CNL-19-056, Response to NRC Request for Additional Information Regarding Application to Revise Technical Specifications Regarding DC Electrical Systems TSTF-500, Revision 2, DC Electrical Rewrite - Update to TSTF-360

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Response to NRC Request for Additional Information Regarding Application to Revise Technical Specifications Regarding DC Electrical Systems TSTF-500, Revision 2, DC Electrical Rewrite - Update to TSTF-360
ML19158A394
Person / Time
Site: Watts Bar  Tennessee Valley Authority icon.png
Issue date: 06/07/2019
From: Henderson E
Tennessee Valley Authority
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
CNL-19-056, EPID L-2018-LLA-0494, WBN-TS-18-09
Download: ML19158A394 (179)


Text

Tennessee Valley Authority, 1101 Market Street, Chattanooga, Tennessee 37402 CNL-1 9-056 June 7, 201 9 10 CFR 50.90 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555

-0001 Watts Bar Nuclear Plant, Unit 1 Facility Operating License No. NPF

-90 Docket No. 50

-390 Watts Bar Nuclear Plant

, Unit 2 Facility Operating License No. NPF

-96 Docket No. 50

-391

Subject:

Response to NRC Request for Additional Information Regarding Application to Revise Technical Specifications Regarding DC Electrical Systems TSTF

-500, Revision 2, "DC Electrical Rewrite

- Update to TSTF-360 (WBN-TS-1 8-0 9) (EPID L-2018-LLA-0494)

References:

1. TVA letter to NRC, CNL 11 8 , "Application to Revise Technical Specifications Regarding DC Electrical Systems TSTF

-500, Revision 2, 'DC Electrical Rewrite

- Update to TSTF -360' (WBN-TS-18-09)," dated November 2 9, 2018 (ML18334A389) 2. NRC Electronic Mail to TVA, "Watts Bar Nuclear Plant

- Final Request for Additional Information Related to Application to Revise Technical Specifications Regarding DC Electrical Systems TSTF

-500, Revision 2 (EPID L-2018-LLA-0494)" dated May 3, 2019 (ML19011A34

9) In Reference 1, TVA submitted a request for an amendment to the technical specifications (TS) for Watts Bar Nuclear Plant (WBN), Units 1 and 2. The proposed amendment revises TS requirements related to direct current (DC) electrical systems in accordance with Technical Specification Task Force (TSTF) Traveler TSTF-500, Revision 2, "DC Electrical Rewrite

- Update to TSTF

-360." In Reference 2, NRC issued a Request for Additional Information (RAI) and requested TVA respond by June 7, 2019. Enclosure 1 to this letter provides the response to the RAI.

As noted in Enclosure 1, the response to this RAI necessitates changes to the proposed TS 3.8.4 and 3.8.6 in Reference 1. Accordingly, Enclosure 2 provides markups of the existing TS and Bases pages to show the proposed changes. Enclosure 3 provides revised (clean) TS pages. The proposed TS changes in Enclosures 2 and 3 supersede the corresponding TS provided in Reference 1.

U.S. Nuclear Regulatory Commission CNL-19-056 Pag e 2 June , 201 9 The enclosure s to this l etter do not change t he no significant hazard considerations or t he environmental considerations contained in Reference 1.

Additionally, in accordance with 10 CFR 50.91(b)(1), TVA i s sending a co py o f this letter and the enclosure to t he Tennessee Department o f Environment and Conservation.

