CNL-22-043, Response to Request for Additional Information and Confirmation of Information Regarding Application to Modify Watts Bar Nuclear Plant Units 1 and 2 Technical Specification 3.7.8 to Support Shutdown Board.

Response to Request for Additional Information and Confirmation of Information Regarding Application to Modify Watts Bar Nuclear Plant Units 1 and 2 Technical Specification 3.7.8 to Support Shutdown Board.

ML22122A248
Person / Time
Site:	Watts Bar
Issue date:	05/02/2022
From:	Jim Barstow Tennessee Valley Authority
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
CNL-22-043, EPID L-2021-LLA-0174
Download: ML22122A248 (48)

Text

1101 Market Street, Chattanooga, Tennessee 37402

CNL-22-043

May 2, 2022

10 CFR 50.90

ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001

Watts Bar Nuclear Plant, Units 1 and 2 Facility Operating License Nos. NPF-90 and NPF-96 NRC Docket Nos. 50-390 and 391

Subject:

Response to Request for Additional Information and Confirmation of Information Regarding Application to Modify Watts Bar Nuclear Plant Units 1 and 2 Technical Specification 3.7.8 to Support Shutdown Board Cleaning (WBN-TS-19-019) (EPID L-2021-LLA-0174)

References:

1. TVA letter to NRC, CNL-21-062, Application to Modify Watts Bar Nuclear Plant Units 1 and 2 Technical Specification 3.7.8 to Support Shutdown Board Cleaning (WBN-TS-19-019), dated September 29, 2021 (ML21273A046)

2. NRC electronic mail to TVA, Request for Additional Information and Confirmation of Information Related to TVA's Request for Changes to Watts Bar Nuclear Plant, Units 1 and 2, Technical Specification 3.7.8 (EPID L-2021-LLA-0174), dated March 24, 2022 (ML22083A237)

In Reference 1, Tennessee Valley Authority (TVA) submitted a request for an amendment to Facility Operating License Nos. NPF-90 and NPF-96 for the Watts Bar Nuclear Plant (WBN), Units 1 and 2, respectively. The proposed amendment revises WBN Units 1 and 2 Technical Specification (TS) 3.7.8 to support future maintenance on the WBN Units 1 and 2 Shutdown Boards and associated 480 Volt boards and motor control centers on a permanent basis.

In Reference 2, the Nuclear Regulatory Commission (NRC) issued a request for additional information (RAI) and request for confirmation of information (RCI) and requested TVA respond by May 2, 2022.

The enclosure to this submittal provides the TVA response to the RAI and RCI. As noted in the enclosure, the TVA response to STSB RCI-1 requires a change to the proposed TS changes in Reference 1. Accordingly, Attachment 1 to the enclosure provides the existing WBN Units 1 and 2 TS pages marked-up to show the revised proposed change. to the enclosure provides the existing WBN Units 1 and 2 TS page retyped to U.S. Nuclear Regulatory Commission CNL-22-043 Page 2 May 2, 2022

show the revised proposed change. There are no changes to the WBN Units 1 and 2 TS Bases provided in Reference 1. The TS changes in Attachments 1 and 2 to the enclosure supersede those provided in Reference 1. Attachment 3 to the enclosure provides further information in response to RAIs SCPB RAI-1 and SCPB RAI-2.

This letter does not change the no significant hazard considerations or the environmental considerations contained in Reference 1. Additionally, in accordance with 10 CFR 50.91(b)(1), TVA is sending a copy of this letter and the enclosure to the Tennessee Department of Environment and Conservation.

There are no new regulatory commitments associated with this submittal. Please address any questions regarding this request to Stuart L. Rymer, Senior Manager, Fleet Licensing, at slrymer@tva.gov.

I declare under penalty of perjury that the foregoing is true and correct. Executed on the 2nd day of May 2022.

Respectfully, Digitally signed by Rearden, Pamela S Date: 2022.05.02 13:57:58 -04'00' James Barstow Vice President, Nuclear Regulatory Affairs & Support Services

Enclosure:

Response to Request for Additional Information and Confirmation of Information

cc (Enclosure):

NRC Regional Administrator - Region II NRC Senior Resident Inspector - Watts Bar Nuclear Plant NRC Project Manager - Watts Bar Nuclear Plant Director, Division of Radiological Health - Tennessee State Department of Environment and Conservation

Enclosure

Response to Request for Additional Information and Confirmation of Information

NRC Introduction

By letter dated September 29, 2021 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML21273A046), the Tennessee Valley Authority (TVA) submitted a license amendment request (LAR) to the U.S. Nuclear Regulatory Commission (NRC) for the Watts Bar Nuclear Plant (Watts Bar), Units 1 and 2. The proposed amendments would revise Watts Bar, Unit 1 and 2, Technical Specification (TS) 3.7.8, Essential Raw Cooling Water (ERCW) System, by adding a new Condition A to Watts Bar, Unit 1, TS 3.7.8, to permanently extend the allowed Completion Time to restore one ERCW system train to operable status from 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to 7 days, to support maintenance on the Watts Bar, Unit 2, 6.9 kilovolt shutdown boards. The proposed amendments would also revise the bounding temperature for the ultimate heat sink (UHS) in Condition A to less than or equal to 78 degrees Fahrenheit. Additionally, the proposed amendments would add and/or revise the Note, numbering, and wording of the Conditions to specify when the Conditions apply.

Regulatory Bases:

General Design Criterion (GDC) 44, Cooling Water, requires, in part, that the system safety function shall be to transfer heat loads to the ultimate heat sink under normal and accident conditions, and that suitable redundancy in components shall be provided to assure that the system safety function can be accomplished, assuming a single failure.

Section 4.1 of the Enclosure to the LAR indicates that the ERCW system is designed to comply with GDC 44. Sections 3.2.4, 3.2.5, and 3.2.6 of the Enclosure to the LAR provide TVAs thermal and hydraulic analyses to demonstrate that the operation of the ERCW system under the proposed LAR conditions (e.g., revised UHS temperature limit, reduced number of operable ERCW pumps and EDGs, and one unit defueled) will be able to maintain its GDC 44 capabilities to perform its safety function of adequate component cooling capability for a design basis accident under the most limiting single failure.

SCPB RAI-1

In TVAs thermal analyses, Table 8 and Table 9 of the Enclosure to the LAR listed the following design parameters to compare against calculated values to show the margin of the heat removal capability (left column).

Parameter Design Minimum Design Maximum (Current LAR) (Previous LAR)

Btu/hr Btu/hr A/B Train - Component Cooling System 88,764,506 106,183,506 (CCS) Heat Exchanger (HX) Duty Residual Heat Removal HX Duty 54,800,000 54,800,000 Spent Fuel Pool HX Duty 32,420,000 32,420,000 Core Spray System (CSS) HX Duty 87,323,731 81,294,921

The design of the ERCW in the proposed LAR has not been changed since the previous LAR for a similar analysis (ADAMS Accession No. ML19038A483). However, the NRC staff noted that the design values for the CCS HX Duty and CSS HX Duty in the proposed LAR are inconsistent with those data used in the previous LAR (right column, see Table 5 of

CNL-22-043 E1 of 5 Enclosure

). For example, the design value (minimum) for the CSS HX duty for the current LAR is higher than the design value (maximum) for the CSS HX duty for the previous LAR.

