CNL-23-028, Application to Revise Technical Specifications to Adopt TSTF-567-A, Revision 1, Add Containment Sump TS to Address GSI-191 Issues (SQN-TS-23-03 and WBN-TS-23-06)

Application to Revise Technical Specifications to Adopt TSTF-567-A, Revision 1, Add Containment Sump TS to Address GSI-191 Issues (SQN-TS-23-03 and WBN-TS-23-06)

ML23214A385
Person / Time
Site:	Watts Bar, Sequoyah
Issue date:	08/02/2023
From:	Hulvey K Tennessee Valley Authority
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
CNL-23-028
Download: ML23214A385 (1)

Text

1101 Market Street, Chattanooga, Tennessee 37402 CNL-23-028 August 2, 2023 10 CFR 50.90 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Sequoyah Nuclear Plant, Units 1 and 2 Renewed Facility Operating License Nos. DPR-77 and DPR-79 NRC Docket Nos. 50-327 and 50-328 Watts Bar Nuclear Plant, Units 1 and 2 Facility Operating License Nos. NPF-90 and NPF-96 NRC Docket Nos. 50-390 and 50-391

Subject:

Sequoyah Nuclear Plant, Units 1 and 2, and Watts Bar Nuclear Plant, Units 1 and 2, Application to Revise Technical Specifications to Adopt TSTF-567-A, Revision 1, "Add Containment Sump TS to Address GSI-191 Issues" (SQN-TS-23-03 and WBN-TS-23-06)

In accordance with the provisions of Title 10 of the Code of Federal Regulations (10 CFR) 50.90, Tennessee Valley Authority (TVA) is submitting a request for an amendment to Renewed Facility Operating License Nos. DPR-77 and DPR-79 for the Sequoyah Nuclear Plant (SQN), Units 1 and 2; and Facility Operating License Nos. NPF-90 and NPF-96 for the Watts Bar Nuclear Plant (WBN), Units 1 and 2, respectively.

TVA requests adoption of Technical Specifications Task Force (TSTF) Traveler TSTF-567-A, Revision 1, "Add Containment Sump TS to Address GSI-191 Issues," which is an approved change to the Standard Technical Specifications (STS), into the SQN Units 1 and 2 and the WBN Units 1 and 2 Technical Specifications (TS). The proposed amendment adds a new TS 3.6.16, "Containment Sump," and adds an Action to address the condition of the containment sump made inoperable due to containment accident generated and transported debris exceeding the analyzed limits. The Action provides time to correct or evaluate the condition in lieu of an immediate plant shutdown.

The enclosure provides a description and assessment of the proposed changes. Attachment 1 provides the existing SQN Units 1 and 2 TS pages marked to show the proposed changes. provides the existing WBN Units 1 and 2 TS pages marked to show the proposed changes. Attachment 3 provides the proposed SQN Units 1 and 2 TS Bases pages marked up to show the proposed changes. Attachment 4 provides the proposed WBN Units 1 and 2 TS Bases pages marked up to show the proposed changes. Changes to the existing TS Bases are provided for information only and will be implemented under the Technical Specification Bases Control Program.

U.S. Nuclear Regulatory Commission CNL-23-028 Page 2 August 2, 2023 TVA has determined that there are no significant hazards considerations associated with the proposed changes and that the TS changes qualify for a categorical exclusion from environmental review pursuant to the provisions of 10 CFR 51.22(c)(9). In accordance with 10 CFR 50.91(b)(1), TVA is sending a copy of this letter and enclosure to the Tennessee State Department of Environment and Conservation.

TVA requests that the proposed amendment be reviewed under the consolidated line item improvement process (CLIIP). Approval of the proposed amendment is requested within six months of completion of the NRCs acceptance review. Once approved, the amendment shall be implemented within 60 days.

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 this 2nd day of August 2023.

Respectfully, Digitally signed by Edmondson, Carla Date: 2023.08.02 15:53:43 -04'00' Kimberly D. Hulvey Director, Nuclear Regulatory Affairs

Enclosure:

Description and Assessment of the Proposed Change cc:(with Enclosure):

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

Enclosure Description and Assessment of the Proposed Change

Subject:

Sequoyah Nuclear Plant, Units 1 and 2, and Watts Bar Nuclear Plant, Units 1 and 2, Application to Revise Technical Specifications to Adopt TSTF-567-A, Revision 1, "Add Containment Sump TS to Address GSI-191 Issues" (SQN-TS-23-03 and WBN-TS-23-06)

Table of Contents

1.0 DESCRIPTION

................................................................................................................... 2 2.0 ASSESSMENT................................................................................................................... 2 2.1 Applicability of Safety Evaluation .................................................................................... 2 2.2 Variations ........................................................................................................................ 2

3.0 REGULATORY ANALYSIS

................................................................................................ 3 3.1 No Significant Hazards Consideration Analysis.............................................................. 3 3.2 Conclusion ...................................................................................................................... 5

4.0 ENVIRONMENTAL CONSIDERATION

............................................................................. 5 ATTACHMENTS

1. Proposed Technical Specification Changes (Mark-Up) for SQN Units 1 and 2

2. Proposed Technical Specification Changes (Mark-Up) for WBN Units 1 and 2

3. Proposed Technical Specification Bases Changes (Mark-Up) for SQN Units 1 and 2 (For Information Only)

4. Proposed Technical Specification Bases Changes (Mark-Up) for WBN Units 1 and 2 (For Information Only)

CNL-23-028 E1 of 5

Enclosure

1.0 DESCRIPTION

In accordance with the provisions of Title 10 of the Code of Federal Regulations (10 CFR) 50.90, Tennessee Valley Authority (TVA) is submitting a request for an amendment to Renewed Facility Operating License Nos. DPR-77 and DPR-79 for the Sequoyah Nuclear Plant (SQN), Units 1 and 2; and Facility Operating License Nos. NPF-90 and NPF-96 for the Watts Bar Nuclear Plant (WBN), Units 1 and 2, respectively.

TVA requests adoption of Technical Specifications Task Force (TSTF) Traveler TSTF-567-A, Revision 1, "Add Containment Sump TS to Address GSI-191 Issues," which is an approved change to the Standard Technical Specifications (STS), into the SQN Units 1 and 2 and the WBN Units 1 and 2 Technical Specifications (TS). The proposed amendment adds a new TS 3.6.16, "Containment Sump," and adds an Action to address the condition of the containment sump made inoperable due to containment accident generated and transported debris exceeding the analyzed limits. The Action provides time to correct or evaluate the condition in lieu of an immediate plant shutdown. This Action is placed in a new specification on the containment sump that otherwise retains the existing TS requirements. An existing Surveillance Requirement (SR) is moved from SQN Units 1 and 2 and the WBN Units 1 and 2 TS 3.5.2, ECCS - Operating, to the new specification. The requirement to perform the SR in SQN Units 1 and 2 and the WBN Units 1 and 2 TS 3.5.3, ECCS - Shutdown, is deleted.

The proposed amendment also revises the WBN Units 1 and 2 Safety Function Determination Program (TS 5.7.2.18) to clarify its application when a supported system is made inoperable by the inoperability of a single Technical Specification support system. The SQN Units 1 and 2 TS 5.5.13, Safety Function Determination Program (SFDP), already reflect this change.

2.0 ASSESSMENT 2.1 Applicability of Safety Evaluation TVA has reviewed the safety evaluation for TSTF-567-A, Revision 1, provided to the TSTF in a letter dated July 3, 2018. This review included the Nuclear Regulatory Commission (NRC) staffs evaluation, as well as the information provided in TSTF-567-A, Revision 1. TVA has concluded that the justifications presented in TSTF-567-A, Revision 1, and the safety evaluation prepared by the NRC staff are applicable to TVA and justify this amendment for the incorporation of the changes to the SQN Units 1 and 2 and the WBN Units 1 and 2 TS.

2.2 Variations TVA is proposing the following variations from the TS changes described in TSTF-567-A, Revision 1, or the applicable parts of the NRC staffs safety evaluation. These variations do not affect the applicability of TSTF-567-A, Revision 1, or the NRC staffs safety evaluation to the proposed license amendment.

x The SQN Units 1 and 2 and the WBN Units 1 and 2 TS utilize different numbering and titles than the STS on which TSTF-567-A, Revision 1, was based. Specifically, TSTF-567-A, Revision 1, identifies the new sump TS as 3.6.19. For SQN Units 1 and 2 and the WBN Units 1 and 2 this new TS is numbered 3.6.16. Also, TSTF-567-A, Revision 1, identifies the Safety Function Determination Program (SFDP) as TS 5.5.15, whereas for WBN Units 1 and 2 this TS is numbered 5.7.2.18 [no changes are needed to SQN Units 1 and 2 TS 5.5.13, Safety Function Determination Program (SFDP)]. These differences are CNL-23-028 E2 of 5

Enclosure administrative and do not affect the applicability of TSTF-567-A, Revision 1, to the SQN Units 1 and 2 and the WBN Units 1 and 2 TS.

x The SQN Units 1 and 2 and the WBN Units 1 and 2 TS contain a Surveillance Frequency Control Program1. Therefore, the frequency of SR 3.6.16.1 is In accordance with the Surveillance Frequency Control Program. This is appropriate because these new SRs are eligible for the SFCP per the criteria of the NRC staff's model safety evaluation dated July 6, 2009 (74 FR 31996).

x The Background Section of WBN Units 1 and 2 Bases 3.5.3, ECCS - Shutdown, currently addresses the containment sump; therefore, the recommended changes in TSTF-567-A, Revision 1, do not apply to these Bases.

3.0 REGULATORY ANALYSIS

3.1 No Significant Hazards Consideration Analysis The proposed amendment adds a new Technical 6SHFLILFDWLRQ (TS) 3.6.16, "Containment Sump," and adds an Action to address the condition of the containment sump made inoperable due to containment accident generated and transported debris exceeding the analyzed limits.

The Action provides time to correct or evaluate the condition in lieu of an immediate plant shutdown. This Action is placed in a new specification on the containment sump that otherwise retains the existing TS requirements. An existing Surveillance Requirement (SR) is moved from TS 3.5.2 to the new specification. The requirement to perform the SR in TS 3.5.3 is deleted.