Enclosure 4 contains t he revised regulatory commitment associated wit h this su bmittal that supersede s t he commitment provided in Reference 1. Please addr ess a ny questions regarding t his request t o Kim berly D. Hulvey at (423) 751-3 275. I dec lare under penal ty o f pe rjury t hat t he foregoing is t rue and c orrect. Executed on t his th day o f June 201 9. Respectfully, Erin K. Henderson Director, Nuclear Regulatory Affairs

Enclosures:

1.Response to NRC Request for Additional Information Regarding LicenseAmendment Request to Revise Technical Specifications to Adopt TechnicalSpecifications Task Force (TSTF)

-500, Revision 2, "

DC Electrical Rewrite

-Update to TSTF-360" Docket Nos. 50

-390 and 50

-391 2.Markups of Technical Specification s and Bases Changes 3.Clean Technical Specification s and Bases Changes 4.Revised Regulatory Commitment cc (Enclosures): NRC Regional Administrator

- Region II NRC Project Manager - Watts Bar Nuclear Plant NRC Senior Resident Inspector - Watts Bar Nuclear Plant Director, Division of Radiological Health - Tennessee State Department of Environment and Conservation CNL-19-056 E 1-1 of 11 Response to NRC Request for Additional Information Regarding License Amendment Request to Revise Technical Specifications to Adopt Technical Specifications Task Force (TSTF) -500, Revision 2, "DC Electrical Rewrite

- Update to TSTF

-360" Docket Nos. 50-390 and 50-391 INTRODUCTION By letter dated November 29, 2018 (Agencywide Documents Access and Management System (ADAMS) Accession number ML18334A389), Tennessee Valley Authority (TVA, the licensee), requested an amendment to Facility Operating Licenses NPF

-90 and NPF

-96 for Watts Bar Nuclear Plant (WBN), Units 1 and 2. The proposed license amendment request would revise the WBN Units 1 and 2 TS to adopt the Nuclear Regulatory Commission (NRC)

-approved Technical Specifications Task Force (TSTF)

-500, Revision 2, "DC [direct current] Electrical Rewrite

- Update to TSTF

-360." Specifically, the licensee proposed changes to the TS requirements related to DC electrical power systems in TS 3.8.4, "DC sources

- Operating," TS 3.8.5, "DC Sources - Shutdown," and TS 3.8.6, "Battery Cell Parameters." Additionally, the licensee proposed to add to the TS Section 5.7, "Procedures, Programs, and Manuals," a new program titled "Battery Monitoring and Maintenance Program."

The Electrical Engineering Operating Branch (EEOB) staff has determined that the following additional information is needed to complete the review of the WBN license amendment request (LAR). Regulatory Requirements Title 10 of the Code of Federal Regulations, Part 50 (10 CFR 50), Section 36, "Technical Specifications," requires, in part, that the operating license of a nuclear production facility include TS. 10 CFR 50.36 (c)(2) requires that the TS include limiting conditions for operation (LCOs) which are the lowest functional capability or performance levels of equipment required for safe operation of the facility. When an LCO of a nuclear reactor is not met, the licensee shall shut down the reactor or follow any remedial action permitted by the technical specifications until the condition can be met.

10 CFR 50, Appendix A, General Design Criterion (GDC) 17, "Electric power systems," states, in part, that "an onsite electric power system and an offsite electric power system shall be provided to permit functioning of structures, systems, and components important to safety.- The onsite electric power supplies, including the batteries, and the onsite electric distribution system, shall have sufficient independence, redundancy, and testability to perform their safety functions assuming a single failure."

Regulatory Guidance TSTF-500, Revision 2, "DC Electrical Rewrite

- Update to TSTF

-360," dated September 22, 2009 (ADAMS Accession No. ML092670242).

CNL-19-056 E 1-2 of 11 EEOB RAI -1 The licensee proposed a new TS 3.8.4 Condition A with associated Required Actions and Completion Time for the required vital battery charger(s).

Condition A would state: Condition A One or two required vital battery charger (s) on one subsystem inoperable Required Actions A.1, A.2, and A.3 would state:

Required Action A.1 Restore battery terminal voltage to greater than or equal to the minimum established float voltage. Completion Time 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> AND Required Action A.2 Completion Time Once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> In Enclosure 4 of the LAR, the licensee provided a commitment to include in the WBN updated safety analysis report (UFSAR) "a requirement to maintain a 2 percent design margin for the vital batteries which corresponds to a 2 amp float current value being used as an indication that the battery is at least 98 percent charged."

