limits and Settings The EDG Voltage limits and settings are tabulated below:

Local Indicators (4160 V base}:

Division Division 1 2 1&2 Calculation Limit V V V Settin~ Section Alim 4314 4400 9.7 AV 4314 4400 10.2 4300 As-found 10.6.5 4225 As-left 10.6.5 4160 Nominal 10.6.5 4100 As-left 10.6.5 4050 As-found 10.6.5 AV 3950 3950 10.2 AL 3903 I 3668 10.1 Control Room Indicators (120 V base}:

Division Division 1 2 1&2 Calculation Limit V V V Settin~ Section Alim 124.5 127.0 10.2 AV 124.5 127.0 10.2 124.0 As-found 10.6.5 122.0 As-left 10.6.5 120.0 Nominal 10.6.5 118.0 As-left 10.6.5 117.0 As-found 10.6.5 AV 114.0 114.0 10.2 AL 112.7 I 105.9 10.1 The range of Allowable Values in Technical Specifications section 3.8.1 is 3950 - 4314 V for Division 1 and 3950 - 4400 V for Division 2.

Local Indicators (4160 V base}:

The recommended as-found range for EDG surveillance and operating procedures is 4050 - 4300 V for both divisions.

The recommended as-left range for EDG surveillance and operating procedures is 4100 - 4225 V for both divisions.

Control Room Indicators (120 V base}:

The recommended as-found range for EDG surveillance and operating procedures is 117.0 - 124.0 V for both divisions.

The recommended as-left range for EDG surveillance and operating procedures is 118.0 - 122.0 V for both divisions.

to NRC-23-0031 Page 5 DTE Energy- DC-6538 VOL I DCD 1 A Page 26 of44

, Calculation No. Revision Project No. NIA 9.6. EDG steady state frequency Alims are identified in DC-6447, DC-0182 , and DC-0758 (References 1.5.1 - 1.5.3). The upper Alim is based on maintaining the EDG loading within the continuous rating of the engine (loading increases as frequency increases). The lower Alim is based on ensuring that ESF pumps maintain the flows necessary to meet the requirements of the accident analyses in the FSAR (pump flow decreases as frequency falls).

Alim Upper= 60.66 Hz (Reference 1.5.1)

Alim Lower= 59.34 Hz (References 1.5.2 & 1.5.3) 9.7. EDG steady state voltage upper Alim is identified in DC-6447 (Reference 1.5.1). The upper Alim is based on maintaining the voltage at ESF motors within the continuous rating of the motors (+10% of nameplate). Division 2 has voltage regulators to control the voltage at the 480 V ESF buses (Reference 1.1.11 ), while Division 1 has a fixed boost to ensure adequate voltage at the ESF buses.

As a result, DC-6447 identifies a separate upper Alim voltage for each division.

Alim Upper Div 1 = 4314 V Alim Upper Div 2 = 4400 The lower Alim for EDG voltage is developed in this calculation based on the minimum ESF bus voltage under maximum EDG loading conditions, worst case voltage drop from the EDGs to the ESF buses, and the ESF bus Alim voltages in section 10.2.6 of DC-6447 (Reference 1.5.1 ).

EDG minimum voltage (both divisions)= 3950 V Minimum ESF Bus Voltage Div 1 = 4299 V ESF Bus Alim = 3873 V t:,,.V Div 1 EDG to ESF Bus= 15 V Minimum ESF Bus Voltage Div 2 = 4385 V ESF Bus Alim Div 2 = 3628 V t:N Div 2 EDG to ESF Bus= 15 V 9.8. The voltmeter scaling on the meter face is 0 to 5000V in 100V minor division for the local meters and 0 to 150V in 2V minor divisions for the control room voltmeters. (Ref. Attachment C).

9.9. The frequency meter scaling on the meter face is 55 Hz to 65 Hz in 0.2 Hz minor divisions for the local and the control room meters (Ref. Attachment C).

9.10. The EDGs #11, #12, #13, #14 are all equipped with a Woodward 2301A/EGB-13P governor per references 1.4.2 and 1.6.3.

9.11. The EDGs #11, #12, #13, #14 are all equipped with a Basler Series-Boost Exciter-Regulator, Model SBSR-HV per references 1.4.2 and 1.6.4.

to NRC-23-0031 Page 6 DTE Energy- DC-6538 VOL I DCD 1 A Page 29 of44

, Calculation No. Revision Project No. N/A

10. Calculations 10.1. Developing EDG Voltage Lower Analytical Limits Division 1:

Using voltages from Input 9.7, the initial estimate of EDG minimum voltage required is:

3873 V + 15 V = 3888 V Difference from voltage used to determine voltage drop in DC-6447 (Input 9.7):

3888 Voltage ti = 1 - ( v) = 0.956 pu, or 9.6% (rounding up), use 10% for conservatism 4299V A 10% drop in voltage will result in a 10% increase in current and therefore voltage drop if the entire load is conservatively treated as constant power. This increases the 15 V drop to 16.5 V. This is conservatively increased to 30 V to provide margin. This results in a Division 1 voltage lower Alim of:

20 3873 V + 30 V = 3903 V, or 3903 V ( ; v )

3 2400 V

= 112.7 Von a 120 V base Division 2:

Using voltages from Input 9.7, the initial estimate of EDG minimum voltage required is:

3628 V + 15 V = 3643 V Difference from voltage used to determine voltage drop in DC-6447 (Input 9.7):

Voltage ti= 1 - (

36~V) 4385V

= 0.169 pu, or 16.9%, use 17% for conservatism.