The proposed amendment also revises the Watts Bar Nuclear Plant (WBN) Units 1 and 2 Safety Function Determination Program (TS 5.7.2.18) to clarify its application when a supported system is made inoperable by the inoperability of a single TS support system. The Sequoyah Nuclear Plant (SQN) Units 1 and 2 TS  already reflect this change.

Tennessee Valley Authority (TVA) has evaluated whether or not a significant hazards consideration is involved with the proposed amendment(s) by focusing on the three standards set forth in Title 10 of the Code of Federal Regulations (10 CFR) 50.92, "Issuance of amendment," as discussed below:

1. Does the proposed amendment involve a significant increase in the probability or consequence of an accident previously evaluated?

Response: No.

The proposed change adds a new specification to the TS for the containment sump. An existing SR on the containment sump is moved to the new specification and a duplicative requirement to perform the SR in TS 3.5.3 is removed. The new specification retains the existing requirements on the containment sump and the actions to be taken when the containment sump is inoperable with the exception of adding new actions to be taken when the containment sump is inoperable due to containment accident generated and transported debris exceeding the analyzed limits. The new action provides time to evaluate and correct the condition instead of requiring an immediate plant shutdown.

1

Reference:

SQN Amendments 334/327 (ML15238B499) and WBN Amendments 132/26 (ML20028F733)

CNL-23-028 E3 of 5

Enclosure The containment sump is not an initiator of any accident previously evaluated. The containment sump is a passive component and the proposed change does not increase the likelihood of the malfunction. As a result, the probability of an accident is unaffected by the proposed change.

The containment sump is used to mitigate accidents previously evaluated by providing a borated water source for the Emergency Core Cooling System (ECCS) and Containment Spray System (CSS). The design of the containment sump and the capability of the containment sump assumed in the accident analysis is not changed. The proposed action requires implementation of mitigating actions while the containment sump is inoperable and more frequent monitoring of reactor coolant leakage to detect any increased potential for an accident that would require the containment sump. The consequences of an accident during the proposed action are no different than the current consequences of an accident if the containment sump is inoperable.

Therefore, the proposed change does not involve a significant increase in the probability or consequences of an accident previously evaluated.

2. Does the proposed amendment create the possibility of a new or different kind of accident from any accident previously evaluated?

Response: No.

The proposed change adds a new specification to the TS for the containment sump. An existing SR on the containment sump is moved to the new specification and a duplicative requirement to perform the SR in TS 3.5.3 is removed. The new specification retains the existing requirements on the containment sump and the actions to be taken when the containment sump is inoperable with the exception of adding new actions to be taken when the containment sump is inoperable due to containment accident generated and transported debris exceeding the analyzed limits. The new action provides time to evaluate and correct the condition instead of requiring an immediate plant shutdown.

The proposed change does not alter the design or design function of the containment sump or the plant. No new systems are installed or removed as part of the proposed change. The containment sump is a passive component and cannot initiate a malfunction or accident. No new credible accident is created that is not encompassed by the existing accident analyses that assume the function of the containment sump.

Therefore, the proposed change does not create the possibility of a new or different kind of accident from any accident previously evaluated.

3. Does the proposed amendment involve a significant reduction in a margin of safety?

Response: No.

The proposed change adds a new specification to the TS for the containment sump. An existing SR on the containment sump is moved to the new specification and a duplicative requirement to perform the SR in TS 3.5.3 is removed. The new specification retains the existing requirements on the containment sump and the actions to be taken when the containment sump is inoperable with the exception of adding new actions to be taken when the containment sump is inoperable due to containment accident generated and transported CNL-23-028 E4 of 5

Enclosure debris exceeding the analyzed limits. The new action provides time to evaluate and correct the condition instead of requiring an immediate plant shutdown.

The proposed change does not affect the controlling values of parameters used to avoid exceeding regulatory or licensing limits. No Safety Limits are affected by the proposed change. The proposed change does not affect any assumptions in the accident analyses that demonstrate compliance with regulatory and licensing requirements.

Therefore, the proposed change does not involve a significant reduction in a margin of safety.

Based on the above, TVA concludes that the proposed change presents no significant hazards consideration under the standards set forth in 10 CFR 50.92(c), and, accordingly, a finding of "no significant hazards consideration" is justified.

3.2 CONCLUSION

In conclusion, based on the considerations discussed above, (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commissions regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.

4.0 ENVIRONMENTAL CONSIDERATION

A review has determined that the proposed amendment would change a requirement with respect to installation or use of a facility component located within the restricted area, as defined in 10 CFR 20, or would change an inspection or surveillance requirement. However, the proposed amendment does not involve (i) a significant hazards consideration, (ii) a significant change in the types or a significant increase in the amounts of any effluents that may be released offsite, or (iii) a significant increase in individual or cumulative occupational radiation exposure. Accordingly, the proposed amendment meets the eligibility criterion for categorical exclusion set forth in 10 CFR 51.22(c)(9). Therefore, pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the proposed amendment.

CNL-23-028 E5 of 5

Attachment 1 Proposed Technical Specification Changes (Mark-Up) for SQN Units 1 and 2 CNL-23-028

ECCS - Operating 3.5.2 SURVEILLANCE REQUIREMENTS (continued)

SURVEILLANCE FREQUENCY SR 3.5.2.7 Verify, for each ECCS throttle valve listed below, each In accordance mechanical stop is in the correct position. with the Surveillance Frequency Charging Pump Safety Injection Safety Injection Control Program Injection Cold Leg Hot Leg Throttle Throttle Valves Throttle Valves Valves63-582 63-550 63-542 63-583 63-552 63-544 63-584 63-554 63-546 63-585 63-556 63-548 SR 3.5.2.8 Verify, by visual inspection, each ECCS train In accordance containment sump suction inlet is not restricted by with the debris and the suction inlet trash racks and screens Surveillance show no evidence of structural distress or abnormal Frequency corrosion. Control Program SEQUOYAH - UNIT 1 3.5.2-3 Amendment 334,

ECCS - Shutdown 3.5.3 SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.5.3.1 The following SRs are applicable for all equipment In accordance required to be OPERABLE: with applicable SRs SR 3.5.2.3 SR 3.5.2.7 SR 3.5.2.4 SR 3.5.2.8 SEQUOYAH - UNIT 1 3.5.3-2 Amendment 334,

Containment Sump 3.6.16 3.6 CONTAINMENT SYSTEMS 3.6.16 Containment Sump LCO 3.6.16 The containment sump shall be OPERABLE.

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

ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME A. Containment sump A.1 Initiate action to mitigate Immediately inoperable due to containment accident containment accident generated and transported generated and debris.

transported debris exceeding the analyzed AND limits.

A.2 Perform SR 3.4.13.1 Once per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> AND A.3 Restore the containment 90 days sump to OPERABLE status.

SEQUOYAH - UNIT 1 3.6.16-1 Amendment

Containment Sump 3.6.16 ACTIONS (continued)

CONDITION REQUIRED ACTION COMPLETION TIME B. Containment sump B.1 -------------NOTES--------------

inoperable for reasons 1. Enter applicable other than Condition A. Conditions and Required Actions of LCO 3.5.2, ECCS - Operating, and LCO 3.5.3, ECCS -

Shutdown, for emergency core cooling trains made inoperable by the containment sump.

2. Enter applicable Conditions and Required Actions of LCO 3.6.6, Containment Spray System, for containment spray trains made inoperable by the containment sump.

Restore the containment 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> sump to OPERABLE status.

C. Required Action 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 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 /> SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.6.16.1 Verify by visual inspection, the containment In accordance with sump does not show structural damage, abnormal the Surveillance corrosion, or debris blockage. Frequency Control Program SEQUOYAH - UNIT 1 3.6.16-2 Amendment

ECCS - Operating 3.5.2 SURVEILLANCE REQUIREMENTS (continued)

SURVEILLANCE FREQUENCY SR 3.5.2.7 Verify, for each ECCS throttle valve listed below, each In accordance mechanical stop is in the correct position. with the Surveillance Frequency Charging Pump Safety Injection Safety Injection Control Program Injection Cold Leg Hot Leg Throttle Throttle Valves Throttle Valves Valves63-582 63-550 63-542 63-583 63-552 63-544 63-584 63-554 63-546 63-585 63-556 63-548 SR 3.5.2.8 Verify, by visual inspection, each ECCS train In accordance containment sump suction inlet is not restricted by with the debris and the suction inlet trash racks and screens Surveillance show no evidence of structural distress or abnormal Frequency corrosion. Control Program SEQUOYAH - UNIT 2 3.5.2-3 Amendment 327,

ECCS - Shutdown 3.5.3 SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.5.3.1 The following SRs are applicable for all equipment In accordance required to be OPERABLE: with applicable SRs SR 3.5.2.3 SR 3.5.2.7 SR 3.5.2.4 SR 3.5.2.8 SEQUOYAH - UNIT 2 3.5.3-2 Amendment 327,

Containment Sump 3.6.16 3.6 CONTAINMENT SYSTEMS 3.6.16 Containment Sump LCO 3.6.16 The containment sump shall be OPERABLE.

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

ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME A. Containment sump A.1 Initiate action to mitigate Immediately inoperable due to containment accident containment accident generated and transported generated and debris.

transported debris exceeding the analyzed AND limits.

A.2 Perform SR 3.4.13.1 Once per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> AND A.3 Restore the containment 90 days sump to OPERABLE status.

SEQUOYAH - UNIT 2 3.6.16-1 Amendment

Containment Sump 3.6.16 ACTIONS (continued)

CONDITION REQUIRED ACTION COMPLETION TIME B. Containment sump B.1 -------------NOTES--------------

inoperable for reasons 1. Enter applicable other than Condition A. Conditions and Required Actions of LCO 3.5.2, ECCS - Operating, and LCO 3.5.3, ECCS -

Shutdown, for emergency core cooling trains made inoperable by the containment sump.

2. Enter applicable Conditions and Required Actions of LCO 3.6.6, Containment Spray System, for containment spray trains made inoperable by the containment sump.

Restore the containment 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> sump to OPERABLE status.

