CNL-17-044, Response to Request for Additional Information Related to License Amendment Request to Revise Technical Specification 3.7.12, Auxiliary Building Gas Treatment System (Abgts), for Watts Bar Nuclear Plant, Units 1 and 2

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Response to Request for Additional Information Related to License Amendment Request to Revise Technical Specification 3.7.12, Auxiliary Building Gas Treatment System (Abgts), for Watts Bar Nuclear Plant, Units 1 and 2
ML17125A244
Person / Time
Site: Watts Bar  Tennessee Valley Authority icon.png
Issue date: 05/05/2017
From: James Shea
Tennessee Valley Authority
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
CNL-17-044
Download: ML17125A244 (50)
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Text

Tennessee Valley Authority, 1101 Market Street, Chattanooga, Tennessee 37402 CNL-17-044 May 5, 2017 10 CFR 50.90 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Watts Bar Nuclear Plant, Unit 1 Facility Operating License No. NPF-90 NRC Docket No. 50-390 Watts Bar Nuclear Plant, Unit 2 Facility Operating License No. NPF-96 NRC Docket No. 50-391

Subject:

Response to Request for Additional Information Related to License Amendment Request To Revise Technical Specification 3.7.12, Auxiliary Building Gas Treatment System (ABGTS), for Watts Bar Nuclear Plant, Units 1 and 2 (CAC Nos. MF8526 and MF8527)

Reference:

1. TVA Letter to NRC, CNL-16-141, Application to Modify Watts Bar Nuclear Plant Units 1 and 2 Technical Specifications Regarding Intermittent Opening of the Auxiliary Building Secondary Containment Closure Technical Specification 3.7.12, Auxiliary Building Gas Treatment System (WBN-TS-16-19), dated October 20, 2016 (ML16294A551)
2. NRC Electronic Mail to TVA, Watts Bar, Units 1 and 2 - Final Request for Additional Information Concerning Request to Amend ABGTS TS (CAC Nos. MF8526 and MF8527), dated March 16, 2017 In Reference 1, Tennessee Valley Authority (TVA) submitted a request for an amendment to the Watts Bar Nuclear Plant (WBN) Unit 1 and Unit 2 Technical Specifications (TS) to revise TS 3.7.12, Auxiliary Building Gas Treatment System (ABGTS), to provide an action when both trains of the ABGTS are inoperable due to the auxiliary building secondary containment enclosure (ABSCE) boundary being inoperable. The proposed license amendment request (LAR) also adds a Note to the TS Limiting Condition for Operation (LCO) that allows the ABSCE boundary to be opened intermittently under administrative controls, consistent with NUREG-1431, Standard Technical Specifications - Westinghouse Plants. In Reference 2, the Nuclear Regulatory Commission (NRC) transmitted a request for additional information (RAI).

U.S. Nuclear Regulatory Commission CNL-17-044 Page 2 May 5, 2017 to this letter provides the TVA response to the RAI. As noted in Enclosure 1, Attachments 1 and 2 to Enclosure 2 provide the revised WBN Unit 1 and Unit 2 TS 3.7.12 pages marked-up to show the proposed changes, respectively. Attachments 3 and 4 to provide the revised WBN Unit 1 and Unit 2 TS 3.7.12 Bases pages marked-up to show the proposed changes, respectively. Attachments 5 and 6 to Enclosure 2 provide the revised WBN Unit 1 and Unit 2 TS pages retyped to show the proposed changes, respectively. Attachments 7 and 8 to Enclosure 2 provide the revised WBN Unit 1 and Unit 2 TS Bases pages retyped to show the proposed changes, respectively. The revised TS and TS Bases pages in Attachments 1 though 8 supersede those submitted in Reference 1. Changes to the existing TS Bases are provided for information only and will be implemented under the Technical Specification Bases Control Program. Enclosure 3 also provides a summary of the calculation in support of the changes to the revised WBN Unit 1 and Unit 2 TS 3.7.12.

These responses do not change the no significant hazards considerations determination contained in Reference 1. The WBN Plant Operations Review Committee and the TVA Nuclear Safety Review Board have reviewed the proposed TS changes in Enclosure 2 and determined that operation of WBN Unit 1 and Unit 2 in accordance with the proposed change will not endanger the health and safety of the public.

There are no new regulatory commitments associated with this submittal. Please address any questions regarding this response to Ed Schrull at 423-751-3850.

I declare under penalty of perjury that the foregoing is true and correct. Executed on this 5th day of May 2017.

Respectfully, J. W . Shea Vice President, Nuclear Licensing Enclosures cc (see Page 3)

U.S. Nuclear Regulatory Commission CNL-17-044 Page 3 May 5, 2017

Enclosures:

1. Response to Request for Additional Information Related to License Amendment Request To Revise Technical Specification 3.7.12, Auxiliary Building Gas Treatment System (ABGTS), for Watts Bar Nuclear Plant, Units 1 and 2 (CAC Nos. MF8526 and MF8527)
2. Revised Technical Specification 3.7.12 and Bases for Watts Bar Nuclear Plant, Units 1 and 2
3. Summary of TVA Calculation MDQ0000302014000618 cc (Enclosures):

NRC Regional Administrator - Region II NRC Senior Resident Inspector - Watts Bar Nuclear Plant NRR Project Manager - Watts Bar Nuclear Plant

Enclosure 1 Response to Request for Additional Information Related to License Amendment Request To Revise Technical Specification 3.7.12, Auxiliary Building Gas Treatment System (ABGTS), for Watts Bar Nuclear Plant, Units 1 and 2 (CAC Nos. MF8526 and MF8527)

Nuclear Regulatory Commission (NRC) Introduction By letter dated October 20, 2016, (Agencywide Documents Access and Management System Accession Number ML16294A551), Tennessee Valley Authority (TVA), the licensee, proposed changes to the Watts Bar Nuclear Plant (WBN), Units 1 and 2, technical specifications (TSs). The proposed changes would revise WBN TS 3.7.12, Auxiliary Building Gas Treatment System (ABGTS), to provide an action when both trains of the ABGTS are inoperable due to the auxiliary building secondary containment enclosure boundary being inoperable.

During the Nuclear Regulatory Commission (NRC) staffs review of the impact of the proposed changes on all DBAs currently analyzed in the WBN updated final safety analysis report (UFSAR) that could have the potential for significant dose consequences per Regulatory Guide (RG) 1.195 and 1.183, the NRC staff determined that more information was needed to complete the review.

NRC Request for Additional Information (RAI) ARCB-RAI-1 In the application a proposed change adds a Note to TS Limiting Condition of Operation (LCO) 3.7.12, Auxiliary Building Gas Treatment System (ABGTS). The proposed Note states, The Auxiliary Building Secondary Containment Enclosure (ABSCE) boundary may be opened intermittently under administrative control.

In addition, the proposed change adds the following sentences to TS 3.7.12 LCO Bases.

The LCO is modified by a Note allowing the ABSCE boundary to be opened intermittently under administrative controls. For entry and exit through doors the administrative control of the opening is performed by the person(s) entering or exiting the area. For other openings, these controls consist of stationing a dedicated individual at the opening who is in continuous communication with the control room. This individual will have a method to rapidly close the opening when a need for auxiliary building isolation is indicated.

Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Section 50.36 requires the technical specifications be derived from the analyses and evaluation included in the safety analysis report.

Section 15.5.3 of the WBN Updated Final Safety Analysis Report (UFSAR) contains the analysis of the environmental consequences of a postulated Loss of Coolant Accident (LOCA). This analysis assumes that activity leaking to the Auxiliary Building is directly released to the environment for the first four minutes, after which it is held up for 0.3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> and then released through the ABGTS filter system.

CNL-17-044 E1-1 of 10

Enclosure 1 The proposed LCO note to TS 3.7.12 described above is not consistent with the environmental consequences of a LOCA licensing basis for WBN, which assumes the ABSCE boundary is established with a negative internal pressure within 4 minutes after occurrence of a LOCA. The proposed note allows the ABSCE boundary to be opened for an indefinite length of time, in addition to its unlimited use. Furthermore, the referenced administrative control is not defined in the operating license or proposed TS for WBN. The administrative control is discussed in the TS Bases. The TS Bases should describe or clarify the TS; the TS bases are not allowed to change the TS. The proposed TS 3.7.12 Bases state requirements for TS 3.7.12 and therefore the TS 3.7.12 Bases are changing the TS.

Therefore, the NRC staff requests TVA to provide the following:

  • a proposed change to TS 3.7.12 that is consistent with the NRC-approved design basis as reflected in the UFSAR Section 15.5.3, Environmental Consequences of a LOCA analysis, and

TVA Response:

As requested by the NRC and shown in Enclosure 2, the new Note to the LCO for WBN Unit 1 and Unit 2 TS 3.7.12, as proposed in the referenced letter, will be revised as follows (changes shown in bold italics) for consistency with the design bases in WBN dual-unit UFSAR Section 15.5.3:

The Auxiliary Building Secondary Containment Enclosure (ABSCE) boundary may be opened intermittently under administrative controls that ensure the ABSCE can be closed consistent with the safety analysis.