Also, the design values (minimum and maximum) for the RHR HX duty and spent fuel pool HX duty are the same.

Provide the following:

a. Explain the above apparent inconsistences

b. Clarify which values (minimum or maximum) should be used for the determination of the margin of the heat removal capability and revise accordingly, if needed, and

c. Identify the source of the design data used for the current LAR.

TVA Response

a. The change from maximum in the current LAR (Reference 1) to minimum in the previous LAR (Reference 2) was a change in terminology only.

The previous LAR used design maximum to signify the maximum duty of each HX during accident conditions. However, comparisons between predicted capability of the HX to remove heat and the required duty should show predicted capability greater than the required duty. Therefore; utilizing design minimum, signifying the minimum heat removal requirement of the HX during an accident, is the more appropriate terminology.

The two uses are functionally equivalent; the maximum HX duty listed in Table 5 of the previous LAR is equivalent to the minimum heat removal requirement listed in Tables 8 and 9 of the current LAR.

Changes in values from the previous LAR are explained in the response to SCPB RAI-2.

b. See response in Part a of this RAI response.

c. The following table identifies the source of the design data used for the current LAR.

Parameter Source of Required Duty Design Data CCS HX Duty Tables 13A and 31 for the limiting accident case of the CCS Load List calculation.

See Attachment 3 to this enclosure for an explanation of the differing values from the current LAR and the previous LAR.

Residual Heat Tables 13A and 31 for the limiting accident case of the CCS Load List Removal (RHR) calculation.

HX Duty Spent Fuel Pool 100-hour full core offload maximum from the Alternate SFP Decay Heat (SFP) HX Duty calculation.

CSS HX Duty Appendix B of the calculation that evaluates the CSS Heat Exchangers for a decrease in ERCW Flow Rate.

See Attachment 3 of this enclosure for an explanation of the differing values from the current LAR (Reference 1) and the previous LAR (Reference 2).

CNL-22-043 E2 of 5 Enclosure

SCPB RAI-2

Section 3.2.4 of the Enclosure to the LAR describes the thermal hydraulic evaluation method developed by TVA to support its request to extend the completion time for restoring one train of ERCW to operable status and to increase the UHS temperature. The methodology of the current analysis is similar to the one developed for the previous LAR (ADAMS Accession No. ML19038A483). Section 3.2.7 of both LARs (current and previous) list the analysis assumptions and conservatisms used in the respective analysis. In addition to the differences as identified in SCPB RAI-1 above, the NRC staff noted some differences in the assumptions and conservatisms. For example, in the current LAR, the flow values determined in the ERCW hydraulic analysis are reduced by 5 percent, whereas in the previous analysis, the flow values were reduced by 10 percent. Also, for the CSS HX model (LAR Section 3.2.6.1), the benchmarked PROTO-HX model for the LOCA analysis assumed 10 percent of the tubes were plugged, whereas in the previous LAR model, 5 percent of the tubes were assumed to be plugged (LAR Section 3.2.5.1).

a. Confirm or clarify whether the methodology developed for the proposed LAR is the same as, or different from, the methodology developed for the previous LAR.

b. Identify all the differences (including, but not limited to the above examples) in the assumptions, methodology, and acceptance criteria.

c. Provide the reasons for any differences.

TVA Response

a. The methodology for the proposed LAR (Reference 1) is the same as the methodology developed for the previous LAR (Reference 2) except for the differences detailed in Attachment 3 to this enclosure.

b. The differences in the assumptions, methodology, and acceptance criteria are described in the response in Attachment 3 to this enclosure regarding Methodology, Assumptions, and Design Input differences.

c. The requested information is described in Attachment 3 to this enclosure.

STSB RCI-1

Regulatory Basis:

Pursuant to 10 CFR 50.36, TSs for operating reactors are required, in part, to include items in the following five specific categories: (1) safety limits, limiting safety system settings, and limiting control settings; (2) limiting conditions for operation; (3) surveillance requirements; (4) design features; and (5) administrative controls.

Issue:

The proposed Condition C states: Required Action and associated Completion Time of Condition A not met.

Proposed Required Action A.2 states Verify UHS temperature is 78° F with a Completion Time of 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />.

CNL-22-043 E3 of 5 Enclosure

Required Action A.1 and A.2 are joined by the logical connector AND. As the proposed TS is currently constructed, if while in Condition A the temperature were to exceed 78° F, Required Action A.2 would not be met, and Condition C would be entered. Therefore, the purpose of the second part of the Completion Time for Required Action A.1 it is not clear to the NRC staff.

Request:

Confirm that this is the intent of the proposed TS.

TVA Response

The proposed change to Condition C of WBN Units 1 and 2 TS 3.7.8 in the Reference 1 LAR was in error. TVA is revising Condition C of Watts Bar Nuclear Plant (WBN), Units 1 and 2 TS 3.7.8 from Required Action and associated Completion Time of Condition A not met. to Required Action A.1 and associated Completion Time not met." Attachment 1 to this enclosure provides the existing WBN Units 1 and 2 TS pages marked-up to show the revised proposed change. Attachment 2 to this enclosure provides the existing WBN Units 1 and 2 TS page retyped to show the revised proposed change. There are no changes to the WBN Unit 1 and Unit 2 TS Bases provided in Reference 1. The TS changes in Attachments 1 and 2 to the enclosure supersede those provided in Reference 1.

In the Reference 3 safety evaluation (SE), WBN Unit 2 TS 3.7.8, Condition C was revised to state Required Action A.1 and associated Completion Time not met. " However, in Reference 1, TVA stated:

WBN Unit 2 TS 3.7.8, Condition C is revised to change Required Action A.1 and associated Completion Time not met, to Required Action and associated Completion Time of Condition A not met. This is an administrative change to reflect that Condition C applies to both Required Actions A.1 and A.2.

A similar change was also made to WBN Unit 1 TS 3.7.8, Condition C. If Action A.2 of WBN Units 1 and 2 TS 3.7.8 (i.e., verify UHS temperature is less than or equal to 78°Fahrenheit (F) within one hour and once every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> thereafter) is not met then the affected unit enters Action A.1 of WBN Units 1 and 2 TS 3.7.8, which requires restoration of an ERCW train to Operable status within seven days and 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> from discovery of Condition A entry greater than or equal to 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> concurrent with UHS temperature greater than 78°F. This logic is consistent with Section 2.3 of Reference 1, which states:

If UHS temperature exceeds 78ºF after 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> of continuous ERCW train inoperability, then the specified conditions for crediting the availability of the inoperable ERCW train are no longer met and action must be taken to restore the ERCW train to an operable status within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. Otherwise, the unit must enter WBN Unit 2 TS 3.7.8, Condition C, which requires the unit to be in Mode 3 within six hours and Mode 5 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. If UHS temperature is discovered to be > 78º F, prior to 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> of continuous operation in Condition A, then the 24-hour Completion Time to restore the inoperable ERCW train to operable status starts after 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> of continuous operation in Condition A. However, the proposed change to WBN Unit 2 TS 3.7.8 does not allow continued operation in Condition A for greater than seven days.

CNL-22-043 E4 of 5 Enclosure

As noted in Reference 4, the above logic is similar to WBN Units 1 and 2 TS 3.8.1, Condition B for the extended allowed outage time allowed for an inoperable diesel generator that also relies on the availability of a compensatory measure. Specifically.

the Completion Time for WBN Units 1 and 2 TS 3.8.1, Required Action B.5 allows 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> from discovery of unavailability of 6.9 kV FLEX DG AND 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> from discovery of Condition B entry 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> concurrent with unavailability of 6.9 kV FLEX DG.