In Enclosure 6 of the LAR, the licensee stated that the "normal recharging of the battery from the design discharged condition can be accomplished in approximately 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> (with accident loads being supplied) following a 30

-minute AC power outage and in approximately 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> (with normal loads being supplied) following a 4

-hour AC power outage."

The NRC has identified the following discrepancies:

The 2-amp float current value for the vital batteries provides an indication that the batteries are less than 100 percent charged. It does not appear that a discussion about how the 2 percent design margin would ensure that the vial batteries would be 100 percent charged at a 2

-amp float current was provided.

It appears that it could take longer than 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> to fully recharge a vital battery that would be discharged for a period longer than 30 minutes before connecting the spare charger.

The staff requests the following information to address these discrepancies:

a) Explain how maintaining a "2 percent design margin - as an indication that the battery is at least 98 percent charged" will ensure that the WBN vital batteries are fully charged (i.e., capable of performing their design function). b) Provide a discussion to demonstrate that the vital battery can be fully recharged in 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> from Condition A after a 2

-hour discharge (i.e., the time allowed by Required Action A.1 to place the spare charger on the battery).

CNL-19-056 E 1-3 of 11 TVA Response to EEOB RAI -1 a) TVA has verified

, via the battery manufacturer

, that a charging current less than or equal to two amps (A) is an indication that the battery is at least 98 percent charged. Therefore, maintaining an additional two percent design margin in the WBN battery sizing calculation is needed to ensure that 100 percent battery capacity is available once charging current is 2 A or less. This is equivalent to the battery being 100 percent charged, because the sizing calculation ensures that the battery can perform its safety related function during a design bases event.

b) The time to return the battery to its fully charged condition is a function of the battery charger capacity, the amount of loads on the associated direct current (DC) system, the amount of the previous discharge, and the recharge characteristic of the battery. Total normal steady state loads on the battery chargers average less than 100 A based on walk down data. Each vital battery is rated for 2320 A

-hours. Each battery charger is rated for 200 A.

200 A available

- 100 A steady state load = 100 A excess capacity for battery charging.

Assuming the battery charger is offline for two hours (the time allowed by TSTF

-500 to place a charger on the battery) and assuming normal steady state DC system loads remain on battery during this time would equate to a two hour x 100 A (or 200 A

-hour) loss. Assuming 110 percent of 200 A

-hour (or 220 A-hour) would be required to restore the battery to a fully recharged state and given the 100 A excess battery charger capacity above, the battery can be restored to fully recharged within:

220 A-hour / 100 A = 2.2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />.

However, because the battery chargers are constant voltage chargers rather than constant current chargers, it is recognized that the battery charging current will taper off from the initial maximum current that the charger can supply to a final value of less than 2 A. TVA does not possess battery recharge current characteristic curves, but it is considered reasonable to expect that the battery would be fully recharged in less than 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> to less than 2 A charging current, given the above charger capacity and relatively small amount of capacity removed from the batteries.

EEOB RAI-2 The licensee proposed a new TS 3.8.4 Condition D with associated Required Actions and Completion Time for the diesel generator (DG) battery charger(s).

Condition D would state:

Condition D One DG DC battery charger inoperable Required Actions D.1, D.2, and D.3 would state:

Required Action D.1 Restore DG battery terminal voltage to greater than or equal to the minimum established float voltage.