Furthermore, as shown in Enclosure 2, the change to WBN Unit 1 and Unit 2 TS 3.7.12 Bases, LCO Section, as proposed in the referenced letter, will be revised as follows (changes shown in bold italics) for consistency with the design bases in WBN dual-unit UFSAR Section 15.5.3:

The LCO is modified by a Note allowing the ABSCE boundary to be opened intermittently under administrative controls that ensure the ABSCE can be closed consistent with the safety analysis. For entry and exit through doors, the administrative control of the opening is performed by the person(s) entering or exiting the area. For other openings, these controls are proceduralized and consist of stationing a dedicated individual at the opening who is in continuous communication with the control room. This individual will have a method to rapidly close the opening when a need for auxiliary building isolation is indicated.

The ABSCE boundary must be able to be restored within four minutes (including the time for restoration of the ABSCE boundary and drawdown) in accordance with UFSAR Section 15.5.3.

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Enclosure 1 NRC ARCB-RAI 2 WBN current TS 3.7.12 requires the plant to be in hot standby (mode 3) in six hours and in cold shutdown (mode 5) in 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> if both ABGTS trains are inoperable for any reason. In this license amendment request (LAR) a new Condition B is proposed which will address both trains of ABGTS being inoperable due to the ABSCE boundary being inoperable and would allow 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to restore the ABSCE boundary and therefore restore operability to both ABGTS trains. Section 3.2 "Technical Analysis," of the LAR states:

During the period that the ABSCE boundary is inoperable, appropriate compensatory measures will be utilized. The preplanned measures will be available to address these concerns for intentional and unintentional entry into proposed new LCO 3.7.12 Condition B. TVA will have approved written procedures in place that describe the compensatory measures to be taken in the event of an intentional or unintentional entry into LCO 3.7.12 Condition B. The procedures will provide appropriate, preplanned compensatory measures consistent with the intent, as applicable, of

[Generic Design Criteria] GDCs 19, 60, and 64 and 10 CFR Part 100 to protect plant personnel from potential hazards such as radioactive contamination, toxic chemicals, smoke, temperature and relative humidity, and physical security (see Enclosure 2).

The proposed 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> completion time is reasonable based on the low probability of a DBA occurring during this period and the use of preplanned compensatory measures.

Reasonable assurance of adequate protection cannot be based solely on the probability of the accident occurring. With both trains of ABGTS inoperable, the plant is in an unanalyzed condition because the radiological consequence analysis for LOCA does not show that the limits of the 10 CFR 100 and GDC 19 of 10 CFR 50 Appendix A can be met without operation of the ABGTS. This proposal will allow the plant to remain in modes 1, 2, 3, or 4 for an additional 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> before requiring the plant to be placed in cold shutdown or mode 5. However, the technical analysis section of the LAR does not provide reasonable assurance that adequate protection will be maintained without the ABGTS and that the limits in GDC 19 of 10 CFR 50 Appendix A and 10 CFR 100 will be met by use of compensatory measures. The conclusion section of the LAR states that the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> time limit to restore the inoperable boundary is based on the availability of compensatory measures and the low probability of an accident occurring during the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> periods that the ABGTS trains are inoperable, and TVA concludes that the proposed change is acceptable and complies with applicable regulatory requirements. However, there is no information presented to support this conclusion. Therefore, please:

1. Explain what compensatory measures will be used when the ABSCE boundary is inoperable and in what document they are located; and
2. Explain how the requirements of 10 CFR 100 and GDC 19 of 10 CFR 50 Appendix A are met using these compensatory measures.

In addition, if compensatory measures are relied upon as the safety basis for the proposed change then they must be either a condition of the license or be incorporated into the TS, not the TS Bases.

CNL-17-044 E1-3 of 10

Enclosure 1

3. Please provide a license condition or proposed TS change that requires immediate use of the compensatory measures.

TVA Response

1. During the period the ABSCE is inoperable, appropriate compensatory measures (consistent with the intent, as applicable, of GDC 19, 60, 61, 63, 64 and 10 CFR Part 100) will be taken to protect plant personnel from potential hazards such as radioactive contamination, toxic chemicals, smoke, temperature and relative humidity, and physical security. This could include limiting the size of the opening until repairs are made (e.g., covering the opening with plywood, steel plates, foam, or thaxton plugs),

limiting access to the opening, or protective measures for personnel [e.g., self-contained breathing apparatus (SCBA)]. As committed to in Enclosure 2 of the referenced letter, TVA will have written procedures describing compensatory measures to be taken in the event of an intentional or unintentional entry into TS 3.7.12 Condition B. The following response refers to the administrative controls for the proposed Note in TS 3.7.12.

As noted in the referenced letter, the proposed Note in TS 3.7.12 eliminates the need to enter LCO 3.7.12 when the ABSCE boundary is opened intermittently under administrative controls. This action is needed when one unit is operating and the other unit is shutdown. Without the proposed TS 3.7.12 change of adding the Note to intermittently open the ABSCE boundary under administrative controls, the unit in Mode 1, 2, 3, or 4 may be forced into an unnecessary shutdown in order to open the ABSCE boundary. When the ABSCE boundary is open under administrative controls, the ABSCE boundary must be capable of being restored and a negative 1/4-inch water gauge (-0.25 in. WG) achieved within four minutes consistent with the design basis. If the ABSCE boundary cannot be restored within this time frame, the affected unit would enter the proposed Condition B of TS 3.7.12.

In accordance with TVA procedure TI-65, Breaching the Containment Annulus, ABSCE, or MCRHZ Pressure Boundaries, a breach tracking permit (BTP) is used to control any planned breach entries of the ABSCE boundary. Additionally, ABSCE boundary breaches are logged and tracked using a breach permit tracking log. This log includes the breach open area (BOA), the start and stop times for the breach, and the BTP number.

The proposed Note in TS 3.7.12 applies to any breach of the ABSCE that will exceed the total allowable breach area for the ABSCE. The total allowable breach area for operability of the ABSCE boundary (approximately 150 in2) is derived from ABSCE pressure testing and assures the required pressure criteria of -0.25 in. WG is maintained 1. The maximum allowable breach area is adjusted based on the ABGTS 1

The maximum ABSCE breach margin is calculated in accordance with Appendix F to TI-65. The breach margin value is not static, but changes based on SR 3.7.12.4 ABGTS testing, performed on an 18 month staggered test basis. As noted in Section 4.6 of TVA System Description Document (SDD) N3-30AB-4001, The maximum allowable building infiltration (inleakage) rate is 7,930 cubic feet per minute (cfm). For ABSCE in-leakage tests, the vacuum relief makeup air flow will be verified as 1,370 cfm, which will ensure that maximum ABSCE inleakage is not exceeded. The difference between the actual measured value and 1,370 cfm will provide the margin for breaching permits during plant operation. The ABSCE breach margin is recorded on the ABSCE breach permit tracking log in accordance with TI-65.

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Enclosure 1 surveillance testing results. In accordance with TI-65, the following administrative controls are used for ABSCE breaches in excess of the total allowable breach area for the ABSCE:

  • The breach opening can be closed at all times within two minutes of notification from the main control room (MCR). This allows sufficient time to be able to drawdown the ABSCE to -0.25 in. WG within four minutes.
  • Operations personnel are briefed on the breach location, duration of the administrative controls, personnel location in the field to close the breach, and method of communication.
  • Individuals associated with the breach are briefed to ensure they understand their roles and responsibilities.
  • Individuals performing the administrative actions are stationed at both the breach location and in the MCR and clear communications are established.
  • Non-routine ABSCE boundary breaches require that a mock-up be performed prior to the entry to ensure that the breach can be restored within two minutes.
  • Means to restore the breach, if required, are staged (e.g., blind flanges, foam penetrations, fabric roll-up doors).
  • Attachment 5 to TI-65 ensures the administrative controls are in place prior to opening the breach and requires a senior reactor operator approval to commence work.
2. TVA performed a calculation that determined the time needed to restore the ABSCE boundary following a LOCA before exceeding the 10 CFR 100 and 10 CFR 50 Appendix A, GDC 19 limits without crediting any compensatory measures. TVA calculated the offsite Exclusion Area Boundary (EAB), Low Population Zone (LPZ), and MCR doses without the ABSCE established following a LOCA. This calculation used the same computer models as was used for the NRC-approved design basis LOCA described in UFSAR Section 15.3.3. The results of this calculation determined that the ABSCE boundary could be inoperable indefinitely without 10 CFR 100 limits being exceeded. However, the calculation determined that the ABSCE boundary can only be inoperable for up to six hours following a LOCA without exceeding the limits of 10 CFR 50 Appendix A, GDC 19. Six hours is more than enough time to take appropriate actions to ensure 10 CFR 50 Appendix A, GDC 19 limits are not exceeded (e.g., requiring MCR personnel to don SCBAs). A summary of this calculation is provided in Enclosure 3.
3. As requested by the NRC and as shown in Enclosure 2, the new Condition B to WBN Unit 1 and Unit 2 TS 3.7.12, as proposed in the referenced letter, will be revised to include new Required Action B.1 to require an immediate initiation of the compensatory measures as originally proposed in the Bases for TS 3.7.12, Condition B. Accordingly, a new Required Action B.2 has also been added to WBN Unit 1 and Unit 2 TS 3.7.12 to verify within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> that the mitigating actions ensure MCR occupants do not exceed 10 CFR 50 Appendix A, GDC 19 limits. Corresponding changes have also been made to the Bases for TS 3.7.12, Condition B. The 24-hour Completion Time is reasonable based on the low probability of a design basis accident (DBA) occurring during this time period, and the use of mitigating actions. The proposed changes to WBN Unit 1 and Unit 2 TS 3.7.12 are similar to WBN Unit 1 and Unit 2 TS 3.7.10, CREVS.