A 17% drop in voltage will result in a 17% increase in current and therefore voltage drop if the entire load is conservatively treated as constant power. This increases the 15 V drop to 17.6 V. This is conservatively increased to 40 V to provide margin. This results in a Division 2 voltage lower Alim of:

3628 V + 40 V = 3668 V, or 3668 v(~ ov ) = 105.9 Von a 120 V base.

2 3 2400 V 10.2. EDG Voltage Allowable Values The EDG Technical Specification Voltage Upper AV is set equal to the Alim value for each division.

The analytical limits are the EDG voltage that puts the most limiting safety related motor(s) in each division at 110% of rated voltage. Exceeding this voltage can overexcite the motor, leading to overheating and shortened service life. Exceeding the voltage does not result in immediate equipment failure or inability of the equipment to perform its design function during a design basis event. Therefore, it is acceptable to set the Technical Specification Upper AVs at:

20 TS Upper AV for Division 1 = 4314 V, or 4314 v ( ; v )

3 2400 V

= 124.5 v on a 120 V base 20 TS Upper AV for Division 2 = 4400 V, or 4400 v ( ; v )

3 2400 V

= 127.0 v on a 120 V base The EDG Technical Specification Voltage Lower AV is set at 3950 V for both divisions based on the analysis in DC-6447 (Reference 1.5.1)

Enclosure 2 to NRC-23-0031 Fermi 2 NRC Docket No. 50-341 Operating License No. NPF-43 Response to RAI-1 (EEEB) requesting pages from DTE's DC-6447 and Related DTE Verification Memo TMPE-23-0050 to NRC-23-0031 Page 1 DTE Date: May 12, 2023 TMPE-23-0050 0801.26 To: Eric Frank Manager - Licensing From: Anthony Dawes Supervisor, Design-I&C/Electrical

Subject:

Transmittal of DC-6447 VOL I REV F Non-Proprietary and Non-Confidential Information for NRC-23-0031 Please, see Attachment 1 for NRC request for Non-Proprietary DC-6447 VOL I REV F information. Design-I&C/Electrical has reviewed Attachment 1 and verified that the attachment does not contain PROPRIETARY information and does not contain CONFIDENTIAL information.

AJD

Attachment:

1) Response to RAI-1 (EEEB) requesting pages of DC-6447 (Reference NRC-23-0031) cc:

Information and Procedures Sandra McMullin to Attachment 1 to NRC-23-0031 Page 2 f~OflUt!T.MlY TMPE23-0050 Page 1 001 Wt0E1 fFt/tts 5-12-23 Pa e I of 15 067 PART 1: DESIGN CALCULATION IDENTIFICATION A) Design Calculation Number DC-6447 B) Volume Number 1 C) Revision D) PIS Number E) QA Level F ROOOO []Non-Q [X] I [] IM F) ASME Code Classification [X] NA G) Certification Required [] Yes X No H) Lead Discipline Electrical I) Incorporation Code F J) Title Auxiliary Power System Analysis K) Design Change Documents Incorporated (Number and Revision)

See pg 2 for a listing of design change documents incorporated L) Design Calculations Superseded (Number and Revision)

DC-6447 Vol I Rev. E M) Revision Summary See pg. 5.

N) Review of Assumptions, Methods, and Inputs Completed (Step 4.3,2)

D Standard review; completed in revision _ _ _ _ _ __

IZJ Key calculation review, completed in revision _ ____,B=-------

0 NIA (Non-Q)

0) Key Calculation Review Incorporated in revision B D N/A, Not a Key Calculation P) PPRNs are required: [] Yes [X) No Issuing DCD 'T$&.-'3k':f> 02;> * - IA Q) Key Calculation: (X] Yes [] No Justification for Yes or No: Calculation determines electrical system ability to stay connected to the grid during transients per GDC 17, Demonstrates equipment functionality @ Tech. Spec DVR Analytical Limit and EDG loading.

PART 2: PREPARATION, REVIEW, AND APPROVAL A) Prepared By ~ PSE-52 Qualified and additional qualifications per Step 2.3: _ _ D N/A or O Common-33 Qualified for EQRs Print/Si n 8/19/2020 Date B) Checked By ~ PSE-52 Qualified and additional qualifications per Step 2.3: -- N/A or O Common-33 Qualified for EQRs Print/Si 11 Ken Netzel/Gene Paletta , /i/) Date 8/19/2020 C) Verified By Jg) PSE-52 Qualified and add tional qualifications per Step 2.3: _ _ D N/A or O Verification (N'o verification r ~l ired)

Print/Si 1 e o /e D) Design Calculation Utility hus been updated JIYes NIA Approved By Print/Si n Issued 12/18/2020 ISFSI Related: 1 Yes P No DTC: TPMMES DSN: MES15001 Rev. 9 PI/I File: 1703.22 Issued:__._1,;,,le-0"-"4;;,,*lc.,,I_ _ __

DTC: TDPCAS r TDPELE ~ TDPINC r TDPMEC r DSN: DC 6447 Vol I Rev:_E,__ File: 1801 IP: I to Attachment 1 to NRC-23-0031 TMPE23-0050 Page 3 Page 2 D'IE,En l'tlW DC-6447, Vol I F Page 58 of 234 Calculation No. Revision Project No. N/A 3.5.2. Circuit Breakers and Fuses All evaluated circuit breakers and fuses are within their short circuit ratings except for the overdutied devices tabulated below. The short circuit values below represent the maximum value for all evaluated scenarios/configurations.