Completion Time 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> CNL-19-056 E 1-4 of 11 AND Required Action D.2 Verify Completion Time Once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> AND Required Action D.3 Restore DG battery charger to OPERABLE status Completion Time 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> In Enclosure 4 of the LAR, the licensee provided a commitment to include in the WBN UFSAR "a requirement to maintain a 2 percent design margin for the DG batteries which corresponds to a 1 amp float current value being used as an indication that the battery is at least 98 percent charged." The NRC has identified the following discrepancies:

The 1-amp float current value for the DG batteries provides an indication that the DG batteries are less than 100 percent charged. It does not appear that a discussion about how the 2 percent design margin would ensure that the vial batteries would be 100 percent charged at a 2

-amp float current was provided.

The 12-hour and 72

-hour completion times for verifying battery float current and for restoring the battery to operable status, respectively, are bracketed in the TSTF

-500. It does not appear that the bases for the proposed 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> for Required Actions D.2 and D.3, respectively, were provided.

The staff requests the following information to address these discrepancies:

a) Explain how maintaining a "2 percent design margin - as an indication that the battery is at least 98 percent charged" will ensure that the WBN DG batteries are fully charged (i.e., capable of performing their design function).

b) Provide the WBN basis for the 12

-hour and the 72

-hour completion times for Required Actions D.2 and D.3, respectively.

TVA response to EEOB RAI

-2 a) TVA has verified via the DG battery manufacturer that a charging current less than or equal to 1 A is an indication that the battery is at least 98 percent charged. Therefore, maintaining an additional 2 percent design margin in the WBN battery sizing calculation is needed to ensure that 100 percent battery capacity is available once charging current is 1 A or less. This is equivalent to the battery being 100 percent charged, because the sizing calculation ensures that the battery can perform its safety related function during a design bases event.

b) The 12-hour time to return the DG battery to its fully charged condition in this case is a function of the battery charger capacity, the amount of loads on the associated DG DC system, the amount of the previous discharge, and the recharge characteristic of the battery. Typical normal steady state loads on a DG battery charger is 10.41 A, based on pre-operational testing of DG battery charger 2B-B. Each DG battery is rated for 192 A-hours. Each battery charger is rated for 20 A. 20 A available

- 10.41 A steady state load = 9.59 A excess capacity for battery charging.

CNL-19-056 E 1-5 of 11 Assuming the battery charger is offline for two hours (the time allowed by TSTF

-500 to place a charger on the battery) and assuming normal steady state DG DC system loads remain on battery during this time would equate to a two hour x 10.41 A (or 20.82 A-hour) loss. Assuming 110 percent of 20.82 A

-hour (or 22.90 A

-hour) would be required to restore the battery to a fully recharged state and given the 9.59 A excess battery charger capacity above, the battery can be restored to fully recharged within:

22.90 A-hour / 9.59 A = 2.39 hours4.513889e-4 days <br />0.0108 hours <br />6.448413e-5 weeks <br />1.48395e-5 months <br />.

However, because the battery chargers are constant voltage chargers rather than constant current chargers, it is recognized that the battery charging current will taper off from the initial maximum current that the charger can supply to a final value of less than 1 A. TVA does not possess battery recharge current characteristic curves, but it is considered reasonable to expect that the battery would be fully recharged in less than 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> to less than 1 A charging current, given the above charger capacity and relatively small amount of capacity removed from the batteries.

The 72-hour completion time for the DG batteries is consistent with the 72

-hour completion time for TS 3.8.4, Required Action A.3, and TS 3.8.5, Required Action A.3 in TSTF-500. As noted in TSTF

-500, the 72-hour completion time must be adopted unless a licensee wishes to adopt a longer completion time. Furthermore, the 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> will allow, in many cases, a sufficient period of time to correct a charger problem. The 72-hour completion time is also commensurate with the importance of maintaining the DG DC system's capability to adequately respond to a design basis event.

EEOB RAI-3 The licensee proposed to revise SR 3.8.4.12 and renumber it as SR 3.8.4.6.

Renumbered SR 3.8.4.6 would state:

SR 3.8.4.6 --------------------------------------NOTE-----------------------------------------

Credit may be taken for unplanned events that satisfy this SR.