References

1. TVA letter to NRC, CNL-21-062, Application to Modify Watts Bar Nuclear Plant Units 1 and 2 Technical Specification 3.7.8 to Support Shutdown Board Cleaning (WBN-TS-19-019), dated September 29, 2021 (ML21273A046)

2. TVA letter to NRC, CNL-19-014, Application to Modify Watts Bar Nuclear Plant Unit 2 Technical Specifications 3.7.8 to Extend the Completion Time for an Inoperable Essential Raw Cooling Water Train on a One-Time Basis (WBN-TS-18-07), dated February 7, 2019 (ML19038A483)

3. NRC letter to TVA, Watts Bar Nuclear Plant, Unit 2-Issuance of Amendment No. 35 Regarding One-Time Extension of Completion Time for Technical Specification 3.7.8 for Inoperable Essential Raw Cooling Water Train (EPID L-2019-LLA-0020), dated February 24, 2020 (ML20024F835)

4. TVA letter to NRC, CNL-19-124, Response to Request for Additional Information to Application to Modify Watts Bar Nuclear Plant Unit 2 Technical Specifications 3.7.8 to Extend the Completion Time for an Inoperable Essential Raw Cooling Water Train on a One-Time Basis (WBN-TS-18-07) (EPID L-2019-LLA-0020), dated January 13, 2020 (ML20014D230)

CNL-22-043 E5 of 5 Enclosure

Attachment 1

Revised Proposed TS Changes (Mark ups) for WBN Units 1 and 2

CNL-22-043 ERCW 3.7.8

3.7 PLANT SYSTEMS

3.7.8 Essential Raw Cooling Water (ERCW) System

LCO 3.7.8 Two ERCW trains shall be OPERABLE.

APPLICABILITY: MODES 1, 2, 3, and 4.

ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME

---

NOTES ------------------- A.1 ------------------NOTES ------------

1. Only applicable when Unit 2 is 1. Enter applicable defueled. Conditions and Required Actions of

2. Only applicable during planned LCO 3.8.1, "AC maintenance of a Unit 2 6.9kV Sources-Operating,"

shutdown board and the for diesel generator associated 480V boards and made inoperable by motor control centers. ERCW.

2. Enter applicable A. One ERCW train Conditions and inoperable. Required Actions of LCO 3.4.6, "RCS Loops-MODE 4," for residual heat removal loops made inoperable by ERCW.

Restore ERCW train to 7 days OPERABL E status.

AND

24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> from discovery of Condition A entry 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> concurrent with UHS AND temperature > 78°F.

(continued)

Watts Bar-Unit 1 3.7-19 Amendment 69,

ERCW 3.7.8

ACTIONS (continued)

CONDITION REQUIRED ACTION COMPLETION TIME

A. (continued) A.2 Verify UHS temperature is1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> 78°F.

AND

Once every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> thereafter.

AB. One ERCW train AB.1 ------------------NOTES ------------

inoperable for reasons 1. Enter applicable other than Condition A, Conditions and other than for Condition C. Required Actions of LCO 3.8.1, "AC Sources-Operating,"

for emergency diesel generator made inoperable by ERCW.

2. Enter applicable Conditions and Required Actions of LCO 3.4.6, "RCS Loops-MODE 4," for residual heat removal loops made inoperable by ERCW.

Res tore ERCW train 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> OPERABL E status.

BC. Required Action A.1 and BC.1 Be in MODE 3. 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> associated Completion Time not met. AND

OR BC.2 Be in MODE 5. 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />

Required Action and associated Completion Time of Condition B not met.

Watts Bar-Unit 1 3.7-20 Amendment 69, 132, 135, ERCW 3.7.8

SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY

SR 3.7.8.1 -----------------------------NOTE -----------------------------

Isolation of ERCW flow to individual components does not render the ERCW inoperable.

Verify each ERCW manual, power operated, and In accordance with automatic valve in the flow path servicing safety the Surveillance related equipment, that is not locked, sealed, or Frequency Control otherwise secured in position, is in the correct Program position.

SR 3.7.8.2 Verify each ERCW automatic valve in the flow path In accordance with that is not locked, sealed, or otherwise secured in the Surveillance position, actuates to the correct position on an actual Frequency Control or simulated actuation signal. Program

SR 3.7.8.3 Verify each ERCW pump starts automatically on an In accordance with actual or simulated actuation signal. the Surveillance Frequency Control Program

Watts Bar-Unit 1 3.7-2 0a Amendment132, ERCW 3.7.8

3.7 PLANT SYSTEMS

3.7.8 Essential Raw Cooling Water (ERCW) System

LCO 3.7.8 Two ERCW trains shall be OPERABLE.

APPLICABILITY: MODES 1, 2, 3, and 4.

ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME

---

NOTES ---------------- A.1 ------------NOTE S-----------

1. Only applicable during the 1. Enter applicable Unit 1 spring 2020 outage Conditions and (U1R16), but no later than Required Actions of May 31, 2020. LCO 3.8.1, "AC

2. Only applicable when Unit Sources - Operating,"

1 is defueled. for diesel generator made inoperable by

32. Only applicable during ERCW.

planned maintenance of a 2. Enter applicable Unit 1 n 6.9 kV shutdown Conditions and board and the 1 A-A Required Actions of and associated 480 V LCO 3.4.6, "RCS boards and motor control Loops - MODE 4," for centers. residual heat removal

---

loops made inoperable by ERCW.

A. One ERCW train ----------------------------------

inoperable.

Restore ERCW train to 7 days OPERABLE status.

AND

24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> from discovery of Condition A entry 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> concurrent with UHS temperature > 718 °F AND (continued)

Watts Bar - Unit 2 3.7-18 Amendment 35,

ERCW 3.7.8

ACTIONS (continued)

CONDITION REQUIRED ACTION COMPLETION TIME

A. (continued) A.2 Verify UHS temperature 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> is 718° F.

AND

Once every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> thereafter

B. One ERCW train B.1 -----------NOTES -------------

inoperable for reasons 1. Enter applicable other than Condition A. Conditions and Required Actions of LCO 3.8.1, "AC Sources-Operating,"

for diesel generator made inoperable by ERCW.

2. Enter applicable Conditions and Required Actions of LCO 3.4.6, "RCS Loops-MODE 4," for residual heat removal loops made inoperable by ERCW.

Restore ERCW train to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> OEPRABLE status.

C. Required Action A.1 and C.1 Be in MODE 3. 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> associated Completion Time not met. AND

OR C.2 Be in MODE 5. 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />

Required Action and associated Completion Time of Condition B not met.

Watts Bar - Unit 2 3.7-18a Amendment 35,

Enclosure

Attachment 2

Revised Proposed TS Change (Final Typed) for WBN Units 1 and 2

CNL-22-043 ERCW 3.7.8

3.7 PLANT SYSTEMS

3.7.8 Essential Raw Cooling Water (ERCW) System

LCO 3.7.8 Two ERCW trains shall be OPERABLE.

APPLICABILITY: MODES 1, 2, 3, and 4.

ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME

---

NOTES ------------------- A.1 ------------------NOTES ------------

1. Only applicable when Unit 2 is 1. Enter applicable defueled. Conditions and Required Actions of

2. Only applicable during planned LCO 3.8.1, "AC maintenance of a Unit 2 6.9kV Sources-Operating,"

shutdown board and the for diesel generator associated 480V boards and made inoperable by motor control centers. ERCW.

2. Enter applicable A. One ERCW train Conditions and inoperable. Required Actions of LCO 3.4.6, "RCS Loops-MODE 4," for residual heat removal loops made inoperable by ERCW.

Restore ERCW train to 7 days OPERABL E status.

AND

24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> from discovery of Condition A entry 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> concurrent with UHS AND temperature > 78°F.

(continued)

Watts Bar-Unit 1 3.7-19 Amendment 69,

ERCW 3.7.8

ACTIONS (continued)

CONDITION REQUIRED ACTION COMPLETION TIME

A. (continued) A.2 Verify UHS temperature is 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> 78°F.

AND

Once every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> thereafter.

B. One ERCW train B.1 ------------------NOTES ------------

inoperable for reasons 1. Enter applicable other than Condition A. Conditions and Required Actions of LCO 3.8.1, "AC Sources-Operating,"

for emergency diesel generator made inoperable by ERCW.

2. Enter applicable Conditions and Required Actions of LCO 3.4.6, "RCS Loops-MODE 4," for residual heat removal loops made inoperable by ERCW.

Restore ERCW train 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> OPERABL E status.

C. Required Action A.1 and C.1 Be in MODE 3. 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> associated Completion Time not met. AND

OR C.2 Be in MODE 5. 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />

Required Action and associated Completion Time of Condition B not met.

Watts Bar-Unit 1 3.7-20 Amendment 69, 132, 135,

ERCW 3.7.8

SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY

SR 3.7.8.1 -----------------------------NOTE -----------------------------

Isolation of ERCW flow to individual components does not render the ERCW inoperable.

Verify each ERCW manual, power operated, and In accordance with automatic valve in the flow path servicing safety the Surveillance related equipment, that is not locked, sealed, or Frequency Control otherwise secured in position, is in the correct Program position.

SR 3.7.8.2 Verify each ERCW automatic valve in the flow path In accordance with that is not locked, sealed, or otherwise secured in the Surveillance position, actuates to the correct position on an actual Frequency Control or simulated actuation signal. Program

SR 3.7.8.3 Verify each ERCW pump starts automatically on an In accordance with actual or simulated actuation signal. the Surveillance Frequency Control Program

Watts Bar-Unit 1 3.7-20a Amendment132,

ERCW 3.7.8

3.7 PLANT SYSTEMS

3.7.8 Essential Raw Cooling Water (ERCW) System

LCO 3.7.8 Two ERCW trains shall be OPERABLE.

APPLICABILITY: MODES 1, 2, 3, and 4.

ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME

---

NOTES ---------------- A.1 ------------NOTE S-----------

1. Only applicable when Unit 1 1. Enter applicable is defueled. Conditions and Required Actions of

2. Only applicable during LCO 3.8.1, "AC planned maintenance of a Sources - Operating,"

Unit 1 6.9 kV shutdown for diesel generator board and the associated made inoperable by 480 V boards and motor ERCW.

control centers. 2. Enter applicable

---

Conditions and Required Actions of A. One ERCW train LCO 3.4.6, "RCS inoperable. Loops - MODE 4," for residual heat removal loops made inoperable by ERCW.

Restore ERCW train to 7 days OPERABLE status.

AND

24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> from discovery of Condition A entry 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> concurrent with UHS temperature > 78 °F AND (continued)

Watts Bar - Unit 2 3.7-18 Amendment 35,

ERCW 3.7.8

ACTIONS (continued)

CONDITION REQUIRED ACTION COMPLETION TIME

A. (continued) A.2 Verify UHS temperature 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> is 78° F.

AND

Once every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> thereafter

B. One ERCW train B.1 -----------NOTES -------------

inoperable for reasons 1. Enter applicable other than Condition A. Conditions and Required Actions of LCO 3.8.1, "AC Sources-Operating,"

for diesel generator made inoperable by ERCW.

2. Enter applicable Conditions and Required Actions of LCO 3.4.6, "RCS Loops-MODE 4," for residual heat removal loops made inoperable by ERCW.

Restore ERCW train to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> OEPRABLE status.

C. Required Action A.1 and C.1 Be in MODE 3. 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> associated Completion Time not met. AND

OR C.2 Be in MODE 5. 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />

Required Action and associated Completion Time of Condition B not met.

Watts Bar - Unit 2 3.7-18a Amendment 35,

Enclosure Attachment 3 Response to SCPB RAI-2

METHODOLOGY

The methodology applied in the proposed license amendment request (LAR) (Reference 1) analysis is essentially the same as that applied in the previous LAR (Reference 2).

Assumptions and design inputs are compared in the table below and differences are explained. The significant differences are as follows.

1. The current LAR analysis credits the Essential Raw Cooling Water (ERCW) system modifications, which replaced and relocated the discharge valve from the component cooling system (CCS) heat exchanger (HX) C (0-FCV-67-152), cross-ties the CCS HX ERCW discharge header by opening existing valves, and rebalances ERCW header flow.

These alignment changes modify ERCW hydraulic performance.

2. Margins added to individual design inputs/outputs were removed or minimized to eliminate stacking of margins and provide a more realistic prediction of available ERCW cooling water flow rates and maximum allowable ERCW temperature. The most significant example is the reduction of the predicted ERCW flows by five percent (%)

rather than 10%, as was applied in the previous LAR analysis method. Other examples are provided in Tables 1 and 2.

Margin was removed to gain a larger range of acceptable ERCW temperatures for the permanent two-season LAR (note the resultant increase in acceptable maximum ultimate heat sink (UHS) temperature from 71° F to 78° F to support autumn river temperatures).

It was also considered that this approach allows a more accurate assessment of margin by design engineering and the regulator, since margin can be analyzed by examining only the conclusions of the analysis rather than considering both the conclusions and any subsidiary supporting margins.

3. The thermal performance calculations for each heat exchanger and heating, ventilation, and air conditioning (HVAC cooler were revised to incorporate curves of thermal performance as a function of ERCW flow rate and temperature rather than executing the models within the SDBD Cleaning calculation. This was done to incorporate station configuration changes and to ensure future revisions to these calculations are evaluated for impact to the LAR analysis. These analyses use the same methods and inputs as those in the previous LAR, with exceptions noted in the tables below.

References

1. TVA letter to NRC, CNL-21-062, Application to Modify Watts Bar Nuclear Plant Units 1 and 2 Technical Specification 3.7.8 to Support Shutdown Board Cleaning (WBN-TS-19-019), dated September 29, 2021 (ML21273A046)

2. TVA letter to NRC, CNL-19-014, Application to Modify Watts Bar Nuclear Plant Unit 2 Technical Specifications 3.7.8 to Extend the Completion Time for an Inoperable Essential Raw Cooling Water Train on a One-Time Basis (WBN-TS-18-07), dated February 7, 2019 (ML19038A483)

CNL-22-043 Encl A3-1 of 29 Enclosure Attachment 3 Response to SCPB RAI-2

Table 1 Analysis Assumptions

Previous LAR Current LAR Difference Basis

5.1 Minimum ERCW pump 5.1 Minimum ERCW pump None performance is assumed by performance is assumed by specifying a lower bounding head specifying a lower bounding head versus flow curve relative to the versus flow curve relative to the vendor pump curves. vendor pump curves.