Interrupting Current Calculated Interrupting SC Amps  %

Breaker rating (kA) (kA) overduty 72C-3B-1B 14 16.575 18.39 (1) 72F-5B-1B 14 18.090 29.22 (1)

(1) MCCs 72C-3B and 72F-5B each have a Bussmann FRS-R 200A current limiting fuse. These fuses will limit a 20kA fault current to 6600A (Ref. 1.2.34 and 1.12.8). Therefore, these breakers are not overdutied.

Recloser J is shown as overdutied in all configurations because no rating information has been entered for the close and latching ratings. No conclusions can be drawn relative to acceptability of its close and latch ratings.

The breakers on non safety related Bus 72W and Bus 72G-W are unknown, therefore no conclusions can be drawn relative to acceptability of these breaker's interrupting rating.

All of the unknown breaker and bus ratings are associated with non safety related equipment. None of the BOP pieces of equipment perform a safety function. The inability to verify adequacy of the ratings has no adverse impact on safety systems as the failure of any of these buses or breakers will not propagate to the safety system. Should the non safety related breakers be unable to interrupt the maximum fault current, there are upstream breakers that are within their ratings which can interrupt the fault current before a portion of the safety related system would be isolated. A fault occurring on a safety related bus will not propagate to the redundant division. A fault is considered a single active failure and no single fault can affect both divisions. Thus, the unfaulted division will remain unaffected and available to mitigate any accident. Upstream safety related breakers are sufficiently rated to interrupt the fault.

3.6. Degraded Voltage Relay Analytical Limit These results are based on an analytical voltage limit of 3873V and 3628V for Div 1 and Div 2 respectively.

3.6.1. All safety related motors have adequate running terminal voltage.

3.6.2. All battery chargers have at least 90% rated voltage.

to Attachment 1 to NRC-23-0031 TMPE23-0050 Page 4 Page 3 D'IE,En l'tlW DC-6447, Vol I F Page 59 of 234 Calculation No. Revision Project No. N/A 3.6.3. All of the safety related MCCs and MPUs have adequate voltage to allow pickup of the various 120V loads except for the following. The component ID provided below describes a specific circuit path for a given device and is identified in references 1.6.6 and 1.6.7.

Division 1 Component MCC/Panel Req'd Voltage Ckt 1 D1100C005A H21P557 127.6 (pickup) 121C SBGT Node Div 1 458.7 (pickup) 122C SBGT Node Div 1 457.4 (pickup)

Division 2 Device MCC/Panel Req'd Voltage D1100C005B H21-P558 127.6 (pickup) 3.6.4. All cables, buses, busducts and transformers evaluated as part of this calculation are within their ratings.

3.6.5. Each safety related motor (plus G3305C003A and B) can be successfully individually started. Loads T41008021 and G1101C002A/B are able to start with cable temperatures elevated to post S8O values.

3.6.6. The MCC voltages during starting of each safety related MOV are shown below. The purpose of this table is to provide input for Calculation DC-6397 (Ref. 1.6.4).

Div 1 Div2 MCC Voltage MCC Voltage PIS Number MCCNo. PIS Number MCCNo.

(%of 480V) (% of 480V)

P4400F613 72B-2A 93.509 B2103F600 72E-5A 95.885 P4400F616 72B-2A 93.513 E1150F004B 72E-5A 95.434 E1150F004A 72B-3A 92.999 E1150F006B 72E-5A 95.527 E1150F006A 72B-3A 92.721 E1150F007B 72E-5A 95.934 E1150F007A 72B-3A 93.433 E1150F024B 72E-5A 93.632 E1150F024A 72B-3A 91 .709 E1150F027B 72E-5A 95.891 E1150F027A 72B-3A 93.392 E1150F028B 72E-5A 94.973 E1150F028A 72B-3A 92.765 E2150F015B 72E-5A 95.676 E2150F015A 72B-3A 93.185 E2150F031B 72E-5A 95.931 E2150F031A 72B-3A 93.426 E2150F036B 72E-5A 95.781 E2150F036A 72B-3A 93.218 G3352F220 72E-5A 95.809 G3352F001 72B-3A 93.092 G5100F601 72E-5A 95.937 G5100F600 72B-3A 93.434 G5100F603 72E-5A 95.93 G5100F602 72B-3A 93.434 G5100F605 72E-5A 95.93 G5100F604 72B-3A 93.434 G5100F607 72E-5A 95.933 G5100F606 72B-3A 93.434 N1100F607 72E-5A 95.512 T4100F601 72B-3A 93.394 N1100F608 72E-5A 95.481 T4803F601 72B-3A 93.112 N1100F609 72E-5A 95.499 T4803F602 72B-3A 93.118 N1100F610 72E-5A 95.491 T4901F601 72B-3A 93.454 T4901F602 72E-5A 95.954 to Attachment 1 to NRC-23-0031 TMPE23-0050 Page 5 Page 4 D'IE,En l'tlW DC-6447, Vol I F Page 61 of 234 Calculation No. Revision Project No. N/A 3.7. Emergency Diesel Generator Loading and Voltage These results are based on LOOP/LOCA and LOOP only plant operation. A +/-1.1 % frequency variation on the diesel is also considered along with a maximum EOG voltage of 4314V for Div 1 and 4400V for Div 2. Above these voltages, safety related motors can potentially be overvoltaged.

CARDs 13-24841 and 16-28585 are tracking the License Amendment Request (LAR) to revise the Technical Specification limits for allowable EOG voltage and frequency. CARD 13-24841 identifies that the applicable Operation's EOG Surveillance and System Operating Procedures have been revised to reflect tighter EOG frequency and voltage tolerances, which are bound by the +/-1.1 %

frequency tolerance and maximum EOG voltage of 4314V and 4400V (for Div 1 and Div 2, respectively) used in this calculation.