Verify ea OR Verify each DG battery charger can recharge the battery to the fully charged state within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> while supplying the largest combined demands of the various continuous steady state loads, after a battery discharge to the bounding design basis event discharge state.

The NRC staff notes that a discussion about the basis for the proposed 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> and 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> testing durations in the renumbered SR 3.8.4.6 was not provided.

CNL-19-056 E 1-6 of 11 Explain the basis for the proposed 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> and 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> testing durations for the WBN DG battery chargers.

TVA Response to EEOB RAI

-3 Current TS SR 3.8.4.12 requires verification every 18 months that each DG battery charger is capable of recharging the associated battery from a service or capacity discharge test while supplying normal loads. TVA has decided to not adopt the TSTF

-500 SR option to verify that an or equal to the minimum recharging the associated battery from a service or capacity discharge test while supplying normal loads is sufficient to verify the operability of the battery charger. Enclosure s 2 and 3 provide the revised Technical Specifications (TS) and Bases to reflect this change.

Regarding the basis for the 24

-hour testing duration for the DG batter chargers, the WBN battery sizing calculations for the DG batteries indicate that the battery chargers are capable of fully charging the batteries within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, while simultaneously supporting the connected loads. Similar to the response to EEOB RAI

-2b, the time to return the DG battery to its fully charged condition is a function of the battery charger capacity, the amount of loads on the associated DG DC system, the amount of the previous discharge, and the recharge characteristic of the battery. Typical normal steady state loads on a DG battery charger is 10.41 A, based on pre-operational testing of DG battery charger 2B

-B. Each battery charger is rated for 20 A.

20 A available

- 10.41 A steady state load = 9.59 A excess capacity for battery charging.

The duty cycle for the DG batteries is based on the batteries supplying DG loads without benefit of chargers for four hours during a station blackout (SBO) event. The duty cycle of the DG batteries for a SBO event is approximately 66.5 A hours. Therefore, recharging the DG battery would equate to 66.5 A

-hours / 9.59 A = 6.93 hours0.00108 days <br />0.0258 hours <br />1.537698e-4 weeks <br />3.53865e-5 months <br /> (assuming the battery is completely discharged and assuming normal steady state DG DC system loads remain on battery during this time).

Assuming 110 percent of DG battery capacity of 66.50 A

-hour (or 73.15 A

-hour) would be required to restore the battery to a fully recharged state and given the 9.59 A excess battery charger capacity above, the battery can be restored to fully recharged within:

73.15 A-hours / 9.59 A = 7.63 hours7.291667e-4 days <br />0.0175 hours <br />1.041667e-4 weeks <br />2.39715e-5 months <br />.

However, because the battery chargers are constant voltage chargers rather than constant current chargers, it is recognized that the battery charging current will taper off from the initial maximum current that the charger can supply to a final value of less than 1 A. TVA does not possess battery recharge current characteristic curves, but it is considered reasonable to expect that the battery would be fully recharged in less than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to less than 1 A charging current, given the above charger capacity and relatively small amount of capacity removed from the batteries.

CNL-19-056 E 1-7 of 11 EEOB RAI-4 In Enclosure, Section 1.0 of the LAR, the licensee proposed relocating the Technical Specification (TS) Table 3.8.6

-1, "Battery Surveillance Requirements," to the proposed Battery Monitoring and Maintenance Program in TS 5.7. The Table 3.8.6

-1 includes Category A, B, and C limits for the battery cell parameters (i.e., electrolyte level, float voltage, specific gravity).

Confirm that the battery cell parameters (electrolyte level, float voltage, specific gravity) will continue to be controlled at their current Categories A, B, and C levels in the TS Battery Monitoring and Maintenance Program, and that actions to restore deficient values will be implemented in accordance with the licensee's corrective action program.