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Enclosure 1 Because of the NRC requested change to modify TS 3.7.12, Condition B, to require immediate use of the compensatory measures as described in the proposed Bases for TS 3.7.12, TVA is also proposing to revise the Completion Time for proposed Required Action B.3 from 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to seven days when two ABGTS trains are inoperable due to inoperable ABSCE boundary. As noted in the response to item 2 of this RAI, TVA performed a calculation that determined the time needed to restore the ABSCE boundary following a LOCA before exceeding the 10 CFR 100 and 10 CFR 50 Appendix A, GDC 19 limits without crediting any compensatory measures. The results of this calculation determined that there is adequate time before limits are exceeded to implement compensatory measures. This calculation has also been added as a reference to the proposed TS 3.7.12 Bases in Enclosure 2. Therefore, the seven-day Completion Time is reasonable based on the determination that the mitigating actions will ensure protection of MCR occupants within analyzed limits while limiting the probability that MCR occupants will have to implement protective measures that may adversely affect their ability to control the reactor and maintain it in a safe shutdown condition in the event of a DBA.

NRC ARCB-RAI 3 The licensee states in the amendment request:

In order to support normal operation, short duration events (e.g., venting operations, test evolutions, fire damper testing, annulus entries), penetration openings, and auxiliary building (AB) isolations may be required. These events have been analyzed and do not exceed Title 10 of the Code of Federal Regulations (10 CFR)

Part 100 limits for offsite dose and 10 CFR Part 50, Appendix A, General Design Criterion (GDC) 19 for the control room dose.

It is not clear to the NRC staff which events have been analyzed that support the addition of the new Condition B. Please clarify the statement above, identifying which events have been analyzed, and explain the details of the analysis performed for each event showing that the 10 CFR Part 100 and 10 CFR Part 50, Appendix A, GDC 19 limits are not exceeded.

TVA Response The short duration events referred to in the RAI and the referenced letter were intended to apply to those events whereby the ABSCE would be open under administrative controls.

While these specific events were not analyzed, as noted in the response to item 2 of the response to NRC ARCB RAI-2, TVA performed a bounding calculation with the ABSCE boundary inoperable following a LOCA to address the limits of 10 CFR Part 100 and 10 CFR Part 50, Appendix A, GDC 19. It should be noted that the examples listed of short duration events in the referenced letter are not entirely correct. The short duration events that apply to ASBCE openings include door openings, fire damper testing and inspections, and damper strokes. See the response to NRC ARCB-RAI 2, item 3 regarding further information on the basis for the Completion Time for the revised Condition B.

Additionally, as part of developing these RAI responses, TVA proactively re-evaluated the cited precedent regarding Amendment 136 for NextEra Energy Seabrook, LLCs Seabrook Station, Unit 1, and determined that the NRC RAIs regarding that amendment should have been addressed in the referenced letter.

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Enclosure 1 NRC SPBP-RAI 1 The LAR proposes two changes to the TSs. One of the changes proposes to revise LCO 3.7.12 by adding a note stating The Auxiliary Building Secondary Containment Enclosure (ABSCE) boundary may be opened intermittently under administrative control. The second change adds a new Condition B to specify Required Action with a completion Time of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to restore an inoperable ABSCE boundary to operable status. Based on the discussion provided in the LAR (e.g. Sections 2.2 and 3.2 of Enclosure 1):

  • The intent of the new Condition B is to support normal operation, short duration events (e.g. venting operations, test evolutions, fire damper testing, annulus entries).

The proposed Condition B would allow the completion time for restoration of the ABSCE boundary to be extended to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, significantly reducing the potential to enter LCO 3.7.12, Condition C (Condition B under the current TS).

Please provide a brief synopsis of how many entries into current LCO 3.7.12, Condition B resulted under the current TS in the last 5 years and if they proceeded into unnecessary shutdowns.

  • The intent of the new note under LCO 3.7.12 is to allow normal personnel entry and exit through the doors, and to allow breaches through the ABSCE boundary above those limits applied on a normal basis (i.e. 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> as a result of new Condition B) during refueling and maintenance outage activities such as ice blowing activities. All the associated breaches will be handled by administrative procedures. Additionally, the new note will also be used during future replacement of WBN Unit 2 steam generators. Section 2.2 of Enclosure 1 to the LAR states Otherwise with the proposed changes, intermittent opening of the ABSCE boundary under administrative controls will be allowed in Modes 1, 2, 3, and 4 without entering LCO 3.7.12. This note could be interpreted to allow indefinite breaching of the ABSCE boundary (i.e., in excess of the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> limitation imposed as a result of new Condition B).
1) Please provide additional information about the frequency and duration of the expected ABSCE boundary breaches to support the work activities as stated in the LAR, and the extent of control the proposed TS may have on the frequency and duration of the breaches.
2) Please provide appropriate licensing basis changes to limit the application of the new note to short duration breaches of the ABSCE boundary (i.e., not to exceed the 24-hour period permitted by proposed new Condition B).
3) SR 3.7.2.4 requires to "Verify one ABGTS train can maintain a pressure between 0.25 and 0.5 inches water gauge with respect to atmospheric pressure during the post-accident mode of operation at a flow rate 9300 and 9900 cfm". Is there any drawdown test applicable to the ABGTS to pull the ABSCE to a minimum vacuum?

Please provide available data to verify the capability of ABGTS to establish a negative pressure in the ABSCE (see item 2 above) and discuss the margins embedded in that data.

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Enclosure 1 TVA Response

1. NRC requested TVA provide a brief synopsis of how many entries into current LCO 3.7.12, Condition B resulted under the current TS in the last five years and if they proceeded into unnecessary shutdowns. There have been no official entries into current LCO 3.7.12, Condition B for either WBN Unit 1 or Unit 2 under the current TS in the last five years. On March 17, 2016, TVA initially informed the NRC of an entry into TS 3.0.3 and TS 3.7.12 Condition B for ABGTS for WBN Unit 1. This notification was a result of both trains of the emergency gas treatment system (EGTS) and ABGTS being declared inoperable when the train A auxiliary air system cooling water supply bypass valve was isolated, prior to completing the requisite post maintenance testing following repairs to the normal cooling water supply solenoid valve. At the time the condition was recognized, train B EGTS and train B ABGTS were inoperable for scheduled maintenance. On March 17, 2016, at 0133, the train A auxiliary air compressor was declared inoperable, and TS LCO 3.0.3 and 3.7.12 Condition B were entered.

Approximately 20 minutes later, the train A auxiliary air compressor was declared operable, and TS LCO 3.0.3 and TS 3.7.12 Condition B were exited. WBN Unit 1 remained in Mode 1 at 100% power and no safety functions were required during the event.

Subsequently, TVA retracted this notification on April 19, 2016, following post maintenance testing of the train A auxiliary air system ERCW normal supply solenoid valve, which determined that the valve was operable and capable of performing its safety function. Therefore, entry into TS LCO 3.0.3 and 3.7.12 Condition B was not necessary.

2. NRC requested TVA provide additional information about the frequency and duration of the expected ABSCE boundary breaches to support the work activities as stated in the LAR, and the extent of control the proposed TS may have on the frequency and duration of the breaches. ABSCE boundary breaches are generally expected to occur during plant outages. For example, during the current WBN1 RFO14 outage there have been three breaches of the ABSCE boundary (approximately one week each) that would have necessitated the use of administrative controls in accordance with the proposed Note to TS 3.7.12. The steam generator replacement activity for WBN Unit 2 (as noted in the referenced letter this activity is tentatively scheduled during RFO 4 in 2022, but could occur as early as 2019 during RFO 2) will require a single breach manned for approximately one to two months. However, the breach (e.g., a roll-up door) will only be opened when needed to move equipment or personnel into the area. The TS 3.7.12 Condition B would apply to those breaches where the maximum allowable breach area is expected to be exceeded and the ABSCE boundary cannot be restored to design limits within four minutes (e.g., a fire damper inspection where an individual is inside a section of duct work).
3. NRC requested TVA provide appropriate licensing basis changes to limit the application of the new note to short duration breaches of the ABSCE boundary. See the response to RAI ARCB-RAI-1 regarding the licensing basis changes associated with the proposed Note for TS 3.7.12.
4. NRC requested TVA provide available data, in accordance with SR 3.7.2.4, to verify the capability of ABGTS to establish a negative pressure in the ABSCE and discuss the margins embedded in that data (the correct reference is SR 3.7.12.4). The results of a review of the performance of surveillance instructions (SIs) for this SR over the past CNL-17-044 E1-8 of 10

Enclosure 1 six years are provided in Table 1. As shown in Table 1, the differential pressure and the flowrates were within the margins of SR 3.7.12.4 (i.e., between -0.25 and -0.5 in. WG and between 9300 and 9900 cfm). Additionally, NRC asked if there is a drawdown test applicable to the ABGTS to pull the ABSCE to a minimum vacuum. The drawdown test is performed as part of the SIs for SR 3.7.12.4 and includes documenting the time required to drawdown the ABSCE to -0.25 in. WG, as shown in Table 1.