These loading values are based on required loads for each scenario split amongst the EDGs on each division in a specific manner. Specifically, the RHR pump used in the T=1 0+ minute scenario is aligned to EOG 11 and 13 for Div 1 and 2 respectively. By inspection, EOG loading will not be able to be maintained within the EOG rating with only 1 Division available if the RHR pump (~1600KW) is aligned to EOG 12 and 14 during the T=10+ time period. EOG load limits are contained in EOG loading procedure 20.300.Offsite to ensure operation is withn limits (Ref. 1.9.32). The diesel loading for LOOP/LOCA is calculated for short term (0 to 10 min) and long term (1 0+ min). Loading on the EDGs for each scenario is shown below.

LOCA Load (0-10 Minutes)

Load Increase Total Total Due to Total EDG EDG Load Rotating Max Freq Loading Rating Margin EDG (kW) Load (kW) (kW) (kW) (kW) (kW) 11 2561 2445 82 2643 3135 492 12 2888 2663 89 2977 3135 158 13 2502 2443 82 2584 3135 551 14 2898 2673 89 2987 3135 148 LOCA Load (10+ Minutes)

Load Increase Total Total Due to Total EDG EDG Load Rotating Max Freq Loading Rating Margin EDG (kW) Load (kW) (kW) (kW) (kW) (kW) 11 2704 2585 86 2790 2850 60 12 1852 1563 52 1904 2850 946 13 2631 2584 86 2717 2850 133 14 1657 1396 47 1704 2850 1146 LOOP Load (No LOCA)

Load Increase Total Total Due to Total EDG EDG Load Rotating Max Freq Loading Rating Margin EDG (kW) Load (kW) (kW) (kW) (kW) (kW) 11 2292 2174 73 2365 2850 485 12 1024 815 27 1051 2850 1799 13 2222 2175 73 2295 2850 555 14 1080 845 28 1108 2850 1742 to Attachment 1 to NRC-23-0031 TMPE23-0050 Page 6 Page 5 D'IE,En l'tlW DC-6447, Vol I F Page 62 of 234 Calculation No. Revision Project No. N/A The Technical Specification minimum allowable EOG voltage results in system bus voltages that are bounded by the degraded voltage relay analytical limit. The maximum allowable EOG voltages that ensure no continuous duty motors are overvoltaged is 4314V and 4400V for the Div 1 and Div 2 EDGs respectively. Acceptability of EOG loading is based on these maximum voltages. The acceptability of the EOG loading is also based on a maximum frequency variation of 1.1 %.

Safety related bus voltages are higher and thus are bounded by the voltage evaluations performed with Bus 64B, 64C, 65E and 65F at the analytical limit.

3.8. Miscellaneous Analyses Plant operations during SBO and Appendix R are analyzed by this calculation.

3.8.1. During SBO and dedicated shutdown plant operations, the CTG 11-1 Gas Turbine does not exceed its 16MW rating. The loading on CTG 11-1 during each of these events is provided below.

CTG 11-1 Rating CTG 11-1 Scenario (kW) Loading (KW) Margin (kW)

SBO 16000 8240 7760 Appendix R 16000 4727 11273 3.8.2. The calculated short circuit currents when fed from CTG-11-1 are within the ratings of all buses and protective devices. Buses 1-2A, 1-2B and 3-4A do not have known bracing ratings, therefore, acceptability of the bracing for these buses is indeterminate. The buswork will have to be inspected prior to energization should these buses experience fault current.

3.9. Degraded Voltage Relay LOCA and non LOCA timer There are a number of loads that may trip protective devices during a LOCA transient concurrent with a degraded bus voltage as identified in the subsections below. The ability of TOLs and induction disc relays to ride through the DVR time delay to allow loads to start once the EDGs are feeding the buses is not presently evaluated as a design requirement within this calculation. CARD 16-26533 addresses this condition and has identified that existing alarms and procedural guidance will direct operators to mitigate lowering ESF bus voltage conditions such that operation within the degraded voltage LOCA time delay window will not occur. Additionally, CARD 16-26533 identifies that detailed evaluation of the potentially nonconforming SSCs, using more accurate methodologies than those presently utilized in the calculation, has shown that the SSCs maintain design functions during a sustained degraded voltage event concurrent with a LOCA. CARD 16-26533 is being used to track enhancements to a future revision to the calculation to show the successful transfer to the EDGs and start of all required loads during concurrent LOCA and degraded voltage conditions as a design requirement.

3.9.1. LOCA Timer The following results are based on scenarios that are considered outside of the design basis of the plant. The switchyard voltages necessary for these scenarios is below the minimum switchyard voltage.

3.9.1.1. A LOCA occurring with safety related 4k bus voltages between the minimum loss of voltage relay setpoint and the DVR maximum reset voltage will result in a transfer to the EDGs within a maximum time period of 7.3 second.

All loads are determined to be capable of withstanding the degraded voltage condition and subsequent restart on the EOG without tripping the over-current protective devices.