TVA Response to EEOB RAI

-4 TVA confirms that the battery cell parameters (electrolyte level, float voltage, specific gravity) will be relocated to the Battery Monitoring and Maintenance Program at their current Categories A, B, and C levels. The battery cell parameters within the program will be controlled consistent with IEEE 450

-2002, as specified in proposed TS 5.7.2.22, "Battery Monitoring and Maintenance Program." Actions to restore deficient values of any of the battery cell parameters specified in the program will be tracked and implemented in accordance with the TVA corrective action program.

EEOB RAI-5 The proposed new TS 3.8.6 Condition A would apply when one DG battery is found with one or more battery cell(s) with a float voltage of less than 2.07 volts (V).

The NRC staff notes that the 2.07

-V for the battery cell float voltage is bracketed in TSTF

-500. It does not appear that the basis for the proposed 2.07

-V limit for the WBN DG battery cell float voltage was provid ed. Explains the WBN basis for the 2.07

-V limit for the WBN DG battery cell float voltage.

TVA Response to EEOB RAI

-5 The 2.07 volt limit is consistent with the most limiting float voltage limit in WBN TS Table 3.8.6-1, "Battery Cell Parameters Requirements." The WBN battery cells are of the vented lead

-acid type with a nominal electrolyte specific gravity of 1.215. Open circuit voltage of the lead-acid battery cell is related to the specific gravity by a constant as shown in the following:

Open Circuit Voltage = Specific Gravity + 0.845 Therefore, for the WBN battery cells, the nominal cell open circuit voltage is 1.215 + 0.845 = 2.06 volts DC. A cell voltage of less than or equal to cell open circuit voltage indicates the cell is no longer being floated at a voltage sufficient to prevent discharge.

CNL-19-056 E 1-8 of 11 EEOB RAI-6 The licensee proposed adding a new TS 3.8.6 Condition F which would apply to one or two required vital battery (ies) on one subsystem or one DG battery found with a pilot cell electrolyte temperature less than the minimum established design limits. The Required Action F.1 would restore the pilot cell electrolyte temperature to greater than or equal to minimum establis hed design limits within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

In Enclosure 1 of the LAR, the licensee states: "TVA verifies that battery room temperature is routinely monitored such that a room temperature excursion could reasonably expect to be detected and corrected prior to the average battery electrolyte temperature dropping below the minimum electrolyte temperature."

Regarding the selection of pilot cells, the TSTF

-500 states:

Previously, average battery temperature was monitored instead of pilot cell temperature. As a result, temperature was not a criterion with selecting a pilot cell. In order to use pilot cell temperature instead of the average battery temperature, temperature must be used as a criterion when selecting the pilot cell. [-] For batteries where it could be shown that the maximum temperature deviation across the battery did not exceed the IEEE 450 recommended maximum of 5°F [degrees Fahrenheit], the NRC has accepted that the cell temperature was not a critical parameter. Therefore, for these batteries, cell temperature did not have to be taken into account when selecting pilot cells.

The NRC has identified the following discrepancies:

It appears that a discussion about the frequency of monitoring the battery room and how the battery room temperature would be restored if it was outside the temperature design limits was not provided.

It appears that a discussion about the selection of the WBN battery pilot cell based on temperature was not provided.

The staff requests the following information to address these discrepancies:

a) Provide a discussion about how the vital and DG battery rooms temperatures are monitored at WBN and provide the minimum frequencies at which the temperatures are monitored. Also explain how the licensee would restore the vital and DG battery rooms' temperatures if they were outside the temperature design limits.

b) Provide a discussion about the selection of the battery pilot cell based on temperature. If the temperature will not be used as a criterion for selecting battery pilot cells, provide an analysis of temperature deviations for the WBN batteries based on operation experience to show that the maximum temperature deviation across the batteries does not exceed the IEEE 450 recommended maximum of 5°F.