C. Required Action 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 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 /> SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.6.16.1 Verify by visual inspection, the containment In accordance with sump does not show structural damage, abnormal the Surveillance corrosion, or debris blockage. Frequency Control Program SEQUOYAH - UNIT 2 3.6.16-2 Amendment

Attachment 2 Proposed Technical Specification Changes (Mark-Up) for WBN Units 1 and 2 CNL-23-028

ECCS - Operating 3.5.2 SURVEILLANCE REQUIREMENTS (continued)

SURVEILLANCE FREQUENCY SR 3.5.2.6 Verify each ECCS pump starts automatically on an In accordance with actual or simulated actuation signal. the Surveillance Frequency Control Program SR 3.5.2.7 Verify for each ECCS throttle valve In accordance with listed below, each position stop is the Surveillance in the correct position. Frequency Control Program Valve Number CCP Discharge SI Cold Leg SI Hot Leg Throttle Throttle Throttle Valves Valves Valves63-582 63-550 63-542 63-583 63-552 63-544 63-584 63-554 63-546 63-585 63-556 63-548 SR 3.5.2.8 Verify, by visual inspection, each ECCS train In accordance with containment sump suction inlet is not restricted by the Surveillance debris and the suction inlet trash racks and screens Frequency Control show no evidence of structural distress or abnormal Program corrosion.

Watts Bar-Unit 1 3.5-6 Amendment 132,

ECCS - Shutdown 3.5.3 ACTIONS (continued)

CONDITION REQUIRED ACTION COMPLETION TIME C. Required Action and C.1 Be in MODE 5. 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> associated Completion Time of Condition B not met.

SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.5.3.1 -------------------------------NOTE-------------------------------

An RHR train may be considered OPERABLE during alignment and operation for decay heat removal, if capable of being manually realigned to the ECCS mode of operation.

The following SRs are applicable for all equipment In accordance with required to be OPERABLE: applicable SRs SR 3.5.2.1 SR 3.5.2.7 SR 3.5.2.3 SR 3.5.2.8 SR 3.5.2.4 Watts Bar-Unit 1 3.5-8 Amendment

Containment Sump 3.6.16 3.6 CONTAINMENT SYSTEMS 3.6.16 Containment Sump LCO 3.6.16 The Fontainment Vump shall be OPERABLE.

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

ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME A. Containment sump A.1 Initiate action to mitigate Immediately inoperable due to containment accident containment accident generated and transported generated and transported debris.

debris exceeding the analyzed limits. AND A.2 Perform SR 3.4.13.1 Once per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> AND A.3 Restore the containment 90 days sump to OPERABLE status.

Watts Bar-Unit 1 3.6-42 Amendment

Containment Sump 3.6.16 ACTIONS (continued)

CONDITION REQUIRED ACTION COMPLETION TIME B. Containment sump B.1 -------------- NOTES -------------

inoperable for reasons other 1. Enter applicable than Condition A. Conditions and Required Actions of LCO 3.5.2, ECCS - Operating, and LCO 3.5.3, ECCS -

Shutdown, for emergency core cooling trains made inoperable by the containment sump.

2. Enter applicable Conditions and Required Actions of LCO 3.6.6, Containment Spray System, for containment spray trains made inoperable by the containment sump.

Restore the containment sump 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to OPERABLE status.

C. Required Action 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 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 /> Watts Bar-Unit 1 3.6-43 Amendment

Containment Sump 3.6.16 SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.6.16.1 Verify by visual inspection, the containment sump In accordance with does not show structural damage, abnormal the Surveillance corrosion, or debris blockage. Frequency Control Program Watts Bar-Unit 1 3.6-44 Amendment

Procedures, Programs, and Manuals 5.7 5.7 Procedures, Programs, and Manuals 5.7.2.18 Safety Function Determination Program (SFDP) (continued)

A loss of safety function exists when, assuming no concurrent single failure, a safety function assumed in the accident analysis cannot be performed. For the purpose of this program, a loss of safety function may exist when a support system is inoperable, and:

a. A required system redundant to the system(s) supported by the inoperable support system is also inoperable; or

b. A required system redundant to the system(s) in turn supported by the inoperable supported system is also inoperable; or

c. A required system redundant to the support system(s) for the supported systems (a) and (b) above is also inoperable.

The SFDP identifies where a loss of safety function exists. If a loss of safety function is determined to exist by this program, the appropriate Conditions and Required Actions of the LCO in which the loss of safety function exists are required to be entered. When a loss of safety function is caused by the inoperability of a single Technical Specification support system, the appropriate Conditions and Required Actions to enter are those of the support system.

5.7.2.19 Containment Leakage Rate Testing Program A program shall be established to implement the leakage rate testing of the containment as required by 10 CFR 50.54(o) and 10 CFR 50 Appendix J, Option B, as modified by approved exemptions. This program shall be in accordance with the guidelines contained in NEI 94-01, "Industry Guideline for Implementing Performance-Based Option of 10 CFR 50, Appendix J," Revision 3-A, July 2012, and Section 4.1, "Limitations and Conditions for NEI TR 94-01, Revision 2," of the NRC Safety Evaluation Report in NEI 94-01, Revision 2-A, dated October 2008, as modified below:

For containment leakage rate testing purposes, a value of 15.0 psig, which is equivalent to the maximum allowable internal containment pressure, is utilized for Pa to bound a range of peak calculated containment internal pressures from 9.0 to 15.0 psig for the design basis loss of coolant accident.

The maximum allowable containment leakage rate, La, at Pa, is 0.25% of the primary containment air weight per day.

(continued)

Watts Bar-Unit 1 5.0-24 Amendment 5, 63, 135, 149,

ECCS - Operating 3.5.2 SURVEILLANCE REQUIREMENTS (continued)

SURVEILLANCE FREQUENCY SR 3.5.2.7 Verify, for each ECCS throttle valve listed below, In accordance with each position stop is in the correct position. the Surveillance Frequency Control Valve Number Program CCP SI SI Discharge Cold Leg Hot Leg Throttle Throttle Throttle Valves Valves Valves 2-63-582 2-63-550 2-63-542 2-63-583 2-63-552 2-63-544 2-63-584 2-63-554 2-63-546 2-63-585 2-63-556 2-63-548 SR 3.5.2.8 Verify, by visual inspection, each ECCS train In accordance with containment sump suction inlet is not restricted by the Surveillance debris and the suction inlet trash racks and screens Frequency Control show no evidence of structural distress or abnormal Program corrosion.

Watts Bar - Unit 2 3.5-5 Amendment 36,

ECCS - Shutdown 3.5.3 ACTIONS (continued)

CONDITION REQUIRED ACTION COMPLETION TIME B. Required ECCS centrifugal B.1 Restore required ECCS 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> charging subsystem centrifugal charging inoperable. subsystem to OPERABLE status.

C. Required Action and C.1 Be in MODE 5. 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> associated Completion Time of Condition B not met.

SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.5.3.1 -------------------------------NOTE------------------------------

An RHR train may be considered OPERABLE during alignment and operation for decay heat removal, if capable of being manually realigned to the ECCS mode of operation.

The following SRs are applicable for all equipment In accordance with required to be OPERABLE: applicable SRs SR 3.5.2.1 SR 3.5.2.3 SR 3.5.2.4 SR 3.5.2.7 SR 3.5.2.8 Watts Bar - Unit 2 3.5-7 Amendment

Containment Sump 3.6.16 3.6 CONTAINMENT SYSTEMS 3.6.16 Containment Sump LCO 3.6.16 The containment sump shall be OPERABLE.

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

ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME A. Containment sump A.1 Initiate action to mitigate Immediately inoperable due to containment accident containment accident generated and generated and transported transported debris.

debris exceeding the analyzed limits.

AND A.2 Perform SR 3.4.13.1 Once per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> AND A.3 Restore the containment 90 days sump to OPERABLE status.

Watts Bar - Unit 2 3.6-37 Amendment

Containment Sump 3.6.16 ACTIONS (continued)

CONDITION REQUIRED ACTION COMPLETION TIME

---

NOTES ---------

B. Containment sump B.1 1. Enter applicable inoperable for reasons other Conditions and than Condition A. Required Actions of LCO 3.5.2, ECCS -

Operating, and LCO 3.5.3, ECCS -

Shutdown, for emergency core cooling trains made inoperable by the containment sump.

2. Enter applicable Conditions and Required Actions of LCO 3.6.6, Containment Spray System, for containment spray trains made inoperable by the containment sump Restore the containment 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> sump to OPERABLE status.

C. Required Action 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 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 /> Watts Bar - Unit 2 3.6-38 Amendment

Containment Sump 3.6.16 SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.6.16.1 Verify by visual inspection, the containment sump In accordance with does not show structural damage, abnormal the Surveillance corrosion, or debris blockage. Frequency Control Program Watts Bar - Unit 2 3.6-39 Amendment

Procedures, Programs, and Manuals 5.7 5.7 Procedures, Programs, and Manuals 5.7.2.18 Safety Function Determination Program (SFDP) (continued)

A loss of safety function exists when, assuming no concurrent single failure, a safety function assumed in the accident analysis cannot be performed. For the purpose of this program, a loss of safety function may exist when a support system is inoperable, and:

a. A required system redundant to the system(s) supported by the inoperable support system is also inoperable; or

b. A required system redundant to the system(s) in turn supported by the inoperable supported system is also inoperable; or

c. A required system redundant to the support system(s) for the supported systems (a) and (b) above is also inoperable.

The SFDP identifies where a loss of safety function exists. If a loss of safety function is determined to exist by this program, the appropriate Conditions and Required Actions of the LCO in which the loss of safety function exists are required to be entered. When a loss of safety function is caused by the inoperability of a single Technical Specification support system, the appropriate Conditions and Required Actions to enter are those of the support system.

5.7.2.19 Containment Leakage Rate Testing Program A program shall be established to implement the leakage rate testing of the containment as required by 10 CFR 50.54(o) and 10 CFR 50 Appendix J, Option B, as modified by approved exemptions. This program shall be in accordance with the guidelines contained in NEI 94-01, "Industry Guideline for Implementing Performance-Based Option of 10 CFR 50, Appendix J," Revision 3-A, July 2012, and Section 4.1, "Limitations and Conditions for NEI TR 94-01, Revision 2," of the NRC Safety Evaluation Report in NEI 94-01, Revision 2-A, dated October 2008, as modified below:

For containment leakage rate testing purposes, a value of 15.0 psig, which is equivalent to the maximum allowable internal containment pressure, is utilized for Pa to bound a range of peak calculated containment internal pressures from 9.0 to 15.0 psig for the design basis loss of coolant accident.

The maximum allowable containment leakage rate, La, at Pa, is 0.25%

of the primary containment air weight per day.