Reference TVA Letter to NRC, CNL-16-141, Application to Modify Watts Bar Nuclear Plant Units 1 and 2 Technical Specifications Regarding Intermittent Opening of the Auxiliary Building Secondary Containment Closure Technical Specification 3.7.12, Auxiliary Building Gas Treatment System (WBN-TS-16-19), dated October 20, 2016 (ML16294A551)

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Enclosure 1 Table 1 SR 3.7.12.4 Results for the ABGTS Differential Pressure Drawdown Flowrate Train Date Reading Time 2 (cfm)

(in. WG) (sec)

B 1/19/2016 -0.37 9610 31 A 1/15/16 -0.37 9353 39 B 6/17/2015 -0.32 9411 10 B 9/5/2013 -0.39 9341 10 A 7/10/2013 -0.36 9369.5 23 A 2/8/2013 -0.30 9318.0 0 A 1/19/2012 -0.31 9313.0 0 B 4/4/2011 -0.38 9879 0 2

The normal 18-month ABGTS pressure tests SI performs a drawdown time of the ABSCE boundary. This drawdown test is performed under normal plant conditions when the AB is being maintained slightly negative (required by the UFSAR) by general ventilation, approximately -0.31 in.

to -0.37 in. WG. An AB isolation (ABI) is initiated and isolates the non-safety related fans, closes all the associated train ABSCE boundary dampers, and starts the associated train of ABGTS. The drawdown time starts when the ABI is initiated and stops when the AB pressure is more negative than

-0.28 in. WG. Depending on initial AB pressures being maintained by general ventilation, the AB pressures, in some cases, do not go below the minimum required pressure (-0.28 in. WG), hence the zero seconds for SI performances on February 8, 2013, January 19, 2012, and April 4, 2011. The pressure tests on January 19, 2016 and January 15, 2016, performed the post-maintenance test for including the WBN Unit 2 reactor building within the ABSCE boundary. These two pressure tests performed an initial drawdown test from zero in. WG to -0.28 in. WG to ensure the drawdown times are met from zero in. WG.

CNL-17-044 E1-10 of 10

Enclosure 2 Revised Technical Specification Surveillance 3.7.12 and Bases for Watts Bar Nuclear Plant, Units 1 and 2 Attachment 1 Proposed TS Changes (Mark-Ups) for WBN Unit 1 CNL-17-044

ABGTS 3.7.12 3.7 PLANT SYSTEMS 3.7.12 Auxiliary Building Gas Treatment System (ABGTS)

LCO 3.7.12 Two ABGTS trains shall be OPERABLE.

NOTE --------------------------------------------

The Auxiliary Building Secondary Containment Enclosure (ABSCE) boundary may be opened intermittently under administrative controls that ensure the ABSCE can be closed consistent with the safety analysis.

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

ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME A. One ABGTS train A.1 Restore ABGTS train to 7 days inoperable. OPERABLE status.

B. Two ABGTS trains B.1 Initiate actions to implement Immediately inoperable due to mitigating actions.

inoperable ABSCE boundary. AND B.2 Verify mitigating actions 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> ensure main control room occupants do not exceed 10 CFR 50 Appendix A GDC 19 limits.

AND B.3 Restore ABSCE boundary to 7 days OPERABLE status.

Watts Bar-Unit 1 3.7-27 Amendment No. 92, XX

ABGTS 3.7.12 ACTIONS (continued)

CONDITION REQUIRED ACTION COMPLETION TIME CB. Required Action CB.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 /> and associated Completion Time of AND Condition A or B not met.

CB.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 /> OR Two ABGTS trains inoperable for reasons other than Condition B.

Watts Bar-Unit 1 3.7-27a Amendment No. 92, XX

Enclosure 2 Revised Technical Specification Surveillance 3.7.12 and Bases for Watts Bar Nuclear Plant, Units 1 and 2 Attachment 2 Proposed TS Changes (Mark-Ups) for WBN Unit 2 CNL-17-044

ABGTS 3.7.12 3.7 PLANT SYSTEMS 3.7.12 Auxiliary Building Gas Treatment System (ABGTS)

LCO 3.7.12 Two ABGTS trains shall be OPERABLE

NOTE --------------------------------------------

The Auxiliary Building Secondary Containment Enclosure (ABSCE) boundary may be opened intermittently under administrative controls that ensure the ABSCE can be closed consistent with the safety analysis.

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

ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME A. One ABGTS train A.1 Restore ABGTS train to 7 days inoperable OPERABLE status.

B. Two ABGTS trains B.1 Initiate actions to Immediately inoperable due to implement mitigating inoperable ABSCE actions.

boundary.

AND B.2 Verify mitigating actions 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> ensure main control room occupants do not exceed 10 CFR 50 Appendix A GDC 19 limits.

AND B.3 Restore ABSCE 7 days boundary to OPERABLE status.

Watts Bar - Unit 2 3.7-26 Amendment xx

ABGTS 3.7.12 ACTIONS (continued)

CONDITION REQUIRED ACTION COMPLETION TIME B.C. Required Action and CB.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 of Condition A or B AND not met.

CB.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 /> OR Two ABGTS trains inoperable for reasons other than Condition B.

Watts Bar - Unit 2 3.7-26a Amendment xx

Enclosure 2 Revised Technical Specification Surveillance 3.7.12 and Bases for Watts Bar Nuclear Plant, Units 1 and 2 Attachment 3 Proposed TS Bases Changes (Mark-Ups) for WBN Unit 1 CNL-17-044

ABGTS B 3.7.12 BASES (continued)

LCO Two independent and redundant trains of the ABGTS are required to be OPERABLE to ensure that at least one train is available, assuming a single failure that disables the other train, coincident with a loss of offsite power. Total system failure, such as from a loss of both ventilation trains or from an inoperable ABSCE boundary, could result in exceeding a dose of 5 rem whole body or its equivalent to any part of the body to the main control room occupants in the event of a large radioactive release.could result in the atmospheric release from the ABSCE exceeding the 10 CFR 100 (Ref. 6) limits in the event of a LOCA.

The ABGTS is considered OPERABLE when the individual components necessary to control exposure in the fuel handling building are OPERABLE in both trains. An ABGTS train is considered OPERABLE when its associated:

a. Fan is OPERABLE;
b. HEPA filter and charcoal adsorber are not excessively restricting flow, and are capable of performing their filtration function; and
c. Heater, moisture separator, ductwork, valves, and dampers are OPERABLE, and air circulation can be maintained.

The LCO is modified by a Note allowing the ABSCE boundary to be opened intermittently under administrative controls that ensure the ABSCE can be closed consistent with the safety analysis. For entry and exit through doors the administrative control of the opening is performed by the person(s) entering or exiting the area. For other openings, these controls are proceduralized and consist of stationing a dedicated individual at the opening who is in continuous communication with the control room. This individual will have a method to rapidly close the opening when a need for auxiliary building isolation is indicated.

The ABSCE boundary must be able to be restored within four minutes (including the time for restoration of the ABSCE boundary and drawdown) in accordance with UFSAR Section 15.5.3.

APPLICABILITY In MODE 1, 2, 3, or 4, the ABGTS is required to be OPERABLE to provide fission product removal associated with ECCS leaks due to a LOCA and leakage from containment and annulus.

In MODE 5 or 6, the ABGTS is not required to be OPERABLE since the ECCS is not required to be OPERABLE.

(continued)

Watts Bar-Unit 1 B 3.7-63 Revision 55, 87, 119, yyy Amendment 92, xx

ABGTS B 3.7.12 BASES (continued)

ACTIONS A.1 With one ABGTS train inoperable, action must be taken to restore OPERABLE status within 7 days. During this period, the remaining OPERABLE train is adequate to perform the ABGTS function. The 7 day Completion Time is based on the risk from an event occurring requiring the inoperable ABGTS train, and the remaining ABGTS train providing the required protection.

B.1, B.2, and B.3 If the ABSCE boundary is inoperable, the ABGTS trains cannot perform their intended functions. Actions must be taken to restore an OPERABLE ABSCE boundary within seven days. During the period that the ABSCE boundary is inoperable, action must be initiated to implement mitigating actions consistent with the intent, as applicable, of GDC 19, 60, 61, 63, 64 and 10 CFR Part 100 (Ref. 7) to protect plant personnel from potential hazards such as radioactive contamination, temperature and relative humidity, and physical security. Actions must be taken within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to verify that, in the event of a DBA, main control room occupant radiological exposures will not exceed 10 CFR 50 Appendix A GDC 19 limits. These mitigating actions (i.e., actions that are taken to offset the consequences of the inoperable ABSCE boundary) should be preplanned to address these concerns for intentional and unintentional entry into the condition.