Enclosure 3 to NRC-23-0031 Fermi 2 NRC Docket No. 50-341 Operating License No. NPF-43 Response to RAI-2 (EMIB) requesting pages from DTE's DC-0182 and DC-0758 to NRC-23-0031 Page 1 DESIGN CALCULATION COVER SHEET A Desi n Calculation Number DC-0182 C) Revision G D) PIS Number E) QA Level E1156 [] Non- [X] 1 [] lM F) ASME Code Classification [X]NA G) Certification Required [] Yes [X] No H Lead Disci line: Mechanical I Incor oration Code F J) Title RHRSW Mechanical Draft Cooling Towers-Post LOCA Analysis ofUHS K) Design Change Documents Incorporated (Number and Revision)

TSR-34207 rev. 0, TSR-37111 rev. 0, TSR-37163 rev. A, ee1tt-iflttea-0tr' a ~ * ,N. 1-1.,:-*1c.

L) Design Calculations Superseded (Number and Revision)

DC-0182 VOL I Rev. F M) Revision Summary Incorporate changes for GE SC06-0l (CARD 06-20273) to include new case for failed RHR Hx with revised GE torus heat input and increase number of running ECCS pumps for torus heat input, delete bounded sensitivity cases for failed MDCT fans, revise RHRSW, EESW, and DGSW flow rates to more conservative values relative to UHS, update EDG and EECW heat inputs, add technical clarifications, update format for MES 15.

N) Review of Assumptions, Methods, and Inputs Completed (Step 4.3.2)

D Standard review, completed in revision _ _ __

~ Key Calculation Review, completed in revision ~G~--

0 NIA ForNon-Key Calculation Review Incorporated in revision _G_ __

D NIA, Not a Key Calculation

0) PPRNs are required: [] Yes [X No Issuing DCD TSR-36863 rev.0 [] NIA P) Key Calculation: [ x] Yes [] No 1----

Justification for Yes or No: Calculates accident res onse I desi n TION, REVIEW, AND APPRO~

A) Prepared By ~ PSE-52 Qualified and additional qualifications per Step 2.3: _ _

or D Common-33 Qualified for EQRs Print/Si n p,sE~ 10 minutes 1833 hp (note 2) . 6 Qrlupump = 4.666xl0 Btu/h LPCIPump

. 6 0-10 minutes 2150 hp (note 1) [Ref. 7] Q LPClpump = 5 .4 73 X10 Btu/h

> 10 minutes 2150 hp (note 1) . 6 QLPC!pump = 5.473xl0 Btu/h Core Spray Pump

. 6 0-10 minutes 762 hp (note 3) [Ref. 57] Qcspump= 1.940xl0 Btu/h

> 10 minutes 685 hp (note 4)

• 6 Qcspump = l .744 X10 Btu/h

. 5 RHRSWPump 285 hp (note 5) [Ref. 2] Q,.J,rswpump = 7.255x 10 Btu/h

• 4 DGSWPump 35 hp (note 5) [Ref. 2] Qdgswpwnp = 8 .909 X10 Btu/h

• 5 EESWPump 82 hp (note 5) [Ref. 2] Qeeswpump = 2.087X 10 Btu/h

. 5 EECWPump 100 hp (note 5) [Ref.41] Qeecwpump = 2.546x 10 Btu/h MDCT fan 150 bhp (full speed) na

[Reference 52 and CECO]

Notes:

1- LPCI: DC-0367 VOL I (ref. 7), Mode B (two-pump LPCI with 2% overspeed), cases B-3 and B-4 shaft horsepower averages <2200 bhp with 2% EOG overspeed included. Scaled to reduce the overspeed to 1.1 %, this is 2142hp = 2200 ( 1.011/1. 02)"'3, which is rounded to 215 0 bhp. This is conservatively retained at> 10 minutes for pumps remaining in LPCI mode; i.e. no assumed throttling.

2- RHR: DC-0367 VOL I (ref. 7), Mode C-2, D-2, E, or F: pump flow averages approximately 10,000 gpm. Representative case C-6 requires 1833bhp = 1563hp (hydraulic) /83%(efficiency) x (1.011/1.02)"'3.

3- Core Spray, 0-10 minutes: DC-0230 VOL I, (Mode G including 2% overspeed), Case 6, Appendix H-1d, initial runout flow with RPV at 0 psig. Representative pump D requires 782.6 bhp ~ 603.75 hp (hydraulic)/ 77.15% (efficiency). Corrected for 1.1% frequency, 762 bhp =782.6 x (1.011/1.02)"3 4- Core Spray, long term: 23.203 throttles flow to 6350 gpm. Mode Eis based on throttled flow of 6500 gpm/division at nominal speed. DC-0230 VOL I, ref. 57, app. F-2, and using highest pump, E2101C001D): 685 hp ::::'.552.74hp/ 80.86%. This load is manually throttled so frequency is not adjusted.

5- The value cited is representative for all pumps, irrespective of division.

22 to NRC-23-0031 Page 3 RHRSW Mech. Draft Cooling Towers - Heat Load and Water Losses DC-0182 VOL I Revision G 5 .17 Cooling water and service water system metal and water warm-up effects and losses will occur, but are assumed to be zero in this calculation for conservatism.

5.18 The effectiveness of MDCTs depends on both the effective air to water temperature difference, and the ability of the water to evaporate. At higher input process water temperature, both the vapor pressure of the water and the water-air temperature difference are increased, which causes an increase in evaporative and sensible heat transfer. If cooling flow rates to process heat exchangers are increased, a greater amount of heat will tend to be transferred to cooling water, but at a lower cooling water outlet temperature. If flow rates to process loads with fixed heat inputs are increased, the process water temperature will fall even more and temperature difference (water to air) will decrease. Thus (not accounting for potential benefits of greater flow to the load being served), increasing process system flow rates will tend to slightly decrease the effectiveness of the MDCTs, and increase URS throughput and temperature rise rate. For this reason, it is conservative for the UHS design analysis to use full (undegraded) EESW, DGSW, and RHRSW pump flow rates (refer to design inputs 4.7, 4.8, 4.9).