(continued)

Watts Bar - Unit 2 5.0-25 Amendment 11, 39, 56,

Attachment 3 Proposed Technical Specification Bases Changes (Mark-Up) for SQN Units 1 and 2 (For Information Only)

CNL-23-028

ECCS - Operating B 3.5.2 BASES BACKGROUND (continued)

During low temperature conditions in the RCS, limitations are placed on the maximum number of ECCS pumps that may be OPERABLE. Refer to the Bases for LCO 3.4.12, "Low Temperature Overpressure Protection (LTOP) System," for the basis of these requirements.

The ECCS subsystems are actuated upon receipt of an SI signal. If offsite power is available, the safeguard loads start immediately in the programmed sequence. If offsite power is not available, the Engineered Safety Feature (ESF) buses shed normal operating loads and are connected to the emergency diesel generators (EDGs). Safeguard loads are then actuated in the programmed time sequence. The time delay associated with diesel starting, sequenced loading, and pump starting determines the time required before pumped flow is available to the core following a LOCA.

The active ECCS components, along with the passive accumulators, and the RWST, and the containment sump, are covered in LCO 3.5.1, "Accumulators," and LCO 3.5.4, "Refueling Water Storage Tank (RWST),"

and LCO 3.6.16, "Containment Sump," and provide the cooling water necessary to meet GDC 35 (Ref. 1).

APPLICABLE The LCO helps to ensure that the following acceptance criteria for the SAFETY ECCS, established by 10 CFR 50.46 (Ref. 2), will be met with a high level ANALYSES of probability following a LOCA:

a. 0D[LPXPIXHOHOHPHQWFODGGLQJWHPSHUDWXUHLV 2200°F,

b. Maximum FODGGLQJR[LGDWLRQLV 0.17 times the total cladding thickness before oxidation,

c. Maximum hydrogen generation from a zirconium water reaction is 0.01 times the hypothetical amount generated if all of the metal in the cladding cylinders surrounding the fuel, excluding the cladding surrounding the plenum volume, were to react,

d. Core is maintained in a coolable geometry, and

e. Adequate long term core cooling capability is maintained.

The LCO also limits the potential for a post trip return to power following an MSLB event and ensures that containment temperature limits are met.

SEQUOYAH - UNIT 1 B 3.5.2-3 Revision 67,

ECCS - Operating B 3.5.2 BASES SURVEILLANCE REQUIREMENTS (continued)

The ASME Code provides the activities and Frequencies necessary to satisfy the requirements.

SR 3.5.2.5 and SR 3.5.2.6 These Surveillances demonstrate that each automatic ECCS valve actuates to the required position on an actual or simulated SI signal and that each ECCS pump starts on receipt of an actual or simulated SI signal. This Surveillance is not required for valves that are locked, sealed, or otherwise secured in the required position under administrative controls.

The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.

SR 3.5.2.7 Realignment of valves in the flow path on an SI signal is necessary for proper ECCS performance. These valves have stops to allow proper positioning for restricted flow to a ruptured cold leg, ensuring that the other cold legs receive at least the required minimum flow.

The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.

SR 3.5.2.8 Periodic inspections of the containment sump suction inlet ensure that it is unrestricted and stays in proper operating condition.

The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.

SEQUOYAH - UNIT 1 B 3.5.2-9 Revision 45,

Containment Sump B 3.6.16 B 3.6 CONTAINMENT SYSTEMS B 3.6.16 Containment Sump BASES BACKGROUND The containment sump provides a borated water source to support recirculation of coolant from the containment sump for residual heat removal, emergency core cooling, containment cooling, and containment atmosphere cleanup during accident conditions.

The containment sump supplies both trains of the Emergency Core Cooling System (ECCS) and the Containment Spray System (CSS) during any accident that requires recirculation of coolant from the containment sump. The recirculation mode is initiated when the pump suction is transferred to the containment sump at a level, which ensures the containment sump has enough water to supply the net positive suction head to the ECCS and CSS pumps. A single containment sump is used to supply both trains of the ECCS and CSS.

The containment sump contains strainers to limit the quantity of the debris materials from entering the sump suction piping. Debris accumulation on the strainers can lead to undesirable hydraulic effects including air ingestion through vortexing or deaeration, and reduced net positive suction head (NPSH) at pump suction piping.

While the majority of debris accumulates on the strainers, some fraction penetrates the strainers and is transported to downstream components in the ECCS, CSS, and the Reactor Coolant System (RCS). Debris that penetrates the strainer can result in wear to the downstream components, blockages, or reduced heat transfer across the fuel cladding. Excessive debris in the containment sump water source could result in insufficient recirculation of coolant during the accident, or insufficient heat removal from the core during the accident.

APPLICABLE During all accidents that require recirculation, the containment sump SAFETY provides a source of borated water to the ECCS and CSS System pumps.

ANALYSES As such, it supports residual heat removal, emergency core cooling, containment cooling, and containment atmosphere cleanup during an accident. It also provides a source of negative reactivity (Ref. 1). The design basis transients and applicable safety analyses concerning each of these systems are discussed in the Applicable Safety Analyses section of B 3.5.2, "ECCS -Operating," B 3.5.3, "ECCS - Shutdown," and B 3.6.6, "Containment Spray System.

SEQUOYAH - UNIT 1 B 3.6.16-1 Amendment

Containment Sump B 3.6.16 BASES APPLICABLE SAFETY ANALYSES (continued)

UFSAR Section 6.3.2.2 (Ref. 2) describes evaluations that confirm long term core cooling is assured following any accident that requires recirculation from the containment sump.

The containment sumps satisfy Criterion 3 of 10 CFR 50.36(c)(2)(ii).

LCO The containment sump is required to ensure a source of borated water to support ECCS and CSS OPERABILITY. A containment sump consists of the containment drainage flow paths, debris intercepting devices, a volume of lower containment formed by sealed penetrations inside the lower crane wall, the containment sump strainers, and the inlet to the ECCS and CSS piping. The piping inlet is protected by the advanced design strainers. Each strainer contains perforations to reduce the size of debris that may enter the sump. The water flows through mesh screens, which suppress vortices that may occur in the sump at the entrance to the twin recirculation pipes. Internal baffles are provided to allow the escape of air during initial filling and to prevent the formation of vortices. An OPERABLE containment sump has no structural damage or abnormal corrosion that could prevent recirculation of coolant and will not be restricted by containment accident generated and transported debris.

Containment accident generated and transported debris consists of the following:

a. Accident generated debris sources - Insulation, coatings, and other materials which are damaged by the high-energy line break (HELB) and transported to the containment sump. This includes materials within the HELB zone of influence and other materials (e.g., unqualified coatings) that fail due to the post-accident containment environment following the accident;

b. Latent debris sources - Pre-existing dirt, dust, paint chips, fines or shards of insulation, and other materials inside containment that do not have to be damaged by the HELB to be transported to the containment sump; and

c. Chemical product debris sources - Aluminum, zinc, carbon steel, copper, and non-metallic materials such as paints, thermal insulation, and concrete that are susceptible to chemical reactions within the post-accident containment environment leading to corrosion products that are generated within the containment sump pool or are generated within containment and transported to the containment sump.

SEQUOYAH - UNIT 1 B 3.6.16-2 Amendment

Containment Sump B 3.6.16 BASES LCO (continued)

Containment debris limits are defined in TVA Calculation SQNSQS20240 (Ref. 3).

APPLICABILITY In MODES 1, 2, 3, and 4, containment sump OPERABILITY requirements are dictated by the ECCS and CSS OPERABILITY requirements. Since both the ECCS and the CSS must be OPERABLE in MODES 1, 2, 3, and 4, the containment sump must also be OPERABLE to support their operation.

In MODES 5 and 6, the probability and consequences of these events are reduced due to the pressure and temperature limitations of these MODES. Thus, the containment sump is not required to be OPERABLE in MODES 5 or 6.

ACTIONS A.1, A.2, and A.3 Condition A is applicable when the containment sump is inoperable due to containment accident generated and transported debris exceeding the analyzed limits. Examples that would require entry into TS 3.6.16 Condition A include:

x Unanalyzed debris sources that are discovered inside containment x Errors that are discovered in debris-related analyses x Discovery of a previously unevaluated phenomenon that can affect containment sump performance.

Containment debris limits are defined in TVA Calculation SQNSQS20240 (Ref. 3). Immediate action must be initiated to mitigate the condition.

Examples of mitigating actions are:

x Removing the debris source from containment or preventing the debris from being transported to the containment sump; x Evaluating the debris source against the assumptions in the analysis; x Deferring maintenance that would affect availability of the affected systems and other LOCA mitigating equipment; x Deferring maintenance that would affect availability of primary defense-in-depth systems; SEQUOYAH - UNIT 1 B 3.6.16-3 Amendment

Containment Sump B 3.6.16 BASES ACTIONS (continued) x Briefing operators on LOCA debris management actions; or x Applying an alternative method to establish new limits.

While in this condition, the RCS water inventory balance, SR 3.4.13.1, must be performed at an increased Frequency of once per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. An unexpected increase in RCS leakage could be indicative of an increased potential for an RCS pipe break, which could result in debris being generated and transported to the containment sump. The more frequent monitoring allows operators to act in a timely fashion to minimize the potential for an RCS pipe break while the containment sump is inoperable.

The inoperable containment sump must be restored to OPERABLE status in 90 days. A 90-day Completion Time is reasonable for emergent conditions that involve debris in excess of the analyzed limits that could be generated and transported to the containment sump under accident conditions. The likelihood of an initiating event in the 90-day Completion Time is very small and there is margin in the associated analyses. The mitigating actions of Required Action A.1 provide additional assurance that the effects of debris in excess of the analyzed limits will be mitigated during the Completion Time.

B.1 When the containment sump is inoperable for reasons other than Condition A, such as blockage, structural damage, or abnormal corrosion that could prevent recirculation of coolant, it must be restored to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. The 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> Completion Time takes into account the reasonable time for repairs, and low probability of an accident that requires the containment sump occurring during this period.

Required Action B.1 is modified by two Notes. The first Note indicates that the applicable Conditions and Required Actions of LCO 3.5.2, "ECCS

- Operating," and LCO 3.5.3, "ECCS - Shutdown," should be entered if an inoperable containment sump results in an inoperable ECCS train. The second Note indicates that the applicable Conditions and Required Actions of LCO 3.6.6, "Containment Spray System," should be entered if an inoperable containment sump results in an inoperable CSS train. This is an exception to LCO 3.0.6 and ensures the proper actions are taken for these components.