The 24-hour Completion Time is reasonable based on the low probability of a DBA occurring during this time period, and the use of mitigating actions. The seven-day Completion Time is reasonable based on the determination that the mitigating actions will ensure protection of main control room occupants within analyzed limits (Ref. 11) while limiting the probability that main control room occupants will have to implement protective measures that may adversely affect their ability to control the reactor and maintain it in a safe shutdown condition in the event of a DBA. In addition, the seven-day Completion Time is a reasonable time to diagnose, plan and possibly repair, and test most problems with the ABSCE boundary.

CB.1 and CB.2 When Required Action A.1 or Required Actions B.1, B.2, and B.3 cannot be completed within the associated Completion Time, or when both ABGTS trains are inoperable for reasons other than an inoperable ABSCE boundary (i.e., Condition B), the plant must be placed in a MODE in which the LCO does not apply. To achieve this status, the plant must be placed in MODE 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />, and in MODE 5 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. The 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 3.7-64 Revision 119, yyy Amendment 92, xx

ABGTS B 3.7.12 BASES REFERENCES 5. Deleted (continued)

6. Regulatory Guide 1.4, "Assumptions Used for Evaluating the Potential Radiological Consequences of a Loss of Coolant Accident for Pressurized Water Reactors."
7. Title 10, Code of Federal Regulations, Part 100.11, "Determination of Exclusion Area, Low Population Zone, and Population Center Distance."
8. Regulatory Guide 1.52 (Rev. 2), "Design, Testing and Maintenance Criteria for Post Accident Engineered-Safety-Feature Atmospheric Cleanup System Air Filtration and Adsorption Units of Light-Water Cooled Nuclear Power Plants."
9. NUREG-0800, Section 6.5.1, "Standard Review Plan," Rev. 2, "ESF Atmosphere Cleanup System," July 1981.
10. Watts Bar Drawing 1-47W605-242, "Electrical Tech Spec Compliance Tables."
11. DeletedTVA Calculation MDQ0000302014000618, Offsite and Control Room Doses without the Auxiliary Building Secondary Containment Enclosure (ABSCE) during a LOCA.

Watts Bar-Unit 1 B 3.7-67 Revision 29, 55, 119 Amendment 92, XX

Enclosure 2 Revised Technical Specification Surveillance 3.7.12 and Bases for Watts Bar Nuclear Plant, Units 1 and 2 Attachment 4 Proposed TS Bases Changes (Mark-Ups) for WBN Unit 2 CNL-17-044

ABGTS B 3.7.12 BASES (continued)

APPLICABLE The ABGTS design basis is established by the consequences of the SAFETY limiting Design Basis Accident (DBA), which is a LOCA. The analysis of ANALYSES the LOCA assumes that radioactive materials leaked from the Emergency Core Cooling System (ECCS) are filtered and adsorbed by the ABGTS.

The DBA analysis of the fuel handling accident assumes that only one train of the ABGTS is functional due to a single failure that disables the other train. The accident analysis accounts for the reduction in airborne radioactive material provided by the one remaining train of this filtration system. The amount of fission products available for release from the ABSCE is determined for a LOCA. The assumptions and analysis for a LOCA follow the guidance provided in Regulatory Guide 1.4 (Ref. 5).

The ABGTS satisfies Criterion 3 of 10 CFR 50.36(c)(2)(ii).

LCO Two independent and redundant trains of the ABGTS are required to be OPERABLE to ensure that at least one train is available, assuming a single failure that disables the other train, coincident with a loss of offsite power. Total system failure, such as from a loss of both ventilation trains or from an inoperable ABSCE boundary, could result in exceeding a dose of 5 rem whole body or its equivalent to any part of the body to the main control room occupants in the event of a large radioactive release. could result in the atmospheric release from the ABSCE exceeding the 10 CFR 100 (Ref. 6) limits in the event of a LOCA.

The ABGTS is considered OPERABLE when the individual components necessary to control exposure in the Auxiliary Building are OPERABLE in both trains. An ABGTS train is considered OPERABLE when its associated:

a. Fan is OPERABLE;
b. HEPA filter and charcoal adsorber are not excessively restricting flow, and are capable of performing their filtration function; and
c. Heater, moisture separator, ductwork, valves, and dampers are OPERABLE, and air circulation can be maintained.

The LCO is modified by a Note allowing the ABSCE boundary to be opened intermittently under administrative controls that ensure the ABSCE can be closed consistent with the safety analysis. For entry and exit through doors the administrative control of the opening is performed by the person(s) entering or exiting the area. For other openings, these controls are proceduralized and consist of stationing a dedicated individual at the opening who is in continuous communication with the control room. This individual will have a method to rapidly close the opening when a need for auxiliary building isolation is indicated. The (continued)

Watts Bar - Unit 2 B 3.7-64 Amendment XX

ABGTS B 3.7.12 BASES (continued)

ABSCE boundary must be able to be restored within four minutes (including the time for restoration of the ABSCE boundary and drawdown) in accordance with UFSAR Section 15.5.3.

APPLICABILITY In MODE 1, 2, 3, or 4, the ABGTS is required to be OPERABLE to provide fission product removal associated with ECCS leaks due to a LOCA and leakage from containment and annulus.

In MODE 5 or 6, the ABGTS is not required to be OPERABLE since the ECCS is not required to be OPERABLE.

ACTIONS A.1 With one ABGTS train inoperable, action must be taken to restore OPERABLE status within 7 days. During this period, the remaining OPERABLE train is adequate to perform the ABGTS function. The 7-day Completion Time is based on the risk from an event occurring requiring the inoperable ABGTS train, and the remaining ABGTS train providing the required protection.

B.1, B.2, and B.3 If the ABSCE boundary is inoperable, the ABGTS trains cannot perform their intended functions. Actions must be taken to restore an OPERABLE ABSCE boundary within seven days. During the period that the ABSCE boundary is inoperable, action must be initiated to implement mitigating actions consistent with the intent, as applicable, of GDC 19, 60, 61, 63, 64 and 10 CFR Part 100 (Ref. 6) to protect plant personnel from potential hazards such as radioactive contamination, temperature and relative humidity, and physical security. Actions must be taken within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to verify that, in the event of a DBA, main control room occupant radiological exposures will not exceed 10 CFR 50 Appendix A GDC 19 limits. These mitigating actions (i.e., actions that are taken to offset the consequences of the inoperable ABSCE boundary) should be preplanned to address these concerns for intentional and unintentional entry into the condition.

The 24-hour Completion Time is reasonable based on the low probability of a DBA occurring during this time period, and the use of mitigating actions. The seven-day Completion Time is reasonable based on the determination that the mitigating actions will ensure protection of main control room occupants within analyzed limits (Ref. 9) while limiting the probability that main control room occupants will have to implement protective measures that may adversely affect their ability to control the reactor and maintain it in a safe shutdown condition in the event of a DBA. In addition, the seven-day Completion Time is a reasonable time to diagnose, plan and possibly repair, and test most problems with the ABSCE boundary.

(continued)

Watts Bar - Unit 2 B 3.7-65 Amendment XX

ABGTS B 3.7.12 BASES (continued)

ACTIONS CB.1 and CB.2 (continued)

When Required Action A.1 or Required Actions B.1, B.2, and B.3 cannot be completed within the associated Completion Time, or when both ABGTS trains are inoperable for reasons other than an inoperable ABSCE boundary (i.e., Condition B), the plant must be placed in a MODE in which the LCO does not apply. To achieve this status, the plant must be placed in MODE 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />, and in MODE 5 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

The 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 3.7.12.1 REQUIREMENTS Standby systems should be checked periodically to ensure that they function properly. As the environmental and normal operating conditions on this system are not severe, testing each train once every month provides an adequate check on this system.

Monthly heater operation dries out any moisture accumulated in the charcoal from humidity in the ambient air. The system must be operated for 10 continuous hours with the heaters energized. The 31-day Frequency is based on the known reliability of the equipment and the two train redundancy available.

SR 3.7.12.2 This SR verifies that the required ABGTS testing is performed in accordance with the Ventilation Filter Testing Program (VFTP). The ABGTS filter tests are in accordance with Regulatory Guide 1.52 (Ref. 7).

The VFTP includes testing HEPA filter performance, charcoal adsorber efficiency, minimum system flow rate, and the physical properties of the activated charcoal (general use and following specific operations).

Specific test frequencies and additional information are discussed in detail in the VFTP.

(continued)

Watts Bar - Unit 2 B 3.7-66 Amendment XX

ABGTS B 3.7.12 BASES REFERENCES 7. Regulatory Guide 1.52 (Rev. 2), Design, Testing and Maintenance (continued) Criteria for Post Accident Engineered-Safety-Feature Atmospheric Cleanup System Air Filtration and Adsorption Units of Light-Water Cooled Nuclear Power Plants.

8. NUREG-0800, Section 6.5.1, Standard Review Plan, Rev. 2, ESF Atmosphere Cleanup System, July 1981.
9. TVA Calculation MDQ0000302014000618, Offsite and Control Room Doses without the Auxiliary Building Secondary Containment Enclosure (ABSCE) during a LOCA.