Note: The above discussion relates only to UHS temperature rise and should not be construed to imply that restricting water flow to the UHS (i.e. by plugging spray nozzles) is beneficial. In that case, while entering water may be hotter, the loss of effective spray pattern coverage would impair the overall tower performance characteristics. The magnitude of the impact would depend on the relative position of the clogged nozzles. Thus, no unqualified "upfront" estimate or allowance can be made. Additionally, reduction in service water flow would be adverse to process heat exchanger pe1formance.

Since it is not necessarily intuitive that higher water flow rates are conservative for UHS temperature, the basis is further illustrated with an example using the Marley Cooling tower performance curves included in appendix C, with an exaggerated change in water flow rate for illustrative purposes. Example:

Suppose a cooling tower is operating with full speed fans at Twb=76 °F, with 4450 gpm of return hot water at 130 °F. From the tower perfonnance curve on page C-3, the cold water outlet temperature would be approximately 85.5 °P, for a range of 130 - 85.5 = 44.5°P. If the water flow rate is increased to 6300 gpm, in order to transfer the same amount of heat, the required range would be reduced to approximately 4450/6300 = 31.4 °F. From page C-5 for 6300 gpm, it is found that an inlet hot water temperature of 121 0

P will exit the tower at approximately 89.5 °F (range= 31.5 °F, which is approximately the desired 31.4

°F). However, assuming that the reservoir is at its initial 80 °F, the heat input to the reservoir for the two cases is approximately:

low flow: 4450 gpm x 500 lbm/(hr-gpm) x 1 btu/(lbm-F) x (85.5 - 80) = 12.2 Mbtu/hr high flow: 6300 gpm x 500 lbm/(hr-gpm) x 1 btu/(lbm-P) x (89.4 - 80) = 30.0 Mbtu/hr Clearly the high flow case adds more heat to the reservoir for constant tower heat input and air flow. If the greater flow is realistically allowed to also induce greater MDCT heat input, the effect is even larger.

5.19 EDG frequency effects: In the immediate post accident scenario, power is supplied from 4 EDGs on non-interconnected busses operating at a nominal 60 hz. However, the EDGs are considered operable with a speed variation of up to +/-2% based on Technical Specification 3 .8.1 (ref. 8), but which is restricted to

+/- 1.1 o/o based on DC-6447 VOL I and DC-6538 VOL I (ref. 1, 58). It is possible for some EDGs to operate high, with others low, or all high or all low, making for a large number of combinations and permutations. EDG electrical loads from DC-6447 VOL I (ref. 1) are detailed in appendix F, as are used in the UHS Spreadsheets of appendices I, J, K, and L to determine electrical power dependent EDG heat input to the UHS. The base reference values for EDG loads utilize overfrequency because it is important from an EDG load control standpoint for DC-6447 VOL I. However, the loads are conservatively rounded in appendix F such that frequency consideration simply adds additional margin beyond the apparent load margin.

26 to NRC-23-0031 Page 4 RHRSW Mech. Draft Cooling Towers - Heat Load and Water Losses DC-0182 VOLI Revision G However, the sensitivity of the UHS analysis is such that a qualitative assessment of EDG frequency effects is sufficient relative to other heat loads and MDCT performance. Evaporative cooling tower effectiveness is directly related to the evaporation rate, which in turn is influenced by both water and air flow rates. This is often assessed using chatis based on fixed values of the quantity RL/G. "R" is the tower range (the inlet-outlet temperature difference of the liquid), "L" is the mass flow of inlet liquid, and "G" is the mass flow of dry entering air. With EDG overspeed, both Land G will move approximately

• linearly with EDG speed and in the same direction, thus tending to cancel each other. Due to higher mass flow associated with EDG overs peed, the overall heat removal capacity of the towers will increase at any given temperature difference. However, the benefit would be lessened by the physical limitations of the tower (i.e the fill surface area to mass flow would be less) making the tower slightly less effective at higher flow rates. Additionally, although pump heat loads are small compared to decay heat, at higher EDG speed the pump heat inputs would increase by the speed ratio cubed, and greater torus heat would be transmitted due to increased RHR heat exchanger flow. Thus, the overall effect on RHR reservoir temperature will be ve1y small. (The reverse arguments can be made for an EDG experiencing under-speed.) Considering that the typical nmning EDG variations are considerably smaller than 1.1 %, and it is even less likely for all 4 EDGs to be operating either high or low, it is considered unnecessary to quantitatively address EDG overspeed since it is judged to have an insignificant effect.

5 .20 The maximum amount of time that the initial RHR reservoir inventory must be sufficient without makeup (post-LOCA) is 7 days (reference Sg). It is assumed that within 7 days, alternative and backup sources of water will become available.

5.21 Piping and equipment are kept charged with water (Note: Reference 9 shows that 70,389 gallons of water are required for charging both divisions).

5.22 It is assumed that any heat release effects on torus water temperature during a design basis LOCA (from up to 5% Zirconium water reaction) is addressed in the GE data provided in Appendix B. It is further assumed that this data is acceptable for use in this calculation.

5.23 GE SC/06-01 presents a scenario where both divisions are available, but only one RHR heat exchanger is supplied with RHRSW (represented by case 3). This results in a greater number of ECCS pumps that can continue to run and add pump heat to the torus, but with all torus heat being deposited in only one RHR reservoir. This is contrasted with the typical "worst case" single failure that is considered, i.e. loss on an EDG. In that case, only one division of low pressure ECCS pumps are available for long term cooling (i.e. one RHR pump aligned to torus cooling and 2 Core Spray pumps to provide core inventory). If both EDG divisions are available, the "surplus" ECCS pump division would be operated per procedures. Some of the pumps could be shutdown at operator discretion, but this is scenario (core level) dependent.