Technical Justification: This Technical Justification: This ensures that the actual ERCW ensures that the actual ERCW flow rates supplied in this unlikely flow rates supplied in this unlikely accident scenario will accident scenario will conservatively exceed the conservatively exceed the analysis predicted flow rates. analysis predicted flow rates.

CNL-22-043 Enc A3-2 of 29 Enclosure Attachment 3 Response to SCPB RAI-2

Table 1 Analysis Assumptions

Previous LAR Current LAR Difference Basis

5.2 The flow values determined in the 5.2 The flow values determined in the Predicted ERCW flow The additional ERCW hydraulic analysis are ERCW hydraulic analysis are rates are reduced by margin from the reduced by ten percent to account reduced by five percent to account 5% instead of 10% 10% reduction is for the measurement and analysis for analysis uncertainties. deemed overly uncertainties. conservative Technical Justification: This considering the Technical Justification: This reasonably bounds the minimum ERCW reasonably bounds the uncertainties associated with pump performance uncertainties associated with baseline model development and curve applied in baseline model development and testing. both analyses testing. under Assumption 5.1.

This allows the margin to be retained in the proposed technical specification (TS) temperature limit versus potentially narrowing the gap between the proposed limit and the actual UHS temperature expected during the spring and fall outages.

CNL-22-043 Enc A3-3 of 29 Enclosure Attachment 3 Response to SCPB RAI-2

Table 1 Analysis Assumptions

Previous LAR Current LAR Difference Basis

5.3 Maximum heat transfer to the 5.3 Maximum heat transfer to the None CCS is assumed in order to CCS is assumed in order to maximize the CCS heat maximize the CCS heat exchanger ERCW outlet exchanger ERCW outlet temperature. This is temperature. This is accomplished by specifying zero accomplished by specifying zero fouling inside and outside of the fouling inside and outside of the heat exchanger tubes and zero heat exchanger tubes and zero plugged tubes in the respective plugged tubes in the respective PROTO-HX models. PROTO-HX models.

Technical Justification: This Technical Justification: This maximizes the ERCW heat load, maximizes the ERCW heat load, which is conservative with respect which is conservative with respect to the objective. to the objective.

5.4 The ERCW system B-train fails in 5.4 The emergency power train failure None Generalized to its entirety. is assumed to apply to both units dual-unit LAR.

such that no credit is taken for the Technical Justification: No shutdown unit associated credit is taken for the Unit 1 equipment even though the B-train equipment even though the shutdown unit diesel generator Unit 1 B-train diesel generator and and SDBD are likely to be SDBD are likely to be available. available.

This is a conservative assumption which maximizes the demand on Technical Justification: This is the A-train of ERCW. a conservative assumption which maximizes the demand on the available train of ERCW.

CNL-22-043 Enc A3-4 of 29 Enclosure Attachment 3 Response to SCPB RAI-2

Table 1 Analysis Assumptions

Previous LAR Current LAR Difference Basis

5.5 The 1A-A 6.9kV Shutdown Board 5.5 The respective 6.9kV SDBD is not None Generalized to is not removed from service until removed from service until the dual-unit LAR.

WBN Unit 1 is in a refueling shutdown unit is in a refueling outage, with the fuel removed. outage, with the fuel removed.

Technical Justification: This is Technical Justification: This is stipulated as a limiting condition stipulated as a limiting condition for operation in the subject LAR for operation in the subject LAR system alignment. system alignment.

CNL-22-043 Enc A3-5 of 29 Enclosure Attachment 3 Response to SCPB RAI-2

Table 1 Analysis Assumptions

Previous LAR Current LAR Difference Basis

5.6 The spent fuel pool (SFP) heat 5.6 The SFP heat load is maximized The previous LAR The previous LAR load is maximized by assuming by assuming that the full core applied a CCS HX value incorporated that the full core offload for the offload for the refueling unit occurs duty acceptance a beyond design refueling unit occurs at 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> at 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> after shutdown. This criterion of basis SFP load of after shutdown. This is is conservative because the 106,183,506 BTU/hr 50,215,000 conservative because the earliest earliest time defueling can begin versus the current BTU/hr deemed time defueling can begin per WBN per TS 3.9.10 is 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br />, and LAR value of overly Units 1 and 2 TS 3.9.10, Decay the SDBD outage cannot begin 88,764,506 BTU/hr. conservative. The Time, is 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br />, and the 1A-A until the full core has been design basis SFP 6.9kV SDBD outage cannot begin offloaded per the LAR. Therefore, heat load of until the full core has been the outage on the 6.9kV SDBD 32,420,000 offloaded per the LAR. Therefore, selected for maintenance does not BTU/hr plus the the outage on the 1A-A 6.9kV begin until the unit has been shut shutdown unit seal SDBD selected for maintenance down for at least 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br />. water HX duty of does not begin until WBN Unit 1 376,000 BTU/hr has been shut down for at least Technical Justification: This is are applied in the 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br />. stipulated as a limiting condition current LAR.

for operation in the subject LAR Technical Justification: This is system alignment and is stipulated as a limiting condition consistent with the TVA Alternate for operation in the subject LAR SFP Decay Heat Analysis.

system alignment and is consistent with the TVA Alternate SFP Decay Heat Analysis.

CNL-22-043 Enc A3-6 of 29 Enclosure Attachment 3 Response to SCPB RAI-2

Table 1 Analysis Assumptions

Previous LAR Current LAR Difference Basis

5.7 It is assumed that all Unit 1, 5.7 It is assumed that all shutdown None Generalized to non-essential cooling loads are unit, non-essential cooling loads dual-unit LAR.

isolated prior to and in preparation supplied by the train in service for removal of the SDBD from post loss of offsite service. power (LOOP)/loss of train (LOT) are isolated prior to and in Technical Justification: This is preparation for removal of the stipulated as a limiting condition SDBD from service.

for operation in the subject LAR system alignment. Technical Justification: This is stipulated as a limiting condition for operation in the subject LAR system alignment.

CNL-22-043 Enc A3-7 of 29 Enclosure Attachment 3 Response to SCPB RAI-2

Table 1 Analysis Assumptions

Previous LAR Current LAR Difference Basis

5.8 It is assumed that the SFP is 5.8 It is assumed that the SFP is Loss of spent fuel No credit was and initially at the maximum normal initially at the maximum pool cooling and pool taken for SFP 5.9 temperature of 127 degrees temperature of 159.24 F. heat-up from the heat-up from Fahrenheit (F). maximum normal 127 F to 159.24 F Technical Justification: This operation temperature in either analysis.

Technical Justification: This temperature is consistent with the of 127F is not maximizes the heat load on the maximum allowable SFP heat postulated in the CCS and ERCW system and load which established this as the current analysis.

minimizes the time for SFP design maximum SFP heat-up and approach to boiling. temperature from the TVA Alternate SFP Decay Heat It is assumed that the SFP heats Analysis.

up following initial loss of cooling to a temperature less than or equal to 159.24F.