Watts Bar - Unit 2 B 3.7-67a Amendment XX

Enclosure 2 Revised Technical Specification Surveillance 3.7.12 and Bases for Watts Bar Nuclear Plant, Units 1 and 2 Attachment 5 Proposed TS Changes (Final Typed) for WBN Unit 1 CNL-17-044

ABGTS 3.7.12 3.7 PLANT SYSTEMS 3.7.12 Auxiliary Building Gas Treatment System (ABGTS)

LCO 3.7.12 Two ABGTS trains shall be OPERABLE.

NOTE --------------------------------------------

The Auxiliary Building Secondary Containment Enclosure (ABSCE) boundary may be opened intermittently under administrative controls that ensure the ABSCE can be closed consistent with the safety analysis.

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

ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME A. One ABGTS train A.1 Restore ABGTS train to 7 days inoperable. OPERABLE status.

B. Two ABGTS trains B.1 Initiate actions to implement Immediately inoperable due to mitigating actions.

inoperable ABSCE boundary. AND B.2 Verify mitigating actions 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> ensure main control room occupants do not exceed 10 CFR 50 Appendix A GDC 19 limits.

AND B.3 Restore ABSCE boundary to 7 days OPERABLE status.

Watts Bar-Unit 1 3.7-27 Amendment No. 92, XX

ABGTS 3.7.12 ACTIONS (continued)

CONDITION REQUIRED ACTION COMPLETION TIME C. Required Action 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 /> and associated Completion Time of AND Condition A or B not met.

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 /> OR Two ABGTS trains inoperable for reasons other than Condition B.

Watts Bar-Unit 1 3.7-27a Amendment No. 92, XX

Enclosure 2 Revised Technical Specification Surveillance 3.7.12 and Bases for Watts Bar Nuclear Plant, Units 1 and 2 Attachment 6 Proposed TS Changes (Final Typed) for WBN Unit 2 CNL-17-044

ABGTS 3.7.12 3.7 PLANT SYSTEMS 3.7.12 Auxiliary Building Gas Treatment System (ABGTS)

LCO 3.7.12 Two ABGTS trains shall be OPERABLE

NOTE --------------------------------------------

The Auxiliary Building Secondary Containment Enclosure (ABSCE) boundary may be opened intermittently under administrative controls that ensure the ABSCE can be closed consistent with the safety analysis.

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

ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME A. One ABGTS train A.1 Restore ABGTS train to 7 days inoperable OPERABLE status.

B. Two ABGTS trains B.1 Initiate actions to Immediately inoperable due to implement mitigating inoperable ABSCE actions.

boundary.

AND B.2 Verify mitigating actions 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> ensure main control room occupants do not exceed 10 CFR 50 Appendix A GDC 19 limits.

AND B.3 Restore ABSCE 7 days boundary to OPERABLE status.

Watts Bar - Unit 2 3.7-26 Amendment xx

ABGTS 3.7.12 ACTIONS (continued)

CONDITION REQUIRED ACTION COMPLETION TIME 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 of Condition A or B AND not met.

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 /> OR Two ABGTS trains inoperable for reasons other than Condition B.

Watts Bar - Unit 2 3.7-26a Amendment xx

Enclosure 2 Revised Technical Specification Surveillance 3.7.12 and Bases for Watts Bar Nuclear Plant, Units 1 and 2 Attachment 7 Proposed TS Bases Changes (Final Typed) for WBN Unit 1 CNL-17-044

ABGTS B 3.7.12 BASES (continued)

LCO Two independent and redundant trains of the ABGTS are required to be OPERABLE to ensure that at least one train is available, assuming a single failure that disables the other train, coincident with a loss of offsite power. Total system failure, such as from a loss of both ventilation trains or from an inoperable ABSCE boundary, could result in exceeding a dose of 5 rem whole body or its equivalent to any part of the body to the main control room occupants in the event of a large radioactive release.

The ABGTS is considered OPERABLE when the individual components necessary to control exposure in the fuel handling building are OPERABLE in both trains. An ABGTS train is considered OPERABLE when its associated:

a. Fan is OPERABLE;
b. HEPA filter and charcoal adsorber are not excessively restricting flow, and are capable of performing their filtration function; and
c. Heater, moisture separator, ductwork, valves, and dampers are OPERABLE, and air circulation can be maintained.

The LCO is modified by a Note allowing the ABSCE boundary to be opened intermittently under administrative controls that ensure the ABSCE can be closed consistent with the safety analysis. For entry and exit through doors the administrative control of the opening is performed by the person(s) entering or exiting the area. For other openings, these controls are proceduralized and consist of stationing a dedicated individual at the opening who is in continuous communication with the control room. This individual will have a method to rapidly close the opening when a need for auxiliary building isolation is indicated.

The ABSCE boundary must be able to be restored within four minutes (including the time for restoration of the ABSCE boundary and drawdown) in accordance with UFSAR Section 15.5.3.

APPLICABILITY In MODE 1, 2, 3, or 4, the ABGTS is required to be OPERABLE to provide fission product removal associated with ECCS leaks due to a LOCA and leakage from containment and annulus.

In MODE 5 or 6, the ABGTS is not required to be OPERABLE since the ECCS is not required to be OPERABLE.

(continued)

Watts Bar-Unit 1 B 3.7-63 Revision 55, 87, 119, yyy Amendment 92, xx

ABGTS B 3.7.12 BASES (continued)

ACTIONS A.1 With one ABGTS train inoperable, action must be taken to restore OPERABLE status within 7 days. During this period, the remaining OPERABLE train is adequate to perform the ABGTS function. The 7 day Completion Time is based on the risk from an event occurring requiring the inoperable ABGTS train, and the remaining ABGTS train providing the required protection.

B.1, B.2, and B.3 If the ABSCE boundary is inoperable, the ABGTS trains cannot perform their intended functions. Actions must be taken to restore an OPERABLE ABSCE boundary within seven days. During the period that the ABSCE boundary is inoperable, action must be initiated to implement mitigating actions consistent with the intent, as applicable, of GDC 19, 60, 61, 63, 64 and 10 CFR Part 100 (Ref. 7) to protect plant personnel from potential hazards such as radioactive contamination, temperature and relative humidity, and physical security. Actions must be taken within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to verify that, in the event of a DBA, main control room occupant radiological exposures will not exceed 10 CFR 50 Appendix A GDC 19 limits. These mitigating actions (i.e., actions that are taken to offset the consequences of the inoperable ABSCE boundary) should be preplanned to address these concerns for intentional and unintentional entry into the condition.

The 24-hour Completion Time is reasonable based on the low probability of a DBA occurring during this time period, and the use of mitigating actions. The seven-day Completion Time is reasonable based on the determination that the mitigating actions will ensure protection of main control room occupants within analyzed limits (Ref. 11) while limiting the probability that main control room occupants will have to implement protective measures that may adversely affect their ability to control the reactor and maintain it in a safe shutdown condition in the event of a DBA. In addition, the seven-day Completion Time is a reasonable time to diagnose, plan and possibly repair, and test most problems with the ABSCE boundary.

C.1 and C.2 When Required Action A.1 or Required Actions B.1, B.2, and B.3 cannot be completed within the associated Completion Time, or when both ABGTS trains are inoperable for reasons other than an inoperable ABSCE boundary (i.e., Condition B), the plant must be placed in a MODE in which the LCO does not apply. To achieve this status, the plant must be placed in MODE 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />, and in MODE 5 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. The 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 3.7-64 Revision 119, yyy Amendment 92, xx

ABGTS B 3.7.12 BASES REFERENCES 5. Deleted (continued)

6. Regulatory Guide 1.4, "Assumptions Used for Evaluating the Potential Radiological Consequences of a Loss of Coolant Accident for Pressurized Water Reactors."
7. Title 10, Code of Federal Regulations, Part 100.11, "Determination of Exclusion Area, Low Population Zone, and Population Center Distance."
8. Regulatory Guide 1.52 (Rev. 2), "Design, Testing and Maintenance Criteria for Post Accident Engineered-Safety-Feature Atmospheric Cleanup System Air Filtration and Adsorption Units of Light-Water Cooled Nuclear Power Plants."
9. NUREG-0800, Section 6.5.1, "Standard Review Plan," Rev. 2, "ESF Atmosphere Cleanup System," July 1981.
10. Watts Bar Drawing 1-47W605-242, "Electrical Tech Spec Compliance Tables."
11. TVA Calculation MDQ0000302014000618, Offsite and Control Room Doses without the Auxiliary Building Secondary Containment Enclosure (ABSCE) during a LOCA.

Watts Bar-Unit 1 B 3.7-67 Revision 29, 55, 119 Amendment 92, XX

Enclosure 2 Revised Technical Specification Surveillance 3.7.12 and Bases for Watts Bar Nuclear Plant, Units 1 and 2 Attachment 8 Proposed TS Bases Changes (Final Typed) for WBN Unit 2 CNL-17-044

ABGTS B 3.7.12 BASES (continued)

APPLICABLE The ABGTS design basis is established by the consequences of the SAFETY limiting Design Basis Accident (DBA), which is a LOCA. The analysis of ANALYSES the LOCA assumes that radioactive materials leaked from the Emergency Core Cooling System (ECCS) are filtered and adsorbed by the ABGTS.