SEQUOYAH - UNIT 1 B 3.6.16-4 Amendment

Containment Sump B 3.6.16 BASES ACTIONS (continued)

C.1 and C.2 If the containment sump cannot be restored to OPERABLE status within the associated Completion Time, the plant must be brought to a MODE in which the LCO does not apply. To achieve this status, the plant must be brought to at least MODE 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and to MODE 5 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. The allowed Completion Times are reasonable, based on operating experience, to reach the required plant conditions from full power conditions in an orderly manner and without challenging plant systems.

SURVEILLANCE SR 3.6.16.1 REQUIREMENTS Periodic inspections are performed to verify the containment sump does not show current or potential debris blockage, structural damage, or abnormal corrosion to ensure the operability and structural integrity of the containment sump (Ref. 1). The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.

REFERENCES 1. UFSAR, Chapter 6 and Chapter 15.

2. UFSAR Section 6.3.2.2, Equipment and Component Design.

3. TVA Calculation SQNSQS20240, Evaluation of Debris Inside Containment.

SEQUOYAH - UNIT 1 B 3.6.16-5 Amendment

ECCS - Shutdown B 3.5.3 B 3.5 EMERGENCY CORE COOLING SYSTEMS (ECCS)

B 3.5.3 ECCS - Shutdown BASES BACKGROUND The Background section for Bases 3.5.2, "ECCS - Operating," is applicable to these Bases, with the following modifications.

In MODE 4, the required ECCS train consists of two separate subsystems: centrifugal charging (high head) and residual heat removal (RHR) (low head).

The ECCS flow paths consist of piping, valves, RHR heat exchangers, and pumps such that water from the refueling water storage tank (RWST) and the containment sump can be injected into the Reactor Coolant System (RCS) following the accidents described in Bases 3.5.2.

APPLICABLE The Applicable Safety Analyses section of Bases 3.5.2 also applies to this SAFETY Bases section.

ANALYSES Due to the stable conditions associated with operation in MODE 4 and the reduced probability of occurrence of a Design Basis Accident (DBA), the ECCS operational requirements are reduced. It is understood in these reductions that automatic safety injection (SI) actuation is not available.

In this MODE, sufficient time exists for manual actuation of the required ECCS to mitigate the consequences of a DBA.

Only one train of ECCS is required for MODE 4. This requirement dictates that single failures are not considered during this MODE of operation. The ECCS trains satisfy Criterion 3 of 10 CFR 50.36(c)(2)(ii).

LCO In MODE 4, one of the two independent (and redundant) ECCS trains is required to be OPERABLE to ensure that sufficient ECCS flow is available to the core and adequate core cooling is maintained following a DBA.

In MODE 4, an ECCS train consists of a centrifugal charging subsystem and an RHR subsystem. Each train includes the piping, instruments, and controls to ensure an OPERABLE flow path capable of taking suction from the RWST and transferring suction to the containment sump.

During an event requiring ECCS actuation, a flow path is required to provide an abundant supply of water from the RWST to the RCS via the ECCS pumps and their respective supply headers to each of the four cold leg injection nozzles. In the long term, this flow path may be switched to take its supply from the containment sump and to deliver its flow to the RCS hot and cold legs.

SEQUOYAH - UNIT 1 B 3.5.3-1 Revision 45,

ECCS - Operating B 3.5.2 BASES BACKGROUND (continued)

During low temperature conditions in the RCS, limitations are placed on the maximum number of ECCS pumps that may be OPERABLE. Refer to the Bases for LCO 3.4.12, "Low Temperature Overpressure Protection (LTOP) System," for the basis of these requirements.

The ECCS subsystems are actuated upon receipt of an SI signal. If offsite power is available, the safeguard loads start immediately in the programmed sequence. If offsite power is not available, the Engineered Safety Feature (ESF) buses shed normal operating loads and are connected to the emergency diesel generators (EDGs). Safeguard loads are then actuated in the programmed time sequence. The time delay associated with diesel starting, sequenced loading, and pump starting determines the time required before pumped flow is available to the core following a LOCA.

The active ECCS components, along with the passive accumulators, and the RWST, and the containment sump, are covered in LCO 3.5.1, "Accumulators," and LCO 3.5.4, "Refueling Water Storage Tank (RWST),"

and LCO 3.6.16, "Containment Sump," and provide the cooling water necessary to meet GDC 35 (Ref. 1).

APPLICABLE The LCO helps to ensure that the following acceptance criteria for the SAFETY ECCS, established by 10 CFR 50.46 (Ref. 2), will be met with a high level ANALYSES of probability following a LOCA:

a. 0D[LPXPIXHOHOHPHQWFODGGLQJWHPSHUDWXUHLV 2200°F,

b. MaxiPXPFODGGLQJR[LGDWLRQLV 0.17 times the total cladding thickness before oxidation,

c. Maximum hydrogen generation from a zirconium water reaction is 0.01 times the hypothetical amount generated if all of the metal in the cladding cylinders surrounding the fuel, excluding the cladding surrounding the plenum volume, were to react,

d. Core is maintained in a coolable geometry, and

e. Adequate long term core cooling capability is maintained.

The LCO also limits the potential for a post trip return to power following an MSLB event and ensures that containment temperature limits are met.

SEQUOYAH - UNIT 2 B 3.5.2-3 Revision 45, 67,

ECCS - Operating B 3.5.2 BASES SURVEILLANCE REQUIREMENTS (continued)

The ASME Code provides the activities and Frequencies necessary to satisfy the requirements.

SR 3.5.2.5 and SR 3.5.2.6 These Surveillances demonstrate that each automatic ECCS valve actuates to the required position on an actual or simulated SI signal and that each ECCS pump starts on receipt of an actual or simulated SI signal. This Surveillance is not required for valves that are locked, sealed, or otherwise secured in the required position under administrative controls.

The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.

SR 3.5.2.7 Realignment of valves in the flow path on an SI signal is necessary for proper ECCS performance. These valves have stops to allow proper positioning for restricted flow to a ruptured cold leg, ensuring that the other cold legs receive at least the required minimum flow.

The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.

SR 3.5.2.8 Periodic inspections of the containment sump suction inlet ensure that it is unrestricted and stays in proper operating condition.

The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.

SEQUOYAH - UNIT 2 B 3.5.2-9 Revision 45,

ECCS - Shutdown B 3.5.3 B 3.5 EMERGENCY CORE COOLING SYSTEMS (ECCS)

B 3.5.3 ECCS - Shutdown BASES BACKGROUND The Background section for Bases 3.5.2, "ECCS - Operating," is applicable to these Bases, with the following modifications.

In MODE 4, the required ECCS train consists of two separate subsystems: centrifugal charging (high head) and residual heat removal (RHR) (low head).

The ECCS flow paths consist of piping, valves, RHR heat exchangers, and pumps such that water from the refueling water storage tank (RWST) and the containment sump can be injected into the Reactor Coolant System (RCS) following the accidents described in Bases 3.5.2.

APPLICABLE The Applicable Safety Analyses section of Bases 3.5.2 also applies to this SAFETY Bases section.

ANALYSES Due to the stable conditions associated with operation in MODE 4 and the reduced probability of occurrence of a Design Basis Accident (DBA), the ECCS operational requirements are reduced. It is understood in these reductions that automatic safety injection (SI) actuation is not available.

In this MODE, sufficient time exists for manual actuation of the required ECCS to mitigate the consequences of a DBA.

Only one train of ECCS is required for MODE 4. This requirement dictates that single failures are not considered during this MODE of operation. The ECCS trains satisfy Criterion 3 of 10 CFR 50.36(c)(2)(ii).

LCO In MODE 4, one of the two independent (and redundant) ECCS trains is required to be OPERABLE to ensure that sufficient ECCS flow is available to the core and adequate core cooling is maintained following a DBA.

In MODE 4, an ECCS train consists of a centrifugal charging subsystem and an RHR subsystem. Each train includes the piping, instruments, and controls to ensure an OPERABLE flow path capable of taking suction from the RWST and transferring suction to the containment sump.

During an event requiring ECCS actuation, a flow path is required to provide an abundant supply of water from the RWST to the RCS via the ECCS pumps and their respective supply headers to each of the four cold leg injection nozzles. In the long term, this flow path may be switched to take its supply from the containment sump and to deliver its flow to the RCS hot and cold legs.

SEQUOYAH - UNIT 2 B 3.5.3-1 Revision 45,

Containment Sump B 3.6.16 B 3.6 CONTAINMENT SYSTEMS B 3.6.16 Containment Sump BASES BACKGROUND The containment sump provides a borated water source to support recirculation of coolant from the containment sump for residual heat removal, emergency core cooling, containment cooling, and containment atmosphere cleanup during accident conditions.

The containment sump supplies both trains of the Emergency Core Cooling System (ECCS) and the Containment Spray System (CSS) during any accident that requires recirculation of coolant from the containment sump. The recirculation mode is initiated when the pump suction is transferred to the containment sump at a level, which ensures the containment sump has enough water to supply the net positive suction head to the ECCS and CSS pumps. A single containment sump is used to supply both trains of the ECCS and CSS.

The containment sump contains strainers to limit the quantity of the debris materials from entering the sump suction piping. Debris accumulation on the strainers can lead to undesirable hydraulic effects including air ingestion through vortexing or deaeration, and reduced net positive suction head (NPSH) at pump suction piping.

While the majority of debris accumulates on the strainers, some fraction penetrates the strainers and is transported to downstream components in the ECCS, CSS, and the Reactor Coolant System (RCS). Debris that penetrates the strainer can result in wear to the downstream components, blockages, or reduced heat transfer across the fuel cladding. Excessive debris in the containment sump water source could result in insufficient recirculation of coolant during the accident, or insufficient heat removal from the core during the accident.

APPLICABLE During all accidents that require recirculation, the containment sump SAFETY provides a source of borated water to the ECCS and CSS System pumps.

ANALYSES As such, it supports residual heat removal, emergency core cooling, containment cooling, and containment atmosphere cleanup during an accident. It also provides a source of negative reactivity (Ref. 1). The design basis transients and applicable safety analyses concerning each of these systems are discussed in the Applicable Safety Analyses section of B 3.5.2, "ECCS -Operating," B 3.5.3, "ECCS - Shutdown," and B 3.6.6, "Containment Spray System.