Technical Justification: As the SFP temperature increases, the heat transfer to the CCS increases until the SFP decay load is matched. This temperature is the design maximum SFP temperature from the Tennessee Valley Authority (TVA) Alternate SFP Decay Heat Analysis.

CNL-22-043 Enc A3-8 of 29 Enclosure Attachment 3 Response to SCPB RAI-2

Table 1 Analysis Assumptions

Previous LAR Current LAR Difference Basis

N/A It is assumed that the ERCW 5.9 It is assumed that the ERCW ERCW temperature Provides a more water temperature is 85F for this water temperature is 70 F for this for hydraulic analysis conservative hydraulic analysis. hydraulic analysis. reduced by 15F. prediction of delivered flow Technical Justification: The Technical Justification: The rates and is not base case models set this base case models set this applied in the heat temperature at the UHS maximum temperature at the UHS maximum transfer analyses.

of 85 F. of 85 F. Specifying 70F for This temperature this analysis conservatively reduction accounts increases the water density for a minor and hydraulic resistance, increase in the consistent with expected results in hydraulic the 70 F to 80 F range. resistance on the order of 0.2%.

5.10 For the 1A-A SDBD maintenance, N/A N/A None This assumption is it is assumed that SFP cooling will specific to the be transferred from the A SFP HX 1A-A SDBD to the B SFP HX. cleaning scenario.

(Similar alignments are However, this is Technical Justification: For this implemented for each SDBD generalized to the scenario, only one CCS pump cleaning scenario as required and dual-unit LAR by supplying the Unit 2 A CCS train is explained in detail in the analysis). evaluating similar available due to loss of the alignments for redundant power supplies to the each additional C-S CCS pump (LOT B and loss case in the current of the 1A-A SDBD). LAR.

CNL-22-043 Enc A3-9 of 29 Enclosure Attachment 3 Response to SCPB RAI-2

Table 1 Analysis Assumptions

Previous LAR Current LAR Difference Basis

5.11 It is assumed that ERCW flow to 5.10 It is assumed that ERCW flow to The current LAR The current LAR the Auxiliary Feedwater (AFW) is the AFW is isolated for this assumption did not analysis also isolated for this analysis. analysis. specifically address provides more the potential impact to than adequate Technical Justification: This is Technical Justification: This is AFW pump available suction head for conservative, as the AFW pumps conservative, as the AFW pumps net positive suction the AFW pumps take suction from the ERCW take suction from the ERCW head. based on the discharge headers. Flow to the discharge headers. Flow to the discharge header AFW pumps would reduce the AFW pumps would reduce the flow rate and ERCW discharge flow and the ERCW discharge flow and the elevation relative backpressure in the discharge backpressure in the discharge to the AFW pumps headers, resulting in higher headers, resulting in higher suction.

available flow rates to all users of available flow rates to all users of ERCW. Also, the ERCW ERCW.

discharge header flow rate and elevation (730-6) relative to the AFW pump elevation (715-1) are such that more than adequate suction head and flow is available to supply the AFW pumps.

CNL-22-043 Enc A3-10 of 29 Enclosure Attachment 3 Response to SCPB RAI-2

Table 1 Analysis Assumptions

Previous LAR Current LAR Difference Basis

5.12 The SFP heat load, for analysis 5.11 The SFP heat load, for analysis None purposes, is conservatively purposes, is conservatively assumed to be the design basis assumed to be the design basis 100 hour0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> full core offload 100 hour0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> full core offload maximum of 32.42 MBtu/hr listed maximum consistent with the in Table 7.2 of the Alternate SFP predicted CCS temperature in Decay Heat Analysis. Because Table 7.2 of the Alternate SFP the 1A-A 6.9 kV SDBD outage Decay Heat Analysis. Because cannot begin, due to LAR the 6.9 kV SDBD outage cannot restrictions, until the full core begin, due to analysis restrictions, offload is complete, the actual fuel until the full core offload is pool total heat load will be less complete, the actual fuel pool total due to the additional time, not heat load will be less due to the considered herein, and required to additional time, not considered offload the core (approximately 40 herein, and required to offload the hours). core (approximately 40 hours4.62963e-4 days <br />0.0111 hours <br />6.613757e-5 weeks <br />1.522e-5 months <br />).

Technical Justification: This is the SFP heat load used to establish Technical Justification: This is the the design maximum pool SFP heat load used to establish temperature of 159.24 F. This the design maximum pool heat load is applied as the temperature of 159.24 F. This minimum acceptance criterion to heat load is applied as the which the predicted SFP HX duty minimum acceptance criterion to under the LAR conditions is which the predicted SFP HX duty compared to demonstrate the under the LAR conditions is available heat transfer margin. It compared to demonstrate the is noted that actual conditions will available heat transfer margin. It be utilized to determine the time to is noted that actual conditions will begin WBN Unit 1 core offload be utilized to determine the time to begin core offload and the rate at CNL-22-043 Enc A3-11 of 29 Enclosure Attachment 3 Response to SCPB RAI-2

Table 1 Analysis Assumptions

Previous LAR Current LAR Difference Basis

and the rate at which the WBN which the core can be off loaded, Unit 1 core can be off loaded, as as described in UFSAR Section described in WBN dual-unit Final 9.1.3.1.1.

Safety Analysis Report (UFSAR)

Section 9.1.3.1.

CNL-22-043 Enc A3-12 of 29 Enclosure Attachment 3 Response to SCPB RAI-2

Table 1 Analysis Assumptions

Previous LAR Current LAR Difference Basis

5.13 The maximum residual heat 5.12 The maximum RHR HX duty None removal (RHR) HX duty of of 54,800,000 Btu/hr 54,80,000 Btu/hr (loss of cooling (LOCA-RECIRC mode) and accident (LOCA)-RECIRC mode) design CCS flowrate of 5000 gpm and design CCS flowrate of 5000 are assumed as listed in Table A.1 gallons per minute (gpm) are of the CCS Load List calculation.

assumed as listed in Table A.1 of the CCS Load List calculation. Technical Justification: This conservatively maximizes the load Technical Justification: This on the CCS HX and maximizes conservatively maximizes the load the ERCW cooling flow required.

on the CCS HX and maximizes This heat load is applied as the the ERCW cooling flow required. minimum acceptance criterion to This heat load is applied as the which the predicted RHR duty minimum acceptance criterion to under the LAR conditions is which the predicted RHR duty compared to demonstrate the under the LAR conditions is available heat transfer margin.

compared to demonstrate the available heat transfer margin.

CNL-22-043 Enc A3-13 of 29 Enclosure Attachment 3 Response to SCPB RAI-2

Table 1 Analysis Assumptions

Previous LAR Current LAR Difference Basis

5.14 It is assumed that the non-seismic 5.13 It is assumed that the non-seismic None Conservatively portion of the ERCW piping portion of the ERCW piping generalized to supplying the station air supplying the station air dual-unit LAR.

compressors in the Turbine compressors in the Turbine Building fails and discharges Building fails and discharges ERCW flow through each 4-inch ERCW flow through both 4-inch diameter pipe. diameter pipes.

Technical Justification: The low Technical Justification: The low pressure and high flow control pressure and high flow control system logic would normally system logic would normally isolate valves 0-FCV-67-0205-A isolate valves 0-FCV-67-0205-A and 0-FCV-67-0208-B. However, and 0-FCV-67-0208-B.

for this scenario neither of these The 67-0205-A valve is powered valves will be powered and will fail from the 1A-A SDBD and the as-is. Assuming both valves wide 67 0208-B is powered from the open provides a conservative loss 1B-B SDBD. Therefore, neither of of ERCW flow in excess of the these valves will be powered and 350 gpm flow switch setpoint. will fail as-is for a scenario involving LOT A and 1B-B SDBD out of service (e.g., Case 2D1BB).