CNL-19-056 E 1-9 of 11 TVA Response to EEOB RAI

-6 a) The temperatures of the vital battery rooms and DG battery rooms are monitored once per shift (12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />) by Operations personnel. This satisfies Technical Requirement Manual (TRM) Surveillance Requirement (TSR) 3.7.5.1 to verify each area temperature is within limits every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. The room temperatures are documented in the applicable Shift and Daily Surveillance Log and verified to be in compliance with TSR 3.7.5. For the vital battery rooms, the Auxiliary Building heating, ventilation, and air conditioning (HVAC) is designed to maintain the room temperature and relative humidity within the environmental design limits. The Auxiliary Building HVAC operating procedures include compensatory actions for coping with and recovery from loss of train cooling so that design temperatures for the area are not exceeded. For the DG batteries, the DG building ventilation system is design to maintain temperatures within the limits of the environmental design criteria. Should the battery room temperatures approach temperature limits specified in TR 3.7.5 , operations would employ existing HVAC features to improve room temperatures. DG room dampers may be closed to isolate outside air or fans can be energized to circulate air. Should design features fail to provide the needed heating or cooling, the site could proceed with temporary equipment installation or DG operation, if increasing room temperature is warranted.

b) WBN's current vital and DG battery surveillance performance practices and a review of actual electrolyte temperature deviations for these batteries demonstrates compliance with the IEEE 450 recommended maximum temperature deviation of 5°F.

Current WBN weekly surveillance instructions identify the basis for pilot cell section is based on voltage and specific gravity parameters, because cell temperatures are typically maintained within +/-3° F. The review of actual quarterly battery surveillance data since 2014 for the five vital batteries included 12 cells per battery for approximately 20 tests with a total of 100 tests reviewed. All recorded vital battery electrolyte temperatures were within the IEEE 450 recommended maximum of 5°F. The review of actual quarterly battery surveillance data since 2014 for the four DG batteries included 12 cells per battery for approximately 21 tests with a total of 84 tests reviewed. The tests were conducted at various times of the year, which is representative of the full range of ambient temperatures the DG rooms are subjected to. The recorded DG battery electrolyte temperatures were within the IEEE 450 recommended maximum of 5° F. This data supports that the maximum temperature deviation across the vital and DG batteries does not exceed the IEEE 450 recommended maximum of 5° F. This is consistent with the IEEE 450 recommendations for determining that cell temperature is not a critical parameter for selection of pilot cells. Therefore, the vital and DG battery pilot cells will not be chosen based on temperature.

EEOB RAI-7 The licensee proposed a new TS 3.8.6 Condition G out

-of-limit parameters for batteries in redundant subsystems based on the TSTF

-500 TS 3.8.6 Condition E for NUREG

-1431, "Standard Technical Specifications Westinghouse Plants," Revision 1.

WBN TS 3.8.6 Condition G and associated Required Action G.1 would state:

Condition G One or more batteries in redundant subsystems with battery parameters not within limits.

OR More than one DG battery with battery parameters not within limits.

CNL-19-056 E 1-10 of 11 Required Action G.1 Restore battery parameters to within limits.

Completion Time 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> The NRC has identified the following discrepancies:

The first option of the proposed Condition G did not specify the type of batteries which the condition pertains to.

The Required Action E.1 in TSTF

-500 restores the parameters for the batteries in one subsystem whereas the proposed Required Action G.1 would restore the parameters for all batteries [in the redundant (both) subsystems].

a) Clarify the type of batteries that would be addressed in in the first option condition of the proposed TS 3.8.6 Condition G.

b) Explain the basis for deviating from the TSTF

-500 Required Action for restoring th e parameters for the batteries in one subsystem.