The DBA analysis of the fuel handling accident assumes that only one train of the ABGTS is functional due to a single failure that disables the other train. The accident analysis accounts for the reduction in airborne radioactive material provided by the one remaining train of this filtration system. The amount of fission products available for release from the ABSCE is determined for a LOCA. The assumptions and analysis for a LOCA follow the guidance provided in Regulatory Guide 1.4 (Ref. 5).

The ABGTS satisfies Criterion 3 of 10 CFR 50.36(c)(2)(ii).

LCO Two independent and redundant trains of the ABGTS are required to be OPERABLE to ensure that at least one train is available, assuming a single failure that disables the other train, coincident with a loss of offsite power. Total system failure, such as from a loss of both ventilation trains or from an inoperable ABSCE boundary, could result in exceeding a dose of 5 rem whole body or its equivalent to any part of the body to the main control room occupants in the event of a large radioactive release.

The ABGTS is considered OPERABLE when the individual components necessary to control exposure in the Auxiliary Building are OPERABLE in both trains. An ABGTS train is considered OPERABLE when its associated:

a. Fan is OPERABLE;
b. HEPA filter and charcoal adsorber are not excessively restricting flow, and are capable of performing their filtration function; and
c. Heater, moisture separator, ductwork, valves, and dampers are OPERABLE, and air circulation can be maintained.

The LCO is modified by a Note allowing the ABSCE boundary to be opened intermittently under administrative controls that ensure the ABSCE can be closed consistent with the safety analysis. For entry and exit through doors the administrative control of the opening is performed by the person(s) entering or exiting the area. For other openings, these controls are proceduralized and consist of stationing a dedicated individual at the opening who is in continuous communication with the control room. This individual will have a method to rapidly close the opening when a need for auxiliary building isolation is indicated. The ABSCE boundary must be able to be restored within four minutes (including the time for restoration of the ABSCE boundary and drawdown) in accordance with UFSAR Section 15.5.3.

(continued)

Watts Bar - Unit 2 B 3.7-64 Amendment XX

ABGTS B 3.7.12 BASES (continued)

APPLICABILITY In MODE 1, 2, 3, or 4, the ABGTS is required to be OPERABLE to provide fission product removal associated with ECCS leaks due to a LOCA and leakage from containment and annulus.

In MODE 5 or 6, the ABGTS is not required to be OPERABLE since the ECCS is not required to be OPERABLE.

ACTIONS A.1 With one ABGTS train inoperable, action must be taken to restore OPERABLE status within 7 days. During this period, the remaining OPERABLE train is adequate to perform the ABGTS function. The 7-day Completion Time is based on the risk from an event occurring requiring the inoperable ABGTS train, and the remaining ABGTS train providing the required protection.

B.1, B.2, and B.3 If the ABSCE boundary is inoperable, the ABGTS trains cannot perform their intended functions. Actions must be taken to restore an OPERABLE ABSCE boundary within seven days. During the period that the ABSCE boundary is inoperable, action must be initiated to implement mitigating actions consistent with the intent, as applicable, of GDC 19, 60, 61, 63, 64 and 10 CFR Part 100 (Ref. 6) to protect plant personnel from potential hazards such as radioactive contamination, temperature and relative humidity, and physical security. Actions must be taken within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to verify that, in the event of a DBA, main control room occupant radiological exposures will not exceed 10 CFR 50 Appendix A GDC 19 limits. These mitigating actions (i.e., actions that are taken to offset the consequences of the inoperable ABSCE boundary) should be preplanned to address these concerns for intentional and unintentional entry into the condition.

The 24-hour Completion Time is reasonable based on the low probability of a DBA occurring during this time period, and the use of mitigating actions. The seven-day Completion Time is reasonable based on the determination that the mitigating actions will ensure protection of main control room occupants within analyzed limits (Ref. 9) while limiting the probability that main control room occupants will have to implement protective measures that may adversely affect their ability to control the reactor and maintain it in a safe shutdown condition in the event of a DBA. In addition, the seven-day Completion Time is a reasonable time to diagnose, plan and possibly repair, and test most problems with the ABSCE boundary.

(continued)

Watts Bar - Unit 2 B 3.7-65 Amendment XX

ABGTS B 3.7.12 BASES (continued)

ACTIONS C.1 and C.2 (continued)

When Required Action A.1 or Required Actions B.1, B.2, and B.3 cannot be completed within the associated Completion Time, or when both ABGTS trains are inoperable for reasons other than an inoperable ABSCE boundary (i.e., Condition B), the plant must be placed in a MODE in which the LCO does not apply. To achieve this status, the plant must be placed in MODE 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />, and in MODE 5 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

The 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 3.7.12.1 REQUIREMENTS Standby systems should be checked periodically to ensure that they function properly. As the environmental and normal operating conditions on this system are not severe, testing each train once every month provides an adequate check on this system.

Monthly heater operation dries out any moisture accumulated in the charcoal from humidity in the ambient air. The system must be operated for 10 continuous hours with the heaters energized. The 31-day Frequency is based on the known reliability of the equipment and the two train redundancy available.

SR 3.7.12.2 This SR verifies that the required ABGTS testing is performed in accordance with the Ventilation Filter Testing Program (VFTP). The ABGTS filter tests are in accordance with Regulatory Guide 1.52 (Ref. 7).

The VFTP includes testing HEPA filter performance, charcoal adsorber efficiency, minimum system flow rate, and the physical properties of the activated charcoal (general use and following specific operations).

Specific test frequencies and additional information are discussed in detail in the VFTP.

(continued)

Watts Bar - Unit 2 B 3.7-66 Amendment XX

ABGTS B 3.7.12 BASES REFERENCES 7. Regulatory Guide 1.52 (Rev. 2), Design, Testing and Maintenance (continued) Criteria for Post Accident Engineered-Safety-Feature Atmospheric Cleanup System Air Filtration and Adsorption Units of Light-Water Cooled Nuclear Power Plants.

8. NUREG-0800, Section 6.5.1, Standard Review Plan, Rev. 2, ESF Atmosphere Cleanup System, July 1981.
9. TVA Calculation MDQ0000302014000618, Offsite and Control Room Doses without the Auxiliary Building Secondary Containment Enclosure (ABSCE) during a LOCA.

Watts Bar - Unit 2 B 3.7-67a Amendment XX

Enclosure 3 Summary of TVA Calculation MDQ0000302014000618 Summary of MDQ0000302014000618 This calculation analyzed the design basis LOCA as modeled in UFSAR Section 15.5.3 and determined how long it would take to exceed 10 CFR 100 and 10 CFR 50 Appendix A GDC 19 limits when the ABSCE boundary was inoperable. An inoperable ABSCE boundary would result in ABGTS being inoperable as well. Therefore, credit could not be taken for ABGTS filtration. The design basis LOCA models were used as the starting point for this calculation. Instead of crediting ABGTS at four minutes, the model was modified to credit ABGTS filtration at various times (two hours, four hours, six hours, and seven hours) to determine when regulatory limits would be exceeded. One case was also ran to determine the result if ABGTS was not credited at all. The analysis showed that without taking credit for ABGTS filtration at all, the 10 CFR 100 limits and 10 CFR 50 Appendix A GDC 19 whole body and beta limits would not be exceeded. However, 10 CFR 50 Appendix A GDC 19 thyroid limits would be exceeded unless ABGTS filtration was credited at six hours post accident. Figure 1 provides an overall summary of the information provided in this enclosure.

Design Basis LOCA Model inputs and assumptions The following is a summary of the pertinent input parameters and assumptions used in the Design Basis LOCA analysis. It should be noted that this information is all contained in the WBN dual-unit UFSAR except for the delay time assumed for crediting the EGTS. There are two cases modeled that reflect different single failures in the EGTS system:

  • The first case is a pressure control operator (PCO) controller failure that assumes both trains of EGTS starts, but a controller fails such that one train has an exhaust damper that does not modulate and stays fully open. This case assumed that at one hour, operators take action to shutdown one train.
  • The second case assumes that one EGTS train fails to start.

The PCO failure case was shown to have bounding whole body and beta doses, whereas the single train failure has bounding thyroid results.