Although the surplus pumps (2 Core Spray and 2 LPCI pumps) would not likely be run for the full 100 days LOCA mission time, the termination time for the surplus pumps is arbitrarily chosen herein as 7 days. This corresponds with implementation of UHS makeup at 7 days and is well into the accident recovery period. The 7 day run time for all available Core Spray and RHR/LPCI pumps (except one LPCI shut down pump in the division cooling the torus) is sufficient to demonstrate the effects on the UHS invento1y, as well as to capture peak UHS temperature response which occurs within a few hours.

5.24 NOTUSED 5.25 The cooling tower performance data was used to produce third order discrete least squares fits of the outlet temperature as a function of wet bulb temperature for each of the discrete inlet temperatures. Given an arbitrary set of wet bulb temperatures (i.e., different from those requested from the manufacturer),

performance curves may be constructed in the form of service water outlet temperature for each of the discrete inlet temperatures (80°F, 90°F, 100°F, l 10°F, 120°F, 130°F, 140°F, and 150°F) at each of the other specified operating conditions. Third order fits of cooling tower outlet temperature as a function of inlet temperature for the given wet bulb temperature are then produced for each flow and each fan condition.

Next, second order fits of these third order coefficients as a function of flow for each fan operating condition are obtained. This sequence of fits allows modeling of the cooling tower performance as a 27

Enclosure 3 to NRC-23-0031 Page 5 DESIGN CALCULATION COVER SHEET Pa el of 3 5'1, PART 1: DESIGNCALC,CJLA.TIQNIDENTIFICATION'"

- t-A_)__D_e_si_gn_c_a_1c_u_1a_ti_o_n_N_,u,....m_b_e_r_IX_*_o_7_5_8"_ _-4_B_)__v_o_1u_m_e_N_u_m_be_r__ r_________ ----l

• C) Revision D) PIS Number E) QA Level T'I IOOCtJ'f 1 'llf!Ooe,o<IO IM F) ASME Code Classification .1<3 NA G) Certification Required [] Yes No H) Lead Discipline

• M I) Incorporation Code ed*ni'c F J)

K) Design Change Documents Incorporated (Number and Revision)

A L) Design Calculations Superseded (Number and Revision)

(l,-, '(-b- /b

(,-07)~ . c.

N) Review of Assumptions, Methods, and Inputs Completed (Step 4.3.2)

D Standard review, completed in revision _.:;;...D_ _ __

I&] Key Calculation Review, completed in revision _p____

0 NIA (For Non-Q)

0) Key Calculation Review Incorporated in revision _ _ __

• IKJ NIA, Not a Key Calculation A\

~-------------___;_::.:....,:""Jl--_,,.,,.,,,..__:_::..::,.,"'---,j<!..!!e.u.::c.:="-----"=~--_...,'-"'l!l'-"""'"----------l P) PPRNs are required: [ ] Yes ~ No Issuing DCD TS(l- 37nO [] NIA Q) Key Calculation: 00 Yes [] No Justification for Yes or No: s., .,,. <'d ,.,.., s11N.

A) Prepared By ~ PSE-52 Qualified and additional qualifications per Step 2.3: - - ~ NIA or D Common-33 Qualified for EQRs Print/Sign !S.., Date J - z.~ - I(:,

B) Checked By lJ PSE-52 Quali 1ed and additional qualifications per Step 2.3: ~ NIA or D Common-33 Qualified for EQRs Print/Sign lr,'c. L l\'i Date o}/'Lf/w i C) Verified By E] PSE-52 Qualified and additional quali~cations per Step 2.3: - - ~ NIA or D Verification NIA (]'::lo verification required)

Print/Sign lri'l.t. 61isstr ~ ).J~

• Date 0¥/o{

Not Decommissioning Related

. ISFSI Related: Yes j!J No OTC: TPMMES DSN: MESISOOI Rev. 9 Pl/I File: 1703.22 Issued: 1-04-11 OTC: TDPCAS OSN: fl(-01w ~ll~Rev:_Q_

TDPELE TDPINC File: 1801 IP: I TDPMEC Bl

Enclosure 3 to NRC-23-0031 Page 6 DC-0758 Vol. I Revision D Page 16

• A. Solution to the Hydraulic Model The methodology to solving the overall flow and pressure losses in the chilled water subsystem involves three steps: {1} calculate the head loss between adjacent nodes according to the flow within the line,

{2} compare the head loss between nodal systems, (3) consider the solution is final if the error is acceptable.

Head loss between two adjacent nodes is calculated by adding the line losses with losses from any appurtenance (e.g. heat exchanger). This is converted to psi for convenience.

Pressure losses between various node sets are then considered. For example, the pressure loss between nodes 4 and 9 should be equal to that between nodes 5 and 8 plus the differences between nodes 4 /5 and 8/9.

For each comparison the total percentage difference is calculated. These are summed together for convenience of calculation. A total percentage difference of 0.05% is acceptable and implies each individual node maintains a tighter tolerance than 0.05%. This restriction generally limits the total error to less than 0.01 psi. Based on this constraint an error factor is not required to be added to the result.

B. Pump Curves The original pump curves provided by the vendor are used in DC-0758 Vol. I. To assess pump

• performance the vendor curves are adjusted to include head degradation and the associated power supply is operating below the rated frequency.