TVA Response to EEOB RAI-7 a) TS 3.8.6, Condition G, is being revised to indicate that the first option applies to the vital batteries. See the revised TS and Bases in Enclosure s 2 and 3. b) TS 3.8.6, Condition G and associated Required Actions, for vital batteries are being revised to be consistent with TSF

-500. Because the DG batteries support DGs that are arranged in trains (i.e., DG 1A

-A and 2A-A are in Train A, and DG 1B

-B and 2B-B are in Train B), a new condition (Condition H) has been added to address multiple DG batteries in redundant trains with parameters not within limits. The required actions are consistent with TSTF

-500, in that they require the restoration of the DG batteries in one train to within limits in 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />. This will ensure that the DG batteries either can support the operation of one train of DGs or are declared inoperable. Subsequent conditions have been re

-lettered accordingly.

Consistent with the above change, changes are being made to TS 3.8.4, Condition D, so that the condition applies to one or two inoperable DG battery chargers in one train. The wording of TS 3.8.4, Condition E, is being changed from referring to DG DC subsystem to referring to a DG DC train to be consistent with the terminology used for the arrangement of the DGs. See the revised TS and Bases in Enclosure s 2 and 3. Each DG DC electrical power system is independent and dedicated to its respective DG. The DGs that are supported by the DG DC electrical power systems are arranged in redundant trains (i.e., DG 1A

-A and DG 2A

-A are in Train A, and DG 1B

-B and DG 2B

-B are in Train B). When one or two DGs in a train are inoperable, that train of standby electrical power is incapable of performing the safety function and must rely on the redundant DG train to mitigate an event. Likewise, if one or two of the DG DC trains that support the DGs in that train are inoperable, that train of standby electrical power is incapable of performing the safety function and must rely on the redundant train to mitigate an event. Therefore, the LCO requires Train A and Train B DG DC electrical power subsystems to be OPERABLE to support the redundancy of the standby electrical power system.

CNL-19-056 E 1-11 of 11 EEOB RAI-8 In Enclosure 4 of the LAR, the licensee provided a commitment to verify that plant procedures will require verification of the selection of the pilot cell or cells when performing SR 3.8.6.5. The proposed new SR 3.8.6.5 would verify that each required vital battery and each DG battery pilot cell temperature is greater than or equal to minimum established design limits.

The NRC staff notes that the verification of the selection of the pilot cell or cells should be done when performing the SR that verifies the battery connected cell float voltage, as stated in the TSTF-500. Provide the justification for deviating from the TSTF

-500 with respect to the verification of the selection of the pilot cell during the SR for battery cell float voltage.

TVA Response to EEOB RAI-8 TVA is providing a corrected commitment to verify that plant procedures will require verification of the selected battery pilot cell during performance of SR 3.8.6.6 (verification of battery cell float voltage), consistent with TSTF

-500. This commitment supersedes the commitment provided in the referenced LAR to verify that plant procedures will require verification of the selected battery pilot cell during performance of SR 3.8.6.5. The revised commitment is provided in Enclosure 4.

The revised commitment also corrects the title of the reference to TS 5.7, "Procedures, Programs, and Manuals

." Reference TVA letter to NRC, CNL 118, "Application to Revise Technical Specifications Regarding DC Electrical Systems TSTF

-500, Revision 2, 'DC Electrical Rewrite

- Update to TSTF

-360' (WBN-TS-18-09)," dated November 29, 2018 (ML18334A389)

Markups of Technical Specification and Bases Changes CNL-1-E2-1

Markups of Technical Specification and Bases CNL-1-E2-

Markups of Technical Specification and Bases CNL-1-E2-

Clean Technical Specification and Bases Changes CNL-1-E3-1

Technical Specification and Bases CNL-1-E-

Technical Specification and Bases CNL-1-E-

Revised Regulatory Commitment CNL-1 9-056 E4-1 Commitment Due Date/Event TVA commits that the licensee

-controlled program, required and described in TS Section 5.7, "Procedures, Programs, and Manuals," and titled, "Battery Monitoring and Maintenance Program," will require verification of the selection of the pilot cell or cells when performing SR 3.8.6.6

. Prior to implementation of the approved TSTF

-500 license amendment