Source Terms Isotope Percent (%)

Noble Gases 100 Iodine 25 Iodine composition Elemental 91 Particulate 5 Organic 4 Tritium 100 U1 U2 Isotope Ci Ci KR 83M 1.23E+07 1.15E+07 KR 85M 2.69E+07 2.39E+07 KR 85 8.81E+05 1.03E+06 KR 87 5.23E+07 4.81E+07 CNL-17-044 E3-1 of 7

Enclosure 3 Summary of TVA Calculation MDQ0000302014000618 U1 U2 Isotope Ci Ci KR 88 7.38E+07 6.66E+07 KR 89 9.10E+07 8.28E+07 XE131M 9.54E+05 1.05E+06 XE133M 5.80E+06 6.16E+06 XE133 1.88E+08 1.19E+08 XE135M 3.59E+07 4.05E+07 XE135 4.96E+07 6.43E+07 XE138 1.59E+08 1.67E+08 I131 9.01E+07 9.46E+07 I132 1.31E+08 1.39E+08 I133 1.88E+08 1.95E+08 I134 2.08E+08 2.16E+08 I135 1.76E+08 1.86E+08 H3 2.68E+07 0.00E+00 U1 - tritium production core U2 - Conventional Core Volumes Containment 1.27E6 ft3 50% of total volume Annulus 1.88E5 ft3 50% of total volume Auxiliary Building 1.62E5 ft3 effective volume that correlates to a 0.3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> (hr) holdup time Flow Rates Primary containment leak rate 0.25 %/day (0-24 hr) 0.125%/day (1-30 days)

Primary containment leakage 75%

to Annulus Primary containment leakage 25%

to Auxiliary Building EGTS flow rates Variable See tables titled EGTS Flow Rates EGTS Delay time 60 sec PCO failure 114 sec single train EGTS failure Total ABGTS 9000 cfm/train only assume one train ABGTS Delay time 0 - 4 minutes (min) Initial startup of ABGTS 30 - 34 min Assumed single failure AB leakage into EGTS 10.7 cfm assumed leakage enters downstream of filters AB leakage into ABGTS 27.88 cfm assumed leakage enters downstream of filters Leakage from ABGTS to AB 8.87 cfm CNL-17-044 E3-2 of 7

Enclosure 3 Summary of TVA Calculation MDQ0000302014000618 Removal Efficiencies Ice Condenser Removal Efficiency lambda (1/hr) 0-0.156 hr 0.96 1.81 0.156 - 0.267 hr 0.76 1.44 0.267-0.323 hr 0.73 1.38 0.323 - 0.489 hr 0.71 1.34 0.489 - 0.615 hr 0.60 1.13 0.615 - 0.768 hr 0.58 1.10 0.768 - 0.824 hr 0.40 0.76 0.824 - 720 hr 0.0 0.0 EGTS Iodine 99%

Tritium 0%

ABGTS Iodine 99%

Tritium 0%

Control Room Parameters Total Control Room Emergency Ventilation 3600 cfm 4000 cfm - 10%

System (CREVS) flow Rate Pressurization flow 711 cfm Recirculation flow 2889 cfm Total - Pressurization Unfiltered Inleakage 51 cfm CREVS Filters First Pass 95% Iodine only Second Pass 70% Iodine only Occupancy 0-24 hr 100%

1-4 days 60%

4-30 days 40%

Breathing Rate 0-8 hr 1.2492 m3/hr 8-24 hr 0.63 m3/hr 1-30 day 0.8352 m3/hr Volume 257198 ft3 CNL-17-044 E3-3 of 7

Enclosure 3 Summary of TVA Calculation MDQ0000302014000618 Meteorology EAB 6.382E-04 sec/m3 LPZ 0-2 hr 1.784E-04 sec/m3 2-8 hr 8.835E-05 sec/m3 8-24 hr 6.217E-05 sec/m3 1-4 day 2.900E-05 sec/m3 4-30 day 9.811E-06 sec/m3 Control Room 0-2 hr 1.09E-03 sec/m3 2-8 hr 9.44E-04 sec/m3 8-24 hr 1.56E-04 sec/m3 1-4 day 1.16E-04 sec/m3 4-30 day 9.59E-05 sec/m3 CNL-17-044 E3-4 of 7

Enclosure 3 Summary of TVA Calculation MDQ0000302014000618 EGTS Flow Rates U1 PCO Failure with 1 hr operator Action time Time Interval Time Interval Recirculation Rate Exhaust Rate sec sec hr hr cfm cfh cfm cfh 0 30 0 0.0083 0 0 0 0 30 39 0.0083 0.0108 7200 4.32E+05 0 0 39 40 0.0108 0.0111 6573 3.94E+05 627 3.76E+04 40 41 0.0111 0.0l l 4 4705 2.82E+05 2495 l.50E+05 41 42 0.0114 0.0117 2610 l.57E+05 4590 2.75E+05 42 43 0.0117 0.0119 725 4.35E+04 6475 3.88E+05 43 71 0.0119 0.0197 0 0 7200 4.32E+05 71 80 0.0197 0.0222 0 0 7200 4.32E+05 80 81 0.0222 0.0225 1568 9.41E+04 5632 3.38E+05 81 82 0.0225 0.0228 4222 2.53E+05 2978 l.79E+05 82 102 0.0228 0.0283 4064 2.44E+05 3136 l.88E+05 102 132 0.0283 0.0367 3816 2.29E+05 3384 2.03E+05 132 165 0.0367 0.0458 3659 2.20E+05 3541 2.12E+05 165 169 0.0458 0.0469 3619 2.17E+05 3581 2.15E+05 169 210 0.0469 0.0583 3659 2.20E+05 3541 2.12E+05 210 307 0.0583 0.0853 3950 2.37E+05 3250 l.95E+05 307 498 0.0853 0.1383 4701 2.82E+05 2499 l.50E+05 498 602 0.1383 0.1672 5386 3.23E+05 1814 1.09E+05 602 603 0.1672 0.1675 5568.4 3.34E+05 1631.6 9.79E+04 603 850 0.1675 0.2361 4597 2.76E+05 1534 9.20E+04 850 1100 0.2361 0.3056 4694 2.82E+05 1437 8.62E+04 1100 1350 0.3056 0.375 4791 2.87E+05 1340 8.04E+04 1350 1600 0.375 0.4444 4888 2.93E+05 1243 7.46E+04 1600 1850 0.4444 0.5139 4985 2.99E+05 1146 6.88E+04 1850 2100 0.5139 0.5833 5082 3.05E+05 1049 6.29E+04 2100 3600 0.5833 1 5174 3.10E+05 957 5.74E+04 3600 30 1 30days 3584 2.15E+05 694 4.16E+04 Note that the U1 EGTS flows bound those for U2 and so the U2 flows are not given.

CNL-17-044 E3-5 of 7

Enclosure 3 Summary of TVA Calculation MDQ0000302014000618 EGTS Flow Rates Single Train of EGTS failure Time Interval Time Interval Recirculation Rate Exhaust Rate sec sec hr hr cfm cfh cfm cfh 0 30 0 0.0083 0 0 0 0 30 39 0.0083 0.0108 3600 2.16E+05 0 0 39 40 0.0108 0.0111 3287 1.97E+05 313 1.88E+04 40 41 0.0111 0.0114 2352 1.41E+05 1248 7.49E+04 41 42 0.0114 0.0117 1305 7.83E+04 2295 1.38E+05 42 43 0.0117 0.0119 363 2.18E+04 3237 l .94E+05 43 190 0.0119 0.0528 0 0 3600 2.16E+05 190 191 0.0528 0.0531 537 3.22E+04 3063 1.84E+05 191 192 0.0531 0.0533 733 4.40E+04 2867 1.72E+05 192 193 0.0533 0.0536 735 4.41E+04 2865 1.72E+05 193 194 0.0536 0.0539 738 4.43E+04 2862 1.72E+05 194 199 0.0539 0.0553 745 4.47E+04 2855 l.71E+05 199 207 0.0553 0.0575 764 4.58E+04 2836 1.70E+05 207 215 0.0575 0.0597 791 4.74E+04 2809 1.69E+05 215 225 0.0597 0.0625 825 4.95E+04 2775 l .66E+05 225 245 0.0625 0.0681 893 5.36E+04 2707 l.62E+05 245 265 0.0681 0.0736 993 5.96E+04 2607 l.56E+05 265 285 0.0736 0.0792 1102 6.61E+04 2498 l .50E+05 285 305 0.0792 0.0847 1217 7.30E+04 2383 1.43E+05 305 446 0.0847 0.1239 1664 9.98E+04 1936 1.16E+05 446 601 0.1239 0.1669 2357 1.41E+05 1243 7.46E+04 601 602 0.1669 0.1672 2661 1.60E+05 939 5.63E+04 602 1700 0.1672 0.4722 3600 2.16E+05 0 0 1700 1701 0.4722 0.4725 3508 2.10E+05 92 5.51E+03 1701 1702 0.4725 0.4728 3423 2.05E+05 177 1.06E+04 1702 1703 0.4728 0.4731 3411 2.05E+05 189 1.14E+04 1703 1704 0.4731 0.4733 3409 2.05E+05 191 1.15E+04 1704 1705 0.4733 0.4736 3408 2.04E+05 192 l.15E+04 1705 1706 0.4736 0.4739 3408 2.04E+05 192 l.15E+04 1706 1855 0.4739 0.5153 3395 2.04E+05 205 1.23E+04 1855 2100 0.5153 0.5833 3372 2.02E+05 228 1.37E+04 2100 30davs* 0.5833 720 3350 2.01E+05 250 l.50E+04 CNL-17-044 E3-6 of 7

Enclosure 3 Summary of TVA Calculation MDQ0000302014000618 Primary Ice Condenser Removal Containment V = 1.27E6 ft3 0.25%/day (0-24 hr) 0.125%/day (> 24 hr)

> 60 sec 75% 4-30 min, >34 min 25%

0- 4 min, 30-34 min 0-60 sec Annulus Auxiliary Building V = 1.88E5 ft3 V = 1.62E5 ft3 27.88 cfm EGTS 3600 cfm ABGTS or 7200 Recirculation 9000 cfm cfm 8.87 cfm Exhaust Environment 10.7 cfm Figure 1 Calculation Flowchart CNL-17-044 E3-7 of 7

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