Assuming one or both valves wide open depending on the availability of the respective power source for each case in this analysis, provides a conservative loss of ERCW flow in excess of the 350 gpm flow switch setpoint.

CNL-22-043 Enc A3-14 of 29 Enclosure Attachment 3 Response to SCPB RAI-2

Table 1 Analysis Assumptions

Previous LAR Current LAR Difference Basis

5.15 To account for unidentified system 5.14 To account for unidentified system None leakage, it is assumed that leakage, it is assumed that 100 gpm of ERCW flow is 100 gpm of ERCW flow is discharged directly from the discharged directly from the system. system.

Technical Justification: This Technical Justification: This results in a conservative loss of results in a conservative loss of ERCW flow which is in excess of ERCW flow which is in excess of typical system leakage under typical system leakage under normal operating conditions. normal operating conditions.

5.16 ERCW discharge flow is assumed 5.15 ERCW discharge flow is assumed None to be directed over the hydraulic to be directed to the hydraulic gradient rather than the cooling gradient rather than the cooling tower basin. tower basin.

Technical Justification: This Technical Justification: This increases the discharge flow increases the discharge flow resistance and conservatively resistance and conservatively reduces the flow available to the reduces the flow available to the essential components. essential components.

CNL-22-043 Enc A3-15 of 29 Enclosure Attachment 3 Response to SCPB RAI-2

Table 1 Analysis Assumptions

Previous LAR Current LAR Difference Basis

5.17 The CCS supplies to the WBN 5.16 The CCS supplies to the None Generalized to Unit 1 RHR HX and the Non-regen shutdown unit RHR HX and the dual-unit LAR.

letdown HX are assumed to be Non-regen letdown HX are isolated. assumed to be isolated.

Technical Justification: With Technical Justification: With the Unit 1 defueled, there are no heat shutdown unit defueled, there are loads on these heat exchangers, no heat loads on these heat and this preserves CCS flow for exchangers, and this preserves the accident unit. CCS flow for the accident unit.

N/A N/A 5.17 It is assumed that the CCS heat N/A This assumption loads apply to the shutdown and addresses dual LOCA units independent of which unit equivalence unit is shutdown or which is and is specific to undergoing post-LOCA conditions. the current dual unit LAR.

Technical Justification: This is confirmed by inspection of the load list tables in the CCS load list calculation.

CNL-22-043 Enc A3-16 of 29 Enclosure Attachment 3 Response to SCPB RAI-2

Table 2 Design Input

Previous LAR Current LAR Difference Basis

3.1 The dual-unit, flow balanced and 3.1 The dual-unit, flow balanced and None benchmarked PROTO-FLO base benchmarked PROTO-FLO base model of the ERCW system is model of the ERCW system is obtained from the ERCW obtained from the ERCW hydraulic model calculation. hydraulic model calculation.

3.2 The ERCW system alignments 3.2 The ERCW system alignments None and the ERCW flow rates to the and the ERCW minimum applicable operating equipment required flow rates to the are obtained from the ERCW applicable operating equipment Pressure Drop calculation. are obtained from the ERCW Pressure Drop calculation.

3.3 The equipment powered from 3.3 The equipment powered from None each shutdown board is each shutdown board is extracted from the electrical extracted from the electrical single line drawings. single line drawings.

CNL-22-043 Enc A3-17 of 29 Enclosure Attachment 3 Response to SCPB RAI-2

Table 2 Design Input

Previous LAR Current LAR Difference Basis

3.4 The design data for the new 3.7 The maximum allowable ERCW The subject heat This approach diesel generator jacket water cooling water temperature for the exchanger thermal ensures that any heat exchangers was obtained emergency diesel generator performance in subsequent changes from the vendors data sheet (EDG) jacket water heat support of SDBD to the heat included in Appendix 50 of the exchangers was determined cleaning is now exchanger will be jacket water heat exchanger from the jacket water heat incorporated in the evaluated for impact performance calculation. exchanger performance calculation rather on the SDBD calculation, considering the than the SDBD cleaning analysis.

The design heat transfer available flow rate predicted cleaning analysis.

used for this analysis was herein. The previous LAR 7,027,717 BTU/hr. The actual used an overly The design heat transfer acceptance criterion conservative heat used for this analysis was of the EDG jacket transfer rate.

6,750,000 BTU/hr. water heat The value of exchangers is used, 6,750,000 BTU/hr rather than an overly bounds the actual conservative value. operating heat load at 110% overload condition.

3.5 The PROTO-FLO/PROTO-HX 3.4 The PROTO-FLO/PROTO-HX Both CCS trains A Generalized to dual-model of the CCS is taken from models of the CCS are taken and B are evaluated unit LAR.

Appendix I of the CCS Heat from Appendix I of the CCS Heat in the current LAR Exchangers Performance Exchangers Performance calculation. calculation.

CNL-22-043 Enc A3-18 of 29 Enclosure Attachment 3 Response to SCPB RAI-2

Table 2 Design Input

Previous LAR Current LAR Difference Basis

3.6 The PROTO-HX models of the 3.5 The PROTO-HX models of the None RHR, SFP, and CCS heat RHR, SFP, and CCS heat exchangers are obtained from exchangers are obtained from the CCS Heat Exchangers the CCS Heat Exchangers Performance calculation, as Performance calculation, as follows: follows:

• RHR HX - Appendix J

• RHR HX - Appendix J

• SFP HX - Appendix K

• SFP HX - Appendix K

• CCS HX - Appendix L

• CCS HX - Appendix L

3.7 The PROTO-HX model of the 3.6 The PROTO-HX model of the None CSS heat exchanger is obtained CSS heat exchanger is obtained from the CSS HX calculation. from the CSS HX calculation.

N/A N/A 3.8 The maximum allowable ERCW The subject heat This approach cooling water temperature for the exchanger thermal ensures that any (See also 3.13 below) CSS HX was determined from performance in subsequent changes the CSS HX calculation, support of SDBD to the HX will be considering the available flow cleaning is now evaluated for impact rate predicted herein. incorporated in the on the SDBD calculation rather cleaning analysis.

(See also 3.14 below) than the SDBD cleaning analysis.

CNL-22-043 Enc A3-19 of 29 Enclosure Attachment 3 Response to SCPB RAI-2

Table 2 Design Input

Previous LAR Current LAR Difference Basis

3.8 The SDBD room chiller 3.9 The maximum allowable ERCW The subject heat This approach is condenser energy balance cooling water temperature for the exchanger thermal conservative and performance spreadsheet is SDBD room chiller condenser is performance in ensures that any taken from Appendix K-K of the obtained from the SDBR HVAC support of SDBD subsequent changes 6.9 kV SDBD room HVAC Equipment Performance cleaning is now to the heat calculation. calculation, considering the incorporated in the exchanger will be available flow rate predicted calculation rather evaluated for impact herein. than the SDBD on the SDBD cleaning analysis. cleaning analysis.

Impact to the In addition, the maximum allowable calculation is revised; temperature curve it was discovered from the change in that the calculation design input was did not reflect a negligible, on the retrievable source of order of 0.5°F to design input for 1.0°F in the flow certain heat regime of interest.

exchanger dimensions. Further, there is a modification in progress to replace the SDBD chiller condensers that may or may not be completed before

CNL-22-043 Enc A3-20 of 29 Enclosure Attachment 3 Response to SCPB RAI-2

Table 2 Design Input

Previous LAR Current LAR Difference Basis

this LAR (Reference 1) is implemented - the calculation evaluates both cases and chooses the limiting condition.

3.9 The spreadsheet model of the 3.10 The maximum allowable The subject heat This approach is Main Control Room (MCR) ERCW cooling water exchanger thermal conservative, chiller condenser is from temperature for the MCR chiller performance in reflects minor station Appendix A of the MCR HVAC condenser is obtained from the support of SDBD configuration Equipment Performance MCR HVAC Equipment cleaning is now changes, and calculation. Performance calculation, incorporated in the ensures that any considering the available flow calculation rather subsequent changes rate predicted herein. than the SDBD to the heat cleaning analysis. exchanger will be evaluated for impact In addition, the on the SDBD calculation is revised cleaning analysis.

to reflect a prior re tubing of the MCR chiller condenser.

Further, there is a modification in progress to replace the MCR chiller

CNL-22-043 Enc A3-21 of 29 Enclosure Attachment 3 Response to SCPB RAI-2

Table 2 Design Input

Previous LAR Current LAR Difference Basis

condensers that may or may not be completed before this LAR (Reference 1) is implemented - the calculation evaluates both cases and chooses the limiting condition.

CNL-22-043 Enc A3-22 of 29 Enclosure Attachment 3 Response to SCPB RAI-2

Table 2 Design Input

Previous LAR Current LAR Difference Basis

3.10 The spreadsheet model of the 3.11 The maximum allowable ERCW The subject heat This approach Electric Board Room (EBR) cooling water temperature for the exchanger thermal reflects minor station chiller condenser is from EBR chiller condenser is performance in configuration Appendix 13 of the EBR HVAC obtained from the EBR HVAC support of SDBD changes and Equipment Performance Equipment Performance cleaning is now ensures that any calculation. calculation, considering the incorporated in the subsequent changes available flow rate predicted calculation rather to the heat herein. than the SDBD exchanger will be cleaning analysis. evaluated for impact on the SDBD In addition, the cleaning analysis.

calculation is revised Incorporating the to reflect a prior retubing effort re-tubing of the EBR removed excess chiller condensers. margin from the calculation.

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Table 2 Design Input

Previous LAR Current LAR Difference Basis

3.11 The limiting engineering safety 3.12 The limiting ESF room cooler None feature (ESF) room cooler ERCW inlet temperatures during ERCW inlet temperatures during LOCA conditions are from the loss coolant accident (LOCA) Minimum ESF Cooler ERCW conditions as a function of Flow Rates versus Entering ERCW flow rate are from the ERCW Temperatures during Minimum ESF Cooler ERCW LOCA Conditions calculation.

Flow Rates versus Entering ERCW Temperatures during LOCA Conditions calculation.

3.12 The limiting heat exchanger 3.13 The heat exchanger outlet None outlet temperature limits are temperature limits are obtained obtained from the respective from the respective system Op system Op Mode calculations. Mode calculations.

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Table 2 Design Input

Previous LAR Current LAR Difference Basis

3.13 The maximum load on the CSS 3.14 The maximum load on the CSS Previous LAR CSS The previous limit of heat exchanger is based on the heat exchanger is based on the HX duty = 5% tube plugging maximum post-LOCA maximum post-LOCA 81,294,921 BTU/hr. was justifiable due to containment sump temperature containment sump temperature Based on design the known CSS HX of 158.2°F and associated spray of 164.8°F and associated spray max fouling and 5% condition and time flow rate of 4000 gpm consistent flow rate of 4000 gpm consistent tube plugging. limit on the previous with the design basis LOCA with the design basis LOCA LAR, and analysis. analysis. Current LAR CSS conservative for HX duty = purposes of 87,323,731 BTU/hr. calculating Two limits are maximum heat evaluated and the transfer. The actual more conservative is allowable tube used: 1) minimum plugging limit is required heat 10%.

transfer credited in the LOCA analysis The previous LAR based on max. sump developed the CSS temperature of HX acceptance 164.8°F, design max. criterion of fouling and 10% 81,294,921 BTU/hr plugged tubes and 2) based on the maximum allowable maximum post-ERCW outlet LOCA containment temperature of 130°F sump temperature of based on the sump 158.2°F determined temperature of by a Westinghouse

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Table 2 Design Input

Previous LAR Current LAR Difference Basis

158.2°F, zero fouling study in support of and zero plugged increasing the UHS tubes. temperature to 88°F.

That analysis predicted the CSS HX performance margin of 39%.

The current LAR analysis applied the maximum post-LOCA containment sump temperature of 164.8°F from the current LOCA analysis of record (based on the current UHS temperature limit of 85°F) to determine the CSS HX maximum duty acceptance criterion of 87,323,731 BTU/hr. This analysis demonstrates CSS

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Table 2 Design Input

Previous LAR Current LAR Difference Basis

HX margins of 24%

and 31% for a 1/2 B-B SDBD out of service or for a 1/2 A-A SDBD out of service, respectively.

Continued use of a 158.2°F inlet temperature in the current analysis for the exit-temperature-limited case is justified in the CSS calculation.

3.14 The maximum LOCA unit RHR 3.15 The maximum LOCA unit RHR None heat exchanger duty is based on heat exchanger duty is based on the maximum RHR temperature the maximum RHR temperature of 166.2°F and RHR flow rate of of 166.2°F and RHR flow rate of 3100 gpm from the CCS HX 3100 gpm from the CCS HX Performance calculation. Performance calculation.

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Table 2 Design Input

Previous LAR Current LAR Difference Basis

3.15 The pressure switch setpoint for 3.16 The pressure switch setpoint for None 0-PS-67-206 and 209 of 37 psig 0-PS-67-206 and 209 of 37 psig is obtained from the applicable is obtained from the applicable Nuclear Engineering Setpoint NESSD.

Scaling Document (NESSD).

3.16 The flow indicating switch 3.17 The flow indicating switch None setpoint of 350 gpm for setpoint of 350 gpm for 0-FIS-67-206 and 209 is 0-FIS-67-206 and 209 is obtained from the applicable obtained from the applicable NESSD. NESSD.

N/A N/A 3.18 The CCS flow rates delivered to N/A This design input is the RHR and SFP heat specific to the exchangers by the single 1B-B current LAR.

pump for the SDBD 2B-B out of service (OOS) case are obtained from the CCS Pressure Drop calculation.

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Table 2 Design Input

Previous LAR Current LAR Difference Basis

N/A A/B Train CCS (HX) Duty = N/A A/B Train -CCS HX Duty = A conservative and The predicted CCS 106,183,506 BTU/hr. 88,764,506 BTU/hr. beyond design basis HX duty exceeds the SFP duty of overly conservative 50,215,000 BTU/hr acceptance criterion for the shutdown unit in the previous LAR was added to LOCA as well as the unit duty in the correct value in the previous LAR current LAR.

analysis. The correct value is 88,764,506 BTU/hr.

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