SEQUOYAH - UNIT 2 B 3.6.16-1 Amendment

Containment Sump B 3.6.16 BASES APPLICABLE SAFETY ANALYSES (continued)

UFSAR Section 6.3.2.2 (Ref. 2) describes evaluations that confirm long term core cooling is assured following any accident that requires recirculation from the containment sump.

The containment sumps satisfy Criterion 3 of 10 CFR 50.36(c)(2)(ii).

LCO The containment sump is required to ensure a source of borated water to support ECCS and CSS OPERABILITY. A containment sump consists of the containment drainage flow paths, debris intercepting devices, a volume of lower containment formed by sealed penetrations inside the lower crane wall, the containment sump strainers, and the inlet to the ECCS and CSS piping. The piping inlet is protected by the advanced design strainers. Each strainer contains perforations to reduce the size of debris that may enter the sump. The water flows through mesh screens, which suppress vortices that may occur in the sump at the entrance to the twin recirculation pipes. Internal baffles are provided to allow the escape of air during initial filling and to prevent the formation of vortices. An OPERABLE containment sump has no structural damage or abnormal corrosion that could prevent recirculation of coolant and will not be restricted by containment accident generated and transported debris.

Containment accident generated and transported debris consists of the following:

a. Accident generated debris sources - Insulation, coatings, and other materials which are damaged by the high-energy line break (HELB) and transported to the containment sump. This includes materials within the HELB zone of influence and other materials (e.g., unqualified coatings) that fail due to the post-accident containment environment following the accident;

b. Latent debris sources - Pre-existing dirt, dust, paint chips, fines or shards of insulation, and other materials inside containment that do not have to be damaged by the HELB to be transported to the containment sump; and

c. Chemical product debris sources - Aluminum, zinc, carbon steel, copper, and non-metallic materials such as paints, thermal insulation, and concrete that are susceptible to chemical reactions within the post-accident containment environment leading to corrosion products that are generated within the containment sump pool or are generated within containment and transported to the containment sump.

SEQUOYAH - UNIT 2 B 3.6.16-2 Amendment

Containment Sump B 3.6.16 BASES LCO (continued)

Containment debris limits are defined in TVA Calculation SQNSQS20240 (Ref. 3).

APPLICABILITY In MODES 1, 2, 3, and 4, containment sump OPERABILITY requirements are dictated by the ECCS and CSS OPERABILITY requirements. Since both the ECCS and the CSS must be OPERABLE in MODES 1, 2, 3, and 4, the containment sump must also be OPERABLE to support their operation.

In MODES 5 and 6, the probability and consequences of these events are reduced due to the pressure and temperature limitations of these MODES. Thus, the containment sump is not required to be OPERABLE in MODES 5 or 6.

ACTIONS A.1, A.2, and A.3 Condition A is applicable when the containment sump is inoperable due to containment accident generated and transported debris exceeding the analyzed limits. Examples that would require entry into TS 3.6.16 Condition A include:

x Unanalyzed debris sources that are discovered inside containment x Errors that are discovered in debris-related analyses x Discovery of a previously unevaluated phenomenon that can affect containment sump performance.

Containment debris limits are defined in TVA Calculation SQNSQS20240 (Ref. 3). Immediate action must be initiated to mitigate the condition.

Examples of mitigating actions are:

x Removing the debris source from containment or preventing the debris from being transported to the containment sump; x Evaluating the debris source against the assumptions in the analysis; x Deferring maintenance that would affect availability of the affected systems and other LOCA mitigating equipment; x Deferring maintenance that would affect availability of primary defense-in-depth systems; SEQUOYAH - UNIT 2 B 3.6.16-3 Amendment

Containment Sump B 3.6.16 BASES ACTIONS (continued) x Briefing operators on LOCA debris management actions; or x Applying an alternative method to establish new limits.

While in this condition, the RCS water inventory balance, SR 3.4.13.1, must be performed at an increased Frequency of once per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. An unexpected increase in RCS leakage could be indicative of an increased potential for an RCS pipe break, which could result in debris being generated and transported to the containment sump. The more frequent monitoring allows operators to act in a timely fashion to minimize the potential for an RCS pipe break while the containment sump is inoperable.

The inoperable containment sump must be restored to OPERABLE status in 90 days. A 90-day Completion Time is reasonable for emergent conditions that involve debris in excess of the analyzed limits that could be generated and transported to the containment sump under accident conditions. The likelihood of an initiating event in the 90-day Completion Time is very small and there is margin in the associated analyses. The mitigating actions of Required Action A.1 provide additional assurance that the effects of debris in excess of the analyzed limits will be mitigated during the Completion Time.

B.1 When the containment sump is inoperable for reasons other than Condition A, such as blockage, structural damage, or abnormal corrosion that could prevent recirculation of coolant, it must be restored to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. The 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> Completion Time takes into account the reasonable time for repairs, and low probability of an accident that requires the containment sump occurring during this period.

Required Action B.1 is modified by two Notes. The first Note indicates that the applicable Conditions and Required Actions of LCO 3.5.2, "ECCS

- Operating," and LCO 3.5.3, "ECCS - Shutdown," should be entered if an inoperable containment sump results in an inoperable ECCS train. The second Note indicates that the applicable Conditions and Required Actions of LCO 3.6.6, "Containment Spray System," should be entered if an inoperable containment sump results in an inoperable CSS train. This is an exception to LCO 3.0.6 and ensures the proper actions are taken for these components.

SEQUOYAH - UNIT 2 B 3.6.16-4 Amendment

Containment Sump B 3.6.16 BASES ACTIONS (continued)

C.1 and C.2 If the containment sump cannot be restored to OPERABLE status within the associated Completion Time, the plant must be brought to a MODE in which the LCO does not apply. To achieve this status, the plant must be brought to at least MODE 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and to MODE 5 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. The allowed Completion Times are reasonable, based on operating experience, to reach the required plant conditions from full power conditions in an orderly manner and without challenging plant systems.

SURVEILLANCE SR 3.6.16.1 REQUIREMENTS Periodic inspections are performed to verify the containment sump does not show current or potential debris blockage, structural damage, or abnormal corrosion to ensure the operability and structural integrity of the containment sump (Ref. 1). The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.

REFERENCES 1. UFSAR, Chapter 6 and Chapter 15.

2. UFSAR Section 6.3.2.2, Equipment and Component Design.

3. TVA Calculation SQNSQS20240, Evaluation of Debris Inside Containment.

SEQUOYAH - UNIT 2 B 3.6.16-5 Amendment

Attachment 4 Proposed Technical Specification Bases Changes (Mark-Up) for WBN Units 1 and 2 (For Information Only)

CNL-23-028

ECCS - Operating B 3.5.2 BASES BACKGROUND The centrifugal charging subsystem of the ECCS also functions to supply (continued) borated water to the reactor core following increased heat removal events, such as a main steam line break (MSLB). The limiting design conditions occur when the negative moderator temperature coefficient is highly negative, such as at the end of each cycle.

During low temperature conditions in the RCS, limitations are placed on the maximum number of ECCS pumps that may be OPERABLE. Refer to the Bases for LCO 3.4.12, "Cold Overpressure Mitigation System (COMS)," for the basis of these requirements.

The ECCS subsystems are actuated upon receipt of an SI signal. The actuation of safeguard loads is accomplished in a programmed time sequence for a loss of offsite power. If offsite power is available, the safeguard loads start immediately.

If offsite power is not available, the Engineered Safety Feature (ESF) buses shed normal operating loads and are connected to the emergency diesel generators (EDGs). Safeguard loads are then actuated in the programmed time sequence.

The time delay associated with diesel starting, sequenced loading, and pump starting determines the time required before pumped flow is available to the core following a LOCA.

The active ECCS components, along with the passive accumulators, and the RWST, and the containment sump, are covered in LCO 3.5.1, "Accumulators,"

and LCO 3.5.4, "Refueling Water Storage Tank (RWST)," and LCO 3.6.16, "Containment Sump," and provide the cooling water necessary to meet GDC 35 (Ref. 1).

APPLICABLE The LCO helps to ensure that the following acceptance criteria for the ECCS, SAFETY ANALYSES established by 10 CFR 50.46, Paragraph b (Ref. 2), will be met with a high level of probability following a LOCA:

a. Maximum fuel element cladding temperature is d 2200°F;

b. Maximum cladding oxidation is d 0.17 times the total cladding thickness before oxidation; (continued)

Watts Bar-Unit 1 B 3.5-11 Revision 39, 176, Amendment 21, 143,

ECCS - Operating B 3.5.2 BASES SURVEILLANCE SR 3.5.2.7 REQUIREMENTS (continued) Realignment of valves in the flow path on an SI signal is necessary for proper ECCS performance. These valves are secured in a throttled position for restricted flow to a ruptured cold leg, ensuring that the other cold legs receive at least the required minimum flow. The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.

SR 3.5.2.8 Periodic inspections of the containment sump suction inlet ensure that it is unrestricted and stays in proper operating condition. The advanced sump strainer design installed at WBN incorporates both the trash rack function and the screen function. Inspection of the advanced strainer constitutes fulfillment of the trash rack/screen inspection. The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.

REFERENCES 1. Title 10, Code of Federal Regulations, Part 50, Appendix A, General Design Criterion 35, "Emergency Core Cooling System."

2. Title 10, Code of Federal Regulations, Part 50.46, "Acceptance Criteria for Emergency Core Cooling Systems for Light Water Nuclear Power Plant."

3. Watts Bar FSAR, Section 6.3, "Emergency Core Cooling System."

4. FSAR Bar FSAR, Section 15.0, "Accident Analysis."

5. NRC Memorandum to V. Stello, Jr., from R.L. Baer, "Recommended Interim Revisions to LCOs for ECCS Components," December 1, 1975.

6. IE Information Notice No. 87-01, "RHR Valve Misalignment Causes Degradation of ECCS in PWRs," January 6, 1987.

7. Deleted.

8. NEI 09-10, Revision 1a-A Guidelines for Effective Prevention and Management of System Gas Accumulation, dated April, 2013.

Watts Bar-Unit 1 B 3.5-18 Revision 54, 80, 142, 162, 165, Amendment 43, 132, 135,

Containment Sump B 3.6.16 B 3.6 CONTAINMENT SYSTEMS B 3.6.16 Containment Sump BASES BACKGROUND The containment sump provides a borated water source to support recirculation of coolant from the containment sump for residual heat removal, emergency core cooling, containment cooling, and containment atmosphere cleanup during accident conditions.

The containment sump supplies both trains of the Emergency Core Cooling System (ECCS) and the Containment Spray System (CSS) during any accident that requires recirculation of coolant from the containment sump. The recirculation mode is initiated when the pump suction is transferred to the containment sump at a level which ensures the containment sump has enough water to supply the net positive suction head to the ECCS and CSS pumps. A single containment sump is used to supply both trains of the ECCS and CSS.

The containment sump contains strainers to limit the quantity of the debris materials from entering the sump suction piping. Debris accumulation on the strainers can lead to undesirable hydraulic effects including air ingestion through vortexing or deaeration, and reduced net positive suction head (NPSH) at pump suction piping.

While the majority of debris accumulates on the strainers, some fraction penetrates the strainers and is transported to downstream components in the ECCS, CSS, and the Reactor Coolant System (RCS). Debris that penetrates the strainer can result in wear to the downstream components, blockages, or reduced heat transfer across the fuel cladding. Excessive debris in the containment sump water source could result in insufficient recirculation of coolant during the accident, or insufficient heat removal from the core during the accident.

(continued)

Watts Bar-Unit 1 B 3.6-77 Amendment

Containment Sump B 3.6.16 BASES APPLICABLE During all accidents that require recirculation, the containment sump SAFETY ANALYSES provides a source of borated water to the ECCS and CSS pumps. As such, it supports residual heat removal, emergency core cooling, containment cooling, and containment atmosphere cleanup during an accident. It also provides a source of negative reactivity (Ref. 1). The design basis transients and applicable safety analyses concerning each of these systems are discussed in the Applicable Safety Analyses section of B 3.5.2, "ECCS -Operating," B 3.5.3, "ECCS - Shutdown," and B 3.6.6, "Containment Spray System."

UFSAR Section 6.3.2.2 (Ref. 2) describes evaluations that confirm long term core cooling is assured following any accident that requires recirculation from the containment sump.

The containment sumps satisfy Criterion 3 of 10 CFR 50.36(c)(2)(ii).

LCO The containment sump is required to ensure a source of borated water to support ECCS and CSS OPERABILITY. A containment sump consists of the containment drainage flow paths, debris intercepting devices, a volume of lower containment formed by sealed penetrations inside the lower crane wall, the containment sump strainers, and the inlet to the ECCS and CSS piping. The piping inlet is protected by the advanced design strainers. Each strainer contains perforations to reduce the size of debris that may enter the sump. The water flows through mesh screens, which suppress vortices that may occur in the sump at the entrance to the twin recirculation pipes. An OPERABLE containment sump has no structural damage or abnormal corrosion that could prevent recirculation of coolant and will not be restricted by containment accident generated and transported debris.

Containment accident generated and transported debris consists of the following:

a. Accident generated debris sources - Insulation, coatings, and other materials which are damaged by the high-energy line break (HELB) and transported to the containment sump. This includes materials within the HELB zone of influence and other materials (e.g., unqualified coatings) that fail due to the post-accident containment environment following the accident;

b. Latent debris sources - Pre-existing dirt, dust, paint chips, fines or shards of insulation, and other materials inside containment that do not have to be damaged by the HELB to be transported to the containment sump; and

c. Chemical product debris sources - Aluminum, zinc, carbon steel, copper, and non-metallic materials such as paints, thermal insulation, and concrete that are susceptible to chemical reactions within the post-accident containment environment leading to corrosion products that are generated within the containment sump pool or are generated within containment and transported to the containment sump.

(continued)

Watts Bar-Unit 1 B 3.6-78 Amendment

Containment Sump B 3.6.16 BASES LCO (continued)

Containment debris limits are defined in TVA Calculations MDQ0009992014000659 (Ref. 3), ALION-CAL-TVA-2739-03 (Ref. 4), and ALION-CAL-TVA-2739-04 (Ref. 5).

APPLICABILITY In MODES 1, 2, 3, and 4, containment sump OPERABILITY requirements are dictated by the ECCS and CSS OPERABILITY requirements. Since both the ECCS and the CSS must be OPERABLE in MODES 1, 2, 3, and 4, the containment sump must also be OPERABLE to support their operation.

In MODES 5 and 6, the probability and consequences of these events are reduced due to the pressure and temperature limitations of these MODES. Thus, the containment sump is not required to be OPERABLE in MODES 5 or 6.

ACTIONS A.1, A.2, and A.3 Condition A is applicable when the containment sump is inoperable due to containment accident generated and transported debris exceeding the analyzed limits. Examples that would require entry into TS 3.6.16 Condition A include:

x Unanalyzed debris sources that are discovered inside containment x Errors that are discovered in debris-related analyses x Discovery of a previously unevaluated phenomenon that can affect containment sump performance.

Containment debris limits are defined in TVA Calculations MDQ0009992014000659 (Ref. 3), ALION-CAL-TVA-2739-03 (Ref. 4), and ALION-CAL-TVA-2739-04 (Ref. 5). Immediate action must be initiated to mitigate the condition.

Examples of mitigating actions are:

x Removing the debris source from containment or preventing the debris from being transported to the containment sump; x Evaluating the debris source against the assumptions in the analysis; x Deferring maintenance that would affect availability of the affected systems and other LOCA mitigating equipment; x Deferring maintenance that would affect availability of primary defense-in-depth systems; x Briefing operators on LOCA debris management actions; or x Applying an alternative method to establish new limits.

(continued)

Watts Bar-Unit 1 B 3.6-79 Amendment

Containment Sump B 3.6.16 BASES ACTIONS (continued)

While in this condition, the RCS water inventory balance, SR 3.4.13.1, must be performed at an increased Frequency of once per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. An unexpected increase in RCS leakage could be indicative of an increased potential for an RCS pipe break, which could result in debris being generated and transported to the containment sump. The more frequent monitoring allows operators to act in a timely fashion to minimize the potential for an RCS pipe break while the containment sump is inoperable. The inoperable containment sump must be restored to OPERABLE status in 90 days. A 90-day Completion Time is reasonable for emergent conditions that involve debris in excess of the analyzed limits that could be generated and transported to the containment sump under accident conditions. The likelihood of an initiating event in the 90-day Completion Time is very small and there is margin in the associated analyses.

The mitigating actions of Required Action A.1 provide additional assurance that the effects of debris in excess of the analyzed limits will be mitigated during the Completion Time.

B.1 When the containment sump is inoperable for reasons other than Condition A, such as blockage, structural damage, or abnormal corrosion that could prevent recirculation of coolant, it must be restored to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.

The 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> Completion Time takes into account the reasonable time for repairs, and low probability of an accident that requires the containment sump occurring during this period.

Required Action B.1 is modified by two Notes. The first Note indicates that the applicable Conditions and Required Actions of LCO 3.5.2, "ECCS - Operating,"

and LCO 3.5.3, "ECCS - Shutdown," should be entered if an inoperable containment sump results in an inoperable ECCS train. The second Note indicates that the applicable Conditions and Required Actions of LCO 3.6.6, "Containment Spray System," should be entered if an inoperable containment sump results in an inoperable CSS train. This is an exception to LCO 3.0.6 and ensures the proper actions are taken for these components.

C.1 and C.2 If the containment sump cannot be restored to OPERABLE status within the associated Completion Time, the plant must be brought to a MODE in which the LCO does not apply. To achieve this status, the plant must be brought to at least MODE 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and to MODE 5 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. The allowed Completion Times are reasonable, based on operating experience, to reach the required plant conditions from full power conditions in an orderly manner and without challenging plant systems.

(continued)

Watts Bar-Unit 1 B 3.6-80 Amendment

Containment Sump B 3.6.16 BASES SURVEILLANCE SR 3.6.16.1 REQUIREMENTS Periodic inspections are performed to verify the containment sump does not show current or potential debris blockage, structural damage, or abnormal corrosion to ensure the operability and structural integrity of the containment sump (Ref. 1). The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.

REFERENCES 1. UFSAR, Chapter 6 and Chapter 15.

2. UFSAR Section 6.3.2.2, Equipment and Component Design.

3. TVA Calculation MDQ0009992014000659, Watts Bar Evaluation of Long Term Cooling Considering Particulate, Fibrous and Chemical Debris in the Recirculating Fluid using LOCADM."

4. TVA Calculation ALION-CAL-TVA-2739-03, ALION-Watts Bar Reactor Building GSl-191 Debris Generation Calculation.

5. TVA Calculation ALION-CAL-TVA-2739-04, Watts Bar Unit 1 Reactor Building GSl-191 Debris Transport Calculation.

(continued)

Watts Bar-Unit 1 B 3.6-81 Amendment

ECCS - Operating B 3.5.2 BASES BACKGROUND The ECCS subsystems are actuated upon receipt of an SI signal. The (continued) actuation of safeguard loads is accomplished in a programmed time sequence for a loss of offsite power. If offsite power is available, the safeguard loads start immediately. If offsite power is not available, the Engineered Safety Feature (ESF) buses shed normal operating loads and are connected to the diesel generators (DGs). Safeguard loads are then actuated in the programmed time sequence. The time delay associated with diesel starting, sequenced loading, and pump starting determines the time required before pumped flow is available to the core following a LOCA.

The active ECCS components, along with the passive accumulators, and the RWST, and the containment sump, are covered in LCO 3.5.1, Accumulators, and LCO 3.5.4, Refueling Water Storage Tank (RWST),

and LCO 3.6.16, "Containment Sump," and provide the cooling water necessary to meet GDC 35 (Ref. 1).

APPLICABLE The LCO helps to ensure that the following acceptance criteria for the SAFETY ECCS, established by 10 CFR 50.46, Paragraph b (Ref. 2), will be met ANALYSES with a high level of probability following a LOCA:

a. Maximum fuel element cladding temperature is d 2200°F;

b. Maximum cladding oxidation is d 0.17 times the total cladding thickness before oxidation;

c. Maximum hydrogen generation from a zirconium water reaction is d 0.01 times the hypothetical amount generated if all of the metal in the cladding cylinders surrounding the fuel, excluding the cladding surrounding the plenum volume, were to react;

d. Core is maintained in a coolable geometry; and

e. Adequate long term core cooling capability is maintained.

The LCO also limits the potential for a post trip return to power following an MSLB event and ensures that containment temperature limits are met.

(continued)

Watts Bar - Unit 2 B 3.5-11 Revision 57, Amendment 50,

ECCS - Operating B 3.5.2 BASES SURVEILLANCE SR 3.5.2.5 and 3.5.2.6 REQUIREMENTS (continued) These Surveillances demonstrate that each automatic ECCS valve actuates to the required position on an actual or simulated SI signal and that each ECCS pump starts on receipt of an actual or simulated SI signal. This Surveillance is not required for valves that are locked, sealed, or otherwise secured in the required position under administrative control. The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.

SR 3.5.2.7 Realignment of valves in the flow path on an SI signal is necessary for proper ECCS performance. These valves are secured in a throttled position for restricted flow to a ruptured cold leg, ensuring that the other cold legs receive at least the required minimum flow. The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.

SR 3.5.2.8 Periodic inspections of the containment sump suction inlet ensure that it is unrestricted and stays in proper operating condition. The advanced sump strainer design installed at WBN incorporates both the trash rack function and the screen function. Inspection of the advanced strainer constitutes fulfillment of the trash rack/screen inspection. The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.

(continued)

Watts Bar - Unit 2 B 3.5-18 Revision 34, Amendment 36,

Containment Sump B 3.6.16 B 3.6 CONTAINMENT SYSTEMS B 3.6.16 Containment Sump BASES BACKGROUND The containment sump provides a borated water source to support recirculation of coolant from the containment sump for residual heat removal, emergency core cooling, containment cooling, and containment atmosphere cleanup during accident conditions.

The containment sump supplies both trains of the Emergency Core Cooling System (ECCS) and the Containment Spray System (CSS) during any accident that requires recirculation of coolant from the containment sump. The recirculation mode is initiated when the pump suction is transferred to the containment sump at a level which ensures the containment sump has enough water to supply the net positive suction head to the ECCS and CSS pumps. The use of a single containment sump to supply both trains of the ECCS and CSS is acceptable since the containment sump is a passive component, and passive failures are not required to be assumed to occur coincident with Design Basis Events.

The containment sump contains strainers to limit the quantity of the debris materials from entering the sump suction piping. Debris accumulation on the strainers can lead to undesirable hydraulic effects including air ingestion through vortexing or deaeration, and reduced net positive suction head (NPSH) at pump suction piping.

While the majority of debris accumulates on the strainers, some fraction penetrates the strainers and is transported to downstream components in the ECCS, CSS, and the Reactor Coolant System (RCS). Debris that penetrates the strainer can result in wear to the downstream components, blockages, or reduced heat transfer across the fuel cladding. Excessive debris in the containment sump water source could result in insufficient recirculation of coolant during the accident, or insufficient heat removal from the core during the accident.

(continued)

Watts Bar - Unit 2 B 3.6-92 Amendment

Containment Sump B 3.6.16 BASES APPLICABLE During all accidents that require recirculation, the containment sump SAFETY provides a source of borated water to the ECCS and RS System pumps.

ANALYSES As such, it supports residual heat removal, emergency core cooling, containment cooling, and containment atmosphere cleanup during an accident. It also provides a source of negative reactivity (Ref. 1). The design basis transients and applicable safety analyses concerning each of these systems are discussed in the Applicable Safety Analyses section of B 3.5.2, "ECCS -Operating," B 3.5.3, "ECCS - Shutdown," and B 3.6.6, "Containment Spray System."

UFSAR Section 6.3.2.2 (Ref. 2) describes evaluations that confirm long term core cooling is assured following any accident that requires recirculation from the containment sump.

The containment sumps satisfy Criterion 3 of 10 CFR 50.36(c)(2)(ii)

LCO The containment sump is required to ensure a source of borated water to support ECCS and CSS OPERABILITY. A containment sump consists of the containment drainage flow paths, debris intercepting devices, a volume of lower containment formed by sealed penetrations inside the lower crane wall, the containment sump strainers, and the inlet to the ECCS and CSS piping. The piping inlet is protected by the advanced design strainers. Each strainer contains perforations to reduce the size of debris that may enter the sump. The water flows through mesh screens, which suppress vortices that may occur in the sump at the entrance to the twin recirculation pipes. An OPERABLE containment sump has no structural damage or abnormal corrosion that could prevent recirculation of coolant and will not be restricted by containment accident generated and transported debris.

Containment accident generated and transported debris consists of the following:

a. Accident generated debris sources - Insulation, coatings, and other materials which are damaged by the high-energy line break (HELB) and transported to the containment sump. This includes materials within the HELB zone of influence and other materials (e.g.,

unqualified coatings) that fail due to the post-accident containment environment following the accident;

b. Latent debris sources - Pre-existing dirt, dust, paint chips, fines or shards of insulation, and other materials inside containment that do not have to be damaged by the HELB to be transported to the containment sump; and (continued)

Watts Bar - Unit 2 B 3.6-93 Amendment

Containment Sump B 3.6.16 BASES LCO (continued) c. Chemical product debris sources - Aluminum, zinc, carbon steel, copper, and non-metallic materials such as paints, thermal insulation, and concrete that are susceptible to chemical reactions within the post-accident containment environment leading to corrosion products that are generated within the containment sump pool or are generated within containment and transported to the containment sump.

Containment debris limits are defined in TVA Calculations MDQ0009992014000659 (Ref. 3), ALION-CAL-TVA-2739-03 (Ref. 4),

and ALION-CAL-TVA-2739-04 (Ref. 5).

APPLICABILITY In MODES 1, 2, 3, and 4, containment sump OPERABILITY requirements are dictated by the ECCS and CSS OPERABILITY requirements. Since both the ECCS and the CSS must be OPERABLE in MODES 1, 2, 3, and 4, the containment sump must also be OPERABLE to support their operation.

In MODES 5 and 6, the probability and consequences of these events are reduced due to the pressure and temperature limitations of these MODES. Thus, the containment sump is not required to be OPERABLE in MODES 5 or 6.

ACTIONS A.1, A,2, and A.3 Condition A is applicable when the containment sump is inoperable due to containment accident generated and transported debris exceeding the analyzed limits. Examples that would require entry into TS 3.6.16 Condition A include:

x Unanalyzed debris sources that are discovered inside containment x Errors that are discovered in debris-related analyses x Discovery of a previously unevaluated phenomenon that can affect containment sump performance.

Containment debris limits are defined in TVA Calculations MDQ0009992014000659 (Ref. 3), ALION-CAL-TVA-2739-03 (Ref. 4),

and ALION-CAL-TVA-2739-04 (Ref. 5). Immediate action must be initiated to mitigate the condition.

Examples of mitigating actions are:

x Removing the debris source from containment or preventing the debris from being transported to the containment sump; (continued)

Watts Bar - Unit 2 B 3.6-94 Amendment

Containment Sump B 3.6.16 BASES ACTIONS x Evaluating the debris source against the assumptions in the analysis; (continued) x Deferring maintenance that would affect availability of the affected systems and other LOCA mitigating equipment; x Deferring maintenance that would affect availability of primary defense-in-depth systems; x Briefing operators on LOCA debris management actions; or x Applying an alternative method to establish new limits.

While in this condition, the RCS water inventory balance, SR 3.4.13.1, must be performed at an increased Frequency of once per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. An unexpected increase in RCS leakage could be indicative of an increased potential for an RCS pipe break, which could result in debris being generated and transported to the containment sump. The more frequent monitoring allows operators to act in a timely fashion to minimize the potential for an RCS pipe break while the containment sump is inoperable.

The inoperable containment sump must be restored to OPERABLE status in 90 days. A 90-day Completion Time is reasonable for emergent conditions that involve debris in excess of the analyzed limits that could be generated and transported to the containment sump under accident conditions. The likelihood of an initiating event in the 90-day Completion Time is very small and there is margin in the associated analyses. The mitigating actions of Required Action A.1 provide additional assurance that the effects of debris in excess of the analyzed limits will be mitigated during the Completion Time.

B.1 When the containment sump is inoperable for reasons other than Condition A, such as blockage, structural damage, or abnormal corrosion that could prevent recirculation of coolant, it must be restored to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. The 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> Completion Time takes into account the reasonable time for repairs, and low probability of an accident that requires the containment sump occurring during this period.

Required Action B.1 is modified by two Notes. The first Note indicates that the applicable Conditions and Required Actions of LCO 3.5.2, "ECCS

- Operating," and LCO 3.5.3, "ECCS - Shutdown," should be entered if an inoperable containment sump results in an inoperable ECCS train. The second Note indicates that the applicable Conditions and Required Actions of LCO 3.6.6, "Containment Spray System," should be entered if an inoperable containment sump results in an inoperable CSS train. This is an exception to LCO 3.0.6 and ensures the proper actions are taken for these components.

(continued)

Watts Bar - Unit 2 B 3.6-95 Amendment

Containment Sump B 3.6.16 BASES ACTIONS C.1 and C.2 (continued)

If the containment sump cannot be restored to OPERABLE status within the associated Completion Time, the plant must be brought to a MODE in which the LCO does not apply. To achieve this status, the plant must be brought to at least MODE 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and to MODE 5 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. The allowed Completion Times are reasonable, based on operating experience, to reach the required plant conditions from full power conditions in an orderly manner and without challenging plant systems.

SURVEILLANCE SR 3.6.16.1 REQUIREMENTS Periodic inspections are performed to verify the containment sump does not show current or potential debris blockage, structural damage, or abnormal corrosion to ensure the operability and structural integrity of the containment sump (Ref. 1). The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.

REFERENCES 1. UFSAR, Chapter 6 and Chapter 15.

2. UFSAR Section 6.3.2.2, Equipment and Component Design.

3. TVA Calculation MDQ0009992014000659, Watts Bar Evaluation of Long Term Cooling Considering Particulate, Fibrous and Chemical Debris in the Recirculating Fluid using LOCADM."

4. TVA Calculation ALION-CAL-TVA-2739-03, ALION-Watts Bar Reactor Building GSl-191 Debris Generation Calculation.

5. TVA Calculation ALION-CAL-TVA-2739-04, Watts Bar Unit 1 Reactor Building GSl-191 Debris Transport Calculation.

Watts Bar - Unit 2 B 3.6-96 Amendment