1. Standard Degradation To adjust for standard degradation a specific percentage reduction to developed head pressure is applied to the original curves. Pump curves are provided in Attachment 5 for convenience. The specific values associated with degradation are given in Section Vlll.G.

2. Under-frequency To accommodate under-frequency the pump affinity laws associated with impeller speed are applied (Equation 6-42} and is given below:

Nunder-frequency)

Qunder-frequency = QNoinal Speed ( N .

nominal 2

Nunder- frequency)

Hunder-frequency = HNoinalSpeed ( N .

nominal where Q is the flow rate in gpm; H, the pump head in psi (or feet); N, is the speed.

In order to assess the impact of degradation and under-frequency the degradation is applied to the vendor supplied pump curve. Following this the affinity laws are applied to account for reduced speed impacts.

Enclosure 3 to NRC-23-0031 Page 7 DC-0758 Vol. I Revision D Page 19 G. Pump Degradation For Division 1 the allowable percentage is 10% of degradation from the design pump curve and for Division 2 it is 15%.

• Note: These percentages cannot be directly applied to the 1ST baseline pump curves. Minimum required pump head for 1ST is provided in section IV.

H. EDG Under-frequency EDG under-frequency is assumed to reduce the pump speed by 1.1%.

DC-6447 Vol. I (Ref. 40) credits an EDG frequency band of 1.1%. Similarly, DC-6538 Vol. I also credits the tighter band (Ref. 41). Although Technical Specifications maintains a band of 2% CARD 13-24841 (Ref.

42) is tracking an initiative to update Technical Specifications to allow the tighter band.

See also Technical Specification Surveillance Requirement 3.8.1.2, Technical Specification Bases B3.8.1, and CARD 13-24941 (Refs. 13, 14).

I. 1ST Test Equipment Accuracy To accommodate 1ST equipment accuracy a 5 gpm flow adjustment (upwards) (2% of 250gpm per Ref.

65) is applied to the pump curve.

As discharge and suction pressures are individually measured, the accuracy associated with each instrument is assumed to be 0.5% based on Ref. 5. Consistent with general uncertainty analyses, the measurements are assumed to be orthogonal with one another and the root sum of squares is taken.

2 5

• Assuming a full-scale pressure reading of 100 psig this translates into 0.7 psig (=[0.5 x2]°" )

J. 1ST Setup For 1ST, it is assumed that the differential pressure readings are taken at the same elevation. This is based on discussions with the Technicians and 1ST Program Owner.

K. Flow Reduction/Expansion All flow area reductions and expansions were assumed to be abrupt changes. No credit was taken for gradual area changes.

L. Compressor Motor and Oil Cooler Flows and Modeling

1. General Assumption The required flow for the oil cooler and motor are 2 and 12 gpm, respectively (Ref. 43). As the system was design and sized for these required flow rates it is assumed that these are the flows passing through the system. Moreover, temperature modulating valves F382A(B) for the motor and F384A(B) for the oil cooler modulate to maintain specific temperatures associated with the component.

2. Variability Flows in these components may vary slightly. Although the required flow rates discussed above are appropriate, additional conservatism may be included by assessing the observed temperature variability in the components and translating it into an assumed flow rate .

Enclosure 3 to NRC-23-0031 Page 8 DC-0758 Vol. I Revision D Page 24

3. Evaporator

• The pressure drop across the evaporator is given as 23 feet at 235 gpm (Ref. 36) .

4. Vendor Provided Pump Curves Data package T4100C040QO001 (Ref. 38) contains data for the pump curves. Additionally the pump curve is provided by B9-1142 (Ref. 37). These curves are contained in Attachment 5 for convenience.

5. Strainer Differential Pressure (Div. 2-T4100C022/Div. 1-T4100D023)

The strainer coefficient (Cv) is assumed to be 10 based on Attachment 9.

XII. Calculation Details [Microsoft Excel]

Calculation details for the Microsoft Excel spreadsheets are available in Attachments 11 through 15.

A. Design Basis The Design Basis case assumes the worst case scenario to establish a minimum flow across the MER cooler and CCHVAC cold deck. As an extreme, the supporting EDG is assumed to be operating under frequency which in turn reduces pump output. Maximum assumed pump degradation is assumed. The motor and oil cooler are assumed to have maximum flows according to the variability previously discussed. Combination of these items not only shifts (reduction) the pump curve, but also ensures that the minimum cooling flow is achievable under a Design Basis Accident.

B. 1ST

• To establish 1ST testing criteria the pump curves were assumed to be degraded, but the power supply was unaltered. To increase the required differential pressure across the pump it was assumed that the motor and oil cooler were restrictive. Instead of evaluating pump flow at all points within the test band (230-236 gpm) the pressure associated with 230gpm was taken as the limit. Since the test is conducted by varying resistance in the line to produce the associated flow rate, a minimum flow corresponds with the maximum pressure differential generated across the pump.

C. Overspeed (Increased EDG Frequency)

An overspeed case is used to assess NPSHa and assumes that the EDGs are providing a maximum frequency. This case assumes an un-degraded pump curve to maximize flow in the line.

This case also finds the equivalent resistance for the motor and oil cooler which are assumed to be at their nominal values. These resistances are then applied to the sensitivity study.

D. Sensitivity Case This case assesses impacts of variable flow rates of the motor and oil cooler on the design basis case.

XIII. Acceptance Criteria A. NPSH Net positive suction head required for pump operation is nominally 4.5 feet.

• The available suction head is dependent upon the flow velocity and suction tank head and is given by: