CNL-18-118, Application to Revise Technical Specifications Regarding DC Electrical Systems TStf-500, Revision 2, DC Electrical Rewrite - Update to TSTF-360 (WBN-TS-18-09): Difference between revisions

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{{#Wiki_filter:Tennessee Valley Authority, 1101 Market Street, Chattanooga, Tennessee 37402 CNL-18-118 November 29, 2018 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
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==Subject:==
Application to Revise Technical Specifications Regarding DC Electrical Systems TSTF-500, Revision 2, DC Electrical Rewrite - Update to TSTF -360 (WBN-TS-18-09)
In accordance with the provisions of Title 10 of the Code of Federal Regulations (10 CFR) 50.90, "Application for amendment of license, construction permit, or early site permit," Tennessee Valley Authority (TVA) is submitting a request for an amendment to the technical specifications (TS) for Watts Bar Nuclear Plant (WBN), Units 1 and 2.
The proposed amendment would modify 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. provides a description and assessment of the proposed change including the requested confirmation of applicability and plant-specific verifications, technical analyses, regulatory analyses, and environmental considerations. Enclosure 2 provides markups of the existing TS and Bases pages to show the proposed changes. Enclosure 3 provides revised (clean) TS pages. Enclosure 4 provides a summary of the regulatory commitments made in this submittal. Enclosure 5 provides copies of letters from battery manufacturers verifying the acceptability of using float current monitoring. Enclosure 6 provides an evaluation of extending the Completion Time for TS 3.8.4, DC Sources - Operating, Required Action A.3.
 
U.S. Nuclear Regulatory Commission CNL-18-118 Page 2 November 29, 2018 The WBN Plant Operations Review Committee has reviewed this proposed change and determined that operation of WBN Units 1 and 2 in accordance with the proposed change will not endanger the health and safety of the public.
TVA has determined that there are no significant hazard considerations associated with the proposed change and that the change qualifies for a categorical exclusion from environmental review pursuant to the provisions of 10 CFR 51 .22(c)(9). Additionally, in accordance with 10 CFR 50.91 (b)(1 ), TVA is sending a copy of this letter and the enclosures to the Tennessee Department of Environment and Conservation.
TVA requests approval of the proposed license amendment within one year from the date of this submittal, with implementation of the amendment within 90 days to support the WBN Unit 1 Cycle 16 refueling outage scheduled for Spring 2020. contains the new commitments in this submittal. Please address any questions regarding this request to Michael A. Brown at (423) 751-3275.
I declare under penalty of perjury that the foregoing is true and correct. Executed on this 29th day of November 2018.
z:y,~
Erin K. Henderson Director, Nuclear Regulatory Affairs
 
==Enclosures:==
: 1. Description and Assessment of Proposed Change
: 2. Markups of Technical Specification and Bases Changes
: 3. Clean Technical Specification and Bases Changes
: 4. Regulatory Commitments
: 5. Letters from Battery Manufacturers Verifying the Acceptability of Using Float Current Monitoring
: 6. Evaluation of an Extended Completion Time for Technical Specification 3.8.4, Required Action A.3 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
 
Enclosure 1 Description and Assessment of Proposed Change
 
==Subject:==
Application to Revise Technical Specifications Regarding DC Electrical Systems TSTF-500, Revision 2, DC Electrical Rewrite - Update to TSTF-360 (WBN-TS-18-09)
TABLE OF CONTENTS
 
==1.0  DESCRIPTION==
................................................................................................................ 2 2.0  ASSESSMENT ................................................................................................................ 3 2.1    Applicability of TSTF-500 and Model Safety Evaluation ............................................... 3 2.2    Verifications and Required Final Safety Analysis Report Changes............................... 6 2.3    Optional Changes and Variations................................................................................. 8
 
==3.0  REGULATORY ANALYSIS==
............................................................................................. 8 3.1    No Significant Hazards Consideration Determination ................................................... 8 3.2    Applicable Regulatory Requirements/Criteria ..............................................................10
 
==4.0  ENVIRONMENTAL CONSIDERATION==
..........................................................................10
 
==5.0  REFERENCES==
...............................................................................................................11 CNL-18-118                                        E1-1 of 11
 
Enclosure 1 Description and Assessment of Proposed Change
 
==1.0  DESCRIPTION==
 
In accordance with the provisions of Title 10 of the Code of Federal Regulations (10 CFR) 50.90, "Application for amendment of license, construction permit, or early site permit," Tennessee Valley Authority (TVA) is submitting a request for an amendment to the technical specifications (TS) for Watts Bar Nuclear Plant (WBN) Unit 1 and Unit 2.
The TS requirements are being revised from requirements on battery cells to requirements on the battery. This focuses the requirements on the assumed safety function of the battery. The proposed amendment would modify TS requirements related to direct current (DC) electrical systems in Limiting Condition for Operation (LCO) 3.8.4, DC Sources - Operating, LCO 3.8.5, DC Sources - Shutdown, and LCO 3.8.6, Battery Cell Parameters. A new Battery Monitoring and Maintenance Program is being proposed for Section 5.7.2, Programs and Manuals.
Specifically, the proposed change requests new actions for an inoperable battery charger and alternate battery charger testing criteria for LCO 3.8.4 and LCO 3.8.5. The proposed change also includes the relocation of a number of Surveillance Requirements (SRs) in TS 3.8.4 that perform preventive maintenance on the safety-related batteries to a licensee-controlled program. It is proposed that LCO 3.8.6 be modified by relocating Table 3.8.6-1, Battery Cell Parameter Requirements, to a licensee-controlled program, and that specific actions with associated Completion Times (CTs) for out-of-limits conditions for battery cell voltage, electrolyte level, and electrolyte temperature be added to TS 3.8.6. In addition, specific SRs are being proposed for verification of these parameters.
A new program is being proposed for Section 5.7.2 of the Administrative Controls for the maintenance and monitoring of station batteries. The items proposed to be relocated will be contained within this program, titled the Battery Monitoring and Maintenance Program.
The proposed change provides new Actions for an inoperable battery charger and alternate battery charger testing criteria. The longer CT for an inoperable battery charger will allow additional time for maintenance and testing. In addition, a number of SRs are relocated to licensee control including the monitoring of battery cell parameter requirements and performance of battery maintenance activities.
The changes are consistent with Nuclear Regulatory Commission (NRC)-approved Technical Specification Task Force (TSTF) Traveler TSTF-500, Revision 2 (TSTF-500)
(Reference 1). The availability of this TS improvement was published in the Federal Register on September 1, 2011 (76 FR 54510) (Reference 2), as supplemented on November 8, 2011 (76 FR 69296) (Reference 3).
The changes to the TS and Bases are consistent with the changes contained in TSTF-500, Revision 2, Attachment B, as they apply to NUREG-4131, Revision 1.0, as the current WBN Units 1 and 2 TS do not reflect the adoption of TSTF-360.
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Enclosure 1 Description and Assessment of Proposed Change 2.0  ASSESSMENT 2.1  APPLICABILITY OF TSTF-500 AND MODEL SAFETY EVALUATION TVA has reviewed the model Safety Evaluation (SE) referenced in the Federal Register Notice of Availability published on September 1, 2011 (76 FR 54510). The review included the NRC staff's SE, as well as the supporting information provided in TSTF-500. As described herein, TVA has concluded that the technical bases for the proposed changes presented in TSTF-500 and the model SE prepared by the NRC staff are applicable to WBN and support incorporation of this amendment into the WBN Unit 1 and Unit 2 TS.
The current WBN TS 3.8.4, 3.8.5, and 3.8.6 include requirements for the emergency diesel generators (DGs) 125 V DC electrical power subsystems. Therefore, the proposed WBN TS use different numbering than the Standard TS (STS) (NUREG-1431) on which TSTF-500 is based.
The WBN TS 3.8.4, 3.8.5, and 3.8.6 include separate Conditions, Required Actions, and Surveillance Requirements for the DG DC electrical power subsystems to reflect the differences in the designs for the vital DC and DG DC electrical power subsystems. The design of the vital DC subsystems supports a 7-day CT for an inoperable battery charger and the design of the DG DC subsystem does not support a CT longer than 72-hour for an inoperable battery charger. In addition, the minimum established float voltage for the vital DC batteries is less than or equal to 2 amps and the minimum established float current for the DG DC batteries is less than or equal to 1 amp. Although these differences necessitate additional Conditions, Required Actions, and Surveillance Requirements to accommodate the differences between the vital DC and DG DC electrical power subsystems, they do not affect the applicability of the model SE to the WBN Unit 1 and 2 TS.
An additional numbering difference occurs between TSTF-500 and the WBN Unit 1 and Unit 2 TS with the addition of the "Battery Monitoring and Maintenance Program. The Battery Monitoring and Maintenance Program is contained in TS 5.7.2.22, as opposed to TS 5.5.14, as indicated in TSTF-500. This difference is editorial and does not affect the applicability of TSTF-500 to the WBN Unit 1 and Unit 2 TS.
The WBN DC system is similar to the system described in TSTF-500, with respect to its ability to meet the duty cycle assumed in the accident analyses and with its operations in the float and equalize modes. The WBN 125 V Vital DC electrical power system consists of a combined Unit 1 and Unit 2 system, each separated into two independent Class 1E DC electrical power subsystems per unit. A description of the 125 V vital DC Control System is contained in Enclosure 6. Following is a description of the DG 125V DC Control System.
Design Features of the Diesel Generator 125V DC Control System A DG battery subsystem is provided for each DG. Each subsystem is comprised of a battery, dual battery charger assembly, distribution center, and cabling. The DG battery provides DC control power and field-flash when the charger is unavailable. If 480V AC is available, the charger supplies the normal DC loads, maintains the battery in a fully CNL-18-118                                  E1-3 of 11
 
Enclosure 1 Description and Assessment of Proposed Change charged condition, and recharges the battery while supplying the required loads regardless of the status of the plant. The batteries are physically and electrically independent. The DG control power systems are ungrounded and have ground detection instrumentation. Each DG battery has sufficient capacity when fully charged to supply the required loads for a minimum of four-hours following a loss of normal power.
Battery capacity design requirements consider minimum required voltage for loads and the effects of aging and ambient temperature. Each battery is normally required to supply loads only during the time interval between loss of normal feed to its charger and the receipt of emergency power to the charger from its respective diesel-generator. The batteries, comprised of 58 cells, have adequate capacity considering the minimum terminal voltage of 105 volts and derating for 50°F temperature and aging.
The normal supply of DC current to the battery boards is from the battery charger. Each charger maintains a float voltage of approximately 130 volts on the associated battery board with the battery connected to the board and is capable of maintaining 135 volts during an equalizing charge period (all loads can tolerate approximately 135V equalizing voltage). Each of the chargers (normal and alternate) in the dual charger assembly has a dedicated AC source from two respective 480V AC Diesel Generator Auxiliary Boards.
If the normal charger is unavailable, the alternate charger is selected by the 125V DC transfer switch included in the assembly. The charger is a solid-state type that converts a 3-phase 480V AC input to a nominal 125V DC output. The DC output voltage will vary no more than +/- 1.0% for a supply voltage amplitude variation of +/- 10% and frequency variation of +/- 2.0%. Some operational features of the chargers are:
(1)    an output voltage adjustable over the range of 125 to 135 volts, (2)    equalize and float modes of operation (the charger normally operates in the float mode at 130 volts, but can be switched to the equalize mode with an output of 135 volts),
(3)    a current-limit feature that limits continuous overload operation to approximately 140% of rated output, (4)    protective devices which prevent a failed charger from loading the battery, and (5)    metering and alarm circuits to monitor the charger output.
Differences Between WBN Unit 1 and Unit 2 TS and TSTF-500 The WBN Unit 1 and Unit 2 TS differ from the Standard TS (STS) (NUREG-1431) which were the basis for TSTF-500, Revision 2, in the following ways:
* WBN Unit 1 and Unit 2 LCO 3.8.4 refer to four channels of vital DC. NUREG-1431 LCO 3.8.4 refers to Train A and Train B vital DC electrical power subsystems. The WBN Unit 1 and Unit 2 TS are being revised to adopt the NUREG-1431 language.
This change aligns the LCO statement to the current Condition A statement regarding One vital DC electrical power subsystem inoperable. This change reflects the design of the vital DC electrical power subsystems that requires either Train A (Channels I and III) or Train B (Channels II and IV) to perform the safety function associated with the vital DC electrical power subsystems for WBN Unit 1 and Unit 2. This change aligns the WBN Unit 1 and Unit 2 TS to TSTF-500 and therefore, does not affect the applicability of the published model SE.
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Enclosure 1 Description and Assessment of Proposed Change
* WBN Unit 1 LCO 3.8.4 and LCO 3.8.5 are modified by a Note that allows the C-S DG and its associated DC electrical Power subsystem to be substituted for any of the required DGs and their associated DC electrical power subsystem. As documented in Reference 4, the WBN C-S DG is not being maintained. Therefore, the C-S DG cannot meet the requirements specified in TS 3.8.1 Bases that would allow it to be substituted for any required DG. Removal of a similar Note in WBN Unit 1 LCO 3.8.1, AC Sources - Operating, was approved by the NRC in Reference 5. These differences do not affect the applicability of the published model SE.
* WBN Unit 1 and Unit 2 were designed with five qualified class 1E, safety-related vital batteries and eight qualified class 1E, safety-related vital battery chargers.
The fifth vital battery serves as a replacement for any one of the other four vital batteries during their testing, maintenance, and outages with no loss of system reliability under any mode of operation. Each of the four battery boards has a charger normally connected and has access to a spare charger for use upon loss of the normal charger. Based on the operational flexibility of the vital DC system, a loss of one battery on one subsystem does not require a subsystem to be considered inoperable once the fifth battery is adequately surveilled and connected. Therefore, LCO 3.8.4 is modified by a note that allows vital battery V to be substituted for vital battery I, II, III, or IV. In addition, TS 3.8.4, Condition A, and TS 3.8.5, Condition A, are revised to state one or two "required" vital battery charger(s) on one subsystem inoperable. Because this change does not alter the intended application of the LCO and its related Actions, the change is considered a minor variation from TSTF-500.
* The WBN vital DC batteries and the DG DC batteries have different required float currents for determining that their respective batteries are charged. Therefore, the proposed WBN Unit 1 and Unit 2 TS include separate Action Conditions for inoperable batteries and battery chargers for the vital DC and DG DC electrical power subsystems. The additional Action Conditions for the DG DC electrical power subsystem is consistent with the current technical specifications and results in a numbering difference for the Action Conditions. These differences do not affect the applicability of the published model SE.
* The WBN vital DC and the DG DC electrical power subsystems have different required float voltages for verifying the effectiveness of the associated battery chargers. Therefore, the proposed WBN Unit 1 and Unit 2 TS include SR 3.8.4.1 for vital DC electrical power subsystem and SR 3.8.4.2 for DG DC electrical power subsystem. The additional SR for the DG DC electrical power subsystem is in the current technical specifications and results in a difference in the SR numbering.
These differences do not affect the applicability of the published model SE.
* The WBN vital DC and the DG DC electrical power subsystem battery chargers have different design capacities and performance characteristics. Therefore, there are separate SRs to verify the capacity of the charger to restore the associated battery from the design minimum charge state to the fully charged state, irrespective of the status of the plant during the demand occurrence. The additional SR for the DG DC electrical power subsystem is in the current technical CNL-18-118                                  E1-5 of 11
 
Enclosure 1 Description and Assessment of Proposed Change specifications and results in a difference in the SR numbering. These differences do not affect the applicability of the published model SE.
2.2  VERIFICATIONS AND REQUIRED FINAL SAFETY ANALYSIS REPORT CHANGES As described in Section 4.7.1, Verifications, in TSTF-500, TVA provides the following verifications.
: 1. Enclosure 5 contains letters from the manufacturers of the batteries used at WBN Units 1 and 2 verifying the acceptability of using float current monitoring instead of specific gravity monitoring as a reliable and accurate indication of the state-of-charge of the battery and that this will hold true over the life of the battery.
: 2. As indicated in Enclosure 4, TVA commits to verify that the equipment that will be used to monitor float current under SR 3.8.6.1 and SR 3.8.6.2 will have the necessary accuracy and capability to measure electrical currents in the expected range. Additionally, TVA commits to verify that the minimum required procedural time to measure battery float current will be 30 seconds or as recommended by the float current measurement instrument manufacturer. This minimum float current measurement time is required to provide a more accurate battery float current reading.
: 3. 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.
: 4. Enclosure 6 contains a description of the 125V DC vital system, including a discussion of the battery chargers, spare battery chargers, capability of the batteries to be charged from a power source that is independent of the offsite power supply, and a description of the onsite standby power supply that can be used to power the battery chargers.
: 5. Not applicable. TVA is not requesting a CT greater than 2 hours for TS 3.8.4, Required Action B.1 or C.1.
: 6. The cell resistance limits in existing SR 3.8.4.5 and SR 3.8.4.6 are relocated to the "Battery Monitoring and Maintenance Program." The cell connection resistance limits listed in the table below are based on vendor recommendations. The resistance limits apply to overall connection resistance and allows for normal degradation while maintaining battery operability.
Connection                Vital Batteries              DG Batteries (Ohm)                      (Ohm)
Inter-cell                                80                          80 Inter-rack                                50                          50 Inter-tier                                120                          50 Terminal Connections                      50                          50 CNL-18-118                                    E1-6 of 11
 
Enclosure 1 Description and Assessment of Proposed Change
: 7. TVA is proposing to delete the SR 3.8.4.13 (new SR 3.8.4.7) Note once per 60 months restriction on performing the modified performance discharge test instead of the service test. TVA verifies that the modified performance discharge test completely encompasses the load profile of the battery service test and that it adequately confirms the intent of the service test to verify the battery capacity to supply the design basis load profile.
: 8. As indicated in Enclosure 4, TVA commits to relocating the monitoring of battery parameters (i.e., specific gravity, electrolyte level, cell temperature, float voltage, connection resistance, and physical condition) to the licensee-controlled program, required and described in TS Section 5.7, Programs, Programs, and Manuals, and titled the Battery Monitoring and Maintenance Program.
: 9. As indicated in Enclosure 4, TVA commits to verifying that plant procedures will require verification of the selection of the pilot cell or cells when performing SR 3.8.6.5.
The Model SE, Attachment 2, List of Required Final Analysis Report (FSAR)
Descriptions, indicates several statements that are required to be included in the FSAR.
As indicated in Enclosure 4 of this letter, TVA commits to revising the FSAR to include the following, as part of the adoption of TSTF-500, Revision 2:
: 1. How a two percent design margin for the vital batteries corresponds to a two-amp float current value indicating that the battery is at least 98 percent charged.
: 2. How a 2 percent design margin for the DG batteries corresponds to a one-amp float current value indicating that the battery is at least 98 percent charged.
: 3. How long term battery performance is obtained by maintaining a float voltage greater than or equal to the minimum established design limits provided by the battery manufacturer.
: 4. How the batteries are sized with correction margins that include temperature and aging and how these margins are maintained.
: 5. The minimum established design limit for battery terminal float voltage.
: 6. The minimum established design limit for electrolyte level.
: 7. The minimum established design limit for electrolyte temperature.
: 8. How each battery is designed with additional capacity above that required by the design duty cycles to allow for temperature variations and other factors.
: 9. Normal DC system operation i.e., powered from the battery chargers with the batteries floating on the system, and with a loss of normal power to the battery charger.
: 10. The minimum requirements for the alternate means (i.e., spare battery charger) that are used to obtain an extended battery charger CT.
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Enclosure 1 Description and Assessment of Proposed Change 2.3  OPTIONAL CHANGES AND VARIATIONS TVA is proposing the following variation from the TS changes described in the TSTF-500, Revision 2, or the applicable parts of the NRC staffs model SE referenced in the Federal Register on September 1, 2011 (76 FR 54510), as supplemented on November 8, 2011 (76 FR 69296). These options were recognized as acceptable variations in TSTF-500 and the NRC staff's model SE.
TVA is proposing a CT longer than 72 hours for TS 3.8.4, Required Action A.3, and TS 3.8.5, Required Action A.3. An evaluation is included as Enclosure 6, which supports the longer CT and describes the availability of a spare battery charger and that the battery charger is appropriately sized. The CT is consistent with the WBN Units 1 and 2 UFSAR description that a means to charge the batteries is available and that the capability includes power supplied from a source that is independent of the offsite power supply. A description of the power source is also included.
TVA is not requesting a Completion Time longer than 12 hours to restore battery float current with one or two required battery chargers on one subsystem inoperable (TSTF-500, TS 3.8.4, Required Action A.2, and TS 3.8.5, Required Action A.2).
TVA is not requesting a Completion Time longer than 2 hours for one or two batteries on one subsystem inoperable (TSTF-500, TS 3.8.4, Required Action B.1). Therefore, as there is no difference in the Completion Time for Required Action B.1 and the Completion Time for Required Action C.1, TVA is not adopting TSTF-500, TS 3.8.4, Condition B.
WBN Unit 1 and Unit 2 implementation of TSTF-500, as it applies to LCO 3.8.5, includes adoption of new Action A, as the potential exists to require both vital DC electrical power subsystems during a portion of the LCO 3.8.5 applicability.
 
==3.0  REGULATORY ANALYSIS==
 
3.1  NO SIGNIFICANT HAZARDS CONSIDERATION DETERMINATION Tennessee Valley Authority (TVA) has evaluated the proposed changes to the TS using the criteria in Section 50.92 to Title 10 of the Code of Federal Regulations (10 CFR) and has determined that the proposed changes do not involve a significant hazards consideration.
The proposed amendment would revise TS requirements related to direct current (DC) electrical systems in TS limiting condition for operation (LCO) 3.8.4, DC Sources -
Operating, LCO 3.8.5, DC Sources - Shutdown, and LCO 3.8.6, Battery Cell Parameters. A new Battery Monitoring and Maintenance Program is being proposed for Section 5.7.2, Programs and Manuals. As required by 10 CFR 50.91(a), the TVA analysis of the issue of no significant hazards consideration is presented below:
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Enclosure 1 Description and Assessment of Proposed Change
: 1. Does the proposed change involve a significant increase in the probability or consequences of any accident previously evaluated?
Response: No.
The proposed changes restructure the Technical Specifications (TS) for the direct current (DC) electrical power system and are consistent with TSTF-500, Revision 2. The proposed changes modify TS Actions relating to battery and battery charger inoperability. The DC electrical power system, including associated battery chargers, is not an initiator of any accident sequence analyzed in the Final Safety Analysis Report (FSAR). Rather, the DC electrical power system supports equipment used to mitigate accidents. The proposed changes to restructure TS and change surveillances for batteries and chargers to incorporate the updates included in TSTF-500, Revision 2, will maintain the same level of equipment performance required for mitigating accidents assumed in the FSAR. Operation in accordance with the proposed TS would ensure that the DC electrical power system is capable of performing its specified safety function as described in the FSAR. Therefore, the mitigating functions supported by the DC electrical power system will continue to provide the protection assumed by the analysis.
The relocation of preventive maintenance surveillances, and certain operating limits and actions, to a licensee-controlled Battery Monitoring and Maintenance Program will not challenge the ability of the DC electrical power system to perform its design function.
Appropriate monitoring and maintenance that are consistent with industry standards will continue to be performed. In addition, the DC electrical power system is within the scope of 10 CFR 50.65, Requirements for monitoring the effectiveness of maintenance at nuclear power plants, which will ensure the control of maintenance activities associated with the DC electrical power system.
The integrity of fission product barriers, plant configuration, and operating procedures as described in the FSAR will not be affected by the proposed changes. Therefore, the consequences of previously analyzed accidents will not increase by implementing these changes. Therefore, the proposed changes do not involve a significant increase in the probability or consequences of an accident previously evaluated.
: 2. Does the proposed change create the possibility of a new or different kind of accident from any previously evaluated?
Response: No The proposed changes involve restructuring the TS for the DC electrical power system.
The DC electrical power system, including associated battery chargers, is not an initiator to any accident sequence analyzed in the FSAR. Rather, the DC electrical power system supports equipment used to mitigate accidents. The proposed changes to restructure the TS and change surveillances for batteries and chargers to incorporate the updates included in TSTF-500, Revision 2, will maintain the same level of equipment performance required for mitigating accidents assumed in the FSAR. Administrative and mechanical controls are in place to ensure the design and operation of the DC systems continues to meet the plant design basis described in the FSAR. Therefore, operation of the facility in accordance with this proposed change will not create the possibility of a new or different kind of accident from any accident previously evaluated.
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Enclosure 1 Description and Assessment of Proposed Change
: 3. Does the proposed change involve a significant reduction in the margin of safety?
Response: No.
The margin of safety is established through equipment design, operating parameters, and the setpoints at which automatic actions are initiated. The equipment margins will be maintained in accordance with the plant-specific design bases because of the proposed changes. The proposed changes will not adversely affect operation of plant equipment. These changes will not result in a change to the setpoints at which protective actions are initiated. Sufficient DC capacity to support operation of mitigation equipment is ensured. The changes associated with the new battery Maintenance and Monitoring Program will ensure that the station batteries are maintained in a highly reliable manner. The equipment fed by the DC electrical sources will continue to provide adequate power to safety-related loads in accordance with analysis assumptions. TS changes made in accordance with TSTF-500, Revision 2, maintain the same level of equipment performance stated in the FSAR and the current TSs. Therefore, the proposed changes do not involve a significant reduction of safety.
3.2  APPLICABLE REGULATORY REQUIREMENTS/CRITERIA TVA has reviewed the NRC staffs model SE referenced in the Notice of Availability and concluded that the Regulatory Evaluation section is applicable to WBN Units 1 and 2.
WBN Units 1 and 2 commitments to regulatory guidance differs from that provided in the Regulatory Evaluation section in the model SE as described below.
* The model SE refers to Revision 3 of Regulatory Guide (RG) 1 .32, "Criteria for Power Systems for Nuclear Power Plants. However, as described in FSAR Section 8.3.1.1, the design of the DG 125 VDC control power system for WBN Units 1 and 2 conforms to RG 1.32, Revision 2. The other portions of the electrical power system conform to RG 1.32, Revision 0.
* The model SE refers to Revision 3 of RG 1.75, "Criteria for Independence of Electrical Safety Systems. However, as described in FSAR Section 8.1, RG 1.75 was issued after the Watts Bar design was complete. A description of how WBN Units 1 and 2 meet the intent of RG 1.75, Revision 0, is provided in FSAR Section 8.3.1.4.2.
TVA concluded these differences do not result in any needed changes for adoption of TSTF-500, Revision 2, at WBN Units 1 and 2 and do not affect the applicability of the NRC staff model SE.
 
==4.0  ENVIRONMENTAL CONSIDERATION==
 
The proposed TS change would change a requirement with respect to installation or use of a facility component located within the restricted area, as defined in 10 CFR Part 20, and would change an inspection or surveillance requirement. However, the proposed change does not involve (i) a significant hazards consideration, (ii) a significant change in the types or significant increase in the amounts of any effluent that may be released CNL-18-118                                E1-10 of 11
 
Enclosure 1 Description and Assessment of Proposed Change offsite, or (iii) a significant increase in individual or cumulative occupational radiation exposure. Accordingly, the proposed TS change meets the eligibility criterion for categorical exclusion set forth in 10 CFR 51.22(c)(9). Therefore, pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the proposed TS change.
 
==5.0  REFERENCES==
: 1. Technical Specifications Task Force Traveler TSTF-500, Revision 2, "DC Electrical Rewrite-Update to TSTF-360" (ML092670242).
: 2. Federal Register (76 FR 54510): Notice of Availability of Proposed Models for Plant Specific Adoption of Technical Specifications Task Force Traveler TSTF-500, Revision 2, "DC Electrical Rewrite-Update to TSTF-360," dated September 1, 2011.
: 3. Federal Register (76 FR 69296): Notice of Availability of Proposed Models for Plant Specific Adoption of Technical Specifications Task Force Traveler TSTF-500, Revision 2, "DC Electrical Rewrite-Update to TSTF-360," dated November 8, 2011.
: 4. TVA Letter to NRC, "Technical Specification Change Request to Revise Completion Time for Inoperable Diesel Generator," dated November 30, 2009 (ML093640790).
: 5. NRC letter to TVA, "Watts Bar Nuclear Plant, Unit 1 - Issuance of Amendment Regarding the Completion Time for the Inoperable Emergency Diesel Generator(s)
(TAC No. ME2985)," dated July 6, 2010 (ML101390154).
CNL-18-118                                    E1-11 of 11
 
Enclosure 2 Markups of Technical Specification and Bases Changes CNL-18-118                        E2-1
 
WBN Unit 1 Markups of Technical Specification and Bases CNL-18-118                        E2-2
 
DC Sources - Operating 3.8.4 3.8 ELECTRICAL POWER SYSTEMS 3.8.4 DC Sources - Operating LCO 3.8.4              Four channels of The Train A and Train B vital DC electrical power subsystems and four Diesel Generator (DG) DC electrical power subsystems shall be OPERABLE.
                        ------------------------------------------------NOTES------------------------------------------------
: 1.        Vital Battery V may be substituted for any of the required vital batteries.
: 2.        The C-S DG and its associated DC electrical power subsystem may be substituted for any of the required DGs and their associated DC electrical power subsystem.
APPLICABILITY:          MODES 1, 2, 3, and 4.
ACTIONS CONDITION                                    REQUIRED ACTION                            COMPLETION TIME A. One or two required vital            A.1        Restore battery terminal                    2 hours battery charger(s) on one                      voltage to greater than or subsystem inoperable.                          equal to the minimum established float voltage.
AND A.2        Verify battery float current                Once per 12 hours 2 amps.
AND A.3        Restore vital battery charger(s)            7 days to OPERABLE status.
AB. One vital DC electrical              AB.1      Restore vital DC electrical                  2 hours power subsystem                                power subsystem to inoperable for reasons                          OPERABLE status.
other than Condition A.
(continued)
Watts Bar-Unit 1                                        3.8-24
 
DC Sources - Operating 3.8.4 ACTIONS (continued)
CONDITION                  REQUIRED ACTION                COMPLETION TIME BC. Required Action and      BC.1 Be in MODE 3.                  6 hours Associated Completion Time of Condition A or B  AND not met.
BC.2 Be in MODE 5.                  36 hours D. One DG DC battery charger D.1  Restore DG battery terminal    2 hours inoperable.                    voltage to greater than or equal to the minimum established float voltage.
AND D.2  Verify battery float current  Once per 12 hours 1 amp.
AND D.3  Restore DG battery charger to  72 hours OPERABLE status.
CE. One DG DC electrical      CE.1 Restore DG DC electrical      2 hours power subsystem                power subsystem to inoperable for reasons        OPERABLE status.
other than Condition D.
DF. Required Action and      DF.1 Declare associated DG          Immediately associated Completion          inoperable.
Time of Condition CD or E not met.
Watts Bar-Unit 1                        3.8-25
 
DC Sources - Operating 3.8.4 SURVEILLANCE REQUIREMENTS SURVEILLANCE                                        FREQUENCY SR 3.8.4.1      Verify vital battery terminal voltage is  128 V (132 V  7 days for vital battery V) on float charge greater than or equal to the minimum established float voltage.
SR 3.8.4.2      Verify DG battery terminal voltage is  124 V on float    7 days charge greater than or equal to the minimum established float voltage.
SR 3.8.4.3      Verify for the vital batteries that the alternate feeder  7 days breakers to each required battery charger are open.
SR 3.8.4.4      Verify correct breaker alignment and indicated power      7 days availability for each DG 125 V DC distribution panel and associated battery charger.
(continued)
Watts Bar-Unit 1                            3.8-26
 
DC Sources - Operating 3.8.4 SURVEILLANCE REQUIREMENTS (continued)
SURVEILLANCE                                        FREQUENCY SR 3.8.4.5      Verify no visible corrosion at terminals and              92 days connectors for the vital batteries.
OR Verify connection resistance for the vital batteries is 80 E-6 ohm for inter-cell connections,  50 E-6 ohm for inter-rack connections,  120 E-6 ohm for inter-tier connections, and  50 E-6 ohm for terminal connections.
SR 3.8.4.6      Verify no visible corrosion at terminals and              92 days connectors for the DG batteries.
OR Verify connection resistance for the DG batteries is 80 E-6 ohm for inter-cell connections,  50 E-6 ohm for inter-tier connections, and  50 E-6 ohm for terminal connections.
SR 3.8.4.7      Verify battery cells, cell plates, and racks show no      12 months visual indication of physical damage or abnormal deterioration.
SR 3.8.4.8      Remove visible terminal corrosion and verify battery      12 months cell to cell and terminal connections are coated with anti-corrosion material.
(continued)
Watts Bar-Unit 1                            3.8-27                                Amendment 54
 
DC Sources - Operating 3.8.4 SURVEILLANCE REQUIREMENTS (continued)
SURVEILLANCE                                                        FREQUENCY SR 3.8.4.9      Verify connection resistance for the vital batteries is                  12 months 80 E-6 ohm for inter-cell connections,  50 E-6 for inter-rack connections,  120 E-6 ohm for inter-tier connections, and  50 E-6 ohm for terminal connections.
SR 3.8.4.10      Verify connection resistance for the DG batteries is                    12 months 80 E-6 ohm for inter-cell connections,  50 E-6 ohm for inter-tier connections, and  50 E-6 ohm for terminal connections.
SR 3.8.4.115    -------------------------------NOTE-------------------------------
This Surveillance is normally not performed in MODE 1, 2, 3, or 4. However, credit may be taken for unplanned events that satisfy this SR.
Verify each vital battery charger is capable of                          18 months recharging its associated battery from a service or capacity discharge test while supplying normal loads supplies  200 amps at greater than or equal to the minimum established float voltage for  4 hours.
OR Verify each vital battery charger is capable of operating for  4 hours at current limit 220 - 250 amps can recharge the battery to the fully charged state within 36 hours 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.
(continued)
Watts Bar-Unit 1                                  3.8-28                                        Amendment 54
 
DC Sources - Operating 3.8.4 SURVEILLANCE REQUIREMENTS (continued)
SURVEILLANCE                                                        FREQUENCY SR 3.8.4.126    -------------------------------NOTE-------------------------------
Credit may be taken for unplanned events that satisfy this SR.
Verify each diesel generator DG battery charger is                      18 months capable of recharging its associated battery from a service or capacity discharge test while supplying normal loads supplies  20 amps at greater than or equal to the minimum established float voltage for 4 hours.
OR Verify each DG battery charger can recharge the battery to the fully charged state within 24 hours 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.
SR 3.8.4.137    ------------------------------NOTES------------------------------
: 1.        The modified performance discharge test in SR 3.8.4.146.7 may be performed in lieu of the service test in SR 3.8.4.137 once per 60 months.
: 2.        This Surveillance is not performed in MODE 1, 2, 3, or 4 for required vital batteries.
Credit may be taken for unplanned events that satisfy this SR.
Verify battery capacity is adequate to supply, and                      18 months maintain in OPERABLE status, the required emergency loads and any connected nonsafety loads for the design duty cycle when subjected to a battery service test.
(continued)
Watts Bar-Unit 1                                  3.8-29                                        Amendment 12
 
DC Sources - Operating 3.8.4 SURVEILLANCE REQUIREMENTS (continued)
SURVEILLANCE                                                          FREQUENCY SR 3.8.4.14      ------------------------------NOTES------------------------------
This Surveillance is not performed in MODE 1, 2, 3, or 4 for required vital batteries. Credit may be taken for unplanned events that satisfy this SR.
Verify battery capacity is  80% of the manufacturer's                  60 months rating when subjected to a performance discharge test or a modified performance discharge test.                          AND 12 months when battery shows degradation or has reached 85% of expected life with capacity < 100% of manufacturer's rating AND 24 months when battery has reached 85% of the expected life with capacity 100% of manufacturer's rating Watts Bar-Unit 1                                  3.8-30                                            Amendment 12
 
DC Sources - Shutdown 3.8.5 3.8 ELECTRICAL POWER SYSTEMS 3.8.5 DC Sources - Shutdown LCO 3.8.5                Vital DC and Diesel Generator (DG) DC electrical power subsystems shall be OPERABLE to support the DC electrical power distribution subsystem(s) required by LCO 3.8.10, "Distribution Systems - Shutdown" and to support the Diesel Generators (DGs) required by LCO 3.8.2, "AC Sources - Shutdown."
                        --------------------------------------------------NOTES---------------------------------------------
: 1.        Vital Battery V may be substituted for any of the required vital batteries.
: 2.        The C-S DG and its associated DC electrical power subsystem may be substituted for any of the required DGs and their associated DC electrical power subsystems.
APPLICABILITY:          MODES 5 and 6, During movement of irradiated fuel assemblies.
ACTIONS CONDITION                                    REQUIRED ACTION                            COMPLETION TIME A.      One or two required vital            A.1        Restore battery terminal                    2 hours battery charger(s) on one                      voltage to greater than or subsystem inoperable.                          equal to the minimum established float voltage.
AND AND The redundant subsystem vital battery and charger(s)        A.2        Verify battery float current                Once per 12 hours OPERABLE.                                        2 amps.
AND A.3        Restore battery charger(s) to                7 days OPERABLE status.
(continued)
Watts Bar-Unit 1                                          3.8-30
 
DC Sources-Shutdown 3.8.5 ACTIONS (continued)
CONDITION                        REQUIRED ACTION              COMPLETION TIME AB. One or more required vital AB.1.1 Declare affected required    Immediately DC electrical power              feature(s) inoperable.
subsystems inoperable for reasons other than        OR Condition A.
AB.2.1 Suspend CORE                  Immediately OR                                ALTERATIONS.
Required Actions and              AND associated Completion Time of Condition A not    AB.2.2 Suspend movement of          Immediately met.                              irradiated fuel assemblies.
AND AB.2.3 Initiate action to suspend    Immediately operations involving positive reactivity additions.
AND AB.2.4 Initiate action to restore    Immediately required DC electrical power subsystems to OPERABLE status.
BC. One required DG DC        BC.1  Declare associated DG        Immediately electrical power subsystem        inoperable.
inoperable.
Watts Bar-Unit 1                            3.8-31
 
DC Sources-Shutdown 3.8.5 SURVEILLANCE REQUIREMENTS SURVEILLANCE                                                      FREQUENCY SR 3.8.5.1      --------------------------------NOTE-----------------------------
The following SRs are not required to be performed:
SR 3.8.4.115, SR 3.8.4.126, and SR 3.8.4.137, and SR 3.8.4.14.
For DC sources required to be OPERABLE, the                          In accordance with following SRs are applicable:                                        applicable SRs SR 3.8.4.1          SR 3.8.4.6            SR 3.8.4.11 SR 3.8.4.2          SR 3.8.4.7            SR 3.8.4.12 SR 3.8.4.3          SR 3.8.4.8            SR 3.8.4.13 SR 3.8.4.4          SR 3.8.4.9            SR 3.8.4.14 SR 3.8.4.5          SR 3.8.4.10 Watts Bar-Unit 1                                  3.8-32
 
Battery Cell Parameters 3.8.6 3.8 ELECTRICAL POWER SYSTEMS 3.8.6 Battery Cell Parameters LCO 3.8.6                      Battery cell parameters for Train A and Train B electrical power subsystem 125 V vital batteries and 125 V diesel generator (DG) batteries shall be within the limits of Table 3.8.6-1.
APPLICABILITY:                  When associated DC electrical power subsystems and DGs are required to be OPERABLE.
ACTIONS
-------------------------------------------------------------------NOTE---------------------------------------------------------------
Separate Condition entry is allowed for each battery bank.
CONDITION                                        REQUIRED ACTION                            COMPLETION TIME A.        One or more batteries with              A.1        Verify pilot cells electrolyte              1 hour one or more battery cell                          level and float voltage meet parameters not within                              Table 3.8.6-1 Category C Category A or B limits.                            limits.
AND A.2        Verify battery cell parameters              24 hours meet Table 3.8.6-1 Category C limits.                                      AND Once per 7 days thereafter AND A.3        Restore battery cell                        31 days parameters to Category A and B limits of Table 3.8.6-1.
(continued)
Watts Bar-Unit 1                                                  3.8-33
 
Battery Cell Parameters 3.8.6 ACTIONS CONDITION                    REQUIRED ACTION                COMPLETION TIME A.      One or two required vital  A.1 Perform SR 3.8.4.1.            2 hours battery(ies) on one subsystem with one or      AND more battery cells float voltage < 2.07 V.          A.2 Perform SR 3.8.6.1.            2 hours AND A.3 Restore affected cell voltage  24 hours 2.07 V.
B.      One or two required vital  B.1 Perform SR 3.8.4.1.            2 hours battery(ies) on one subsystem with float        AND current > 2 amps.
B.2 Restore vital battery float    12 hours current to  2 amps.
C.      One DG battery with one    C.1 Perform SR 3.8.4.2.            2 hours or more battery cells float voltage < 2.07 V.          AND C.2 Perform SR 3.8.6.2.            2 hours AND C.3 Restore affected cell voltage  24 hours 2.07 V.
D.      One DG battery with float  D.1 Perform SR 3.8.4.2.            2 hours current > 1 amp.
AND D.2 Restore vital battery float    12 hours current to  1 amp.
(continued)
Watts Bar-Unit 1                        3.8-34
 
Battery Cell Parameters 3.8.6 ACTIONS (continued)
CONDITION                                    REQUIRED ACTION                          COMPLETION TIME
------------------NOTE---------------------    ---------------------NOTE----------------------
Required Action E.2 shall be                    Required Actions E.1 and E.2 are only completed if electrolyte level was              applicable if electrolyte level was below below the top of plates.                        the top of plates.
E.          One or two required vital          E.1        Restore electrolyte level to              8 hours battery(ies) on one                            above top of plates.
subsystem with one or more cells electrolyte level        AND less than minimum established design limits.          E.2        Verify no evidence of leakage.            12 hours OR                                  AND One DG battery with one            E.3        Restore electrolyte level to              31 days or more cells electrolyte                      greater than or equal to level less than minimum                        minimum established design established design limits.                      limits.
F.          One or two required vital          F.1        Restore battery pilot cell                12 hours battery(ies) on one                            temperature to greater than or subsystem with pilot cell                      equal to minimum established electrolyte temperature                        design limits.
less than minimum established design limits.
OR One DG battery with pilot cell electrolyte temperature less than minimum established design limits.
(continued)
Watts Bar-Unit 1                                              3.8-35
 
Battery Cell Parameters 3.8.6 ACTIONS (continued)
CONDITION                    REQUIRED ACTION                COMPLETION TIME G.      One or more batteries in    G.1  Restore battery parameters to  2 hours redundant subsystems with        within limits.
battery parameters not within limits.
OR More than one DG battery with battery parameters not within limits.
BH. Required Action and        BH.1 Declare associated battery    Immediately associated Completion            inoperable.
Time of Condition A, B, C, D, E, F, or G not met.
OR One or two required vital battery(ies) on one subsystem with one or more battery cells float voltage < 2.07 V and float current > 2 amps.
OR One DG battery with one or more battery cells float voltage < 2.07 V and float current > 1 amp.
One or more batteries with average electrolyte temperature of the representative cells < 60F for vital batteries and <
50F for DG batteries.
OR One or more batteries with one or more battery cell parameters not within Category C values.
Watts Bar-Unit 1                          3.8-36
 
Battery Cell Parameters 3.8.6 SURVEILLANCE REQUIREMENTS SURVEILLANCE                                            FREQUENCY SR 3.8.6.1            Verify battery cell parameters meet Table 3.8.6-1        7 days Category A limits.
SR 3.8.6.2            Verify battery cell parameters meet Table 3.8.6-1        92 days Category B limits.
AND Once within 24 hours after a battery discharge < 110 V for vital batteries (113.5 V for vital battery V) or 106.5 V for DG batteries AND Once within 24 hours after a battery overcharge > 150 V for vital batteries (155 V for vital battery V) or 145 V for DG batteries SR 3.8.6.3            Verify average electrolyte temperature of                92 days representative cells is  60F for vital batteries and 50F for the DG batteries.
Insert Surveillance Requirements from next page.
Watts Bar-Unit 1                                3.8-37
 
Insert the following Surveillance Requirements for LCO 3.8.6:
SURVEILLANCE                                                      FREQUENCY SR 3.8.6.1                ------------------------------NOTE--------------------------------
Not required to be met when vital battery terminal voltage is less than the minimum established float voltage of SR 3.8.4.1.
Verify each vital battery float current is  2 amps.                  7 days SR 3.8.6.2                ------------------------------NOTE--------------------------------
Not required to be met when DG battery terminal voltage is less than the minimum established float voltage of SR 3.8.4.2.
Verify each DG battery float current is  1 amp.                      7 days SR 3.8.6.3                Verify each required vital battery and each DG                        31 days battery pilot cell float voltage is  2.07 V.
SR 3.8.6.4                Verify each required vital battery and each DG                        31 days battery connected cell electrolyte level is greater than or equal to minimum established design limits.
SR 3.8.6.5                Verify each required vital battery and each DG                        31 days battery pilot cell temperature is greater than or equal to minimum established design limits.
SR 3.8.6.6                Verify each required vital battery and each DG                        92 days battery connected cell float voltage is  2.07 V.
 
SURVEILLANCE                                                        FREQUENCY SR 3.8.6.7  ------------------------------NOTES------------------------------
This Surveillance is not performed in MODE 1, 2, 3, or 4 for required vital batteries. Credit may be taken for unplanned events that satisfy this SR.
Verify battery capacity is  80% of the manufacturer's                  60 months rating when subjected to a performance discharge test or a modified performance discharge test.                          AND 12 months when battery shows degradation or has reached 85% of expected life with capacity < 100% of manufacturer's rating AND 24 months when battery has reached 85% of the expected life with capacity 100% of manufacturer's rating
 
Battery Cell Parameters 3.8.6 Table 3.8.6-1 (page 1 of 1)
Battery Cell Parameters Requirements CATEGORY A:                  CATEGORY B:              CATEGORY C:
PARAMETER                    LIMITS FOR EACH              LIMITS FOR EACH          ALLOWABLE LIMIT DESIGNATED PILOT            CONNECTED CELL          FOR EACH CELL                                                  CONNECTED CELL Electrolyte Level            > Minimum level              > Minimum level          Above top of plates, indication mark, and        indication mark, and    and not overflowing 1/4 inch above              1/4 inch above maximum level                maximum level indication mark (a)          indication mark (a)
Float Voltage                2.13 V                      2.13 V                > 2.07 V Specific Gravity (b)(c)      1.200                      1.195                  Not more than 0.020 below average of all AND                      connected cells Average of all          AND connected cells
                                                            > 1.205                  Average of all connected cells 1.195 (a)      It is acceptable for the electrolyte level to temporarily increase above the specified maximum level during equalizing charges provided it is not overflowing.
(b)      Corrected for electrolyte temperature and level. Level correction is not required, however, when battery charging is < 2 amps when on float charge for vital batteries and < 1.0 amp for DG batteries.
(c)      A battery charging current of < 2 amps when on float charge for vital batteries and < 1.0 amp for DG batteries is acceptable for meeting specific gravity limits following a battery recharge, for a maximum of 31 days. When charging current is used to satisfy specific gravity requirements, specific gravity of each connected cell shall be measured prior to expiration of the 31 day allowance.
Watts Bar-Unit 1                                      3.8-38
 
Procedures, Programs, and Manuals 5.7 5.7      Procedures, Programs, and Manuals 5.7.2.20        Control Room Envelope Habitability Program (continued)
: d.      Measurement, at designated locations, of the CRE pressure relative to all external areas adjacent to the CRE boundary during the pressurization mode of operation by one train of the CREVS, operating at the flow rate defined in the Ventilation Filter Testing Program (VFTP), at a Frequency of 18 months on a STAGGERED TEST BASIS. The results shall be trended and used as part of the 18 month assessment of the CRE boundary.
: e.      The quantitative limits on unfiltered air inleakage into the CRE. These limits shall be stated in a manner to allow direct comparison to the unfiltered air inleakage measured by the testing described in paragraph c. The unfiltered air inleakage limit for radiological challenges is the inleakage flow rate assumed in the licensing basis analyses of DBA consequences. Unfiltered air inleakage limits for hazardous chemicals must ensure that exposure of CRE occupants to these hazards will be within the assumptions in the licensing basis.
: f.      The provisions of SR 3.0.2 are applicable to the frequencies for assessing CRE habitability, determining CRE unfiltered inleakage, and measuring CRE pressure and assessing the CRE boundary as required by paragraphs c and d, respectively.
Note: The addition of TS 5.7.2.21, Spent Fuel Storage Rack Neutron Absorber Monitoring Program, has been proposed per TVA letter CNL-17-144, dated December 20, 2017. Therefore, the proposed addition of the Battery Monitoring and Maintenance Program is numbered TS 5.7.2.22, to reflect the anticipated approval of the license amendment request associated with TVA letter CNL-17-144.
Insert TS 5.7.2.22, Battery Monitoring and Maintenance Program Watts Bar-Unit 1                                    5.0-25a                              Amendment 70, 78
 
INSERT 5.7.2.22 Battery Monitoring and Maintenance Program This Program provides controls for battery restoration and maintenance. The program shall be in accordance with IEEE Standard (Std) 450-2002, "IEEE Recommended Practice for Maintenance, Testing, and Replacement of Vented Lead-Acid Batteries for Stationary Applications," as endorsed by Regulatory Guide 1.129, Revision 2 (RG), with RG exceptions and program provisions as identified below:
: a. The program allows the following RG 1.129, Revision 2 exceptions:
: 1. Battery temperature correction may be performed before or after conducting discharge tests.
: 2. RG 1.129, Regulatory Position 1, Subsection 2, "References," is not applicable to this program.
: 3. In lieu of RG 1.129, Regulatory Position 2, Subsection 5.2, "Inspections," the following shall be used: "Where reference is made to the pilot cell, pilot cell selection shall be based on the lowest voltage cell in the battery.
: 4. In Regulatory Guide 1.129, Regulatory Position 3, Subsection 5.4.1, "State of Charge Indicator," the following statements in paragraph (d) may be omitted: "When it has been recorded that the charging current has stabilized at the charging voltage for three consecutive hourly measurements, the battery is near full charge. These measurements shall be made after the initially high charging current decreases sharply and the battery voltage rises to approach the charger output voltage."
: 5. In lieu of RG 1.129, Regulatory Position 7, Subsection 7.6, "Restoration", the following may be used: "Following the test, record the float voltage of each cell of the string."
: b. The program shall include the following provisions:
: 1. Actions to restore battery cells with float voltage < 2.13 V;
: 2. Actions to determine whether the float voltage of the remaining battery cells is  2.13 V when the float voltage of a battery cell has been found to be < 2.13 V;
: 3. Actions to equalize and test battery cells that had been discovered with electrolyte level below the top of the plates;
: 4. Limits on average electrolyte temperature, battery connection resistance, and battery terminal voltage; and
: 5. A requirement to obtain specific gravity readings of all cells at each discharge test, consistent with manufacturer recommendations.
 
DC Sources-Operating B 3.8.4 B 3.8 ELECTRICAL POWER SYSTEMS B 3.8.4 DC Sources - Operating BASES BACKGROUND            The station DC electrical power system provides the AC emergency power system with control power. It also provides both motive and control power to selected safety related equipment and preferred AC vital bus power (via inverters). As required by 10 CFR 50, Appendix A, GDC 17 (Ref. 1), the DC electrical power system is designed to have sufficient independence, redundancy, and testability to perform its safety functions, assuming a single failure. The DC electrical power system also conforms to the recommendations of Regulatory Guide 1.6 (Ref. 2) and IEEE-308 (Ref. 3).
125 V Vital DC Electrical Power Subsystem The vital 125 VDC electrical power system is a Class IE system whose safety function is to provide control power for engineered safety features equipment, emergency lighting, vital inverters, and other safety-related DC powered equipment for the entire unit. The system capacity is sufficient to supply these loads and any connected nonsafety loads during normal operation and to permit safe shutdown and isolation of the reactor for the "loss of all AC power" condition. The system is designed to perform its safety function subject to a single failure.
The 125V DC vital power system is composed of the four redundant channels (Channels I and III are associated with Train A and Channels II and IV are associated with Train B) and consists of four lead-acid-calcium batteries, eight battery chargers (including two pairs of spare chargers), four distribution boards, battery racks, and the required cabling, instrumentation and protective features.
Each channel is electrically and physically independent from the equipment of all other channels so that a single failure in one channel will not cause a failure in another channel. Each channel consists of a battery charger which supplies normal DC power, a battery for emergency DC power, and a battery board which facilitates load grouping and provides circuit protection. These four channels are used to provide emergency power to the 120V AC vital power system which furnishes control power to the reactor protection system. No automatic connections are used between the four redundant channels.
Battery boards I, II, III, and IV have a charger normally connected to them and also have manual access to a spare (backup) charger for use upon loss of the normal charger.
(continued)
Watts Bar-Unit 1                                  B 3.8-54                                  Revision 105
 
DC Sources-Operating B 3.8.4 BASES BACKGROUND      125 V Vital DC Electrical Power Subsystem (continued)
Additionally, battery boards I, II, III, and IV have manual access to the fifth vital battery system. The fifth 125V DC Vital Battery System is intended to serve as a replacement for any one of the four 125V DC vital batteries during their testing, maintenance, and outages with no loss of system reliability under any mode of operation.
Each of the vital DC electrical power subsystems provide the control power for its associated Class 1E AC power load group, 6.9 kV switchgear, and 480 V load centers. The vital DC electrical power subsystems also provide DC electrical power to the inverters, which in turn power the AC vital buses. Additionally, they power the emergency DC lighting system.
The vital DC power distribution system is described in more detail in Bases for LCO 3.8.9, "Distribution System - Operating," and LCO 3.8.10, "Distribution Systems - Shutdown."
Each vital battery has adequate storage capacity to carry the required load continuously for at least 4 hours in the event of a loss of all AC power (station blackout) without an accident or for 30 minutes with an accident considering a single failure. Load shedding of nonrequired loads will be performed to achieve the required coping duration for station blackout conditions.
Each 125 VDC vital battery is separately housed in a ventilated room apart from its charger and distribution centers, except for Vital Battery V. Each subsystem is located in an area separated physically and electrically from the other subsystem to ensure that a single failure in one subsystem does not cause a failure in a redundant subsystem. There is no sharing between redundant Class 1E subsystems, such as batteries, battery chargers, or distribution panels.
Each battery has adequate storage capacity to meet the duty cycle(s) discussed in the FSAR, Chapter 8 (Ref 4). The battery is designed with additional capacity above that required by the design duty cycle to allow for temperature variations and other factors.
The batteries for the vital DC electrical power subsystems are sized to produce required capacity at 80% of nameplate rating, corresponding to warranted capacity at end of life cycles, derated for minimum ambient temperature and the (continued)
Watts Bar-Unit 1                          B 3.8-55
 
DC Sources-Operating B 3.8.4 BASES BACKGROUND      125 V Vital DC Electrical Power Subsystem (continued) 100% design demand. The minimum design voltage limit is 105 V.The voltage limit is 2.13 V per cell, which corresponds to a total minimum voltage output of 128 V per battery (132 V for Vital Battery V). The criteria for sizing large lead storage batteries are defined in IEEE-485 (Ref. 5).
The battery cells are of flooded lead acid construction with a nominal specific gravity of 1.215. This specific gravity corresponds to an open circuit battery voltage of approximately 120 V for a 60 cell battery (i.e., cell voltage of 2.063 volts per cell (Vpc)). The open circuit voltage is the voltage maintained when there is no charging or discharging. Optimal long term performance however, is obtained by maintaining a float voltage 2.20 to 2.25 Vpc. This provides adequate over-potential, which limits the formation of lead sulfate and self discharge. The nominal float voltage of 2.22 Vpc corresponds to a total float voltage output of 132 V for a 60 cell battery as discussed in the FSAR, Chapter 8 (Ref. 4).
Each Vital DC electrical power subsystem battery charger has ample power output capacity for the steady state operation of connected loads required during normal operation, while at the same time maintaining its battery bank fully charged. Each battery charger also has sufficient excess capacity to restore the battery bank from the design minimum charge to its fully charged state within 12 hours (with accident loads being supplied) following a 30 minute AC power outage and in approximately 36 hours (while supplying normal steady state loads following a 2 hour AC power outage), (Ref. 65).
The battery charger is normally in the float-charge mode. Float-charge is the condition in which the charger is supplying the connected loads and the battery cells are receiving adequate current to optimally charge the battery. This assures the internal losses of a battery are overcome and the battery is maintained in a fully charged state.
When desired, the charger can be placed in the equalize mode. The equalize mode is at a higher voltage than the float mode and charging current is correspondingly higher. The battery charger is operated in the equalize mode after a battery discharge or for routine maintenance. Following a battery discharge, the battery recharge characteristic accepts current at the current limit of the battery charger (if the discharge was significant, e.g., following a battery service test) until the battery terminal voltage approaches the charger voltage setpoint. Charging current then reduces exponentially during the remainder of the recharge cycle. Lead-calcium batteries have recharge efficiencies of greater than 95%, so once at least 105% of the ampere-hours discharged have been returned, the battery capacity would be restored to the same condition as it was prior to the discharge. This can be monitored by direct observation of the exponentially decaying charging current or by evaluating the amp-hours discharged from the battery and amp-hours returned to the battery.
(continued)
Watts Bar-Unit 1                            B 3.8-56                                      Revision 113
 
DC Sources-Operating B 3.8.4 BASES BACKGROUND      125 V Diesel Generator (DG) DC Electrical Power Subsystem (continued)
Control power for the DGs is provided by five DG battery systems, one per DG.
Each system is comprised of a battery, a dual battery charger assembly, distribution center, cabling, and cable ways. The DG 125V DC control power and field-flash circuits have power supplied from their respective 125V distribution panel. The normal supply of DC current is from the associated charger. The battery provides control and field-flash power when the charger is unavailable. The charger supplies the normal DC loads, maintains the battery in a fully charged condition, and recharges (480V AC available) the battery while supplying the required loads regardless of the status of the unit. The batteries are physically and electrically independent. The battery has sufficient capacity when fully charged to supply required loads for a minimum of 30 minutes following a loss of normal power. Each battery is normally required to supply loads during the time interval between loss of normal feed to its charger and the receipt of emergency power to the charger from its respective DG.
APPLICABLE      The initial conditions of Design Basis Accident (DBA) and SAFETY ANALYSES  transient analyses in the FSAR, Section 6 (Ref. 76), and in the FSAR, Section 15 (Ref. 76), assume that Engineered Safety Feature (ESF) systems are OPERABLE. The vital DC electrical power system provides normal and emergency DC electrical power for the emergency auxiliaries, and control and switching during all power for the emergency auxiliaries, and control and switching during all MODES of operation. The DG battery systems provide DC power for the DGs.
The OPERABILITY of the DC sources is consistent with the initial assumptions of the accident analyses and is based upon meeting the design basis of the plant.
This includes maintaining the DC sources OPERABLE during accident conditions in the event of:
: a.      An assumed loss of all offsite AC power or all onsite AC power; and
: b.      A worst case single failure.
The DC sources satisfy Criterion 3 of the NRC Policy Statement.
(continued)
Watts Bar-Unit 1                          B 3.8-57                                    Revision 113
 
DC Sources-Operating B 3.8.4 BASES LCO              Four Two 125V vital DC electrical power subsystems (Train A and Train B), each vital subsystem consisting of two channels. Each channel consisting of a battery bank, associated battery charger and the corresponding control equipment and interconnecting cabling supplying power to the associated DC bus within the channel; and four DG DC electrical power subsystems each consisting of a battery, a dual battery charger assembly, and the corresponding control equipment and interconnecting cabling are required to be OPERABLE to ensure the availability of the required power to shut down the reactor and maintain it in a safe condition after an anticipated operational occurrence (A00) or a postulated DBA. Loss of any DC electrical power subsystem does not prevent the minimum safety function from being performed (Ref. 4).
An OPERABLE vital DC electrical power subsystem requires all required batteries and respective chargers to be operating and connected to the associated DC buses.
The LCO is modified by two a Notes. The Note 1 indicates that Vital Battery V may be substituted for any of the required vital batteries. However, the fifth battery cannot be declared OPERABLE until it is connected electrically in place of another battery and it has satisfied applicable Surveillance Requirements.
Note 2 has been added to indicate that the C-S DG and its associated DC subsystem may be substituted for any of the required DGs. However, the C-S DG and its associated DC subsystem cannot be declared OPERABLE until it is connected electrically in place of another DG, and it has satisfied applicable Surveillance Requirements.
APPLICABILITY    The four vital DC electrical power sources and four DG DC electrical power sources are required to be OPERABLE in MODES 1, 2, 3, and 4 to ensure safe plant operation and to ensure that:
: a.      Acceptable fuel design limits and reactor coolant pressure boundary limits are not exceeded as a result of AOs or abnormal transients; and
: b.      Adequate core cooling is provided, and containment integrity and other vital functions are maintained in the event of a postulated DBA.
The DC electrical power requirements for MODES 5 and 6 are addressed in the Bases for LCO 3.8.5, "DC Sources - Shutdown."
(continued)
Watts Bar-Unit 1                            B 3.8-58
 
DC Sources-Operating B 3.8.4 BASES ACTIONS          A.1, A.2, and A.3 Condition A represents one vital DC subsystem with one or two battery chargers inoperable (e.g., the voltage limit of SR 3.8.4.1 is not maintained). The ACTIONS provide a tiered response that focuses on returning the battery to the fully charged state and restoring a fully qualified charger to OPERABLE status in a reasonable time period. Required Action A.1 requires that the battery terminal voltage be restored to greater than or equal to the minimum established float voltage within 2 hours. This time provides for returning the inoperable charger to OPERABLE status or providing an alternate means of restoring battery terminal voltage to greater than or equal to the minimum established float voltage.
Restoring the battery terminal voltage to greater than or equal to the minimum established float voltage provides good assurance that, within 12 hours, the battery will be restored to its fully charged condition (Required Action A.2) from any discharge that might have occurred due to the charger inoperability.
A discharged battery having terminal voltage of at least the minimum established float voltage indicates that the battery is on the exponential charging current portion (the second part) of its recharge cycle. The time to return a battery to its fully charged state under this condition is simply a function of the amount of the previous discharge and the recharge characteristic of the battery. Thus there is good assurance of fully recharging the battery within 12 hours, avoiding a premature shutdown with its own attendant risk.
If established battery terminal float voltage cannot be restored to greater than or equal to the minimum established float voltage within 2 hours, and the charger is not operating in the current-limiting mode, a faulty charger is indicated. A faulty charger that is incapable of maintaining established battery terminal float voltage does not provide assurance that it can revert to and operate properly in the current limit mode that is necessary during the recovery period following a battery discharge event that the DC system is designed for.
If the charger is operating in the current limit mode after 2 hours that is an indication that the battery is partially discharged and its capacity margins will be reduced. The time to return the battery to its fully charged condition in this case is a function of the battery charger capacity, the amount of loads on the associated DC system, the amount of the previous discharge, and the recharge characteristic of the battery. The charge time can be extensive, and there is not adequate assurance that it can be recharged within 12 hours (Required Action A.2).
Required Action A.2 requires that the battery float current be verified as less than or equal to 2 amps. This indicates that, if the battery had been discharged as the result of the inoperable battery charger, it is now fully capable of supplying the maximum expected load requirement. The 2 amp value is based on returning the battery to 98% charge and assumes a 2% design margin for the battery. If at the (continued)
Watts Bar-Unit 1                          B 3.8-59
 
DC Sources-Operating B 3.8.4 BASES ACTIONS          A.1, A.2, and A.3 (continued) expiration of the initial 12 hour period the battery float current is not less than or equal to 2 amps this indicates there may be additional battery problems and the battery must be declared inoperable.
Required Action A.3 limits the restoration time for the inoperable battery charger to 7 days. This action is applicable if an alternate means of restoring battery terminal voltage to greater than or equal to the minimum established float voltage has been used (e.g., balance of plant non-Class 1E battery charger). The 7 day Completion Time reflects a reasonable time to effect restoration of the qualified battery charger to OPERABLE status.
AB.1 Condition AB represents one vital channel DC electrical power subsystem with a loss of ability to completely respond to an event, and a potential loss of ability to remain energized during normal operation. It is, therefore, imperative that the operator's attention focus on stabilizing the plant, minimizing the potential for complete loss of DC power to the affected train subsystem. The 2 hour limit is consistent with the allowed time for an inoperable DC distribution subsystem train.
If one of the required vital DC electrical power subsystems is inoperable for reasons other than Condition A (e.g., inoperable battery, inoperable battery charger(s), or inoperable battery charger and associated inoperable battery), the remaining vital DC electrical power subsystem has the capacity to support a safe shutdown and to mitigate an accident condition. Since a subsequent worst case single failure of the OPERABLE subsystem would could, however, result in a situation where the ability of the 125V DC electrical power subsystem to support its required ESF function is not assured, the loss of the minimum necessary vital DC electrical power subsystems to mitigate a worst-case accident, continued power operation should not exceed 2 hours. The 2 hour Completion Time is based on Regulatory Guide 1.93 (Ref. 87) and reflects a reasonable time to assess plant status as a function of the inoperable vital DC electrical power subsystem and, if the vital DC electrical power subsystem is not restored to OPERABLE status, to prepare to effect an orderly and safe plant shutdown.
B.1 and B.2C,1 and C.2 If the inoperable vital DC electrical power subsystem cannot be restored to OPERABLE status within the required Completion Time, the plant must be brought to a MODE in which the LCO does not apply. To achieve this status, the plant must be brought to at least MODE 3 within 6 hours and to MODE 5 within 36 hours. The allowed Completion Times are reasonable, based on operating experience, to reach the required plant conditions from full power conditions in an orderly manner and without challenging plant systems. The Completion Time (continued)
Watts Bar-Unit 1                            B 3.8-60
 
DC Sources-Operating B 3.8.4 BASES ACTIONS          B.1 and B.2C,1 and C.2 (continued)
(continued) to bring the plant to MODE 5 is consistent with the time required in Regulatory Guide 1.93 (Ref. 87).
D.1, D.2, and D.3 Condition D represents one DG DC subsystem with one battery charger inoperable (e.g., the voltage limit of SR 3.8.4.1 is not maintained). The ACTIONS provide a tiered response that focuses on returning the battery to the fully charged state and restoring a fully qualified charger to OPERABLE status in a reasonable time period. Required Action D.1 requires that the battery terminal voltage be restored to greater than or equal to the minimum established float voltage within 2 hours. This time provides for returning the inoperable charger to OPERABLE status or providing an alternate means of restoring battery terminal voltage to greater than or equal to the minimum established float voltage.
Restoring the battery terminal voltage to greater than or equal to the minimum established float voltage provides good assurance that, within 12 hours, the battery will be restored to its fully charged condition (Required Action D.2) from any discharge that might have occurred due to the charger inoperability.
A discharged battery having terminal voltage of at least the minimum established float voltage indicates that the battery is on the exponential charging current portion (the second part) of its recharge cycle. The time to return a battery to its fully charged state under this condition is simply a function of the amount of the previous discharge and the recharge characteristic of the battery. Thus there is good assurance of fully recharging the battery within 12 hours, avoiding a premature shutdown with its own attendant risk.
If established battery terminal float voltage cannot be restored to greater than or equal to the minimum established float voltage within 2 hours, and the charger is not operating in the current-limiting mode, a faulty charger is indicated. A faulty charger that is incapable of maintaining established battery terminal float voltage does not provide assurance that it can revert to and operate properly in the current limit mode that is necessary during the recovery period following a battery discharge event that the DG DC system is designed for.
If the charger is operating in the current limit mode after 2 hours that is an indication that the battery is partially discharged and its capacity margins will be reduced. The time to return the battery to its fully charged condition in this case is a function of the battery charger capacity, the amount of loads on the associated DC system, the amount of the previous discharge, and the recharge characteristic of the battery. The charge time can be extensive, and there is not adequate assurance that it can be recharged within 12 hours (Required Action D.2).
(continued)
Watts Bar-Unit 1                          B 3.8-61
 
DC Sources-Operating B 3.8.4 BASES ACTIONS          D.1, D.2, and D.3 (continued)
Required Action D.2 requires that the battery float current be verified as less than or equal to 1 amp. This indicates that, if the battery had been discharged as the result of the inoperable battery charger, it is now fully capable of supplying the maximum expected load requirement. The 1 amp value is based on returning the battery to 98% charge and assumes a 2% design margin for the battery. If at the expiration of the initial 12 hour period the battery float current is not less than or equal to 1 amp this indicates there may be additional battery problems and the battery must be declared inoperable.
Required Action D.3 limits the restoration time for the inoperable battery charger to 72 hours. The 72 hour Completion Time reflects a reasonable time to effect restoration of the qualified battery charger to OPERABLE status.
C.1E.1 Condition CE represents one DG with a loss of ability to completely respond to an event. Since a subsequent single failure on the opposite train could result in a situation where the required ESF function is not assured, continued power operation should not exceed 2 hours. The 2 hour time limit is consistent with the allowed time for an inoperable vital DC electrical power subsystem.
D.1F.1 If the DG DC electrical power subsystem cannot be restored to OPERABLE status in the associated Completion Time, the associated DG may be incapable of performing its intended function and must be immediately declared inoperable.
This declaration also requires entry into applicable Conditions and Required Actions for an inoperable DG, LCO 3.8.1, "AC Sources-Operating."
(continued)
Watts Bar-Unit 1                            B 3.8-62
 
DC Sources-Operating B 3.8.4 BASES (continued)
SURVEILLANCE      SR 3.8.4.1 and SR 3.8.4.2 REQUIREMENTS Verifying battery terminal voltage while on float charge for the batteries helps to ensure the effectiveness of the battery chargers, which support the ability of the batteries to perform their intended function charging system and the ability of the batteries to perform their intended function. Float charge is the condition in which the charger is supplying the continuous charge required to overcome the internal losses of a battery (or battery cell) and maintain the battery (or a battery cell) in a fully charged state while supplying the continuous steady state loads of the associated DC subsystem. On float charge, battery cells will receive adequate current to optimally charge the battery. The voltage requirements are based on the critical nominal design voltage of the battery and are consistent with the initial voltages assumed in the battery sizing calculations minimum float voltage established by the battery manufacturer (2.20 Vpc times the number of connected cells or 132 V at the battery terminals for a 60 cell vital battery; 127.6 V at the battery terminals for a 58 cell DG battery). This voltage maintains the battery plates in a condition that supports maintaining the grid life. The 7 day Frequency is consistent with manufacturer recommendations and IEEE-450 (Ref. 9).
SR 3.8.4.3 Verifying that for the vital batteries that the alternate feeder breakers to each required battery charger is open ensures that independence between the power trains is maintained. The 7-day Frequency is based on engineering judgement, is consistent with procedural controls governing breaker operation, and ensures correct breaker position.
SR 3.8.4.4 This SR demonstrates that the DG 125V DC distribution panel and associated charger are functioning properly, with all required circuit breakers closed and buses energized from normal power. The 7 day Frequency takes into account the redundant DG capability and other indications available in the control room that will alert the operator to system malfunctions.
SR 3.8.4.5 and SR 3.8.4.6 Visual inspection to detect corrosion of the battery cells and connections, or measurement of the resistance of each intercell, interrack, intertier, and terminal connection, provides an indication of physical damage or abnormal deterioration that could potentially degrade battery performance.
(continued)
Watts Bar-Unit 1                            B 3.8-63
 
DC Sources-Operating B 3.8.4 BASES SURVEILLANCE    SR 3.8.4.5 and SR 3.8.4.6 (continued)
REQUIREMENTS The limits established for this SR must be no more than 20% above the resistance as measured during installation, or not above the ceiling value established by the manufacturer.
The Surveillance Frequency for these inspections, which can detect conditions that can cause power losses due to resistance heating, is 92 days. This Frequency is considered acceptable based on operating experience related to detecting corrosion trends.
SR 3.8.4.7 Visual inspection of the battery cells, cell plates, and battery racks provides an indication of physical damage or abnormal deterioration that could potentially degrade battery performance.
The 12 month Frequency for this SR is consistent with IEEE-450 (Ref. 9), which recommends detailed visual inspection of cell condition and rack integrity on a yearly basis.
SR 3.8.4.8, SR 3.8.4.9 and SR 3.8.4.10 Visual inspection and resistance measurements of intercell, interrack, intertier, and terminal connections provide an indication of physical damage or abnormal deterioration that could indicate degraded battery condition. The anticorrosion material is used to help ensure good electrical connections and to reduce terminal deterioration. The visual inspection for corrosion is not intended to require removal of and inspection under each terminal connection. The removal of visible corrosion is a preventive maintenance SR. The presence of visible corrosion does not necessarily represent a failure of this SR provided visible corrosion is removed during performance of SR 3.8.4.8. For the purposes of trending, inter-cell (vital and DG batteries) and inter-tier (vital and DG batteries) connections are measured from battery post to battery post. Inter-rack (vital batteries), inter-tier (DG Batteries), and terminal connections (vital and DG batteries) are measured from terminal lug to battery post.
(continued)
Watts Bar-Unit 1                            B 3.8-61                                    Revision 56, 69 Amendment 54
 
DC Sources-Operating B 3.8.4 BASES SURVEILLANCE    SR 3.8.4.8, SR 3.8.4.9 and SR 3.8.4.10 (continued)
REQUIREMENTS The connection resistance limits for SR 3.8.4.9 and SR 3.8.4.10 shall be no more than 20% above the resistance as measured during installation, or not above the ceiling value established by the manufacturer.
The Surveillance Frequencies of 12 months is consistent with IEEE-450 (Ref. 9),
which recommends cell to cell and terminal connection resistance measurement on a yearly basis.
SR 3.8.4.115 This SR requires that each vital battery charger be capable of recharging its associated battery from a capacity or service discharge test while supplying normal loads, or alternatively, operating at current limit for a minimum of 4 hours at a nominal 125 VDC. These requirements are based on verifies the design capacity of the vital battery chargers (Ref. 4) and their performance characteristic of current limit operation for a substantial portion of the recharge period. Battery charger output current is limited to 110% - 125% of the 200 amp rated output.
Recharging the battery or testing for a minimum of 4 hours is sufficient to verify the output capability of the charger can be sustained, that current limit adjustments are properly set and that protective devices will not inhibit performance at current limit settings. According to Regulatory Guide 1.32 (Ref. 65), the battery charger supply is required recommended to be based on the largest combined demands of the various steady state loads and the charging capacity to restore the battery from the design minimum charge state to the fully charged state, irrespective of the status of the plant during these demand occurrences. Verifying the capability of the charger to operate in a sustained current limit condition The minimum required amperes and duration ensures that these requirements can be satisfied.
This SR provides two options. One option requires that each battery charger be capable of supplying 200 amps at the minimum established float voltage (132 V DC) for 4 hours. The ampere requirements are based on the output rating of the chargers. The voltage requirements are based on the charger voltage level after a response to a loss of AC power.
The other option requires that each vital battery charger be capable of recharging the battery after a service test coincident with supplying the largest coincident demands of the various continuous steady state loads (irrespective of the status of the plant during which these demands occur). This level of loading may not normally be available following the battery service test and will need to be supplemented with additional loads. The duration for this test may be longer than the charger sizing criteria since the battery recharge is affected by float voltage, temperature, and the exponential decay in charging current. The battery is recharged when the measured charging current is  2 amps.
(continued)
Watts Bar-Unit 1                          B 3.8-62
 
DC Sources-Operating B 3.8.4 BASES SURVEILLANCE    SR 3.8.4.115 (continued)
REQUIREMENTS The Surveillance Frequency is acceptable, given the plant conditions required to perform the test and the other administrative controls existing to ensure adequate charger performance during these 18 month intervals. In addition, this Frequency is intended to be consistent with expected fuel cycle lengths.
This SR is modified by a Note. The reason for the Note is that performing the Surveillance may perturb the electrical distribution system and challenge safety systems. This Surveillance is normally performed during MODES 5 and 6 since it would require the DC electrical power subsystem to be inoperable during performance of the test. However, this Surveillance may be performed in MODES 1, 2, 3, or 4 provided the Vital Battery V is substituted in accordance with LCO Note 1. Credit may be taken for unplanned events that satisfy this SR. Examples of unplanned events may include:
: 1)        Unexpected operational events which cause the equipment to perform the function specified by this Surveillance, for which adequate documentation of the required performance is available; and
: 2)        Post corrective maintenance testing that requires performance of this Surveillance in order to restore the component to OPERABLE, provided the maintenance was required, or performed in conjunction with maintenance required to maintain OPERABILITY or reliability.
SR 3.8.4.126 This SR requires that each diesel generator battery charger be capable of recharging its associated battery from a capacity or service discharge test while supplying normal loads, or alternatively, operating at current limit for a minimum of 4 1/2 hours at a nominal 125 VDC. This requirement is based on verifies the design capacity of the DG battery chargers (Ref. 13) and their performance characteristic of current limit operation for a substantial portion of the recharge period. Battery charger output current is limited to a maximum of 140% of the 20 amp rated output. Recharging the battery verifies the output capability of the charger can be sustained, that current limit adjustments are properly set and that protective devices will not inhibit performance at current limit settings. According to Regulatory Guide 1.32 (Ref. 65), the battery charger supply is required recommended to be based on the largest combined demands of the various steady state loads and the charging capacity to restore the battery from the design minimum charge state to the fully charged state, irrespective of the status of the plant during these demand occurrences. Verifying the capability of the charger to operate in a sustained current limit condition The minimum required amperes and duration ensures that these requirements can be satisfied.
(continued)
Watts Bar-Unit 1                            B 3.8-63                                      Revision 112
 
DC Sources-Operating B 3.8.4 BASES SURVEILLANCE    SR 3.8.4.126 (continued)
REQUIREMENTS This SR provides two options. One option requires that each battery charger be capable of supplying 20 amps at the minimum established float voltage (127.6 V DC) for 4 hours. The ampere requirements are based on the output rating of the chargers. The voltage requirements are based on the charger voltage level after a response to a loss of AC power.
The other option requires that each vital battery charger be capable of recharging the battery after a service test coincident with supplying the largest coincident demands of the various continuous steady state loads (irrespective of the status of the plant during which these demands occur). This level of loading may not normally be available following the battery service test and will need to be supplemented with additional loads. The duration for this test may be longer than the charger sizing criteria since the battery recharge is affected by float voltage, temperature, and the exponential decay in charging current. The battery is recharged when the measured charging current is  1 amp.
The Surveillance Frequency is acceptable, given the plant conditions required to perform the test and the other administrative controls existing to ensure adequate charger performance during these 18 month intervals. In addition, this Frequency is intended to be consistent with expected fuel cycle lengths.
For the DG DC electrical subsystem, this Surveillance may be performed in MODES 1, 2, 3, or 4 in conjunction with LCO 3.8.1.B since the DG DC electrical power subsystem supplies loads only for the inoperable diesel generator and would not otherwise challenge safety systems supplied from vital electrical distribution systems. If available, the C-S DG and its associated DC electrical power subsystem may be substituted in accordance with LCO Note 2.
Additionally, credit may be taken for unplanned events that satisfy this SR.
Examples of unplanned events may include:
: 1)      Unexpected operational events which cause the equipment to perform the function specified by this Surveillance, for which adequate documentation of the required performance is available; and
: 2)      Post corrective maintenance testing that requires performance of this Surveillance in order to restore the component to OPERABLE, provided the maintenance was required, or performed in conjunction with maintenance required to maintain OPERABILITY or reliability.
SR 3.8.4.137 A battery service test is a special test of battery capability, as found, to satisfy the design requirements (battery duty cycle) of the DC electrical power system. The discharge rate and test length should correspond to worst case design duty cycle requirements based on References 108 and 1210.
(continued)
Watts Bar-Unit 1                          B 3.8-64                                    Revision 19, 66 Amendment 12
 
DC Sources-Operating B 3.8.4 BASES SURVEILLANCE    SR 3.8.4.137 (continued)
REQUIREMENTS The Surveillance Frequency of 18 months is consistent with the recommendations of Regulatory Guide 1.32 (Ref. 65) and Regulatory Guide 1.129 (Ref. 119), which state that the battery service test should be performed during refueling operations or at some other outage, with intervals between tests, not to exceed 18 months.
This SR is modified by two Notes. Note 1 allows the performance of a modified performance discharge test in lieu of a service test once per 60 months. The modified performance discharge test is a simulated duty cycle consisting of just two rates; the one minute rate published for the battery or the largest current load of the duty cycle, followed by the test rate employed for the performance test, both of which envelope the duty cycle of the service test. Since the ampere-hours removed by a rated one minute discharge represents a very small portion of the battery capacity, the test rate can be changed to that for the performance test without compromising the results of the performance discharge test. The battery terminal voltage for the modified performance discharge test should remain above the minimum battery terminal voltage specified in the battery service test for the duration of time equal to that of the service test.
A modified discharge test is a test of the battery capacity and its ability to provide a high rate, short duration load (usually the highest rate of the duty cycle.) This will often confirm the battery's ability to meet the critical period of the load duty cycle, in addition to determining its percentage of rated capacity. Initial conditions for the modified performance discharge test should be identical to those specified for a service test.
The reason for Note 2 is that performing the Surveillance may perturb the vital electrical distribution system and challenge safety systems. However, this Surveillance may be performed in MODES l, 2, 3, or 4 provided that Vital Battery V is substituted in accordance with LCO Note l. For the DG DC electrical subsystem, this surveillance may be performed in MODES l, 2, 3, or 4 in conjunction with LCO 3.8.l.B since the supplied loads are only for the inoperable diesel generator and would not otherwise challenge safety system loads which are supplied from vital electrical distribution systems. If available, the C-S DG and its associated DC electrical power subsystem may be substituted in accordance with LCO Note 2. Additionally, credit may be taken for unplanned events that satisfy this SR. Examples of unplanned events may include:
: 1)      Unexpected operational events which cause the equipment to perform the function specified by this Surveillance, for which adequate documentation of the required performance is available; and (continued)
Watts Bar-Unit 1                            B 3.8-65                                          Revision 19 Amendment 12
 
DC Sources-Operating B 3.8.4 BASES SURVEILLANCE    SR 3.8.4.137 (continued)
REQUIREMENTS
: 2)      Post corrective maintenance testing that requires performance of this Surveillance in order to restore the component to OPERABLE, provided the maintenance was required, or performed in conjunction with maintenance required to maintain OPERABILITY or reliability.
SR 3.8.4.14 A battery performance discharge test is a test of constant current capacity of a battery, normally done in the as found condition, after having been in service, to detect any change in the capacity determined by the acceptance test. The test is intended to determine overall battery degradation due to age and usage.
A battery modified performance discharge test is described in the Bases for 3.8.4.13. Either the battery performance discharge test or the modified performance discharge test is acceptable for satisfying SR 3.8.4.14; however, only the modified performance discharge test may be used to satisfy SR 3.8.4.14 while satisfying the requirements of SR 3.8.4.13 at the same time.
The acceptance criteria for this Surveillance are consistent with IEEE-450 (Ref. 9) and IEEE-485 (Ref. 5). These references recommend that the battery be replaced if its capacity is below 80% of the manufacturer rating. A capacity of 80% shows that the battery rate of deterioration is increasing, even if there is ample capacity to meet the load requirements.
The Surveillance Frequency for this test is normally 60 months. If the battery shows degradation, or if the battery has reached 85% of its expected life and capacity is < 100% of the manufacturer's rating, the Surveillance Frequency is reduced to 12 months. However, if the battery shows no degradation but has reached 85% of its expected life, the Surveillance Frequency is only reduced to 24 months for batteries that retain capacity > 100% of the manufacturer's rating.
Degradation is indicated, according to IEEE-450 (Ref. 9), when the battery capacity drops by more than 10% relative to its capacity on the previous performance test or when it is > 10% below the manufacturer rating. These Frequencies are consistent with the recommendations in IEEE-450 (Ref. 9).
(continued)
Watts Bar-Unit 1                          B 3.8-66                                      Revision 19 Amendment 12
 
DC Sources-Operating B 3.8.4 BASES SURVEILLANCE    SR 3.8.4.14 (continued)
REQUIREMENTS This SR is modified by a Note. The reason for the Note is that performing the Surveillance may perturb the vital electrical distribution system and challenge safety systems. However, this Surveillance may be performed in MODES l, 2, 3, or 4 provided that Vital Battery V is substituted in accordance with LCO Note l.
For the DG DC electrical subsystem, this surveillance may be performed in MODES l, 2, 3, or 4 in conjunction with LCO 3.8.l.B since the supplied loads are only for the inoperable diesel generator and would not otherwise challenge safety system loads which are supplied from vital electrical distribution systems. If available, the C-S DG and its associated DC electrical power subsystem may be substituted in accordance with LCO Note 2. Additionally, credit may be taken for unplanned events that satisfy this SR. Examples of unplanned events may include:
: 1)      Unexpected operational events which cause the equipment to perform the function specified by this Surveillance, for which adequate documentation of the required performance is available; and
: 2)      Post corrective maintenance testing that requires performance of this Surveillance in order to restore the component to OPERABLE, provided the maintenance was required, or performed in conjunction with maintenance required to maintain OPERABILITY or reliability.
(continued)
Watts Bar-Unit 1                          B 3.8-67                                      Revision 19 Amendment 12
 
DC Sources-Operating B 3.8.4 BASES (continued)
REFERENCES        1. Title 10, Code of Federal Regulations, Part 50, Appendix A, General Design Criterion 17, Electric Power System.
: 2. Regulatory Guide 1.6, Independence Between Redundant Standby (Onsite) Power Sources and Between Their Distribution Systems, U.S.
Nuclear Regulatory Commission, March 10, 1971.
: 3. IEEE-308-1971, IEEE Standard Criteria for Class 1E Power Systems for Nuclear Power Generating Stations, Institute of Electrical and Electronic Engineers.
: 4. Watts Bar FSAR, Section 8.3.2, DC Power System.
: 5. IEEE-485-1983, Recommended Practices for Sizing Large Lead Storage Batteries for Generating Stations and Substations, Institute of Electrical and Electronic Engineers.
: 65. Regulatory Guide 1.32, Criteria for Safety-Related Electric Power Systems for Nuclear Power Plants, February 1977, U.S. Nuclear Regulatory Commission.
: 76. Watts Bar FSAR, Section 15, Accident Analysis and Section 6 Engineered Safety Features.
: 87. Regulatory Guide 1.93, Availability of Electric Power Sources, U.S.
Nuclear Regulatory Commission, December 1974.
: 9. IEEE-450-1980/1995, IEEE Recommended Practice for Maintenance Testing and Replacement of Large Lead Storage Batteries for Generating Stations and Subsystems, Institute of Electrical and Electronic Engineers.
108. TVA Calculation WBN EEB-MS-TI11-0003, 125 VDC Vital Battery and Charger Evaluation.
119. Regulatory Guide 1.129, Maintenance Testing and Replacement of Large Lead Storage Batteries for Generating Stations and Subsystems, U.S. Nuclear Regulatory Commission, February 1978.
(continued)
Watts Bar-Unit 1                        B 3.8-68
 
DC Sources-Operating B 3.8.4 BASES REFERENCES      1210. TVA Calculation WBN EEB-MS-TI11-0062, "125 V DC Diesel Generator (continued)            Control Power System Evaluation."
: 13. Watts Bar FSAR, Section 8.3.1, "AC Power System."
Watts Bar-Unit 1                      B 3.8-69
 
DC Sources - Shutdown B 3.8.5 B 3.8 ELECTRICAL POWER SYSTEMS B 3.8.5 DC Sources - Shutdown BASES BACKGROUND            A description of the DC sources is provided in the Bases for LCO 3.8.4, "DC Sources - Operating."
APPLICABLE            The initial conditions of Design Basis Accident and transient analyses in SAFETY ANALYSES      the FSAR, Section 6 (Ref. 1) and Section 15 (Ref. 1), assume that Engineered Safety Feature systems are OPERABLE. The vital DC electrical power system provides normal and emergency DC electrical power for the emergency auxiliaries, and control and switching during all MODES of operation.
The DG battery systems provide DC power for the DGs.
The OPERABILITY of the DC sources is consistent with the initial assumptions of the accident analyses and the requirements for the supported systems OPERABILITY.
The OPERABILITY of the minimum DC electrical power sources during MODES 5 and 6, and during movement of irradiated fuel assemblies ensures that:
: a.      The plant can be maintained in the shutdown or refueling condition for extended periods;
: b.      Sufficient instrumentation and control capability is available for monitoring and maintaining the plant status; and
: c.      Adequate DC electrical power is provided to mitigate events postulated during shutdown, such as a fuel handling accident.
The DC sources satisfy Criterion 3 of the NRC Policy Statement.
(continued)
Watts Bar-Unit 1                                B 3.8-70
 
DC Sources - Shutdown B 3.8.5 BASES (continued)
LCO              The 125V Vital DC electrical power subsystems, each vital subsystem channel consisting of a battery bank, associated battery charger, and the corresponding control equipment and interconnecting cabling within the channel; and the DG DC electrical power subsystems, each consisting of a battery, a battery charger, and the corresponding control equipment and interconnecting cabling, are required to be OPERABLE to support required trains subsystems of the distribution systems required OPERABLE by LCO 3.8.10, "Distribution Systems -
Shutdown" and the required DGs required OPERABLE by LCO 3.8.2, "AC Sources-Shutdown." As a minimum, one vital DC electrical power train subsystem (i.e., Channels I and III, or II and IV) and two DG DC electrical power subsystems (i.e., 1A-A and 2A-A or 1B-B and 2B-B) shall be OPERABLE. This ensures the availability of sufficient DC electrical power sources to operate the plant in a safe manner and to mitigate the consequences of postulated events during shutdown (e.g., fuel handling accidents).
The LCO is modified by two a Notes. The Note 1 indicates that Vital Battery V may be substituted for any of the required vital batteries. However, the fifth battery cannot be declared OPERABLE until it is connected electrically in place of another battery and it has satisfied applicable Surveillance Requirements.
Note 2 has been added to indicate that the C-S DG and its associated DC subsystem may be substituted for any of the required DGs. However, the C-S DG and its associated DC subsystem cannot be declared OPERABLE until it is connected electrically in place of another DG, and it has satisfied applicable Surveillance Requirements.
APPLICABILITY    The DC electrical power sources required to be OPERABLE in MODES 5 and 6, and during movement of irradiated fuel assemblies, provide assurance that:
: a. Required features needed to mitigate a fuel handling accident are available; (continued)
Watts Bar-Unit 1                            B 3.8-71
 
DC Sources - Shutdown B 3.8.5 BASES APPLICABILITY    b.        Required features necessary to mitigate the effects of events that can (continued)              lead to core damage during shutdown are available; and
: c.        Instrumentation and control capability is available for monitoring and maintaining the plant in a cold shutdown condition or refueling condition.
The DC electrical power requirements for MODES 1, 2, 3, and 4 are covered in LCO 3.8.4.
ACTIONS      A.1, A.2, and A.3 Condition A represents one subsystem with one or two battery charger(s) inoperable (e.g., the voltage limit of SR 3.8.4.1 is not maintained). The ACTIONS provide a tiered response that focuses on returning the battery to the fully charged state and restoring a fully qualified charger to OPERABLE status in a reasonable time period. Required Action A.1 requires that the battery terminal voltage be restored to greater than or equal to the minimum established float voltage within 2 hours. This time provides for returning the inoperable charger to OPERABLE status or providing an alternate means of restoring battery terminal voltage to greater than or equal to the minimum established float voltage.
Restoring the battery terminal voltage to greater than or equal to the minimum established float voltage provides good assurance that, within 12 hours, the battery will be restored to its fully charged condition (Required Action A.2) from any discharge that might have occurred due to the charger inoperability.
A discharged battery having terminal voltage of at least the minimum established float voltage indicates that the battery is on the exponential charging current portion (the second part) of its recharge cycle. The time to return a battery to its fully charged state under this condition is simply a function of the amount of the previous discharge and the recharge characteristic of the battery. Thus there is good assurance of fully recharging the battery within [12] hours, avoiding a premature shutdown with its own attendant risk.
If established battery terminal float voltage cannot be restored to greater than or equal to the minimum established float voltage within 2 hours, and the charger is not operating in the current-limiting mode, a faulty charger is indicated. A faulty charger that is incapable of maintaining established battery terminal float voltage does not provide assurance that it can revert to and operate properly in the current limit mode that is necessary during the recovery period following a battery discharge event that the DC system is designed for.
If the charger is operating in the current limit mode after 2 hours that is an indication that the battery is partially discharged and its capacity margins will be reduced. The time to return the battery to its fully charged condition in this case (continued)
Watts Bar-Unit 1                          B 3.8-72
 
DC Sources - Shutdown B 3.8.5 BASES ACTIONS          A.1, A.2, and A.3 (continued) is a function of the battery charger capacity, the amount of loads on the associated DC system, the amount of the previous discharge, and the recharge characteristic of the battery. The charge time can be extensive, and there is not adequate assurance that it can be recharged within 12 hours (Required Action A.2).
Required Action A.2 requires that the battery float current be verified as less than or equal to 2 amps. This indicates that, if the battery had been discharged as the result of the inoperable battery charger, it has now been fully recharged. If at the expiration of the initial 12 hour period the battery float current is not less than or equal to 2 amps this indicates there may be additional battery problems and the battery must be declared inoperable.
Required Action A.3 limits the restoration time for the inoperable battery charger to 7 days. This action is applicable if an alternate means of restoring battery terminal voltage to greater than or equal to the minimum established float voltage has been used (e.g., balance of plant non-Class 1E battery charger). The 7 day Completion Time reflects a reasonable time to effect restoration of the qualified battery charger to OPERABLE status.
AB.1, AB.2.1, AB.2.2, AB.2.3, and AB.2.4 If two trains subsystems are required by LCO 3.8.10, the remaining train subsystem with DC power available may be capable of supporting sufficient systems to allow continuation of CORE ALTERATIONS and fuel movement. By allowing the option to declare required features inoperable with the associated vital DC power source(s) inoperable, appropriate restrictions will be implemented in accordance with the affected required features LCO ACTIONS. In many instances, this option may involve undesired administrative efforts. Therefore, the allowance for sufficiently conservative actions is made (i.e., to suspend CORE ALTERATIONS, movement of irradiated fuel assemblies, and operations involving positive reactivity additions). The Required Action to suspend positive reactivity additions does not preclude actions to maintain or increase reactor vessel inventory, provided the required SDM is maintained.
Suspension of these activities shall not preclude completion of actions to establish a safe conservative condition. These actions minimize probability of the occurrence of postulated events. It is further required to immediately initiate action to restore the required vital DC electrical power subsystems and to continue this action until restoration is accomplished in order to provide the necessary DC electrical power to the plant safety systems.
(continued)
Watts Bar-Unit 1                            B 3.8-73
 
DC Sources - Shutdown B 3.8.5 BASES ACTIONS          AB.1, AB.2.1, AB.2.2, AB.2.3, and AB.2.4 (continued)
The Completion Time of immediately is consistent with the required times for actions requiring prompt attention. The restoration of the required vital DC electrical power subsystems should be completed as quickly as possible in order to minimize the time during which the plant safety systems may be without sufficient power.
BC.1 If the DG DC electrical power subsystem cannot be restored to OPERABLE status in the associated Completion Time, the associated DG may be incapable of performing its intended function and must be immediately declared inoperable.
This declaration also requires entry into applicable Conditions and Required Actions for an inoperable DG, LCO 3.8.2, "AC Sources-Shutdown."
SURVEILLANCE      SR 3.8.5.1 REQUIREMENTS SR 3.8.5.1 requires performance of all Surveillances required by SR 3.8.4.1 through SR 3.8.4.147. Therefore, see the corresponding Bases for LCO 3.8.4 for a discussion of each SR.
This SR is modified by a Note. The reason for the Note is to preclude requiring the OPERABLE DC sources from being discharged below their capability to provide the required power supply or otherwise rendered inoperable during the performance of SRs. It is the intent that these SRs must still be capable of being met, but actual performance is not required.
REFERENCES      1.        Watts Bar FSAR, Section 15, "Accident Analysis" and Section 6, "Engineered Safety Features."
: 2.        Watts Bar FSAR, Section 8.0, "Electric Power."
Watts Bar-Unit 1                          B 3.8-74
 
Battery Cell Parameters B 3.8.6 B 3.8 ELECTRICAL POWER SYSTEMS B 3.8.6 Battery Cell Parameters BASES BACKGROUND              This LCO delineates the limits on battery float current as well as electrolyte temperature, level, and float voltage, and specific gravity for the 125V vital DC electrical power subsystem and diesel generator (DG) batteries. A discussion of these batteries and their OPERABILITY requirements is provided in the Bases for LCO 3.8.4, "DC Sources - Operating," and LCO 3.8.5, "DC Sources -
Shutdown." In addition to the limitations of this Specification, the Battery Monitoring and Maintenance Program also implements a program specified in Specification 5.7.2.22 for monitoring various battery parameters.
The battery cells are of flooded lead acid construction with a nominal specific gravity of 1.215. This specific gravity corresponds to an open circuit battery voltage of approximately 120 V for 60 cell battery (i.e., cell voltage of 2.063 volts per cell (Vpc)). The open circuit voltage is the voltage maintained when there is no charging or discharging. Optimal long term performance however, is obtained by maintaining a float voltage 2.20 to 2.25 Vpc. This provides adequate over-potential which limits the formation of lead sulfate and self discharge. The nominal float voltage of 2.22 Vpc corresponds to a total float voltage output of 133.2 V for a 60 cell battery as discussed in the FSAR, Chapter 8 (Ref. 3).
APPLICABLE              The initial conditions of Design Basis Accident (DBA) and transient analyses SAFETY                  in the FSAR, Section 6 (Ref. 1) and Section 15 (Ref. 1), assume Engineered ANALYSES                Safety Feature systems are OPERABLE. The vital DC electrical power system provides normal and emergency DC electrical power for the emergency auxiliaries, and control and switching during all MODES of operation. The DG battery systems provide DC power for the DGs.
The OPERABILITY of the DC subsystems is consistent with the initial assumptions of the accident analyses and is based upon meeting the design basis of the plant. This includes maintaining at least one train subsystem of DC sources OPERABLE during accident conditions, in the event of:
: a.      An assumed loss of all offsite AC power or all onsite AC power; and
: b.      A worst case single failure.
Battery cell parameters satisfy the Criterion 3 of the NRC Policy Statement.
(continued)
Watts Bar-Unit 1                                  B 3.8-74
 
Battery Cell Parameters B 3.8.6 BASES (continued)
LCO              Battery cell parameters must remain within acceptable limits to ensure availability of the required DC power to shut down the reactor and maintain it in a safe condition after an anticipated operational occurrence or a postulated DBA.
Electrolyte Battery parameter limits are conservatively established, allowing continued DC electrical system function even with Category A and B limits not met. Additional preventative maintenance, testing, and monitoring performed in accordance with the Battery Monitoring and Maintenance Program is conducted as specified in Specification 5.7.2.22.
APPLICABILITY    The battery cell parameters are required solely for the support of the associated vital DC and DG DC electrical power subsystems. Therefore, battery electrolyte is parameter limits are only required when the DC power source is required to be OPERABLE. Refer to the Applicability discussion in Bases for LCO 3.8.4 and LCO 3.8.5.
ACTIONS          A.1, A.2, and A.3 With one or more cells in one or more batteries not within limits (i.e., Category A limits not met, Category B limits not met, or Category A and B limits not met) but within the Category C limits specified in Table 3.8.6-1 in the accompanying LCO, the battery is degraded but there is still sufficient capacity to perform the intended function. Therefore, the affected battery is not required to be considered inoperable solely as a result of Category A or B limits not met, and operation is permitted for a limited period.
The pilot cell electrolyte level and float voltage are required to be verified to meet the Category C limits within 1 hour (Required Action A.1). This check will provide a quick indication of the status of the remainder of the battery cells. One hour provides time to inspect the electrolyte level and to confirm the float voltage of the pilot cells. One hour is considered a reasonable amount of time to perform the required verification.
Verification that the Category C limits are met (Required Action A.2) provides assurance that during the time needed to restore the parameters to the Category A and B limits, the battery is still capable of performing its intended function. A period of 24 hours is allowed to complete the initial verification because specific gravity measurements must be obtained for each connected cell. Taking into consideration both the time required to perform the required verification and the assurance that the battery cell (continued)
Watts Bar-Unit 1                            B 3.8-75
 
Battery Cell Parameters B 3.8.6 BASES ACTIONS          A.1, A.2, and A.3 (continued) parameters are not severely degraded, this time is considered reasonable. The verification is repeated at 7 day intervals until the parameters are restored to Category A and B limits. This periodic verification is consistent with the normal Frequency of pilot cell surveillances.
Continued operation is only permitted for 31 days before battery cell parameters must be restored to within Category A and B limits. With the consideration that, while battery capacity is degraded, sufficient capacity exists to perform the intended function and to allow time to fully restore the battery cell parameters to normal limits, this time is acceptable prior to declaring the battery inoperable.
A.1, A.2, and A.3 With one or more cells in one or more batteries in one vital DC subsystem
                < 2.07 V, the battery cell is degraded. Within 2 hours verification of the required battery charger OPERABILITY is made by monitoring the battery terminal voltage (SR 3.8.4.1) and of the overall battery state of charge by monitoring the battery float charge current (SR 3.8.6.1). This assures that there is still sufficient battery capacity to perform the intended function. Therefore, the affected battery is not required to be considered inoperable solely as a result of one or more cells in one or more batteries < 2.07 V, and continued operation is permitted for a limited period up to 24 hours.
Since the Required Actions only specify "perform," a failure of SR 3.8.4.1 or SR 3.8.6.1 acceptance criteria does not result in this Required Action not met.
However, if one of the SRs is failed the appropriate Condition(s), depending on the cause of the failures, is entered. If SR 3.8.6.1 is failed then there is not assurance that there is still sufficient battery capacity to perform the intended function and the battery must be declared inoperable immediately.
B.1 and B.2 One or more batteries in one vital DC subsystem with float current > 2 amps indicates that a partial discharge of the battery capacity has occurred. This may be due to a temporary loss of a battery charger or possibly due to one or more battery cells in a low voltage condition reflecting some loss of capacity. Within 2 hours verification of the required battery charger OPERABILITY is made by monitoring the battery terminal voltage. If the terminal voltage is found to be less than the minimum established float voltage there are two possibilities, the battery charger is inoperable or is operating in the current limit mode. Condition A addresses charger inoperability. If the charger is operating in the current limit mode after 2 hours that is an indication that the battery has been substantially discharged and likely cannot perform its required design functions. The time to return the battery to its fully charged condition in this case is a function of the (continued)
Watts Bar-Unit 1                            B 3.8-76
 
Battery Cell Parameters B 3.8.6 BASES ACTIONS          B.1 and B.2 (continued) battery charger capacity, the amount of loads on the associated DC system, the amount of the previous discharge, and the recharge characteristic of the battery.
The charge time can be extensive, and there is not adequate assurance that it can be recharged within 12 hours (Required Action B.2). The battery must therefore be declared inoperable.
If the float voltage is found to be satisfactory but there are one or more battery cells with float voltage less than 2.07 V, the associated "OR" statement in Condition H is applicable and the battery must be declared inoperable immediately. If float voltage is satisfactory and there are no cells less than 2.07 V there is good assurance that, within 12 hours, the battery will be restored to its fully charged condition (Required Action B.2) from any discharge that might have occurred due to a temporary loss of the battery charger.
A discharged battery with float voltage (the charger setpoint) across its terminals indicates that the battery is on the exponential charging current portion (the second part) of its recharge cycle. The time to return a battery to its fully charged state under this condition is simply a function of the amount of the previous discharge and the recharge characteristic of the battery. Thus there is good assurance of fully recharging the battery within 12 hours, avoiding a premature shutdown with its own attendant risk.
If the condition is due to one or more cells in a low voltage condition but still greater than 2.07 V and float voltage is found to be satisfactory, this is not indication of a substantially discharged battery and 12 hours is a reasonable time prior to declaring the battery inoperable.
Since Required Action B.1 only specifies "perform," a failure of SR 3.8.4.1 acceptance criteria does not result in the Required Action not met. However, if SR 3.8.4.1 is failed, the appropriate Condition(s), depending on the cause of the failure, is entered.
C.1, C.2, and C.3 With one or more cells in one or more batteries in one DG DC subsystem
                < 2.07 V, the battery cell is degraded. Within 2 hours verification of the required battery charger OPERABILITY is made by monitoring the battery terminal voltage (SR 3.8.4.2) and of the overall battery state of charge by monitoring the battery float charge current (SR 3.8.6.2). This assures that there is still sufficient battery capacity to perform the intended function.
Therefore, the affected battery is not required to be considered inoperable solely as a result of one or more cells in one or more batteries < 2.07 V, and continued operation is permitted for a limited period up to 24 hours.
(continued)
Watts Bar-Unit 1                            B 3.8-77
 
Battery Cell Parameters B 3.8.6 BASES ACTIONS          C.1, C.2, and C.3 (continued)
Since the Required Actions only specify "perform," a failure of SR 3.8.4.2 or SR 3.8.6.2 acceptance criteria does not result in this Required Action not met.
However, if one of the SRs is failed the appropriate Condition(s), depending on the cause of the failures, is entered. If SR 3.8.6.2 is failed then there is not assurance that there is still sufficient battery capacity to perform the intended function and the battery must be declared inoperable immediately.
D.1 and D.2 One or more batteries in one DG DC subsystem with float current > 1 amps indicates that a partial discharge of the battery capacity has occurred. This may be due to a temporary loss of a battery charger or possibly due to one or more battery cells in a low voltage condition reflecting some loss of capacity. Within 2 hours verification of the required battery charger OPERABILITY is made by monitoring the battery terminal voltage. If the terminal voltage is found to be less than the minimum established float voltage there are two possibilities, the battery charger is inoperable or is operating in the current limit mode. Condition B addresses charger inoperability. If the charger is operating in the current limit mode after 2 hours that is an indication that the battery has been substantially discharged and likely cannot perform its required design functions. The time to return the battery to its fully charged condition in this case is a function of the battery charger capacity, the amount of loads on the associated DC system, the amount of the previous discharge, and the recharge characteristic of the battery.
The charge time can be extensive, and there is not adequate assurance that it can be recharged within 12 hours (Required Action D.2). The battery must therefore be declared inoperable.
If the float voltage is found to be satisfactory but there are one or more battery cells with float voltage less than 2.07 V, the associated "OR" statement in Condition H is applicable and the battery must be declared inoperable immediately. If float voltage is satisfactory and there are no cells less than 2.07 V there is good assurance that, within 12 hours, the battery will be restored to its fully charged condition (Required Action D.2) from any discharge that might have occurred due to a temporary loss of the battery charger.
A discharged battery with float voltage (the charger setpoint) across its terminals indicates that the battery is on the exponential charging current portion (the second part) of its recharge cycle. The time to return a battery to its fully charged state under this condition is simply a function of the amount of the previous discharge and the recharge characteristic of the battery. Thus there is good assurance of fully recharging the battery within 12 hours, avoiding a premature shutdown with its own attendant risk.
If the condition is due to one or more cells in a low voltage condition but still greater than 2.07 V and float voltage is found to be satisfactory, this is not (continued)
Watts Bar-Unit 1                            B 3.8-78
 
Battery Cell Parameters B 3.8.6 BASES ACTIONS          D.1 and D.2 (continued) indication of a substantially discharged battery and 12 hours is a reasonable time prior to declaring the battery inoperable.
Since Required Action D.1 only specifies "perform," a failure of SR 3.8.4.2 acceptance criteria does not result in the Required Action not met. However, if SR 3.8.4.2 is failed, the appropriate Condition(s), depending on the cause of the failure, is entered.
E.1, E.2, and E.3 With one or more required batteries in one vital DC subsystem or one DG battery with one or more cells electrolyte level above the top of the plates, but below the minimum established design limits, the battery still retains sufficient capacity to perform the intended function. Therefore, the affected battery is not required to be considered inoperable solely as a result of electrolyte level not met. Within 31 days the minimum established design limits for electrolyte level must be re-established.
With electrolyte level below the top of the plates there is a potential for dryout and plate degradation. Required Actions E.1 and E.2 address this potential (as well as provisions in Specification 5.7.2.22, Battery Monitoring and Maintenance Program). They are modified by a Note that indicates they are only applicable if electrolyte level is below the top of the plates. Within 8 hours level is required to be restored to above the top of the plates. The Required Action E.2 requirement to verify that there is no leakage by visual inspection and the Specification 5.7.2.22.b item to initiate action to equalize and test in accordance with manufacturer's recommendation. They are performed following the restoration of the electrolyte level to above the top of the plates. Based on the results of the manufacturer's recommended testing the battery(ies) may have to be declared inoperable and the affected cell(s) replaced.
F.1 With one or more batteries in one vital DC subsystem or one DG battery with pilot cell temperature less than the minimum established design limits, 12 hours is allowed to restore the temperature to within limits. A low electrolyte temperature limits the current and power available. Since the battery is sized with margin, while battery capacity is degraded, sufficient capacity exists to perform the intended function and the affected battery is not required to be considered inoperable solely as a result of the pilot cell temperature not met.
(continued)
Watts Bar-Unit 1                            B 3.8-79
 
Battery Cell Parameters B 3.8.6 BASES ACTIONS          G.1 (continued)
With one or more batteries in redundant vital DC subsystems with battery parameters not within limits there is not sufficient assurance that battery capacity has not been affected to the degree that the batteries can still perform their required function, given that redundant batteries are involved. With redundant batteries involved this potential could result in a total loss of function on multiple systems that rely upon the batteries. With more than one DG battery with battery parameters not within limits there is not sufficient assurance that battery capacity has not been affected to the degree that the batteries can still perform their required function.
The longer Completion Times specified for battery parameters on non-redundant batteries not within limits are therefore not appropriate, and the parameters must be restored to within limits on at least one subsystem within 2 hours.
BH.1 With one or more batteries with one or more any battery cell parameters outside the Category C limits for any connected cell, allowances of the Required Actions for Condition A, B, C, D, E, F, or G, sufficient capacity to supply the maximum expected load requirement is not assured and the corresponding vital DC or DG DC electrical power subsystem battery must be declared inoperable.
Additionally, other potentially extreme conditions, such as not completing the Required Actions of Condition A within the required Completion Time or average electrolyte temperature of representative cells falling below 60F for the vital batteries or 50F for DG batteries, are also cause for immediately declaring the associated vital DC or DG DC electrical power subsystem inoperable.
discovering one or more vital DC batteries in one subsystem with one or more battery cells float voltage less than 2.07 V and float current greater than 2 amps, or one DG battery cells float voltage greater than or equal to 2.07 V and float current greater than 1 amp, indicates that the battery capacity may not be sufficient to perform the intended functions. The battery must therefore be declared inoperable immediately.
SURVEILLANCE    SR 3.8.6.1 REQUIREMENTS This SR verifies that Category A battery cell parameters are consistent with IEEE-450 (Ref. 2), which recommends regular battery inspections (at least one per month) including voltage, specific gravity, and electrolyte temperature of pilot cells.
(continued)
Watts Bar-Unit 1                            B 3.8-80
 
Battery Cell Parameters B 3.8.6 BASES SURVEILLANCE    SR 3.8.6.2 REQUIREMENTS (continued)    The quarterly inspection of specific gravity and voltage is consistent with IEEE-450 (Ref. 2). In addition, within 24 hours of a battery discharge < 110 V (113.5V for Vital Battery V or 106.5 for DG batteries) or a battery overcharge
                > 150 V (155 V for Vital Battery V or 145 V for DG batteries), the battery must be demonstrated to meet Category B limits. Transients, such as motor starting transients, which may momentarily cause battery voltage to drop to  110 V (113.5 V for Vital Battery V or 106.5 V for DG batteries), do not constitute a battery discharge provided the battery terminal voltage and float current return to pre-transient values. This inspection is also consistent with IEEE-450 (Ref. 2),
which recommends special inspections following a severe discharge or overcharge, to ensure that no significant degradation of the battery occurs as a consequence of such discharge or overcharge.
SR 3.8.6.3 This Surveillance verification that the average temperature of representative cells is  60F for the vital batteries and  50F for the DG batteries, is consistent with a recommendation of IEEE-450 (Ref. 2), that states that the temperature of electrolytes in representative cells should be determined on a quarterly basis.
Lower than normal temperatures act to inhibit or reduce battery capacity. This SR ensures that the operating temperatures remain within an acceptable operating range. This limit is based on manufacturer recommendations.
Table 3.8.6-1 This table delineates the limits on electrolyte level, float voltage, and specific gravity for three different categories. The meaning of each category is discussed below.
(continued)
Watts Bar-Unit 1                            B 3.8-81
 
Battery Cell Parameters B 3.8.6 BASES SURVEILLANCE    Table 3.8.6-1 (continued)
REQUIREMENTS Category A defines the normal parameter limit for each designated pilot cell in each battery. The cells selected as pilot cells are those whose temperature, voltage, and electrolyte specific gravity approximate the state of charge of the entire battery.
The Category A limits specified for electrolyte level are based on manufacturer recommendations and are consistent with the guidance in IEEE-450 (Ref. 2),
with the extra 1/4 inch allowance above the high water level indication for operating margin to account for temperatures and charge effects. In addition to this allowance, footnote a to Table 3.8.6-1 permits the electrolyte level to be above the specified maximum level during equalizing charge, provided it is not overflowing. These limits ensure that the plates suffer no physical damage, and that adequate electron transfer capability is maintained in the event of transient conditions. IEEE-450 (Ref. 2) recommends that electrolyte level readings should be made only after the battery has been at float charge for at least 72 hours.
The Category A limit specified for float voltage is  2.13 V per cell. This value is based on the recommendations of IEEE-450 (Ref. 2), which states that prolonged operation of cells < 2.13 V can reduce the life expectancy of cells.
The Category A limit specified for specific gravity for each pilot cell is  1.200 (0.015 below the manufacturer fully charged nominal specific gravity or a battery charging current that had stabilized at a low value). This value is characteristic of a charged cell with adequate capacity. According to IEEE-450 (Ref. 2), the specific gravity readings are based on a temperature of 77F (25C).
The specific gravity readings are corrected for actual electrolyte temperature and level. For each 3F (1.67C) above 77F (25C), 1 point (0.001) is added to the reading; 1 point is subtracted for each 3F below 77F. The specific gravity of the electrolyte in a cell increases with a loss of water due to electrolysis or evaporation.
(continued)
Watts Bar-Unit 1                            B 3.8-82
 
Battery Cell Parameters B 3.8.6 BASES SURVEILLANCE    Table 3.8.6-1 (continued)
REQUIREMENTS Category B defines the normal parameter limits for each connected cell. The term "connected cell" excludes any battery cell that may be jumpered out.
The Category B limits specified for electrolyte level and float voltage are the same as those specified for Category A and have been discussed above. The Category B limit specified for specific gravity for each connected cell is  1.195 (0.020 below the manufacturer fully charged, nominal specific gravity) with the average of all connected cells > 1.205 (0.010 below the manufacturer fully charged, nominal specific gravity). These values are based on manufacturer's recommendations. The minimum specific gravity value required for each cell ensures that the effects of a highly charged or newly installed cell will not mask overall degradation of the battery.
Category C defines the limits for each connected cell. These values, although reduced, provide assurance that sufficient capacity exists to perform the intended function and maintain a margin of safety. When any battery parameter is outside the Category C limits, the assurance of sufficient capacity described above no longer exists, and the battery must be declared inoperable.
The Category C limits specified for electrolyte level (above the top of the plates and not overflowing) ensure that the plates suffer no physical damage and maintain adequate electron transfer capability. The Category C limits for float voltage is based on IEEE-450 (Ref. 2), which states that a cell voltage of 2.07 V or below, under float conditions and not caused by elevated temperature of the cell, indicates internal cell problems and may require cell replacement.
The Category C limits of average specific gravity  1.195 is based on manufacturer recommendations (0.020 below the manufacturer recommended (continued)
Watts Bar-Unit 1                            B 3.8-83
 
Battery Cell Parameters B 3.8.6 BASES SURVEILLANCE    Table 3.8.6-1 (continued)
REQUIREMENTS fully charged, nominal specific gravity). In addition to that limit, it is required that the specific gravity for each connected cell must be no less than 0.020 below the average of all connected cells. This limit ensures that the effect of a highly charged or new cell does not mask overall degradation of the battery.
The footnotes to Table 3.8.6-1 are applicable to Category A, B, and C specific gravity. Footnote b to Table 3.8.6-1 requires the above mentioned correction for electrolyte level and temperature, with the exception that level correction is not required when battery charging current is < 2 amps on float charge for vital batteries and < 1.0 amps for DG batteries. This current provides, in general, an indication of overall battery condition.
Because of specific gravity gradients that are produced during the recharging process, delays of several days may occur while waiting for the specific gravity to stabilize. A stabilized charger current is an acceptable alternative to specific gravity measurement for determining the state of charge. This phenomenon is discussed in IEEE-450 (Ref. 2). Footnote c to Table 3.8.6-1 allows the float charge current to be used as an alternate to specific gravity for up to 31 days following a battery recharge. Within 31 days each connected cell's specific gravity must be measured to confirm the state of charge. Following a minor battery recharge (such as equalizing charge that does not follow a deep discharge) specific gravity gradients are not significant, and confirming measurements may be made in less than 31 days.
SR 3.8.6.1 and SR 3.8.6.2 Verifying battery float current while on float charge is used to determine the state of charge of the battery. Float charge is the condition in which the charger is supplying the continuous charge required to overcome the internal losses of a battery and maintain the battery in a charged state. The equipment used to monitor float current must have the necessary accuracy and capability to measure electrical currents in the expected range. The float current requirements are based on the float current indicative of a charged battery. The 7 day Frequency is consistent with IEEE-450 (Ref. 2).
SR 3.8.6.1 is modified by a Note that states the float current requirement is not required to be met when battery terminal voltage is less than the minimum established float voltage of SR 3.8.4.1. When this float voltage is not maintained the Required Actions of LCO 3.8.4 ACTION A are being taken, which provide the necessary and appropriate verifications of the battery condition. Furthermore, the float current limit of 2 amps is established based on the nominal float voltage value and is not directly applicable when this voltage is not maintained.
SR 3.8.6.2 is modified by a Note that states the float current requirement is not required to be met when battery terminal voltage is less than the minimum established float voltage of SR 3.8.4.2. When this float voltage is not maintained (continued)
Watts Bar-Unit 1                            B 3.8-84
 
Battery Cell Parameters B 3.8.6 BASES SURVEILLANCE    SR 3.8.6.1 and SR 3.8.6.2 (continued)
REQUIREMENTS the Required Actions of LCO 3.8.4 ACTION D are being taken, which provide the necessary and appropriate verifications of the battery condition. Furthermore, the float current limit of 1 amp is established based on the nominal float voltage value and is not directly applicable when this voltage is not maintained.
SR 3.8.6.3 and SR 3.8.6.6 Optimal long term battery performance is obtained by maintaining a float voltage greater than or equal to the minimum established design limits provided by the battery manufacturer, which corresponds to 132 V at the battery terminals, or 2.20 Vpc. This provides adequate overpotential, which limits the formation of lead sulfate and self discharge, which could eventually render the battery inoperable. Float voltages in this range or less, but greater than 2.07 Vpc, are addressed in Specification 5.7.2.22. SRs 3.8.6.3 and 3.8.6.6 require verification that the cell float voltages are equal to or greater than the short term absolute minimum voltage of 2.07 V. The Frequency for cell voltage verification every 31 days for pilot cell and 92 days for each connected cell is consistent with IEEE-450 (Ref. 2).
SR 3.8.6.4 The limit specified for electrolyte level ensures that the plates suffer no physical damage and maintains adequate electron transfer capability. The minimum design electrolyte level is the minimum level indication mark on the battery cell jar. The Frequency is consistent with IEEE-450 (Ref. 2).
SR 3.8.6.5 This Surveillance verifies that the pilot cell temperature is greater than or equal to the minimum established design limit (i.e., 60&deg;F for the vital batteries and 50&deg;F for the DG batteries). Pilot cell electrolyte temperature is maintained above this temperature to assure the battery can provide the required current and voltage to meet the design requirements. Temperatures lower than assumed in battery sizing calculations act to inhibit or reduce battery capacity. The Frequency is consistent with IEEE-450 (Ref. 2).
SR 3.8.6.7 A battery performance discharge test is a test of constant current capacity of a battery, normally done in the as found condition, after having been in service, to detect any change in the capacity determined by the acceptance test. The test is intended to determine overall battery degradation due to age and usage.
Either the battery performance discharge test or the modified performance discharge test is acceptable for satisfying SR 3.8.6.7; however, only the modified (continued)
Watts Bar-Unit 1                            B 3.8-85
 
Battery Cell Parameters B 3.8.6 BASES SURVEILLANCE    SR 3.8.6.7 (continued)
REQUIREMENTS performance discharge test may be used to satisfy the battery service test requirements of SR 3.8.4.7.
A modified discharge test is a test of the battery capacity and its ability to provide a high rate, short duration load (usually the highest rate of the duty cycle). This will often confirm the battery's ability to meet the critical period of the load duty cycle, in addition to determining its percentage of rated capacity. Initial conditions for the modified performance discharge test should be identical to those specified for a service test.
It may consist of just two rates; for instance the one minute rate for the battery or the largest current load of the duty cycle, followed by the test rate employed for the performance test, both of which envelope the duty cycle of the service test.
Since the ampere-hours removed by a one minute discharge represents a very small portion of the battery capacity, the test rate can be changed to that for the performance test without compromising the results of the performance discharge test. The battery terminal voltage for the modified performance discharge test must remain above the minimum battery terminal voltage specified in the battery service test for the duration of time equal to that of the service test.
The acceptance criteria for this Surveillance are consistent with IEEE-450 (Ref. 2) and IEEE-485 (Ref. 4). These references recommend that the battery be replaced if its capacity is below 80% of the manufacturer's rating. A capacity of 80% shows that the battery rate of deterioration is increasing, even if there is ample capacity to meet the load requirements. Furthermore, the battery is sized to meet the assumed duty cycle loads when the battery design capacity reaches this 80% limit.
The Surveillance Frequency for this test is normally 60 months. If the battery shows degradation, or if the battery has reached 85% of its expected life and capacity is < 100% of the manufacturer's rating, the Surveillance Frequency is reduced to 12 months. However, if the battery shows no degradation but has reached 85% of its expected life, the Surveillance Frequency is only reduced to 24 months for batteries that retain capacity  100% of the manufacturer's ratings.
Degradation is indicated, according to IEEE-450 (Ref. 2), when the battery capacity drops by more than 10% relative to its capacity on the previous performance test or when it is  10% below the manufacturer's rating. These Frequencies are consistent with the recommendations in IEEE-450 (Ref. 2).
This SR is modified by a Note. The reason for the Note is that performing the Surveillance would perturb the electrical distribution system and challenge safety systems. Credit may be taken for unplanned events that satisfy this SR.
(continued)
Watts Bar-Unit 1                            B 3.8-86
 
Battery Cell Parameters B 3.8.6 BASES REFERENCES      1. Watts Bar FSAR, Section 15, "Accident Analysis," and Section 6, "Engineered Safety Features."
: 2. IEEE-450-1980/19952002, "IEEE Recommended Practice for Maintenance, Testing, and Replacement of Large Vented Lead-Acid Storage Batteries for Generating Stations and SubstationsStationary Applications."
: 3. Watts Bar FSAR, Section 8, "Electric Power."
: 4. IEEE-485-1983, "IEEE Recommended Practice for Sizing Large Lead Storage Batteries for Generating Stations and Substations."
Watts Bar-Unit 1                    B 3.8-87
 
WBN Unit 2 Markups of Technical Specification and Bases CNL-18-118                        E2-61
 
DC Sources - Operating 3.8.4 3.8 ELECTRICAL POWER SYSTEMS 3.8.4 DC Sources - Operating LCO 3.8.4            Four channels of The Train A and Train B vital DC electrical power subsystems and four Diesel Generator (DG) DC electrical power subsystems shall be OPERABLE.
                    ---------------------------------------------NOTE-------------------------------------------
Vital Battery V may be substituted for any of the required vital batteries.
APPLICABILITY:      MODES 1, 2, 3, and 4.
ACTIONS CONDITION                              REQUIRED ACTION                          COMPLETION TIME A. One or two required vital      A.1      Restore battery terminal                  2 hours battery charger(s) on                    voltage to greater than or one subsystem                            equal to the minimum inoperable.                              established float voltage.
AND A.2      Verify battery float current              Once per 12 hours 2 amps.
AND A.3      Restore vital battery                    7 days charger(s) to OPERABLE status.
AB. One vital DC electrical        AB.1      Restore vital DC electrical              2 hours power subsystem                          power subsystem to inoperable for reasons                    OPERABLE status.
other than Condition A.
(continued)
Watts Bar - Unit 2                                  3.8-21
 
DC Sources - Operating 3.8.4 ACTIONS (continued)
CONDITION                  REQUIRED ACTION              COMPLETION TIME BC. Required Action and    BC.1 Be in MODE 3.                6 hours Associated Completion Time of Condition A or  AND B not met.
BC.2 Be in MODE 5.                36 hours D. One DG DC battery      D.1  Restore DG battery terminal  2 hours charger inoperable.          voltage to greater than or equal to the minimum established float voltage.
AND D.2  Verify battery float current  Once per 12 hours 1 amp.
AND D.3  Restore DG battery charger    72 hours to OPERABLE status.
CE. One DG DC electrical    CE.1 Restore DG DC electrical      2 hours power subsystem              power subsystem to inoperable for reasons      OPERABLE status.
other than Condition D.
DF. Required Action and    DF.1 Declare associated DG        Immediately associated Completion        inoperable.
Time of Condition CD or E not met.
Watts Bar - Unit 2                      3.8-22
 
DC Sources - Operating 3.8.4 SURVEILLANCE REQUIREMENTS SURVEILLANCE                                      FREQUENCY SR 3.8.4.1        Verify vital battery terminal voltage is  128 V (132 V    7 days for vital battery V) on float charge greater than or equal to the minimum established float voltage.
SR 3.8.4.2        Verify DG battery terminal voltage is  124 V on float    7 days charge greater than or equal to the minimum established float voltage.
SR 3.8.4.3        Verify for the vital batteries that the alternate feeder  7 days breakers to each required battery charger are open.
SR 3.8.4.4        Verify correct breaker alignment and indicated power      7 days availability for each DG 125 V DC distribution panel and associated battery charger SR 3.8.4.5        Verify no visible corrosion at terminals and              92 days connectors for the vital batteries.
OR Verify connection resistance for the vital batteries is 80 E-6 ohm for inter-cell connections, 50 E-6 ohm for inter-rack connections, 120 E-6 ohm for inter-tier connections, and 50 E-6 ohm for terminal connections.
SR 3.8.4.6        Verify no visible corrosion at terminals and              92 days connectors for the DG batteries.
OR Verify connection resistance for the DG batteries is 80 E-6 ohm for inter-cell connections, 50 E-6 ohm for inter-tier connections, and 50 E-6 ohm for terminal connections.
SR 3.8.4.7        Verify battery cells, cell plates, and racks show no      12 months visual indication of physical damage or abnormal deterioration.
(continued)
Watts Bar - Unit 2                              3.8-23
 
DC Sources - Operating 3.8.4 SURVEILLANCE REQUIREMENTS (continued)
SURVEILLANCE                                                  FREQUENCY SR 3.8.4.8        Remove visible terminal corrosion and verify battery                    12 months cell to cell and terminal connections are coated with anti-corrosion material.
SR 3.8.4.9        Verify connection resistance for the vital batteries is                12 months 80 E-6 ohm for inter-cell connections, 50 E-6 ohm for inter-rack connections, 120 E-6 ohm for inter-tier connections, and 50 E-6 ohm for terminal connections.
SR 3.8.4.10        Verify connection resistance for the DG batteries is                    12 months 80 E-6 ohm for inter-cell connections, 50 E-6 ohm for inter-tier connections, and 50 E-6 ohm for terminal connections.
SR 3.8.4.115      -------------------------------NOTE------------------------------
This Surveillance is normally not performed in MODE 1, 2, 3, or 4. However, credit may be taken for unplanned events that satisfy this SR.
Verify each vital battery charger is capable of                        18 months recharging its associated battery from a service or capacity discharge test while supplying normal loads supplies  200 amps at greater than or equal to the minimum established float voltage for  4 hours.
OR Verify each vital battery charger can recharge the battery to the fully charged state within 36 hours 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 is capable of operating for  4 hours at current limit 220 - 250 amps.
(continued)
Watts Bar - Unit 2                                    3.8-24
 
DC Sources - Operating 3.8.4 SURVEILLANCE REQUIREMENTS (continued)
SURVEILLANCE                                                  FREQUENCY SR 3.8.4.126      -------------------------------NOTE------------------------------
Credit may be taken for unplanned events that satisfy this SR.
Verify each diesel generator DG battery charger is                      18 months capable of recharging its associated battery from a service or capacity discharge test while supplying normal loads supplies  20 amps at greater than or equal to the minimum established float voltage for 4 hours.
OR Verify each DG battery charger can recharge the battery to the fully charged state within 24 hours 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.
SR 3.8.4.137      -------------------------------NOTES----------------------------
: 1. The modified performance discharge test in SR 3.8.4.146.7 may be performed in lieu of the service test in SR 3.8.4.137 once per 60 months.
: 2. This Surveillance is not performed in MODE 1, 2, 3, or 4 for required vital batteries. Credit may be taken for unplanned events that satisfy this SR.
Verify battery capacity is adequate to supply, and                      18 months maintain in OPERABLE status, the required emergency loads and any connected nonsafety loads for the design duty cycle when subjected to a battery service test.
(continued)
Watts Bar - Unit 2                                    3.8-25
 
DC Sources - Operating 3.8.4 SURVEILLANCE REQUIREMENTS (continued)
SURVEILLANCE                                                    FREQUENCY SR 3.8.4.14        -------------------------------NOTE------------------------------
This Surveillance is not performed in MODE 1, 2, 3, or 4 for required vital batteries. Credit may be taken for unplanned events that satisfy this SR.
Verify battery capacity is  80% of the manufacturer's                  60 months rating when subjected to a performance discharge test or a modified performance discharge test.                          AND 12 months when battery shows degradation or has reached 85% of expected life with capacity < 100% of manufacturer's rating AND 24 months when battery has reached 85% of the expected life with capacity 100% of manufacturer's rating Watts Bar - Unit 2                                    3.8-26
 
DC Sources - Shutdown 3.8.5 3.8 ELECTRICAL POWER SYSTEMS 3.8.5 DC Sources - Shutdown LCO 3.8.5            Vital DC and Diesel Generator (DG) DC electrical power subsystems shall be OPERABLE to support the DC electrical power distribution subsystem(s) required by LCO 3.8.10, "Distribution Systems - Shutdown" and to support the Diesel Generators (DGs) required by LCO 3.8.2, "AC Sources - Shutdown."
                      ---------------------------------------------NOTES------------------------------------------
Vital Battery V may be substituted for any of the required vital batteries.
APPLICABILITY:        MODES 5 and 6, During movement of irradiated fuel assemblies.
ACTIONS CONDITION                                REQUIRED ACTION                          COMPLETION TIME A. One or two required              A.1      Restore battery terminal                  2 hours vital battery charger(s)                  voltage to greater than or on one subsystem                          equal to the minimum inoperable.                                established float voltage.
AND                              AND The redundant                    A.2      Verify battery float current              Once per 12 hours subsystem vital battery                    2 amps.
and charger(s)
OPERABLE.                        AND A.3      Restore battery charger(s) to            7 days OPERABLE status.
(continued)
Watts Bar - Unit 2                                  3.8-26
 
DC Sources - Shutdown 3.8.5 ACTIONS (continued)
CONDITION                      REQUIRED ACTION                COMPLETION TIME AB. One or more required      AB.1.1 Declare affected required      Immediately vital DC electrical power        feature(s) inoperable.
subsystems inoperable for reasons other than    OR Condition A.
AB.2.1 Suspend CORE                  Immediately OR                              ALTERATIONS.
Required Actions and            AND associated Completion Time of Condition A not  AB.2.2 Suspend movement of            Immediately met.                            irradiated fuel assemblies.
AND AB.2.3 Initiate action to suspend    Immediately operations involving positive reactivity additions.
AND AB.2.4 Initiate action to restore    Immediately required DC electrical power subsystems to OPERABLE status.
BC. One required DG DC        BC.1  Declare associated DG          Immediately electrical power                inoperable.
subsystem inoperable.
Watts Bar - Unit 2                        3.8-27
 
DC Sources - Shutdown 3.8.5 SURVEILLANCE REQUIREMENTS SURVEILLANCE                                                      FREQUENCY SR 3.8.5.1        -----------------------------NOTE-----------------------------
The following SRs are not required to be performed: SR 3.8.4.115, SR 3.8.4.126, and SR 3.8.4.137, and SR 3.8.4.14.
For DC sources required to be OPERABLE, the                        In accordance with following SRs are applicable:                                      applicable SRs SR 3.8.4.1        SR 3.8.4.6        SR 3.8.4.11 SR 3.8.4.2        SR 3.8.4.7        SR 3.8.4.12 SR 3.8.4.3        SR 3.8.4.8        SR 3.8.4.13 SR 3.8.4.4        SR 3.8.4.9        SR 3.8.4.14 SR 3.8.4.5        SR 3.8.4.10 Watts Bar - Unit 2                              3.8-28
 
Battery Cell Parameters 3.8.6 3.8 ELECTRICAL POWER SYSTEMS 3.8.6 Battery Cell Parameters LCO 3.8.6                    Battery cell parameters for Train A and Train B electrical power subsystem 125 V vital batteries and 125 V diesel generator (DG) batteries shall be within the limits of Table 3.8.6-1.
APPLICABILITY:              When associated DC electrical power subsystems and DGs are required to be OPERABLE.
ACTIONS
--------------------------------------------------------NOTE-------------------------------------------------------------
Separate Condition entry is allowed for each battery bank.
ACTIONS CONDITION                                  REQUIRED ACTION                          COMPLETION TIME A. One or more batteries with                A.1          Verify pilot cells                    1 hour one or more battery cell                              electrolyte level and float parameters not within                                  voltage meet Table 3.8.6-Category A or B limits.                                1 Category C limits.
AND A.2          Verify battery cell                  24 hours parameters meet Table 3.8.6-1 Category C limits.            AND Once per 7 days thereafter AND A.3          Restore battery cell                  31 days parameters to category A and B limits of Table 3.8.6-1.
(continued)
Watts Bar - Unit 2                                        3.8-29
 
Battery Cell Parameters 3.8.6 ACTIONS CONDITION                  REQUIRED ACTION              COMPLETION TIME A. One or two required vital A.1  Perform SR 3.8.4.1.          2 hours battery(ies) on one subsystem with one or    AND more battery cells float voltage < 2.07 V.        A.2  Perform SR 3.8.6.1.          2 hours AND A.3  Restore affected cell        24 hours voltage  2.07 V.
B. One or two required vital B.1  Perform SR 3.8.4.1.          2 hours battery(ies) on one subsystem with float      AND current > 2 amps.
B.2  Restore vital battery float  12 hours current to  2 amps.
C. One DG battery with one  C.1  Perform SR 3.8.4.2.          2 hours or more battery cells float voltage < 2.07 V. AND C.2  Perform SR 3.8.6.2.          2 hours AND C.3  Restore affected cell        24 hours voltage  2.07 V.
D. One DG battery with      D.1  Perform SR 3.8.4.2.          2 hours float current > 1 amp.
AND D.2  Restore vital battery float  12 hours current to  1 amp.
(continued)
Watts Bar - Unit 2                    3.8-30
 
Battery Cell Parameters 3.8.6 ACTIONS (continued)
CONDITION                              REQUIRED ACTION                      COMPLETION TIME
----------------NOTE-------------------    ------------------NOTE-------------------
Required Action E.2 shall be                Required Actions E.1 and E.2 are completed if electrolyte level was          only applicable if electrolyte level below the top of plates.                    was below the top of plates.
E.        One or two required vital        E.1        Restore electrolyte level          8 hours battery(ies) on one                        to above top of plates.
subsystem with one or more cells electrolyte          AND level less than minimum established design              E.2        Verify no evidence of              12 hours limits.                                    leakage.
OR                              AND One DG battery with one          E.3        Restore electrolyte level          31 days or more cells electrolyte                  to greater than or equal to level less than minimum                    minimum established established design                          design limits.
limits.
F.        One or two required vital        F.1        Restore battery pilot cell          12 hours battery(ies) on one                        temperature to greater subsystem with pilot cell                  than or equal to minimum electrolyte temperature                    established design limits.
less than minimum established design limits.
OR One DG battery with pilot cell electrolyte temperature less than minimum established design limits.
(continued)
Watts Bar - Unit 2                                      3.8-31
 
Battery Cell Parameters 3.8.6 (ACTIONS (continued)
CONDITION                        REQUIRED ACTION            COMPLETION TIME G. One or more batteries in    G.1  Restore battery parameters to  2 hours redundant subsystems            within limits.
with battery parameters not within limits.
OR More than one DG battery with battery parameters not within limits.
BH. Required Action and        BH.1 Declare associated battery    Immediately associated Completion            inoperable.
Time of Condition A, B, C, D, E, F, or G not met.
OR One or two required vital battery(ies) on one subsystem with one or more battery cells float voltage < 2.07 V and float current > 2 amps.
OR One DG battery with one or more battery cells float voltage < 2.07 V and float current > 1 amp.
One or more batteries with average electrolyte temperature of the representative cells
      < 60F for vital batteries and < 50F for DG batteries.
OR One or more batteries with one or more battery cell parameters not within Category C values.
Watts Bar - Unit 2                        3.8-32
 
Battery Cell Parameters 3.8.6 SURVEILLANCE REQUIREMENTS SURVEILLANCE                                        FREQUENCY SR 3.8.6.1        Verify battery cell parameters meet Table 3.8.6-1        7 days Category A limits.
SR 3.8.6.2        Verify battery cell parameters meet Table 3.8.6-1        92 days Category B limits.
AND Once within 24 hours after a battery discharge < 110 V for vital batteries (113.5 V for vital battery V) or 106.5 V for DG batteries AND Once within 24 hours after a battery overcharge > 150 V for vital batteries (155 V for vital battery V) or 145 V for DG batteries SR 3.8.6.3        Verify average electrolyte temperature of                92 days representative cells is  60oF for vital batteries and 50oF for the DG batteries.
Insert Surveillance Requirements from next page.
Watts Bar-Unit 2                              3.8-33
 
Insert the following Surveillance Requirements for LCO 3.8.6:
SURVEILLANCE                                                  FREQUENCY SR 3.8.6.1                -----------------------------NOTE--------------------------------
Not required to be met when vital battery terminal voltage is less than the minimum established float voltage of SR 3.8.4.1.
Verify each vital battery float current is  2 amps.                  7 days SR 3.8.6.2                -----------------------------NOTE--------------------------------
Not required to be met when DG battery terminal voltage is less than the minimum established float voltage of SR 3.8.4.2.
Verify each DG battery float current is  1 amp.                      7 days SR 3.8.6.3                Verify each required vital battery and each DG                        31 days battery pilot cell float voltage is  2.07 V.
SR 3.8.6.4                Verify each required vital battery and each DG                        31 days battery connected cell electrolyte level is greater than or equal to minimum established design limits.
SR 3.8.6.5                Verify each required vital battery and each DG                        31 days battery pilot cell temperature is greater than or equal to minimum established design limits.
SR 3.8.6.6                Verify each required vital battery and each DG                        92 days battery connected cell float voltage is  2.07 V.
 
SURVEILLANCE                                                        FREQUENCY SR 3.8.6.7 ------------------------------NOTES------------------------------
This Surveillance is not performed in MODE 1, 2, 3, or 4 for required vital batteries. Credit may be taken for unplanned events that satisfy this SR.
Verify battery capacity is  80% of the manufacturer's                  60 months rating when subjected to a performance discharge test or a modified performance discharge test.                              AND 12 months when battery shows degradation or has reached 85% of expected life with capacity < 100% of manufacturer's rating AND 24 months when battery has reached 85% of the expected life with capacity 100% of manufacturer's rating
 
Battery Cell Parameters 3.8.6 Table 3.8.6-1 (page 1 of 1)
Battery Cell Parameters Requirements CATEGORY A:                CATEGORY B:            CATEGORY C:
PARAMETER              LIMITS FOR EACH            LIMITS FOR EACH        ALLOWABLE LIMIT DESIGNATED              CONNECTED CELL            FOR EACH PILOT CELL                                    CONNECTED CELL Electrolyte Level        > Minimum level            > Minimum level        Above top of plates, indication mark, and        indication mark, and  and not overflowing 1/4 inch above            1/4 inch above maximum level              maximum level indication mark (a)        indication mark (a)
Float Voltage            2.13 V                    2.13 V              > 2.07 V Specific Gravity (b)(c)  1.200                      1.195                Not more than 0.020 below average of all AND                    connected cells Average of all        AND connected cells
                                                      > 1.205                Average of all connected cells 1.195 (a)    It is acceptable for the electrolyte level to temporarily increase above the specified maximum level during equalizing charges provided it is not overflowing.
(b)    Corrected for electrolyte temperature and level. Level correction is not required, however, when battery charging is < 2 amps when on float charge for vital batteries and
      < 1.0 amp for DG batteries.
(c)    A battery charging current of < 2 amps when on float charge for vital batteries and < 1.0 amp for DG batteries is acceptable for meeting specific gravity limits following a battery recharge, for a maximum of 31 days. When charging current is used to satisfy specific gravity requirements, specific gravity of each connected cell shall be measured prior to expiration of the 31 day allowance.
Watts Bar-Unit 2                                3.8-34
 
Procedures, Programs, and Manuals 5.7 5.7.2.20    Control Room Envelope Habitability Program (continued)
: c. Requirements for (i) determining the unfiltered air inleakage past the CRE boundary into the CRE in accordance with the testing methods and at the Frequencies specified in Sections C.1 and C.2 of Regulatory Guide 1.197, "Demonstrating Control Room Envelope Integrity at Nuclear Power Reactors," Revision 0, May 2003, and (ii) assessing CRE habitability at the Frequencies specified in Sections C.1 and C.2 of Regulatory Guide 1.197, Revision 0.
: d. Measurement, at designated locations, of the CRE pressure relative to all external areas adjacent to the CRE boundary during the pressurization mode of operation by one train of the CREVS, operating at the flow rate defined in the Ventilation Filter Testing Program (VFTP), at a Frequency of 18 months on a STAGGERED TEST BASIS. The results shall be trended and used as part of the 18 month assessment of the CRE boundary.
: e. The quantitative limits on unfiltered air inleakage into the CRE.
These limits shall be stated in a manner to allow direct comparison to the unfiltered air inleakage measured by the testing described in paragraph c. The unfiltered air inleakage limit for radiological challenges is the inleakage flow rate assumed in the licensing basis analyses of DBA consequences.
Unfiltered air inleakage limits for hazardous chemicals must ensure that exposure of CRE occupants to these hazards will be within the assumptions in the licensing basis.
: f. The provisions of SR 3.0.2 are applicable to the frequencies for assessing CRE habitability, determining CRE unfiltered inleakage, and measuring CRE pressure and assessing the CRE boundary as required by paragraphs c and d, respectively.
Note: The addition of TS 5.7.2.21, Spent Fuel Storage Rack Neutron Absorber Monitoring Program, has been proposed per TVA letter CNL-17-144, dated December 20, 2017. Therefore, the proposed addition of the Battery Monitoring and Maintenance Program is numbered TS 5.7.2.22, to reflect the anticipated approval of the license amendment request associated with TVA letter CNL-17-144.
Insert TS 5.7.2.22, Battery Monitoring and Maintenance Program Watts Bar-Unit 2                                  5.0-25a                            Amendment 70, 78
 
INSERT 5.7.2.22 Battery Monitoring and Maintenance Program This Program provides controls for battery restoration and maintenance. The program shall be in accordance with IEEE Standard (Std) 450-2002, "IEEE Recommended Practice for Maintenance, Testing, and Replacement of Vented Lead-Acid Batteries for Stationary Applications," as endorsed by Regulatory Guide 1.129, Revision 2 (RG), with RG exceptions and program provisions as identified below:
: a. The program allows the following RG 1.129, Revision 2 exceptions:
: 1. Battery temperature correction may be performed before or after conducting discharge tests.
: 2. RG 1.129, Regulatory Position 1, Subsection 2, "References," is not applicable to this program.
: 3. In lieu of RG 1.129, Regulatory Position 2, Subsection 5.2, "Inspections," the following shall be used: "Where reference is made to the pilot cell, pilot cell selection shall be based on the lowest voltage cell in the battery.
: 4. In Regulatory Guide 1.129, Regulatory Position 3, Subsection 5.4.1, "State of Charge Indicator," the following statements in paragraph (d) may be omitted: "When it has been recorded that the charging current has stabilized at the charging voltage for three consecutive hourly measurements, the battery is near full charge. These measurements shall be made after the initially high charging current decreases sharply and the battery voltage rises to approach the charger output voltage."
: 5. In lieu of RG 1.129, Regulatory Position 7, Subsection 7.6, "Restoration", the following may be used: "Following the test, record the float voltage of each cell of the string."
: b. The program shall include the following provisions:
: 1. Actions to restore battery cells with float voltage < 2.13 V;
: 2. Actions to determine whether the float voltage of the remaining battery cells is  2.13 V when the float voltage of a battery cell has been found to be < 2.13 V;
: 3. Actions to equalize and test battery cells that had been discovered with electrolyte level below the top of the plates;
: 4. Limits on average electrolyte temperature, battery connection resistance, and battery terminal voltage; and
: 5. A requirement to obtain specific gravity readings of all cells at each discharge test, consistent with manufacturer recommendations.
 
DC Sources - Operating B 3.8.4 B 3.8 ELECTRICAL POWER SYSTEMS B 3.8.4 DC Sources - Operating BASES BACKGROUND          The station DC electrical power system provides the AC emergency power system with control power. It also provides both motive and control power to selected safety related equipment and preferred AC vital bus power (via inverters). As required by 10 CFR 50, Appendix A, GDC 17 (Ref. 1), the DC electrical power system is designed to have sufficient independence, redundancy, and testability to perform its safety functions, assuming a single failure. The DC electrical power system also conforms to the recommendations of Regulatory Guide 1.6 (Ref. 2) and IEEE-308 (Ref. 3).
125 V Vital DC Electrical Power Subsystem The vital 125 VDC electrical power system is a Class 1E system whose safety function is to provide control power for engineered safety features equipment, emergency lighting, vital inverters, and other safety related DC powered equipment for the entire unit. The system capacity is sufficient to supply these loads and any connected non-safety loads during normal operation and to permit safe shutdown and isolation of the reactor for the loss of all AC power condition. The system is designed to perform its safety function subject to a single failure.
The 125V DC vital power system is composed of the four redundant channels (Channels I and III are associated with Train A and Channels II and IV are associated with Train B) and consists of four lead-acid-calcium batteries, eight battery chargers (including two pairs of spare chargers),
four distribution boards, battery racks, and the required cabling, instrumentation and protective features. Each channel is electrically and physically independent from the equipment of all other channels so that a single failure in one channel will not cause a failure in another channel.
Each channel consists of a battery charger which supplies normal DC power, a battery for emergency DC power, and a battery board which facilitates load grouping and provides circuit protection. These four channels are used to provide emergency power to the 120V AC vital power system which furnishes control power to the reactor protection system. No automatic connections are used between the four redundant channels.
Battery boards I, II, III, and IV have a charger normally connected to them and also have manual access to a spare (backup) charger for use upon loss of the normal charger.
(continued)
Watts Bar - Unit 2                          B 3.8-53
 
DC Sources - Operating B 3.8.4 BASES BACKGROUND        125 V Vital DC Electrical Power Subsystem (continued)
Additionally, battery boards I, II, III, and IV have manual access to the fifth vital battery system. The fifth 125V DC Vital Battery System is intended to serve as a replacement for any one of the four 125V DC vital batteries during their testing, maintenance, and outages with no loss of system reliability under any mode of operation.
Each of the vital DC electrical power subsystems provides the control power for its associated Class 1E AC power load group, 6.9 kV switchgear, and 480 V load centers. The vital DC electrical power subsystems also provide DC electrical power to the inverters, which in turn power the AC vital buses. Additionally, they power the emergency DC lighting system.
The vital DC power distribution system is described in more detail in Bases for LCO 3.8.9, Distribution System - Operating, and LCO 3.8.10, Distribution Systems - Shutdown.
Each vital battery has adequate storage capacity to carry the required load continuously for at least 4 hours in the event of a loss of all AC power (station blackout) without an accident or for 30 minutes with an accident considering a single failure. Load shedding of non-required loads will be performed to achieve the required coping duration for station blackout conditions.
Each 125 VDC vital battery is separately housed in a ventilated room apart from its charger and distribution centers, except for Vital Battery V.
Each subsystem is located in an area separated physically and electrically from the other subsystem to ensure that a single failure in one subsystem does not cause a failure in a redundant subsystem. There is no sharing between redundant Class 1E subsystems, such as batteries, battery chargers, or distribution panels.
Each battery has adequate storage capacity to meet the duty cycle(s) discussed in the FSAR, Chapter 8 (Ref 4). The battery is designed with additional capacity above that required by the design duty cycle to allow for temperature variations and other factors.
The batteries for the vital DC electrical power subsystems are sized to produce required capacity at 80% of nameplate rating, corresponding to warranted capacity at end of life cycles, de-rated for minimum ambient temperature and the 100% design demand. The minimum design voltage limit is 105 V.The voltage limit is 2.13 V per cell, which corresponds to a total minimum voltage output of 128 V per battery (132 V for Vital Battery V). The criteria for sizing large lead storage batteries are defined in IEEE-485 (Ref. 5).
(continued)
Watts Bar - Unit 2                        B 3.8-54
 
DC Sources - Operating B 3.8.4 BASES BACKGROUND        125 V Vital DC Electrical Power Subsystem (continued)
The battery cells are of flooded lead acid construction with a nominal specific gravity of 1.215. This specific gravity corresponds to an open circuit battery voltage of approximately 120 V for a 60 cell battery (i.e.,
cell voltage of 2.063 volts per cell (Vpc)). The open circuit voltage is the voltage maintained when there is no charging or discharging. Optimal long term performance however, is obtained by maintaining a float voltage 2.20 to 2.25 Vpc. This provides adequate over-potential, which limits the formation of lead sulfate and self discharge. The nominal float voltage of 2.22 Vpc corresponds to a total float voltage output of 133.2 V for a 60 cell battery as discussed in the FSAR, Chapter 8 (Ref. 4).
Each Vital DC electrical power subsystem battery charger has ample power output capacity for the steady state operation of connected loads required during normal operation, while at the same time maintaining its battery bank fully charged. Each battery charger also has sufficient excess capacity to restore the battery bank from the design minimum charge to its fully charged state within 12 hours (with accident loads being supplied) following a 30 minute AC power outage and in approximately 36 hours (while supplying normal steady state loads following a 2 hour AC power outage), (Ref. 65).
The battery charger is normally in the float-charge mode. Float-charge is the condition in which the charger is supplying the connected loads and the battery cells are receiving adequate current to optimally charge the battery. This assures the internal losses of a battery are overcome and the battery is maintained in a fully charged state.
When desired, the charger can be placed in the equalize mode. The equalize mode is at a higher voltage than the float mode and charging current is correspondingly higher. The battery charger is operated in the equalize mode after a battery discharge or for routine maintenance.
Following a battery discharge, the battery recharge characteristic accepts current at the current limit of the battery charger (if the discharge was significant, e.g., following a battery service test) until the battery terminal voltage approaches the charger voltage setpoint. Charging current then reduces exponentially during the remainder of the recharge cycle. Lead-calcium batteries have recharge efficiencies of greater than 95%, so once at least 105% of the ampere-hours discharged have been returned, the battery capacity would be restored to the same condition as it was prior to the discharge. This can be monitored by direct observation of the exponentially decaying charging current or by evaluating the amp-hours discharged from the battery and amp-hours returned to the battery.
Watts Bar - Unit 2                          B 3.8-55                                    (continued)
 
DC Sources - Operating B 3.8.4 BASES BACKGROUND        125 V Diesel Generator (DG) DC Electrical Power Subsystem (continued)
Control power for the DGs is provided by four DG battery systems, one per DG. Each system is comprised of a battery, a battery charger, distribution center, cabling, and cable ways. The DG 125V DC control power and field-flash circuits have power supplied from their respective 125V distribution panel. The normal supply of DC current is from the associated charger. The battery provides control and field-flash power when the charger is unavailable. The charger supplies the normal DC loads, maintains the battery in a fully charged condition, and recharges (480V AC available) the battery while supplying the required loads regardless of the status of the unit. The batteries are physically and electrically independent. The battery has sufficient capacity when fully charged to supply required loads for a minimum of four hours following a loss of normal power. Each battery is normally required to supply loads during the time interval between loss of normal feed to its charger and the receipt of emergency power to the charger from its respective DG.
APPLICABLE        The initial conditions of Design Basis Accident (DBA) and transient SAFETY            analyses in the FSAR, Section 6 (Ref. 76), and in the FSAR, Section 15 ANALYSES          (Ref. 76), assume that Engineered Safety Feature (ESF) systems are OPERABLE. The vital DC electrical power system provides normal and emergency DC electrical power for the emergency auxiliaries, and control and switching during all power for the emergency auxiliaries, and control and switching during all MODES of operation. The DG battery systems provide DC power for the DGs.
The OPERABILITY of the DC sources is consistent with the initial assumptions of the accident analyses and is based upon meeting the design basis of the plant. This includes maintaining the DC sources OPERABLE during accident conditions in the event of:
: a. An assumed loss of all offsite AC power or all onsite AC power; and
: b. A worst case single failure.
The DC sources satisfy Criterion 3 of 10 CFR 50.36(c)(2)(ii).
Watts Bar - Unit 2                        B 3.8-56                                  (continued)
 
DC Sources - Operating B 3.8.4 BASES (continued)
LCO                Four Two 125V vital DC electrical power subsystems (Train A and Train B), each vital subsystem consisting of two channels. Each channel consisting of a battery bank, associated battery charger and the corresponding control equipment and interconnecting cabling supplying power to the associated DC bus within the channel; and four DG DC electrical power subsystems each consisting of a battery, a dual battery charger assembly, and the corresponding control equipment and interconnecting cabling are required to be OPERABLE to ensure the availability of the required power to shut down the reactor and maintain it in a safe condition after an anticipated operational occurrence (A00) or a postulated DBA. Loss of any DC electrical power subsystem does not prevent the minimum safety function from being performed (Ref. 4).
An OPERABLE vital DC electrical power subsystem requires all required batteries and respective chargers to be operating and connected to the associated DC buses.
The LCO is modified by one Note. The Note indicates that Vital Battery V may be substituted for any of the required vital batteries. However, the fifth battery cannot be declared OPERABLE until it is connected electrically in place of another battery and it has satisfied applicable Surveillance Requirements.
APPLICABILITY      The four vital DC electrical power sources and four DG DC electrical power sources are required to be OPERABLE in MODES 1, 2, 3, and 4 to ensure safe plant operation and to ensure that:
: a. Acceptable fuel design limits and reactor coolant pressure boundary limits are not exceeded as a result of AOs or abnormal transients; and
: b. Adequate core cooling is provided, and containment integrity and other vital functions are maintained in the event of a postulated DBA.
The DC electrical power requirements for MODES 5 and 6 are addressed in the Bases for LCO 3.8.5, DC Sources - Shutdown.
Watts Bar - Unit 2                          B 3.8-57                                  (continued)
 
DC Sources - Operating B 3.8.4 BASES (continued)
ACTIONS            A.1, A.2, and A.3 Condition A represents one vital DC subsystem with one or two battery chargers inoperable (e.g., the voltage limit of SR 3.8.4.1 is not maintained). The ACTIONS provide a tiered response that focuses on returning the battery to the fully charged state and restoring a fully qualified charger to OPERABLE status in a reasonable time period.
Required Action A.1 requires that the battery terminal voltage be restored to greater than or equal to the minimum established float voltage within 2 hours. This time provides for returning the inoperable charger to OPERABLE status or providing an alternate means of restoring battery terminal voltage to greater than or equal to the minimum established float voltage. Restoring the battery terminal voltage to greater than or equal to the minimum established float voltage provides good assurance that, within 12 hours, the battery will be restored to its fully charged condition (Required Action A.2) from any discharge that might have occurred due to the charger inoperability.
A discharged battery having terminal voltage of at least the minimum established float voltage indicates that the battery is on the exponential charging current portion (the second part) of its recharge cycle. The time to return a battery to its fully charged state under this condition is simply a function of the amount of the previous discharge and the recharge characteristic of the battery. Thus there is good assurance of fully recharging the battery within 12 hours, avoiding a premature shutdown with its own attendant risk.
If established battery terminal float voltage cannot be restored to greater than or equal to the minimum established float voltage within 2 hours, and the charger is not operating in the current-limiting mode, a faulty charger is indicated. A faulty charger that is incapable of maintaining established battery terminal float voltage does not provide assurance that it can revert to and operate properly in the current limit mode that is necessary during the recovery period following a battery discharge event that the DC system is designed for.
If the charger is operating in the current limit mode after 2 hours that is an indication that the battery is partially discharged and its capacity margins will be reduced. The time to return the battery to its fully charged condition in this case is a function of the battery charger capacity, the amount of loads on the associated DC system, the amount of the previous discharge, and the recharge characteristic of the battery. The charge time can be extensive, and there is not adequate assurance that it can be recharged within 12 hours (Required Action A.2).
Required Action A.2 requires that the battery float current be verified as less than or equal to 2 amps. This indicates that, if the battery had been discharged as the result of the inoperable battery charger, it is now fully capable of supplying the maximum expected load requirement.
(continued)
Watts Bar - Unit 2                        B 3.8-58
 
DC Sources - Operating B 3.8.4 BASES (continued)
ACTIONS            A.1, A.2, and A.3 (continued)
The 2 amp value is based on returning the battery to 98% charge and assumes a 2% design margin for the battery. If at the expiration of the initial 12 hour period the battery float current is not less than or equal to 2 amps this indicates there may be additional battery problems and the battery must be declared inoperable.
Required Action A.3 limits the restoration time for the inoperable battery charger to 7 days. This action is applicable if an alternate means of restoring battery terminal voltage to greater than or equal to the minimum established float voltage has been used (e.g., balance of plant non-Class 1E battery charger). The 7 day Completion Time reflects a reasonable time to effect restoration of the qualified battery charger to OPERABLE status.
AB.1 Condition AB represents one vital channel DC electrical power subsystem with a loss of ability to completely respond to an event, and a potential loss of ability to remain energized during normal operation. It is, therefore, imperative that the operator's attention focus on stabilizing the plant, minimizing the potential for complete loss of DC power to the affected train subsystem. The 2 hour limit is consistent with the allowed time for an inoperable DC distribution subsystem train.
If one of the required vital DC electrical power subsystems is inoperable for reasons other than Condition A (e.g., inoperable battery, inoperable battery charger(s), or inoperable battery charger and associated inoperable battery), the remaining vital DC electrical power subsystem has the capacity to support a safe shutdown and to mitigate an accident condition. Since a subsequent worst case single failure of the OPERABLE subsystem would could, however, result in a situation where the ability of the 125V DC electrical power subsystem to support its required ESF function is not assured, the loss of the minimum necessary vital DC electrical power subsystems to mitigate a worst-case accident, continued power operation should not exceed 2 hours. The 2 hour Completion Time is based on Regulatory Guide 1.93 (Ref. 87) and reflects a reasonable time to assess plant status as a function of the inoperable vital DC electrical power subsystem and, if the vital DC electrical power subsystem is not restored to OPERABLE status, to prepare to effect an orderly and safe plant shutdown.
(continued)
Watts Bar - Unit 2                          B 3.8-59
 
DC Sources - Operating B 3.8.4 BASES ACTIONS            B.1 and B.2C,1 and C.2 (continued)
If the inoperable vital DC electrical power subsystem cannot be restored to OPERABLE status within the required Completion Time, the plant must be brought to a MODE in which the LCO does not apply. To achieve this status, the plant must be brought to at least MODE 3 within 6 hours and to MODE 5 within 36 hours. The allowed Completion Times are reasonable, based on operating experience, to reach the required plant conditions from full power conditions in an orderly manner and without challenging plant systems. The Completion Time to bring the plant to MODE 5 is consistent with the time required in Regulatory Guide 1.93 (Ref. 87).
D.1, D.2, and D.3 Condition D represents one DG DC subsystem with one battery charger inoperable (e.g., the voltage limit of SR 3.8.4.1 is not maintained). The ACTIONS provide a tiered response that focuses on returning the battery to the fully charged state and restoring a fully qualified charger to OPERABLE status in a reasonable time period. Required Action D.1 requires that the battery terminal voltage be restored to greater than or equal to the minimum established float voltage within 2 hours. This time provides for returning the inoperable charger to OPERABLE status or providing an alternate means of restoring battery terminal voltage to greater than or equal to the minimum established float voltage.
Restoring the battery terminal voltage to greater than or equal to the minimum established float voltage provides good assurance that, within 12 hours, the battery will be restored to its fully charged condition (Required Action D.2) from any discharge that might have occurred due to the charger inoperability.
A discharged battery having terminal voltage of at least the minimum established float voltage indicates that the battery is on the exponential charging current portion (the second part) of its recharge cycle. The time to return a battery to its fully charged state under this condition is simply a function of the amount of the previous discharge and the recharge characteristic of the battery. Thus there is good assurance of fully recharging the battery within 12 hours, avoiding a premature shutdown with its own attendant risk.
If established battery terminal float voltage cannot be restored to greater than or equal to the minimum established float voltage within 2 hours, and the charger is not operating in the current-limiting mode, a faulty charger is indicated. A faulty charger that is incapable of maintaining established battery terminal float voltage does not provide assurance that it can revert to and operate properly in the current limit mode that is necessary during the recovery period following a battery discharge event that the DG DC system is designed for.
Watts Bar - Unit 2                        B 3.8-60                                  (continued)
 
DC Sources - Operating B 3.8.4 BASES ACTIONS            D.1, D.2, and D.3 (continued)
If the charger is operating in the current limit mode after 2 hours that is an indication that the battery is partially discharged and its capacity margins will be reduced. The time to return the battery to its fully charged condition in this case is a function of the battery charger capacity, the amount of loads on the associated DC system, the amount of the previous discharge, and the recharge characteristic of the battery. The charge time can be extensive, and there is not adequate assurance that it can be recharged within 12 hours (Required Action D.2).
Required Action D.2 requires that the battery float current be verified as less than or equal to 1 amp. This indicates that, if the battery had been discharged as the result of the inoperable battery charger, it is now fully capable of supplying the maximum expected load requirement. The 1 amp value is based on returning the battery to 98% charge and assumes a 2% design margin for the battery. If at the expiration of the initial 12 hour period the battery float current is not less than or equal to 1 amp this indicates there may be additional battery problems and the battery must be declared inoperable.
Required Action D.3 limits the restoration time for the inoperable battery charger to 72 hours. The 72 hour Completion Time reflects a reasonable time to effect restoration of the qualified battery charger to OPERABLE status.
C.1E.1 Condition CE represents one DG with a loss of ability to completely respond to an event. Since a subsequent single failure on the opposite train could result in a situation where the required ESF function is not assured, continued power operation should not exceed 2 hours. The 2 hour time limit is consistent with the allowed time for an inoperable vital DC electrical power subsystem.
D.1F.1 If the DG DC electrical power subsystem cannot be restored to OPERABLE status in the associated Completion Time, the associated DG may be incapable of performing its intended function and must be immediately declared inoperable. This declaration also requires entry into applicable Conditions and Required Actions for an inoperable DG, LCO 3.8.1, "AC Sources-Operating."
Watts Bar - Unit 2                        B 3.8-61                                  (continued)
 
DC Sources - Operating B 3.8.4 BASES (continued)
SURVEILLANCE      SR 3.8.4.1 and SR 3.8.4.2 REQUIREMENTS Verifying battery terminal voltage while on float charge for the batteries helps to ensure the effectiveness of the battery chargers, which support the ability of the batteries to perform their intended function charging system and the ability of the batteries to perform their intended function.
Float charge is the condition in which the charger is supplying the continuous charge required to overcome the internal losses of a battery (or battery cell) and maintain the battery (or a battery cell) in a fully charged state while supplying the continuous steady state loads of the associated DC subsystem. On float charge, battery cells will receive adequate current to optimally charge the battery. The voltage requirements are based on the critical nominal design voltage of the battery and are consistent with the initial voltages assumed in the battery sizing calculations minimum float voltage established by the battery manufacturer (2.20 Vpc times the number of connected cells or 132 V at the battery terminals for a 60 cell vital battery; 127.6 V at the battery terminals for a 58 cell DG battery). This voltage maintains the battery plates in a condition that supports maintaining the grid life. The 7 day Frequency is consistent with manufacturer recommendations and IEEE-450 (Ref. 9).
SR 3.8.4.3 Verifying that for the vital batteries that the alternate feeder breakers to each required battery charger is open ensures that independence between the power trains is maintained. The 7 day Frequency is based on engineering judgment, is consistent with procedural controls governing breaker operation, and ensures correct breaker position.
SR 3.8.4.4 This SR demonstrates that the DG 125V DC distribution panel and associated charger are functioning properly, with all required circuit breakers closed and buses energized from normal power. The 7 day Frequency takes into account the redundant DG capability and other indications available in the control room that will alert the operator to system malfunctions.
SR 3.8.4.5 and SR 3.8.4.6 Visual inspection to detect corrosion of the battery cells and connections, or measurement of the resistance of each intercell, interrack, intertier, and terminal connection, provides an indication of physical damage or abnormal deterioration that could potentially degrade battery performance.
The limits established for this SR must be no more than 20% above the resistance as measured during installation, or not above the ceiling value (continued)
Watts Bar - Unit 2                        B 3.8-62
 
DC Sources - Operating B 3.8.4 BASES SURVEILLANCE      SR 3.8.4.5 and SR 3.8.4.6 (continued)
REQUIREMENTS established by the manufacturer.
The Surveillance Frequency for these inspections, which can detect conditions that can cause power losses due to resistance heating, is 92 days. This Frequency is considered acceptable based on operating experience related to detecting corrosion trends.
SR 3.8.4.7 Visual inspection of the battery cells, cell plates, and battery racks provides an indication of physical damage or abnormal deterioration that could potentially degrade battery performance.
The 12 month Frequency for this SR is consistent with IEEE-450 (Ref. 9),
which recommends detailed visual inspection of cell condition and rack integrity on a yearly basis.
SR 3.8.4.8, SR 3.8.4.9 and SR 3.8.4.10 Visual inspection and resistance measurements of intercell, interrack, intertier, and terminal connections provide an indication of physical damage or abnormal deterioration that could indicate degraded battery condition. The anticorrosion material is used to help ensure good electrical connections and to reduce terminal deterioration. The visual inspection for corrosion is not intended to require removal of and inspection under each terminal connection. The removal of visible corrosion is a preventive maintenance SR. The presence of visible corrosion does not necessarily represent a failure of this SR provided visible corrosion is removed during performance of SR 3.8.4.8. For the purposes of trending, inter-cell (vital and DG batteries) and inter-tier (vital and DG batteries) connections are measured from battery post to battery post. Inter-rack (vital batteries), inter-tier (DG Batteries), and terminal connections (vital and DG batteries) are measured from terminal lug to battery post.
The connection resistance limits for SR 3.8.4.9 and SR 3.8.4.10 shall be no more than 20% above the resistance as measured during installation, or not above the ceiling value established by the manufacturer.
The Surveillance Frequencies of 12 months is consistent with IEEE-450 (Ref. 9), which recommends cell to cell and terminal connection resistance measurement on a yearly basis.
(continued)
Watts Bar - Unit 2                        B 3.8-63
 
DC Sources - Operating B 3.8.4 BASES SURVEILLANCE      SR 3.8.4.115 REQUIREMENTS (continued)    This SR requires that each vital battery charger be capable of recharging its associated battery from a capacity or service discharge test while supplying normal loads, or alternatively, operating at current limit for a minimum of 4 hours at a nominal 125 VDC. These requirements are based on verifies the design capacity of the vital battery chargers (Ref. 4) and their performance characteristic of current limit operation for a substantial portion of the recharge period. Battery charger output current is limited to 110% - 125% of the 200 amp rated output. Recharging the battery or testing for a minimum of 4 hours is sufficient to verify the output capability of the charger can be sustained, that current limit adjustments are properly set and that protective devices will not inhibit performance at current limit settings. According to Regulatory Guide 1.32 (Ref. 65), the battery charger supply is required recommended to be based on the largest combined demands of the various steady state loads and the charging capacity to restore the battery from the design minimum charge state to the fully charged state, irrespective of the status of the plant during these demand occurrences. Verifying the capability of the charger to operate in a sustained current limit condition The minimum required amperes and duration ensures that these requirements can be satisfied.
This SR provides two options. One option requires that each battery charger be capable of supplying 200 amps at the minimum established float voltage (132 V DC) for 4 hours. The ampere requirements are based on the output rating of the chargers. The voltage requirements are based on the charger voltage level after a response to a loss of AC power.
The other option requires that each vital battery charger be capable of recharging the battery after a service test coincident with supplying the largest coincident demands of the various continuous steady state loads (irrespective of the status of the plant during which these demands occur). This level of loading may not normally be available following the battery service test and will need to be supplemented with additional loads. The duration for this test may be longer than the charger sizing criteria since the battery recharge is affected by float voltage, temperature, and the exponential decay in charging current. The battery is recharged when the measured charging current is  2 amps.
The Surveillance Frequency is acceptable, given the plant conditions required to perform the test and the other administrative controls existing to ensure adequate charger performance during these 18 month intervals.
In addition, this Frequency is intended to be consistent with expected fuel cycle lengths.
This SR is modified by a Note. The reason for the Note is that performing the Surveillance may perturb the electrical distribution system and challenge safety systems. This Surveillance is normally performed during MODES 5 and 6 since it would require the DC (continued)
Watts Bar - Unit 2                        B 3.8-64
 
DC Sources - Operating B 3.8.4 BASES SURVEILLANCE      SR 3.8.4.115 (continued)
REQUIREMENTS electrical power subsystem to be inoperable during performance of the test. However, this Surveillance may be performed in MODES 1, 2, 3, or 4 provided the Vital Battery V is substituted in accordance with LCO Note 1. Credit may be taken for unplanned events that satisfy this SR. Examples of unplanned events may include:
: 1)      Unexpected operational events which cause the equipment to perform the function specified by this Surveillance, for which adequate documentation of the required performance is available; and
: 2)      Post corrective maintenance testing that requires performance of this Surveillance in order to restore the component to OPERABLE, provided the maintenance was required, or performed in conjunction with maintenance required to maintain OPERABILITY or reliability.
SR 3.8.4.126 This SR requires that each diesel generator battery charger be capable of recharging its associated battery from a capacity or service discharge test while supplying normal loads, or alternatively, operating at current limit for a minimum of 4 1/2 hours at a nominal 125 VDC.
This requirement is based on verifies the design capacity of the DG battery chargers (Ref. 13) and their performance characteristic of current limit operation for a substantial portion of the recharge period.
Battery charger output current is limited to a maximum of 140% of the 20 amp rated output. Recharging the battery verifies the output capability of the charger can be sustained, that current limit adjustments are properly set and that protective devices will not inhibit performance at current limit settings. According to Regulatory Guide 1.32 (Ref. 65), the battery charger supply is required recommended to be based on the largest combined demands of the various steady state loads and the charging capacity to restore the battery from the design minimum charge state to the fully charged state, irrespective of the status of the plant during these demand occurrences. Verifying the capability of the charger to operate in a sustained current limit condition The minimum required amperes and duration ensures that these requirements can be satisfied.
This SR provides two options. One option requires that each battery charger be capable of supplying 20 amps at the minimum established float voltage (127.6 V DC) for 4 hours. The ampere requirements are based on the output rating of the chargers. The voltage requirements are based on the charger voltage level after a response to a loss of AC power.
(continued)
Watts Bar - Unit 2                          B 3.8-65
 
DC Sources - Operating B 3.8.4 BASES SURVEILLANCE      SR 3.8.4.126 (continued)
REQUIREMENTS The other option requires that each vital battery charger be capable of recharging the battery after a service test coincident with supplying the largest coincident demands of the various continuous steady state loads (irrespective of the status of the plant during which these demands occur). This level of loading may not normally be available following the battery service test and will need to be supplemented with additional loads. The duration for this test may be longer than the charger sizing criteria since the battery recharge is affected by float voltage, temperature, and the exponential decay in charging current. The battery is recharged when the measured charging current is  1 amp.
The Surveillance Frequency is acceptable, given the plant conditions required to perform the test and the other administrative controls existing to ensure adequate charger performance during these 18 month intervals.
In addition, this Frequency is intended to be consistent with expected fuel cycle lengths.
For the DG DC electrical subsystem, this Surveillance may be performed in MODES 1, 2, 3, or 4 in conjunction with LCO 3.8.1.B since the DG DC electrical power subsystem supplies loads only for the inoperable diesel generator and would not otherwise challenge safety systems supplied from vital electrical distribution systems. Additionally, credit may be taken for unplanned events that satisfy this SR. Examples of unplanned events may include:
: 1)      Unexpected operational events which cause the equipment to perform the function specified by this Surveillance, for which adequate documentation of the required performance is available; and
: 2)      Post corrective maintenance testing that requires performance of this Surveillance in order to restore the component to OPERABLE, provided the maintenance was required, or performed in conjunction with maintenance required to maintain OPERABILITY or reliability.
SR 3.8.4.137 A battery service test is a special test of battery capability, as found, to satisfy the design requirements (battery duty cycle) of the DC electrical power system. The discharge rate and test length should correspond to worst case design duty cycle requirements based on References 108 and 1210.
The Surveillance Frequency of 18 months is consistent with the recommendations of Regulatory Guide 1.32 (Ref. 65) and Regulatory Guide 1.129 (Ref. 119), which state that the battery service test should be (continued)
Watts Bar - Unit 2                          B 3.8-66
 
DC Sources - Operating B 3.8.4 BASES SURVEILLANCE      SR 3.8.4.137 (continued)
REQUIREMENTS performed during refueling operations or at some other outage, with intervals between tests, not to exceed 18 months.
This SR is modified by two Notes. Note 1 allows the performance of a modified performance discharge test in lieu of a service test once per 60 months. The modified performance discharge test is a simulated duty cycle consisting of just two rates; the one minute rate published for the battery or the largest current load of the duty cycle, followed by the test rate employed for the performance test, both of which envelope the duty cycle of the service test. Since the ampere-hours removed by a rated one minute discharge represents a very small portion of the battery capacity, the test rate can be changed to that for the performance test without compromising the results of the performance discharge test. The battery terminal voltage for the modified performance discharge test should remain above the minimum battery terminal voltage specified in the battery service test for the duration of time equal to that of the service test.
A modified discharge test is a test of the battery capacity and its ability to provide a high rate, short duration load (usually the highest rate of the duty cycle.) This will often confirm the battery's ability to meet the critical period of the load duty cycle, in addition to determining its percentage of rated capacity. Initial conditions for the modified performance discharge test should be identical to those specified for a service test.
The reason for Note 2 is that performing the Surveillance may perturb the vital electrical distribution system and challenge safety systems.
However, this Surveillance may be performed in MODES 1, 2, 3, or 4 provided that Vital Battery V is substituted in accordance with LCO Note
: 1. For the DG DC electrical subsystem, this surveillance may be performed in MODES 1, 2, 3, or 4 in conjunction with LCO 3.8.1.B since the supplied loads are only for the inoperable diesel generator and would not otherwise challenge safety system loads which are supplied from vital electrical distribution systems. Additionally, credit may be taken for unplanned events that satisfy this SR. Examples of unplanned events may include:
: 1)      Unexpected operational events which cause the equipment to perform the function specified by this Surveillance, for which adequate documentation of the required performance is available; and
: 2)      Post corrective maintenance testing that requires performance of this Surveillance in order to restore the component to OPERABLE, provided the maintenance was required, or performed in conjunction with maintenance required to maintain OPERABILITY or reliability.
(continued)
Watts Bar - Unit 2                          B 3.8-67
 
DC Sources - Operating B 3.8.4 BASES SURVEILLANCE      SR 3.8.4.14 REQUIREMENTS (continued)        A battery performance discharge test is a test of constant current capacity of a battery, normally done in the as found condition, after having been in service, to detect any change in the capacity determined by the acceptance test. The test is intended to determine overall battery degradation due to age and usage.
A battery modified performance discharge test is described in the Bases for 3.8.4.13. Either the battery performance discharge test or the modified performance discharge test is acceptable for satisfying SR 3.8.4.14; however, only the modified performance discharge test may be used to satisfy SR 3.8.4.14 while satisfying the requirements of SR 3.8.4.13 at the same time.
The acceptance criteria for this Surveillance are consistent with IEEE-450 (Ref. 9) and IEEE-485 (Ref. 5). These references recommend that the battery be replaced if its capacity is below 80% of the manufacturer rating. A capacity of 80% shows that the battery rate of deterioration is increasing, even if there is ample capacity to meet the load requirements.
The Surveillance Frequency for this test is normally 60 months. If the battery shows degradation, or if the battery has reached 85% of its expected life and capacity is < 100% of the manufacturers rating, the Surveillance Frequency is reduced to 12 months. However, if the battery shows no degradation but has reached 85% of its expected life, the Surveillance Frequency is only reduced to 24 months for batteries that retain capacity  100% of the manufacturers rating. Degradation is indicated, according to IEEE-450 (Ref. 9), when the battery capacity drops by more than 10% relative to its capacity on the previous performance test or when it is  10% below the manufacturer rating.
These Frequencies are consistent with the recommendations in IEEE-450 (Ref. 9).
This SR is modified by a Note. The reason for the Note is that performing the Surveillance may perturb the vital electrical distribution system and challenge safety systems. However, this Surveillance may be performed in MODES 1, 2, 3, or 4 provided that Vital Battery V is substituted in accordance with LCO Note 1. For the DG DC electrical subsystem, this surveillance may be performed in MODES 1, 2, 3, or 4 in conjunction with LCO 3.8.1.B since the supplied loads are only for the inoperable diesel generator and would not otherwise challenge safety system loads which are supplied from vital electrical distribution systems. Additionally, credit may be taken for unplanned events that satisfy this SR. Examples of unplanned events may include:
: 1)      Unexpected operational events which cause the equipment to perform the function specified by this Surveillance, for which adequate documentation of the required performance is available; (continued)
Watts Bar - Unit 2                        B 3.8-68
 
DC Sources - Operating B 3.8.4 BASES SURVEILLANCE      SR 3.8.4.14 (continued)
REQUIREMENTS and
: 2)    Post corrective maintenance testing that requires performance of this Surveillance in order to restore the component to OPERABLE, provided the maintenance was required, or performed in conjunction with maintenance required to maintain OPERABILITY or reliability.
(continued)
Watts Bar - Unit 2                      B 3.8-69
 
DC Sources - Operating B 3.8.4 BASES REFERENCES            1. Title 10, Code of Federal Regulations, Part 50, Appendix A, General Design Criterion 17, Electric Power System.
: 2. Regulatory Guide 1.6, Independence Between Redundant Standby (Onsite) Power Sources and Between Their Distribution Systems, U.S. Nuclear Regulatory Commission, March 10, 1971.
: 3. IEEE-308-1971, IEEE Standard Criteria for Class 1E Power Systems for Nuclear Power Generating Stations, Institute of Electrical and Electronic Engineers.
: 4. Watts Bar FSAR, Section 8.3.2, DC Power System.
: 5. IEEE-485-1983, Recommended Practices for Sizing Large Lead Storage Batteries for Generating Stations and Substations, Institute of Electrical and Electronic Engineers.
: 65. Regulatory Guide 1.32, Criteria for Safety-Related Electric Power Systems for Nuclear Power Plants, February 1977, U.S. Nuclear Regulatory Commission.
: 76. Watts Bar FSAR, Section 15, Accident Analysis and Section 6 Engineered Safety Features.
: 87. Regulatory Guide 1.93, Availability of Electric Power Sources, U.S. Nuclear Regulatory Commission, December 1974.
: 9. IEEE-450-1980/1995, IEEE Recommended Practice for Maintenance, Testing and Replacement of Vented Lead - Acid Batteries for Stationary Applications, Institute of Electrical and Electronics Engineers, Inc.
108. TVA Calculation EDQ00023620070003, 125V DC Vital Battery System Analysis 119. Regulatory Guide 1.129, Maintenance Testing and Replacement of Large Lead Storage Batteries for Generating Stations and Subsystems, U.S. Nuclear Regulatory Commission, February 1978.
1210. TVA Calculation WBN EEB-EDQ00023620070003, 125V DC Vital Battery System Analysis.
: 13. Watts Bar FSAR, Section 8.3.1, AC Power System.
Watts Bar - Unit 2                      B 3.8-70
 
DC Sources - Shutdown B 3.8.5 B 3.8 ELECTRICAL POWER SYSTEMS B 3.8.5 DC Sources - Shutdown BASES BACKGROUND          A description of the DC sources is provided in the Bases for LCO 3.8.4, DC Sources - Operating.
APPLICABLE          The initial conditions of Design Basis Accident and transient analyses in SAFETY              the FSAR, Section 6 (Ref. 1) and Section 15 (Ref. 1), assume that ANALYSES            Engineered Safety Feature systems are OPERABLE. The vital DC electrical power system provides normal and emergency DC electrical power for the emergency auxiliaries, and control and switching during all MODES of operation. The DG battery systems provide DC power for the DGs.
The OPERABILITY of the DC sources is consistent with the initial assumptions of the accident analyses and the requirements for the supported systems OPERABILITY.
The OPERABILITY of the minimum DC electrical power sources during MODES 5 and 6, and during movement of irradiated fuel assemblies ensures that:
: a. The plant can be maintained in the shutdown or refueling condition for extended periods;
: b. Sufficient instrumentation and control capability is available for monitoring and maintaining the plant status; and
: c. Adequate DC electrical power is provided to mitigate events postulated during shutdown, such as a fuel handling accident.
The DC sources satisfy Criterion 3 of 10 CFR 50.36(c)(2)(ii).
Watts Bar - Unit 2                        B 3.8-68                                  (continued)
 
DC Sources - Shutdown B 3.8.5 BASES (continued)
LCO                The 125V Vital DC electrical power subsystems, each vital subsystem channel consisting of a battery bank, associated battery charger, and the corresponding control equipment and interconnecting cabling within the channel; and the DG DC electrical power subsystems, each consisting of a battery, a battery charger, and the corresponding control equipment and interconnecting cabling, are required to be OPERABLE to support required trains subsystems of the distribution systems required OPERABLE by LCO 3.8.10, Distribution Systems - Shutdown and the required DGs required OPERABLE by LCO 3.8.2, AC Sources -
Shutdown. As a minimum, one vital DC electrical power train subsystem (i.e., Channels I and III, or II and IV) and two DG DC electrical power subsystems (i.e., 1A-A and 2A-A or 1B-B and 2B-B) shall be OPERABLE.
This ensures the availability of sufficient DC electrical power sources to operate the plant in a safe manner and to mitigate the consequences of postulated events during shutdown (e.g., fuel handling accidents).
The LCO is modified by one Note. The Note indicates that Vital Battery V may be substituted for any of the required vital batteries. However, the fifth battery cannot be declared OPERABLE until it is connected electrically in place of another battery and it has satisfied applicable Surveillance Requirements.
APPLICABILITY      The DC electrical power sources required to be OPERABLE in MODES 5 and 6, and during movement of irradiated fuel assemblies, provide assurance that:
: a. Required features needed to mitigate a fuel handling accident are available;
: b. Required features necessary to mitigate the effects of events that can lead to core damage during shutdown are available; and
: c. Instrumentation and control capability is available for monitoring and maintaining the plant in a cold shutdown condition or refueling condition.
The DC electrical power requirements for MODES 1, 2, 3, and 4 are covered in LCO 3.8.4.
Watts Bar - Unit 2                        B 3.8-69                                    (continued)
 
DC Sources - Shutdown B 3.8.5 BASES (continued)
ACTIONS            A.1, A.2, and A.3 Condition A represents one subsystem with one or two battery charger(s) inoperable (e.g., the voltage limit of SR 3.8.4.1 is not maintained). The ACTIONS provide a tiered response that focuses on returning the battery to the fully charged state and restoring a fully qualified charger to OPERABLE status in a reasonable time period. Required Action A.1 requires that the battery terminal voltage be restored to greater than or equal to the minimum established float voltage within 2 hours. This time provides for returning the inoperable charger to OPERABLE status or providing an alternate means of restoring battery terminal voltage to greater than or equal to the minimum established float voltage. Restoring the battery terminal voltage to greater than or equal to the minimum established float voltage provides good assurance that, within 12 hours, the battery will be restored to its fully charged condition (Required Action A.2) from any discharge that might have occurred due to the charger inoperability.
A discharged battery having terminal voltage of at least the minimum established float voltage indicates that the battery is on the exponential charging current portion (the second part) of its recharge cycle. The time to return a battery to its fully charged state under this condition is simply a function of the amount of the previous discharge and the recharge characteristic of the battery. Thus there is good assurance of fully recharging the battery within [12] hours, avoiding a premature shutdown with its own attendant risk.
If established battery terminal float voltage cannot be restored to greater than or equal to the minimum established float voltage within 2 hours, and the charger is not operating in the current-limiting mode, a faulty charger is indicated. A faulty charger that is incapable of maintaining established battery terminal float voltage does not provide assurance that it can revert to and operate properly in the current limit mode that is necessary during the recovery period following a battery discharge event that the DC system is designed for.
If the charger is operating in the current limit mode after 2 hours that is an indication that the battery is partially discharged and its capacity margins will be reduced. The time to return the battery to its fully charged condition in this case is a function of the battery charger capacity, the amount of loads on the associated DC system, the amount of the previous discharge, and the recharge characteristic of the battery. The charge time can be extensive, and there is not adequate assurance that it can be recharged within 12 hours (Required Action A.2).
Required Action A.2 requires that the battery float current be verified as less than or equal to 2 amps. This indicates that, if the battery had been discharged as the result of the inoperable battery charger, it has now been fully recharged. If at the expiration of the initial 12 hour period the battery float current is not less than or equal to 2 amps this indicates Watts Bar - Unit 2                        B 3.8-70                                    (continued)
 
DC Sources - Shutdown B 3.8.5 BASES (continued)
ACTIONS            A.1, A.2, and A.3 (continued) there may be additional battery problems and the battery must be declared inoperable.
Required Action A.3 limits the restoration time for the inoperable battery charger to 7 days. This action is applicable if an alternate means of restoring battery terminal voltage to greater than or equal to the minimum established float voltage has been used (e.g., balance of plant non-Class 1E battery charger). The 7 day Completion Time reflects a reasonable time to effect restoration of the qualified battery charger to OPERABLE status.
AB.1, AB.2.1, AB.2.2, AB.2.3, and AB.2.4 If two trains subsystems are required by LCO 3.8.10, the remaining train subsystem with DC power available may be capable of supporting sufficient systems to allow continuation of CORE ALTERATIONS and fuel movement. By allowing the option to declare required features inoperable with the associated vital DC power source(s) inoperable, appropriate restrictions will be implemented in accordance with the affected required features LCO ACTIONS. In many instances, this option may involve undesired administrative efforts. Therefore, the allowance for sufficiently conservative actions is made (i.e., to suspend CORE ALTERATIONS, movement of irradiated fuel assemblies, and operations involving positive reactivity additions). The Required Action to suspend positive reactivity additions does not preclude actions to maintain or increase reactor vessel inventory, provided the required SDM is maintained.
Suspension of these activities shall not preclude completion of actions to establish a safe conservative condition. These actions minimize probability of the occurrence of postulated events. It is further required to immediately initiate action to restore the required vital DC electrical power subsystems and to continue this action until restoration is accomplished in order to provide the necessary DC electrical power to the plant safety systems.
The Completion Time of immediately is consistent with the required times for actions requiring prompt attention. The restoration of the required vital DC electrical power subsystems should be completed as quickly as possible in order to minimize the time during which the plant safety systems may be without sufficient power.
BC.1 If one or more DG DC electrical power subsystem cannot be restored to OPERABLE status in the associated Completion Time, the associated DG may be incapable of performing its intended function and must be immediately declared inoperable. This declaration also requires entry into applicable Conditions and Required Actions for an inoperable DG, LCO 3.8.2, AC Sources - Shutdown.
Watts Bar - Unit 2                        B 3.8-71                                  (continued)
 
DC Sources - Shutdown B 3.8.5 BASES (continued)
SURVEILLANCE      SR 3.8.5.1 REQUIREMENTS SR 3.8.5.1 requires performance of all Surveillances required by SR 3.8.4.1 through SR 3.8.4.147. Therefore, see the corresponding Bases for LCO 3.8.4 for a discussion of each SR.
This SR is modified by a Note. The reason for the Note is to preclude requiring the OPERABLE DC sources from being discharged below their capability to provide the required power supply or otherwise rendered inoperable during the performance of SRs. It is the intent that these SRs must still be capable of being met, but actual performance is not required.
REFERENCES        1. Watts Bar FSAR, Section 15, Accident Analysis and Section 6, Engineered Safety Features.
: 2. Watts Bar FSAR, Section 8.0, Electric Power.
Watts Bar - Unit 2                        B 3.8-72
 
Battery Cell Parameters B 3.8.6 B 3.8 ELECTRICAL POWER SYSTEMS B 3.8.6 Battery Cell Parameters BASES BACKGROUND            This LCO delineates the limits on battery float current, electrolyte temperature, electrolyte level, and cell float voltage for the 125V vital DC electrical power subsystem and the diesel generator (DG) batteries. A discussion of these batteries and their OPERABILITY requirements is provided in the Bases for LCO 3.8.4, DC Sources - Operating, and LCO 3.8.5, DC Sources - Shutdown. In addition to the limitations of this Specification, the Battery Monitoring and Maintenance Program also implements a program specified in Specification 5.7.2.22 for monitoring various battery parameters.
The battery cells are of flooded lead acid construction with a nominal specific gravity of 1.215. This specific gravity corresponds to an open circuit battery voltage of approximately 120 V for 60 cell battery (i.e., cell voltage of 2.063 volts per cell (Vpc)). The open circuit voltage is the voltage maintained when there is no charging or discharging. Optimal long term performance however, is obtained by maintaining a float voltage 2.20 to 2.25 Vpc. This provides adequate over-potential which limits the formation of lead sulfate and self discharge. The nominal float voltage of 2.22 Vpc corresponds to a total float voltage output of 133.2 V for a 60 cell battery as discussed in the FSAR, Chapter 8 (Ref. 3).
APPLICABLE            The initial conditions of Design Basis Accident (DBA) and transient SAFETY                analyses in the FSAR, Section 6 (Ref. 1) and Section 15 (Ref. 1), assume ANALYSES              Engineered Safety Feature systems are OPERABLE. The vital DC electrical power system provides normal and emergency DC electrical power for the emergency auxiliaries, and control and switching during all MODES of operation. The DG battery systems provide DC power for the DGs.
The OPERABILITY of the DC subsystems is consistent with the initial assumptions of the accident analyses and is based upon meeting the design basis of the plant. This includes maintaining at least one train subsystem of DC sources OPERABLE during accident conditions, in the event of:
: a. An assumed loss of all offsite AC power or all onsite AC power; and
: b. A worst case single failure.
Battery parameters satisfy the Criterion 3 of 10 CFR 50.36(c)(2)(ii).
Watts Bar - Unit 2                          B 3.8-72                                    (continued)
 
Battery Cell Parameters B 3.8.6 BASES (continued)
LCO                Battery parameters must remain within acceptable limits to ensure availability of the required DC power to shut down the reactor and maintain it in a safe condition after an anticipated operational occurrence or a postulated DBA. Electrolyte Battery parameter limits are conservatively established, allowing continued DC electrical system function even with Category A and B limits not met. Additional preventative maintenance, testing, and monitoring performed in accordance with the Battery Monitoring and Maintenance Program is conducted as specified in Specification 5.7.2.22.
APPLICABILITY      The battery cell parameters are required solely for the support of the associated vital DC and DG DC electrical power subsystems. Therefore, battery electrolyte is parameter limits are only required when the DC power source is required to be OPERABLE. Refer to the Applicability discussion in Bases for LCO 3.8.4 and LCO 3.8.5.
ACTIONS            A.1, A.2, and A.3 With one or more cells in one or more batteries not within limits (i.e.,
Category A limits not met, Category B limits not met, or Category A and B limits not met) but within the Category C limits specified in Table 3.8.6-1 in the accompanying LCO, the battery is degraded but there is still sufficient capacity to perform the intended function. Therefore, the affected battery is not required to be considered inoperable solely as a result of Category A or B limits not met, and operation is permitted for a limited period.
The pilot cell electrolyte level and float voltage are required to be verified to meet the Category C limits within 1 hour (Required Action A.1). This check will provide a quick indication of the status of the remainder of the battery cells. One hour provides time to inspect the electrolyte level and to confirm the float voltage of the pilot cells. One hour is considered a reasonable amount of time to perform the required verification.
Verification that the Category C limits are met (Required Action A.2) provides assurance that during the time needed to restore the parameters to the Category A and B limits, the battery is still capable of performing its intended function. A period of 24 hours is allowed to complete the initial verification because specific gravity measurements must be obtained for each connected cell. Taking into consideration both the time required to perform the required verification and the assurance that the battery cell parameters are not severely degraded, this time is considered reasonable. The verification is repeated at 7 day intervals until the parameters are restored to Category A and B limits. This periodic verification is consistent with the normal Frequency of pilot cell surveillances.
(continued)
Watts Bar - Unit 2                        B 3.8-73
 
Battery Cell Parameters B 3.8.6 BASES ACTIONS            A.1, A.2, and A.3 (continued)
Continued operation is only permitted for 31 days before battery cell parameters must be restored to within Category A and B limits. With the consideration that, while battery capacity is degraded, sufficient capacity exists to perform the intended function and to allow time to fully restore the battery cell parameters to normal limits, this time is acceptable prior to declaring the battery inoperable.
A.1, A.2, and A.3 With one or more cells in one or more batteries in one vital DC subsystem
                  < 2.07 V, the battery cell is degraded. Within 2 hours verification of the required battery charger OPERABILITY is made by monitoring the battery terminal voltage (SR 3.8.4.1) and of the overall battery state of charge by monitoring the battery float charge current (SR 3.8.6.1). This assures that there is still sufficient battery capacity to perform the intended function.
Therefore, the affected battery is not required to be considered inoperable solely as a result of one or more cells in one or more batteries < 2.07 V, and continued operation is permitted for a limited period up to 24 hours.
Since the Required Actions only specify "perform," a failure of SR 3.8.4.1 or SR 3.8.6.1 acceptance criteria does not result in this Required Action not met. However, if one of the SRs is failed the appropriate Condition(s),
depending on the cause of the failures, is entered. If SR 3.8.6.1 is failed then there is not assurance that there is still sufficient battery capacity to perform the intended function and the battery must be declared inoperable immediately.
B.1 and B.2 One or more batteries in one vital DC subsystem with float current > 2 amps indicates that a partial discharge of the battery capacity has occurred. This may be due to a temporary loss of a battery charger or possibly due to one or more battery cells in a low voltage condition reflecting some loss of capacity. Within 2 hours verification of the required battery charger OPERABILITY is made by monitoring the battery terminal voltage. If the terminal voltage is found to be less than the minimum established float voltage there are two possibilities, the battery charger is inoperable or is operating in the current limit mode. Condition A addresses charger inoperability. If the charger is operating in the current limit mode after 2 hours that is an indication that the battery has been substantially discharged and likely cannot perform its required design functions. The time to return the battery to its fully charged condition in this case is a function of the battery charger capacity, the amount of loads on the associated DC system, the amount of the previous discharge, and (continued)
Watts Bar - Unit 2                          B 3.8-74
 
Battery Cell Parameters B 3.8.6 BASES ACTIONS            B.1 and B.2 (continued) the recharge characteristic of the battery. The charge time can be extensive, and there is not adequate assurance that it can be recharged within 12 hours (Required Action B.2). The battery must therefore be declared inoperable.
If the float voltage is found to be satisfactory but there are one or more battery cells with float voltage less than 2.07 V, the associated "OR" statement in Condition H is applicable and the battery must be declared inoperable immediately. If float voltage is satisfactory and there are no cells less than 2.07 V there is good assurance that, within 12 hours, the battery will be restored to its fully charged condition (Required Action B.2) from any discharge that might have occurred due to a temporary loss of the battery charger.
A discharged battery with float voltage (the charger setpoint) across its terminals indicates that the battery is on the exponential charging current portion (the second part) of its recharge cycle. The time to return a battery to its fully charged state under this condition is simply a function of the amount of the previous discharge and the recharge characteristic of the battery. Thus there is good assurance of fully recharging the battery within 12 hours, avoiding a premature shutdown with its own attendant risk.
If the condition is due to one or more cells in a low voltage condition but still greater than 2.07 V and float voltage is found to be satisfactory, this is not indication of a substantially discharged battery and 12 hours is a reasonable time prior to declaring the battery inoperable.
Since Required Action B.1 only specifies "perform," a failure of SR 3.8.4.1 acceptance criteria does not result in the Required Action not met.
However, if SR 3.8.4.1 is failed, the appropriate Condition(s), depending on the cause of the failure, is entered.
C.1, C.2, and C.3 With one or more cells in one or more batteries in one DG DC subsystem
                  < 2.07 V, the battery cell is degraded. Within 2 hours verification of the required battery charger OPERABILITY is made by monitoring the battery terminal voltage (SR 3.8.4.2) and of the overall battery state of charge by monitoring the battery float charge current (SR 3.8.6.2). This assures that there is still sufficient battery capacity to perform the intended function.
Therefore, the affected battery is not required to be considered inoperable solely as a result of one or more cells in one or more batteries < 2.07 V, and continued operation is permitted for a limited period up to 24 hours.
(continued)
Watts Bar - Unit 2                          B 3.8-75
 
Battery Cell Parameters B 3.8.6 BASES ACTIONS            C.1, C.2, and C.3 (continued)
Since the Required Actions only specify "perform," a failure of SR 3.8.4.2 or SR 3.8.6.2 acceptance criteria does not result in this Required Action not met. However, if one of the SRs is failed the appropriate Condition(s),
depending on the cause of the failures, is entered. If SR 3.8.6.2 is failed then there is not assurance that there is still sufficient battery capacity to perform the intended function and the battery must be declared inoperable immediately.
D.1 and D.2 One or more batteries in one DG DC subsystem with float current
                  > 1 amps indicates that a partial discharge of the battery capacity has occurred. This may be due to a temporary loss of a battery charger or possibly due to one or more battery cells in a low voltage condition reflecting some loss of capacity. Within 2 hours verification of the required battery charger OPERABILITY is made by monitoring the battery terminal voltage. If the terminal voltage is found to be less than the minimum established float voltage there are two possibilities, the battery charger is inoperable or is operating in the current limit mode. Condition B addresses charger inoperability. If the charger is operating in the current limit mode after 2 hours that is an indication that the battery has been substantially discharged and likely cannot perform its required design functions. The time to return the battery to its fully charged condition in this case is a function of the battery charger capacity, the amount of loads on the associated DC system, the amount of the previous discharge, and the recharge characteristic of the battery. The charge time can be extensive, and there is not adequate assurance that it can be recharged within 12 hours (Required Action D.2). The battery must therefore be declared inoperable.
If the float voltage is found to be satisfactory but there are one or more battery cells with float voltage less than 2.07 V, the associated "OR" statement in Condition H is applicable and the battery must be declared inoperable immediately. If float voltage is satisfactory and there are no cells less than 2.07 V there is good assurance that, within 12 hours, the battery will be restored to its fully charged condition (Required Action D.2) from any discharge that might have occurred due to a temporary loss of the battery charger.
A discharged battery with float voltage (the charger setpoint) across its terminals indicates that the battery is on the exponential charging current portion (the second part) of its recharge cycle. The time to return a battery to its fully charged state under this condition is simply a function of the amount of the previous discharge and the recharge characteristic of the battery. Thus there is good assurance of fully recharging the battery within 12 hours, avoiding a premature shutdown with its own attendant risk.
(continued)
Watts Bar - Unit 2                          B 3.8-76
 
Battery Cell Parameters B 3.8.6 BASES ACTIONS            D.1 and D.2 (continued)
If the condition is due to one or more cells in a low voltage condition but still greater than 2.07 V and float voltage is found to be satisfactory, this is not indication of a substantially discharged battery and 12 hours is a reasonable time prior to declaring the battery inoperable.
Since Required Action D.1 only specifies "perform," a failure of SR 3.8.4.2 acceptance criteria does not result in the Required Action not met.
However, if SR 3.8.4.2 is failed, the appropriate Condition(s), depending on the cause of the failure, is entered.
E.1, E.2, and E.3 With one or more required batteries in one vital DC subsystem or one DG battery with one or more cells electrolyte level above the top of the plates, but below the minimum established design limits, the battery still retains sufficient capacity to perform the intended function. Therefore, the affected battery is not required to be considered inoperable solely as a result of electrolyte level not met. Within 31 days the minimum established design limits for electrolyte level must be re-established.
With electrolyte level below the top of the plates there is a potential for dryout and plate degradation. Required Actions E.1 and E.2 address this potential (as well as provisions in Specification 5.7.2.22, Battery Monitoring and Maintenance Program). They are modified by a Note that indicates they are only applicable if electrolyte level is below the top of the plates. Within 8 hours level is required to be restored to above the top of the plates. The Required Action E.2 requirement to verify that there is no leakage by visual inspection and the Specification 5.7.2.22.b item to initiate action to equalize and test in accordance with manufacturer's recommendation. They are performed following the restoration of the electrolyte level to above the top of the plates. Based on the results of the manufacturer's recommended testing the battery(ies) may have to be declared inoperable and the affected cell(s) replaced.
F.1 With one or more batteries in one vital DC subsystem or one DG battery with pilot cell temperature less than the minimum established design limits, 12 hours is allowed to restore the temperature to within limits. A low electrolyte temperature limits the current and power available. Since the battery is sized with margin, while battery capacity is degraded, sufficient capacity exists to perform the intended function and the affected battery is not required to be considered inoperable solely as a result of the pilot cell temperature not met.
(continued)
Watts Bar - Unit 2                        B 3.8-77
 
Battery Cell Parameters B 3.8.6 BASES ACTIONS            G.1 (continued)
With one or more batteries in redundant vital DC subsystems with battery parameters not within limits there is not sufficient assurance that battery capacity has not been affected to the degree that the batteries can still perform their required function, given that redundant batteries are involved. With redundant batteries involved this potential could result in a total loss of function on multiple systems that rely upon the batteries. With more than one DG battery with battery parameters not within limits there is not sufficient assurance that battery capacity has not been affected to the degree that the batteries can still perform their required function.
The longer Completion Times specified for battery parameters on non-redundant batteries not within limits are therefore not appropriate, and the parameters must be restored to within limits on at least one subsystem within 2 hours.
BH.1 With one or more batteries with one or more any battery cell parameters outside the Category C limits for any connected cell, allowances of the Required Actions for Condition A, B, C, D, E, F, or G, sufficient capacity to supply the maximum expected load requirement is not assured and the corresponding vital DC or DG DC electrical power subsystem battery must be declared inoperable. Additionally, other potentially extreme conditions, such as not completing the Required Actions of Condition A within the required Completion Time or average electrolyte temperature of representative cells falling below 60F for the vital batteries or 50F for DG batteries, are also cause for immediately declaring the associated vital DC or DG DC electrical power subsystem inoperable. discovering one or more vital DC batteries in one subsystem with one or more battery cells float voltage less than 2.07 V and float current greater than 2 amps, or one DG battery cells float voltage greater than or equal to 2.07 V and float current greater than 1 amp, indicates that the battery capacity may not be sufficient to perform the intended functions. The battery must therefore be declared inoperable immediately.
SURVEILLANCE      SR 3.8.6.1 REQUIREMENTS This SR verifies that Category A battery cell parameters are consistent with IEEE-450 (Ref. 2), which recommends regular battery inspections (at least one per month) including voltage, specific gravity, and electrolyte temperature of pilot cells.
(continued)
Watts Bar - Unit 2                        B 3.8-78
 
Battery Cell Parameters B 3.8.6 BASES SURVEILLANCE      SR 3.8.6.2 REQUIREMENTS (continued)    The quarterly inspection of specific gravity and voltage is consistent with IEEE-450 (Ref. 2). In addition, within 24 hours of a battery discharge
                  < 110 V (113.5V for Vital Battery V or 106.5 for DG batteries) or a battery overcharge > 150 V (155 V for Vital Battery V or 145 V for DG batteries),
the battery must be demonstrated to meet Category B limits. Transients, such as motor starting transients, which may momentarily cause battery voltage to drop to  110 V (113.5 V for Vital Battery V or 106.5 V for DG batteries), do not constitute a battery discharge provided the battery terminal voltage and float current return to pre-transient values. This inspection is also consistent with IEEE-450 (Ref. 2), which recommends special inspections following a severe discharge or overcharge, to ensure that no significant degradation of the battery occurs as a consequence of such discharge or overcharge.
SR 3.8.6.3 This Surveillance verification that the average temperature of representative cells is  60F for the vital batteries and  50F for the DG batteries, is consistent with a recommendation of IEEE-450 (Ref. 2), that states that the temperature of electrolytes in representative cells should be determined on a quarterly basis.
Lower than normal temperatures act to inhibit or reduce battery capacity.
This SR ensures that the operating temperatures remain within an acceptable operating range. This limit is based on manufacturer recommendations.
Table 3.8.6-1 This table delineates the limits on electrolyte level, float voltage, and specific gravity for three different categories. The meaning of each category is discussed below.
Category A defines the normal parameter limit for each designated pilot cell in each battery. The cells selected as pilot cells are those whose temperature, voltage, and electrolyte specific gravity approximate the state of charge of the entire battery.
The Category A limits specified for electrolyte level are based on manufacturer recommendations and are consistent with the guidance in IEEE-450 (Ref. 2), with the extra 1/4 inch allowance above the high water level indication for operating margin to account for temperatures and charge effects. In addition to this allowance, footnote a to Table 3.8.6-1 permits the electrolyte level to be above the specified maximum level during equalizing charge, provided it is not overflowing. These limits ensure that the plates suffer no physical damage, and that adequate (continued)
Watts Bar - Unit 2                        B 3.8-79
 
Battery Cell Parameters B 3.8.6 BASES SURVEILLANCE      electron transfer capability is maintained in the event of transient REQUIREMENTS      conditions. IEEE-450 (Ref. 2) recommends that electrolyte level readings (continued)    should be made only after the battery has been at float charge for at least 72 hours.
The Category A limit specified for float voltage is  2.13 V per cell. This value is based on the recommendations of IEEE-450 (Ref. 2), which states that prolonged operation of cells < 2.13 V can reduce the life expectancy of cells.
The Category A limit specified for specific gravity for each pilot cell is 1.200 (0.015 below the manufacturer fully charged nominal specific gravity or a battery charging current that had stabilized at a low value).
This value is characteristic of a charged cell with adequate capacity.
According to IEEE-450 (Ref. 2), the specific gravity readings are based on a temperature of 77F (25C).
The specific gravity readings are corrected for actual electrolyte temperature and level. For each 3F (1.67C) above 77F (25C), 1 point (0.001) is added to the reading; 1 point is subtracted for each 3F below 77F. The specific gravity of the electrolyte in a cell increases with a loss of water due to electrolysis or evaporation.
Category B defines the normal parameter limits for each connected cell.
The term "connected cell" excludes any battery cell that may be jumpered out.
The Category B limits specified for electrolyte level and float voltage are the same as those specified for Category A and have been discussed above. The Category B limit specified for specific gravity for each connected cell is  1.195 (0.020 below the manufacturer fully charged, nominal specific gravity) with the average of all connected cells > 1.205 (0.010 below the manufacturer fully charged, nominal specific gravity).
These values are based on manufacturer's recommendations. The minimum specific gravity value required for each cell ensures that the effects of a highly charged or newly installed cell will not mask overall degradation of the battery.
Category C defines the limits for each connected cell. These values, although reduced, provide assurance that sufficient capacity exists to perform the intended function and maintain a margin of safety. When any battery parameter is outside the Category C limits, the assurance of sufficient capacity described above no longer exists, and the battery must be declared inoperable.
The Category C limits specified for electrolyte level (above the top of the plates and not overflowing) ensure that the plates suffer no physical (continued)
Watts Bar - Unit 2                        B 3.8-80
 
Battery Cell Parameters B 3.8.6 BASES SURVEILLANCE      damage and maintain adequate electron transfer capability. The REQUIREMENTS      Category C limits for float voltage is based on IEEE-450 (Ref. 2), which (continued)    states that a cell voltage of 2.07 V or below, under float conditions and not caused by elevated temperature of the cell, indicates internal cell problems and may require cell replacement.
The Category C limits of average specific gravity  1.195 is based on manufacturer recommendations (0.020 below the manufacturer recommended fully charged, nominal specific gravity). In addition to that limit, it is required that the specific gravity for each connected cell must be no less than 0.020 below the average of all connected cells. This limit ensures that the effect of a highly charged or new cell does not mask overall degradation of the battery.
The footnotes to Table 3.8.6-1 are applicable to Category A, B, and C specific gravity. Footnote b to Table 3.8.6-1 requires the above mentioned correction for electrolyte level and temperature, with the exception that level correction is not required when battery charging current is < 2 amps on float charge for vital batteries and < 1.0 amps for DG batteries. This current provides, in general, an indication of overall battery condition.
Because of specific gravity gradients that are produced during the recharging process, delays of several days may occur while waiting for the specific gravity to stabilize. A stabilized charger current is an acceptable alternative to specific gravity measurement for determining the state of charge. This phenomenon is discussed in IEEE-450 (Ref. 2).
Footnote c to Table 3.8.6-1 allows the float charge current to be used as an alternate to specific gravity for up to 31 days following a battery recharge. Within 31 days each connected cell's specific gravity must be measured to confirm the state of charge. Following a minor battery recharge (such as equalizing charge that does not follow a deep discharge) specific gravity gradients are not significant, and confirming measurements may be made in less than 31 days.
Watts Bar - Unit 2                          B 3.8-81
 
Battery Cell Parameters B 3.8.6 BASES SURVEILLANCE      SR 3.8.6.1 and SR 3.8.6.2 REQUIREMENTS Verifying battery float current while on float charge is used to determine the state of charge of the battery. Float charge is the condition in which the charger is supplying the continuous charge required to overcome the internal losses of a battery and maintain the battery in a charged state.
The equipment used to monitor float current must have the necessary accuracy and capability to measure electrical currents in the expected range. The float current requirements are based on the float current indicative of a charged battery. The 7 day Frequency is consistent with IEEE-450 (Ref. 2).
SR 3.8.6.1 is modified by a Note that states the float current requirement is not required to be met when battery terminal voltage is less than the minimum established float voltage of SR 3.8.4.1. When this float voltage is not maintained the Required Actions of LCO 3.8.4 ACTION A are being taken, which provide the necessary and appropriate verifications of the battery condition. Furthermore, the float current limit of 2 amps is established based on the nominal float voltage value and is not directly applicable when this voltage is not maintained.
SR 3.8.6.2 is modified by a Note that states the float current requirement is not required to be met when battery terminal voltage is less than the minimum established float voltage of SR 3.8.4.2. When this float voltage is not maintained the Required Actions of LCO 3.8.4 ACTION D are being taken, which provide the necessary and appropriate verifications of the battery condition. Furthermore, the float current limit of 1 amp is established based on the nominal float voltage value and is not directly applicable when this voltage is not maintained.
SR 3.8.6.3 and SR 3.8.6.6 Optimal long term battery performance is obtained by maintaining a float voltage greater than or equal to the minimum established design limits provided by the battery manufacturer, which corresponds to 132 V at the battery terminals, or 2.20 Vpc. This provides adequate overpotential, which limits the formation of lead sulfate and self discharge, which could eventually render the battery inoperable. Float voltages in this range or less, but greater than 2.07 Vpc, are addressed in Specification 5.7.2.22.
SRs 3.8.6.3 and 3.8.6.6 require verification that the cell float voltages are equal to or greater than the short term absolute minimum voltage of 2.07 V. The Frequency for cell voltage verification every 31 days for pilot cell and 92 days for each connected cell is consistent with IEEE-450 (Ref. 2).
SR 3.8.6.4 The limit specified for electrolyte level ensures that the plates suffer no physical damage and maintains adequate electron transfer capability. The minimum design electrolyte level is the minimum level indication mark on the battery cell jar. The Frequency is consistent with IEEE-450 (Ref. 2).
Watts Bar - Unit 2                        B 3.8-82
 
Battery Cell Parameters B 3.8.6 BASES SURVEILLANCE      SR 3.8.6.5 REQUIREMENTS (continued)        This Surveillance verifies that the pilot cell temperature is greater than or equal to the minimum established design limit (i.e., 60&deg;F for vital batteries and 50&deg;F for DG batteries). Pilot cell electrolyte temperature is maintained above this temperature to assure the battery can provide the required current and voltage to meet the design requirements. Temperatures lower than assumed in battery sizing calculations act to inhibit or reduce battery capacity. The Frequency is consistent with IEEE-450 (Ref. 2).
SR 3.8.6.7 A battery performance discharge test is a test of constant current capacity of a battery, normally done in the as found condition, after having been in service, to detect any change in the capacity determined by the acceptance test. The test is intended to determine overall battery degradation due to age and usage.
Either the battery performance discharge test or the modified performance discharge test is acceptable for satisfying SR 3.8.6.7; however, only the modified performance discharge test may be used to satisfy the battery service test requirements of SR 3.8.4.7.
A modified discharge test is a test of the battery capacity and its ability to provide a high rate, short duration load (usually the highest rate of the duty cycle). This will often confirm the battery's ability to meet the critical period of the load duty cycle, in addition to determining its percentage of rated capacity. Initial conditions for the modified performance discharge test should be identical to those specified for a service test.
It may consist of just two rates; for instance the one minute rate for the battery or the largest current load of the duty cycle, followed by the test rate employed for the performance test, both of which envelope the duty cycle of the service test. Since the ampere-hours removed by a one minute discharge represents a very small portion of the battery capacity, the test rate can be changed to that for the performance test without compromising the results of the performance discharge test. The battery terminal voltage for the modified performance discharge test must remain above the minimum battery terminal voltage specified in the battery service test for the duration of time equal to that of the service test.
The acceptance criteria for this Surveillance are consistent with IEEE-450 (Ref. 2) and IEEE-485 (Ref. 4). These references recommend that the battery be replaced if its capacity is below 80% of the manufacturer's rating. A capacity of 80% shows that the battery rate of deterioration is increasing, even if there is ample capacity to meet the load requirements.
Furthermore, the battery is sized to meet the assumed duty cycle loads when the battery design capacity reaches this 80% limit.
Watts Bar - Unit 2                        B 3.8-83
 
Battery Cell Parameters B 3.8.6 BASES SURVEILLANCE      SR 3.8.6.7 (continued)
REQUIREMENTS The Surveillance Frequency for this test is normally 60 months. If the battery shows degradation, or if the battery has reached 85% of its expected life and capacity is < 100% of the manufacturer's rating, the Surveillance Frequency is reduced to 12 months. However, if the battery shows no degradation but has reached 85% of its expected life, the Surveillance Frequency is only reduced to 24 months for batteries that retain capacity  100% of the manufacturer's ratings. Degradation is indicated, according to IEEE-450 (Ref. 2), when the battery capacity drops by more than 10% relative to its capacity on the previous performance test or when it is  10% below the manufacturer's rating.
These Frequencies are consistent with the recommendations in IEEE-450 (Ref. 2).
This SR is modified by a Note. The reason for the Note is that performing the Surveillance would perturb the electrical distribution system and challenge safety systems. Credit may be taken for unplanned events that satisfy this SR.
REFERENCES        1. Watts Bar FSAR, Section 15, Accident Analysis, and Section 6, Engineered Safety Features.
: 2. IEEE-450-1980/19952002, "IEEE Recommended Practice for Maintenance, Testing, and Replacement of Large Vented Lead-Acid Storage Batteries for Generating Stations and SubstationsStationary Applications."
: 3. Watts Bar FSAR, Section 8, Electric Power.
: 4. IEEE-485-1983, "IEEE Recommended Practice for Sizing Large Lead Storage Batteries for Generating Stations and Substations."
Watts Bar - Unit 2                      B 3.8-84
 
Enclosure 3 Clean Technical Specification and Bases Changes CNL-18-118                      E3-1
 
WBN Unit 1 Clean Technical Specification and Bases CNL-18-118                    E3-2
 
DC Sources - Operating 3.8.4 3.8 ELECTRICAL POWER SYSTEMS 3.8.4 DC Sources - Operating LCO 3.8.4              The Train A and Train B vital DC electrical power subsystems and four Diesel Generator (DG) DC electrical power subsystems shall be OPERABLE.
                        ------------------------------------------------NOTE--------------------------------------------------
Vital Battery V may be substituted for any of the required vital batteries.
APPLICABILITY:          MODES 1, 2, 3, and 4.
ACTIONS CONDITION                                    REQUIRED ACTION                            COMPLETION TIME A. One or two required vital            A.1        Restore battery terminal                    2 hours battery charger(s) on one                      voltage to greater than or subsystem inoperable.                          equal to the minimum established float voltage.
AND A.2        Verify battery float current                Once per 12 hours 2 amps.
AND A.3        Restore vital battery charger(s)            7 days to OPERABLE status.
B. One vital DC electrical              B.1        Restore vital DC electrical                  2 hours power subsystem                                power subsystem to inoperable for reasons                          OPERABLE status.
other than Condition A.
(continued)
Watts Bar-Unit 1                                        3.8-24                                              Amendment XX
 
DC Sources - Operating 3.8.4 ACTIONS (continued)
CONDITION                  REQUIRED ACTION                COMPLETION TIME C. Required Action and      C.1 Be in MODE 3.                  6 hours Associated Completion Time of Condition A or B  AND not met.
C.2 Be in MODE 5.                  36 hours D. One DG DC battery charger D.1 Restore DG battery terminal    2 hours inoperable.                  voltage to greater than or equal to the minimum established float voltage.
AND D.2 Verify battery float current  Once per 12 hours 1 amp.
AND D.3 Restore DG battery charger to  72 hours OPERABLE status.
E. One DG DC electrical      E.1 Restore DG DC electrical      2 hours power subsystem              power subsystem to inoperable for reasons        OPERABLE status.
other than Condition D.
F. Required Action and      F.1 Declare associated DG          Immediately associated Completion        inoperable.
Time of Condition D or E not met.
Watts Bar-Unit 1                      3.8-25                              Amendment XX
 
DC Sources - Operating 3.8.4 SURVEILLANCE REQUIREMENTS SURVEILLANCE                                        FREQUENCY SR 3.8.4.1      Verify vital battery terminal voltage is greater than or  7 days equal to the minimum established float voltage.
SR 3.8.4.2      Verify DG battery terminal voltage is greater than or    7 days equal to the minimum established float voltage.
SR 3.8.4.3      Verify for the vital batteries that the alternate feeder  7 days breakers to each required battery charger are open.
SR 3.8.4.4      Verify correct breaker alignment and indicated power      7 days availability for each DG 125 V DC distribution panel and associated battery charger.
SR 3.8.4.5      Verify each vital battery charger supplies  200 amps at greater than or equal to the minimum established float voltage for  4 hours.
OR Verify each vital battery charger can recharge the        18 months battery to the fully charged state within 36 hours 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.
(continued)
Watts Bar-Unit 1                            3.8-26                                Amendment XX
 
DC Sources - Operating 3.8.4 SURVEILLANCE REQUIREMENTS (continued)
SURVEILLANCE                                                        FREQUENCY SR 3.8.4.6      -------------------------------NOTE-------------------------------
Credit may be taken for unplanned events that satisfy this SR.
Verify each DG battery charger supplies  20 amps at                    18 months greater than or equal to the minimum established float voltage for  4 hours.
OR Verify each DG battery charger can recharge the battery to the fully charged state within 24 hours 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.
SR 3.8.4.7      ------------------------------NOTES------------------------------
: 1.        The modified performance discharge test in SR 3.8.6.7 may be performed in lieu of the service test in SR 3.8.4.7.
: 2.        This Surveillance is not performed in MODE 1, 2, 3, or 4 for required vital batteries.
Credit may be taken for unplanned events that satisfy this SR.
Verify battery capacity is adequate to supply, and                      18 months maintain in OPERABLE status, the required emergency loads and any connected nonsafety loads for the design duty cycle when subjected to a battery service test.
Watts Bar-Unit 1                                  3.8-27                                        Amendment XX
 
DC Sources - Shutdown 3.8.5 3.8 ELECTRICAL POWER SYSTEMS 3.8.5 DC Sources - Shutdown LCO 3.8.5                Vital DC and Diesel Generator (DG) DC electrical power subsystems shall be OPERABLE to support the DC electrical power distribution subsystem(s) required by LCO 3.8.10, "Distribution Systems - Shutdown" and to support the Diesel Generators (DGs) required by LCO 3.8.2, "AC Sources - Shutdown."
                        --------------------------------------------------NOTE-----------------------------------------------
Vital Battery V may be substituted for any of the required vital batteries.
APPLICABILITY:          MODES 5 and 6, During movement of irradiated fuel assemblies.
ACTIONS CONDITION                                    REQUIRED ACTION                            COMPLETION TIME A.      One or two required vital            A.1        Restore battery terminal                    2 hours battery charger(s) on one                      voltage to greater than or subsystem inoperable.                          equal to the minimum established float voltage.
AND AND The redundant subsystem vital battery and charger(s)        A.2        Verify battery float current                Once per 12 hours OPERABLE.                                        2 amps.
AND A.3        Restore battery charger(s) to                7 days OPERABLE status.
(continued)
Watts Bar-Unit 1                                          3.8-30                                              Amendment XX
 
DC Sources-Shutdown 3.8.5 ACTIONS (continued)
CONDITION                      REQUIRED ACTION              COMPLETION TIME B.      One or more required vital B.1.1 Declare affected required    Immediately DC electrical power              feature(s) inoperable.
subsystems inoperable for reasons other than        OR Condition A.
B.2.1 Suspend CORE                  Immediately OR                              ALTERATIONS.
Required Actions and            AND associated Completion Time of Condition A not    B.2.2 Suspend movement of          Immediately met.                            irradiated fuel assemblies.
AND B.2.3 Initiate action to suspend    Immediately operations involving positive reactivity additions.
AND B.2.4 Initiate action to restore    Immediately required DC electrical power subsystems to OPERABLE status.
C.      One required DG DC        C.1  Declare associated DG        Immediately electrical power subsystem      inoperable.
inoperable.
Watts Bar-Unit 1                            3.8-31                            Amendment XX
 
DC Sources-Shutdown 3.8.5 SURVEILLANCE REQUIREMENTS SURVEILLANCE                                                      FREQUENCY SR 3.8.5.1      --------------------------------NOTE-----------------------------
The following SRs are not required to be performed:
SR 3.8.4.5, SR 3.8.4.6, and SR 3.8.4.7.
For DC sources required to be OPERABLE, the                          In accordance with following SRs are applicable:                                        applicable SRs SR 3.8.4.1          SR 3.8.4.5 SR 3.8.4.2          SR 3.8.4.6 SR 3.8.4.3          SR 3.8.4.7 SR 3.8.4.4 Watts Bar-Unit 1                                  3.8-32                                      Amendment XX
 
Battery Parameters 3.8.6 3.8 ELECTRICAL POWER SYSTEMS 3.8.6 Battery Parameters LCO 3.8.6                      Battery parameters for Train A and Train B electrical power subsystem 125 V vital batteries and 125 V diesel generator (DG) batteries shall be within limits.
APPLICABILITY:                  When associated DC electrical power subsystems and DGs are required to be OPERABLE.
ACTIONS
-------------------------------------------------------------------NOTE---------------------------------------------------------------
Separate Condition entry is allowed for each battery bank.
CONDITION                                      REQUIRED ACTION                            COMPLETION TIME A.        One or two required vital              A.1        Perform SR 3.8.4.1.                        2 hours battery(ies) on one subsystem with one or                  AND more battery cells float voltage < 2.07 V.                      A.2        Perform SR 3.8.6.1.                        2 hours AND A.3        Restore affected cell voltage              24 hours 2.07 V.
B.        One or two required vital              B.1        Perform SR 3.8.4.1.                        2 hours battery(ies) on one subsystem with float                    AND current > 2 amps.
B.2        Restore vital battery float                12 hours current to  2 amps.
(continued)
Watts Bar-Unit 1                                                3.8-33                                              Amendment XX
 
Battery Parameters 3.8.6 ACTIONS (continued)
CONDITION                                    REQUIRED ACTION                        COMPLETION TIME C.          One DG battery with one            C.1        Perform SR 3.8.4.2.                      2 hours or more battery cells float voltage < 2.07 V.                  AND C.2        Perform SR 3.8.6.2.                      2 hours AND C.3        Restore affected cell voltage            24 hours 2.07 V.
D.          One DG battery with float          D.1        Perform SR 3.8.4.2.                      2 hours current > 1 amp.
AND D.2        Restore vital battery float              12 hours current to  1 amp.
------------------NOTE---------------------    ---------------------NOTE----------------------
Required Action E.2 shall be                    Required Actions E.1 and E.2 are only completed if electrolyte level was              applicable if electrolyte level was below below the top of plates.                        the top of plates.
E.          One or two required vital          E.1        Restore electrolyte level to            8 hours battery(ies) on one                            above top of plates.
subsystem with one or more cells electrolyte level        AND less than minimum established design limits.          E.2        Verify no evidence of leakage.          12 hours OR                                  AND One DG battery with one            E.3        Restore electrolyte level to            31 days or more cells electrolyte                      greater than or equal to level less than minimum                        minimum established design established design limits.                      limits.
(continued)
Watts Bar-Unit 1                                              3.8-38                                        Amendment XX
 
Battery Parameters 3.8.6 ACTIONS (continued)
CONDITION                      REQUIRED ACTION              COMPLETION TIME F.      One or two required vital    F.1 Restore battery pilot cell    12 hours battery(ies) on one              temperature to greater than or subsystem with pilot cell        equal to minimum established electrolyte temperature          design limits.
less than minimum established design limits.
OR One DG battery with pilot cell electrolyte temperature less than minimum established design limits.
G.      One or more batteries in    G.1 Restore battery parameters to  2 hours redundant subsystems with        within limits.
battery parameters not within limits.
OR More than one DG battery with battery parameters not within limits.
(continued)
Watts Bar-Unit 1                          3.8-39                              Amendment XX
 
Battery Parameters 3.8.6 ACTIONS (continued)
CONDITION                                    REQUIRED ACTION                          COMPLETION TIME H.      Required Action and                H.1        Declare associated battery              Immediately associated Completion                          inoperable.
Time of Condition A, B, C, D, E, F, or G not met.
OR One or two required vital battery(ies) on one subsystem with one or more battery cells float voltage < 2.07 V and float current > 2 amps.
OR One DG battery with one or more battery cells float voltage < 2.07 V and float current > 1 amp.
SURVEILLANCE REQUIREMENTS SURVEILLANCE                                                      FREQUENCY SR 3.8.6.1              ------------------------------NOTE--------------------------------
Not required to be met when vital battery terminal voltage is less than the minimum established float voltage of SR 3.8.4.1.
Verify each vital battery float current is  2 amps.                  7 days (continued)
Watts Bar-Unit 1                                        3.8-40                                        Amendment XX
 
Battery Parameters 3.8.6 SURVEILLANCE REQUIREMENTS (continued)
SURVEILLANCE                                                      FREQUENCY SR 3.8.6.2        ------------------------------NOTE--------------------------------
Not required to be met when DG battery terminal voltage is less than the minimum established float voltage of SR 3.8.4.2.
Verify each DG battery float current is  1 amp.                      7 days SR 3.8.6.3        Verify each required vital battery and each DG                        31 days battery pilot cell float voltage is  2.07 V.
SR 3.8.6.4        Verify each required vital battery and each DG                        31 days battery connected cell electrolyte level is greater than or equal to minimum established design limits.
SR 3.8.6.5        Verify each required vital battery and each DG                        31 days battery pilot cell temperature is greater than or equal to minimum established design limits.
SR 3.8.6.6        Verify each required vital battery and each DG                        92 days battery connected cell float voltage is  2.07 V.
(continued)
Watts Bar-Unit 1                                  3.8-41                                        Amendment XX
 
Battery Parameters 3.8.6 SURVEILLANCE REQUIREMENTS (continued)
SURVEILLANCE                                                        FREQUENCY SR 3.8.6.7        ------------------------------NOTES------------------------------
This Surveillance is not performed in MODE 1, 2, 3, or 4 for required vital batteries. Credit may be taken for unplanned events that satisfy this SR.
Verify battery capacity is  80% of the manufacturer's                  60 months rating when subjected to a performance discharge test or a modified performance discharge test.                          AND 12 months when battery shows degradation or has reached 85% of expected life with capacity < 100% of manufacturer's rating AND 24 months when battery has reached 85% of the expected life with capacity 100% of manufacturer's rating Watts Bar-Unit 1                                  3.8-42                                          Amendment XX
 
Procedures, Programs, and Manuals 5.7 5.7    Procedures, Programs, and Manuals 5.7.2.22        Battery Monitoring and Maintenance Program This Program provides controls for battery restoration and maintenance. The program shall be in accordance with IEEE Standard (Std) 450-2002, "IEEE Recommended Practice for Maintenance, Testing, and Replacement of Vented Lead-Acid Batteries for Stationary Applications," as endorsed by Regulatory Guide 1.129, Revision 2 (RG), with RG exceptions and program provisions as identified below:
: a. The program allows the following RG 1.129, Revision 2 exceptions:
: 1. Battery temperature correction may be performed before or after conducting discharge tests.
: 2. RG 1.129, Regulatory Position 1, Subsection 2, "References," is not applicable to this program.
: 3. In lieu of RG 1.129, Regulatory Position 2, Subsection 5.2, "Inspections," the following shall be used: "Where reference is made to the pilot cell, pilot cell selection shall be based on the lowest voltage cell in the battery.
: 4. In Regulatory Guide 1.129, Regulatory Position 3, Subsection 5.4.1, "State of Charge Indicator," the following statements in paragraph (d) may be omitted:
                            "When it has been recorded that the charging current has stabilized at the charging voltage for three consecutive hourly measurements, the battery is near full charge. These measurements shall be made after the initially high charging current decreases sharply and the battery voltage rises to approach the charger output voltage."
: 5. In lieu of RG 1.129, Regulatory Position 7, Subsection 7.6, "Restoration", the following may be used: "Following the test, record the float voltage of each cell of the string."
: b. The program shall include the following provisions:
: 1. Actions to restore battery cells with float voltage < 2.13 V;
: 2. Actions to determine whether the float voltage of the remaining battery cells is 2.13 V when the float voltage of a battery cell has been found to be
                            < 2.13 V;
: 3. Actions to equalize and test battery cells that had been discovered with electrolyte level below the top of the plates;
: 4. Limits on average electrolyte temperature, battery connection resistance, and battery terminal voltage; and
: 5. A requirement to obtain specific gravity readings of all cells at each discharge test, consistent with manufacturer recommendations.
Watts Bar-Unit 1                                  5.0-25b                                    Amendment XX
 
DC Sources-Operating B 3.8.4 B 3.8 ELECTRICAL POWER SYSTEMS B 3.8.4 DC Sources - Operating BASES BACKGROUND            The station DC electrical power system provides the AC emergency power system with control power. It also provides both motive and control power to selected safety related equipment and preferred AC vital bus power (via inverters). As required by 10 CFR 50, Appendix A, GDC 17 (Ref. 1), the DC electrical power system is designed to have sufficient independence, redundancy, and testability to perform its safety functions, assuming a single failure. The DC electrical power system also conforms to the recommendations of Regulatory Guide 1.6 (Ref. 2) and IEEE-308 (Ref. 3).
125 V Vital DC Electrical Power Subsystem The vital 125 VDC electrical power system is a Class IE system whose safety function is to provide control power for engineered safety features equipment, emergency lighting, vital inverters, and other safety-related DC powered equipment for the entire unit. The system capacity is sufficient to supply these loads and any connected nonsafety loads during normal operation and to permit safe shutdown and isolation of the reactor for the "loss of all AC power" condition. The system is designed to perform its safety function subject to a single failure.
The 125V DC vital power system is composed of the four channels (Channels I and III are associated with Train A and Channels II and IV are associated with Train B) and consists of four lead-acid-calcium batteries, eight battery chargers (including two pairs of spare chargers), four distribution boards, battery racks, and the required cabling, instrumentation and protective features. Each channel is electrically and physically independent from the equipment of all other channels so that a single failure in one channel will not cause a failure in another channel. Each channel consists of a battery charger which supplies normal DC power, a battery for emergency DC power, and a battery board which facilitates load grouping and provides circuit protection. These four channels are used to provide emergency power to the 120V AC vital power system which furnishes control power to the reactor protection system. No automatic connections are used between the four channels.
Battery boards I, II, III, and IV have a charger normally connected to them and also have manual access to a spare (backup) charger for use upon loss of the normal charger.
(continued)
Watts Bar-Unit 1                                  B 3.8-54                                    Revision XX
 
DC Sources-Operating B 3.8.4 BASES BACKGROUND      125 V Vital DC Electrical Power Subsystem (continued)
Additionally, battery boards I, II, III, and IV have manual access to the fifth vital battery system. The fifth 125V DC Vital Battery System is intended to serve as a replacement for any one of the four 125V DC vital batteries during their testing, maintenance, and outages with no loss of system reliability under any mode of operation.
Each of the vital DC electrical power subsystems provide the control power for its associated Class 1E AC power load group, 6.9 kV switchgear, and 480 V load centers. The vital DC electrical power subsystems also provide DC electrical power to the inverters, which in turn power the AC vital buses. Additionally, they power the emergency DC lighting system.
The vital DC power distribution system is described in more detail in Bases for LCO 3.8.9, "Distribution System - Operating," and LCO 3.8.10, "Distribution Systems - Shutdown."
Each 125 VDC vital battery is separately housed in a ventilated room apart from its charger and distribution centers, except for Vital Battery V. Each subsystem is located in an area separated physically and electrically from the other subsystem to ensure that a single failure in one subsystem does not cause a failure in a redundant subsystem. There is no sharing between Class 1E subsystems, such as batteries, battery chargers, or distribution panels.
Each battery has adequate storage capacity to meet the duty cycle(s) discussed in the FSAR, Chapter 8 (Ref 4). The battery is designed with additional capacity above that required by the design duty cycle to allow for temperature variations and other factors.
The batteries for the vital DC electrical power subsystems are sized to produce required capacity at 80% of nameplate rating, corresponding to warranted capacity at end of life cycles and the 100% design demand. The minimum design voltage limit is 105 V.
The battery cells are of flooded lead acid construction with a nominal specific gravity of 1.215. This specific gravity corresponds to an open circuit battery voltage of approximately 120 V for a 60 cell battery (i.e., cell voltage of 2.063 volts per cell (Vpc)). The open circuit voltage is the voltage maintained when there is no charging or discharging. Optimal long term performance however, is obtained by maintaining a float voltage 2.20 to 2.25 Vpc. This provides adequate over-potential, which limits the formation of lead sulfate and self discharge. The nominal float voltage of 2.22 Vpc corresponds to a total float voltage output of 132 V for a 60 cell battery as discussed in the FSAR, Chapter 8 (Ref. 4).
(continued)
Watts Bar-Unit 1                          B 3.8-55                                      Revision XX
 
DC Sources-Operating B 3.8.4 BASES BACKGROUND      125 V Vital DC Electrical Power Subsystem (continued)
Each Vital DC electrical power subsystem battery charger has ample power output capacity for the steady state operation of connected loads required during normal operation, while at the same time maintaining its battery bank fully charged. Each battery charger also has sufficient excess capacity to restore the battery bank from the design minimum charge to its fully charged state within 12 hours (with accident loads being supplied) following a 30 minute AC power outage and in approximately 36 hours (while supplying normal steady state loads following a 2 hour AC power outage), (Ref. 5).
The battery charger is normally in the float-charge mode. Float-charge is the condition in which the charger is supplying the connected loads and the battery cells are receiving adequate current to optimally charge the battery. This assures the internal losses of a battery are overcome and the battery is maintained in a fully charged state.
When desired, the charger can be placed in the equalize mode. The equalize mode is at a higher voltage than the float mode and charging current is correspondingly higher. The battery charger is operated in the equalize mode after a battery discharge or for routine maintenance. Following a battery discharge, the battery recharge characteristic accepts current at the current limit of the battery charger (if the discharge was significant, e.g., following a battery service test) until the battery terminal voltage approaches the charger voltage setpoint. Charging current then reduces exponentially during the remainder of the recharge cycle. Lead-calcium batteries have recharge efficiencies of greater than 95%, so once at least 105% of the ampere-hours discharged have been returned, the battery capacity would be restored to the same condition as it was prior to the discharge. This can be monitored by direct observation of the exponentially decaying charging current or by evaluating the amp-hours discharged from the battery and amp-hours returned to the battery.
(continued)
Watts Bar-Unit 1                          B 3.8-56                                        Revision XX
 
DC Sources-Operating B 3.8.4 BASES (continued)
BACKGROUND        125 V Diesel Generator (DG) DC Electrical Power Subsystem Control power for the DGs is provided by five DG battery systems, one per DG.
Each system is comprised of a battery, a dual battery charger assembly, distribution center, cabling, and cable ways. The DG 125V DC control power and field-flash circuits have power supplied from their respective 125V distribution panel. The normal supply of DC current is from the associated charger. The battery provides control and field-flash power when the charger is unavailable. The charger supplies the normal DC loads, maintains the battery in a fully charged condition, and recharges (480V AC available) the battery while supplying the required loads regardless of the status of the unit. The batteries are physically and electrically independent. The battery has sufficient capacity when fully charged to supply required loads for a minimum of 30 minutes following a loss of normal power. Each battery is normally required to supply loads during the time interval between loss of normal feed to its charger and the receipt of emergency power to the charger from its respective DG.
APPLICABLE        The initial conditions of Design Basis Accident (DBA) and SAFETY ANALYSES  transient analyses in the FSAR, Section 6 (Ref. 6), and in the FSAR, Section 15 (Ref. 6), assume that Engineered Safety Feature (ESF) systems are OPERABLE. The vital DC electrical power system provides normal and emergency DC electrical power for the emergency auxiliaries, and control and switching during all power for the emergency auxiliaries, and control and switching during all MODES of operation. The DG battery systems provide DC power for the DGs.
The OPERABILITY of the DC sources is consistent with the initial assumptions of the accident analyses and is based upon meeting the design basis of the plant.
This includes maintaining the DC sources OPERABLE during accident conditions in the event of:
: a.      An assumed loss of all offsite AC power or all onsite AC power; and
: b.      A worst case single failure.
The DC sources satisfy Criterion 3 of the NRC Policy Statement.
(continued)
Watts Bar-Unit 1                            B 3.8-57                                    Revision XX
 
DC Sources-Operating B 3.8.4 BASES (continued)
LCO              Two 125V vital DC electrical power subsystems (Train A and Train B), each vital subsystem consisting of two channels. Each channel consisting of a battery bank, associated battery charger and the corresponding control equipment and interconnecting cabling supplying power to the associated DC bus within the channel; and four DG DC electrical power subsystems each consisting of a battery, a dual battery charger assembly, and the corresponding control equipment and interconnecting cabling are required to be OPERABLE to ensure the availability of the required power to shut down the reactor and maintain it in a safe condition after an anticipated operational occurrence (A00) or a postulated DBA. Loss of any DC electrical power subsystem does not prevent the minimum safety function from being performed (Ref. 4).
An OPERABLE vital DC electrical power subsystem requires all required batteries and respective chargers to be operating and connected to the associated DC buses.
The LCO is modified by a Note. The Note indicates that Vital Battery V may be substituted for any of the required vital batteries. However, the fifth battery cannot be declared OPERABLE until it is connected electrically in place of another battery and it has satisfied applicable Surveillance Requirements.
APPLICABILITY    The vital DC electrical power sources and DG DC electrical power sources are required to be OPERABLE in MODES 1, 2, 3, and 4 to ensure safe plant operation and to ensure that:
: a.      Acceptable fuel design limits and reactor coolant pressure boundary limits are not exceeded as a result of AOs or abnormal transients; and
: b.      Adequate core cooling is provided, and containment integrity and other vital functions are maintained in the event of a postulated DBA.
The DC electrical power requirements for MODES 5 and 6 are addressed in the Bases for LCO 3.8.5, "DC Sources - Shutdown."
(continued)
Watts Bar-Unit 1                            B 3.8-58                                    Revision XX
 
DC Sources-Operating B 3.8.4 BASES (continued)
ACTIONS          A.1, A.2, and A.3 Condition A represents one vital DC subsystem with one or two battery chargers inoperable (e.g., the voltage limit of SR 3.8.4.1 is not maintained). The ACTIONS provide a tiered response that focuses on returning the battery to the fully charged state and restoring a fully qualified charger to OPERABLE status in a reasonable time period. Required Action A.1 requires that the battery terminal voltage be restored to greater than or equal to the minimum established float voltage within 2 hours. This time provides for returning the inoperable charger to OPERABLE status or providing an alternate means of restoring battery terminal voltage to greater than or equal to the minimum established float voltage.
Restoring the battery terminal voltage to greater than or equal to the minimum established float voltage provides good assurance that, within 12 hours, the battery will be restored to its fully charged condition (Required Action A.2) from any discharge that might have occurred due to the charger inoperability.
A discharged battery having terminal voltage of at least the minimum established float voltage indicates that the battery is on the exponential charging current portion (the second part) of its recharge cycle. The time to return a battery to its fully charged state under this condition is simply a function of the amount of the previous discharge and the recharge characteristic of the battery. Thus there is good assurance of fully recharging the battery within 12 hours, avoiding a premature shutdown with its own attendant risk.
If established battery terminal float voltage cannot be restored to greater than or equal to the minimum established float voltage within 2 hours, and the charger is not operating in the current-limiting mode, a faulty charger is indicated. A faulty charger that is incapable of maintaining established battery terminal float voltage does not provide assurance that it can revert to and operate properly in the current limit mode that is necessary during the recovery period following a battery discharge event that the DC system is designed for.
If the charger is operating in the current limit mode after 2 hours that is an indication that the battery is partially discharged and its capacity margins will be reduced. The time to return the battery to its fully charged condition in this case is a function of the battery charger capacity, the amount of loads on the associated DC system, the amount of the previous discharge, and the recharge characteristic of the battery. The charge time can be extensive, and there is not adequate assurance that it can be recharged within 12 hours (Required Action A.2).
Required Action A.2 requires that the battery float current be verified as less than or equal to 2 amps. This indicates that, if the battery had been discharged as the result of the inoperable battery charger, it is now fully capable of supplying the maximum expected load requirement. The 2 amp value is based on returning the battery to 98% charge and assumes a 2% design margin for the battery. If at the (continued)
Watts Bar-Unit 1                            B 3.8-59                                      Revision XX
 
DC Sources-Operating B 3.8.4 BASES ACTIONS          A.1, A.2, and A.3 (continued) expiration of the initial 12 hour period the battery float current is not less than or equal to 2 amps this indicates there may be additional battery problems and the battery must be declared inoperable.
Required Action A.3 limits the restoration time for the inoperable battery charger to 7 days. This action is applicable if an alternate means of restoring battery terminal voltage to greater than or equal to the minimum established float voltage has been used (e.g., balance of plant non-Class 1E battery charger). The 7 day Completion Time reflects a reasonable time to effect restoration of the qualified battery charger to OPERABLE status.
B.1 Condition B represents one vital DC electrical power subsystem with a loss of ability to completely respond to an event, and a potential loss of ability to remain energized during normal operation. It is, therefore, imperative that the operator's attention focus on stabilizing the plant, minimizing the potential for complete loss of DC power to the affected subsystem. The 2 hour limit is consistent with the allowed time for an inoperable DC distribution subsystem.
If one of the required vital DC electrical power subsystems is inoperable for reasons other than Condition A (e.g., inoperable battery charger and associated inoperable battery), the remaining vital DC electrical power subsystem has the capacity to support a safe shutdown and to mitigate an accident condition. Since a subsequent worst case single failure of the OPERABLE subsystem could, however, result in the loss of the minimum necessary vital DC electrical power subsystems to mitigate a worst-case accident, continued power operation should not exceed 2 hours. The 2 hour Completion Time is based on Regulatory Guide 1.93 (Ref. 7) and reflects a reasonable time to assess plant status as a function of the inoperable vital DC electrical power subsystem and, if the vital DC electrical power subsystem is not restored to OPERABLE status, to prepare to effect an orderly and safe plant shutdown.
C.1 and C.2 If the inoperable vital DC electrical power subsystem cannot be restored to OPERABLE status within the required Completion Time, the plant must be brought to a MODE in which the LCO does not apply. To achieve this status, the plant must be brought to at least MODE 3 within 6 hours and to MODE 5 within 36 hours. The allowed Completion Times are reasonable, based on operating experience, to reach the required plant conditions from full power conditions in an orderly manner and without challenging plant systems. The Completion Time to bring the plant to MODE 5 is consistent with the time required in Regulatory Guide 1.93 (Ref. 7).
(continued)
Watts Bar-Unit 1                            B 3.8-60                                        Revision XX
 
DC Sources-Operating B 3.8.4 BASES (continued)
ACTIONS          D.1, D.2, and D.3 Condition D represents one DG DC subsystem with one battery charger inoperable (e.g., the voltage limit of SR 3.8.4.1 is not maintained). The ACTIONS provide a tiered response that focuses on returning the battery to the fully charged state and restoring a fully qualified charger to OPERABLE status in a reasonable time period. Required Action D.1 requires that the battery terminal voltage be restored to greater than or equal to the minimum established float voltage within 2 hours. This time provides for returning the inoperable charger to OPERABLE status or providing an alternate means of restoring battery terminal voltage to greater than or equal to the minimum established float voltage.
Restoring the battery terminal voltage to greater than or equal to the minimum established float voltage provides good assurance that, within 12 hours, the battery will be restored to its fully charged condition (Required Action D.2) from any discharge that might have occurred due to the charger inoperability.
A discharged battery having terminal voltage of at least the minimum established float voltage indicates that the battery is on the exponential charging current portion (the second part) of its recharge cycle. The time to return a battery to its fully charged state under this condition is simply a function of the amount of the previous discharge and the recharge characteristic of the battery. Thus there is good assurance of fully recharging the battery within 12 hours, avoiding a premature shutdown with its own attendant risk.
If established battery terminal float voltage cannot be restored to greater than or equal to the minimum established float voltage within 2 hours, and the charger is not operating in the current-limiting mode, a faulty charger is indicated. A faulty charger that is incapable of maintaining established battery terminal float voltage does not provide assurance that it can revert to and operate properly in the current limit mode that is necessary during the recovery period following a battery discharge event that the DG DC system is designed for.
If the charger is operating in the current limit mode after 2 hours that is an indication that the battery is partially discharged and its capacity margins will be reduced. The time to return the battery to its fully charged condition in this case is a function of the battery charger capacity, the amount of loads on the associated DC system, the amount of the previous discharge, and the recharge characteristic of the battery. The charge time can be extensive, and there is not adequate assurance that it can be recharged within 12 hours (Required Action D.2).
(continued)
Watts Bar-Unit 1                            B 3.8-61                                      Revision XX
 
DC Sources-Operating B 3.8.4 BASES ACTIONS          D.1, D.2, and D.3 (continued)
Required Action D.2 requires that the battery float current be verified as less than or equal to 1 amp. This indicates that, if the battery had been discharged as the result of the inoperable battery charger, it is now fully capable of supplying the maximum expected load requirement. The 1 amp value is based on returning the battery to 98% charge and assumes a 2% design margin for the battery. If at the expiration of the initial 12 hour period the battery float current is not less than or equal to 1 amp this indicates there may be additional battery problems and the battery must be declared inoperable.
Required Action D.3 limits the restoration time for the inoperable battery charger to 72 hours. The 72 hour Completion Time reflects a reasonable time to effect restoration of the qualified battery charger to OPERABLE status.
E.1 Condition E represents one DG with a loss of ability to completely respond to an event. Since a subsequent single failure on the opposite train could result in a situation where the required ESF function is not assured, continued power operation should not exceed 2 hours. The 2 hour time limit is consistent with the allowed time for an inoperable vital DC electrical power subsystem.
F.1 If the DG DC electrical power subsystem cannot be restored to OPERABLE status in the associated Completion Time, the associated DG may be incapable of performing its intended function and must be immediately declared inoperable.
This declaration also requires entry into applicable Conditions and Required Actions for an inoperable DG, LCO 3.8.1, "AC Sources-Operating."
(continued)
Watts Bar-Unit 1                            B 3.8-62                                        Revision XX
 
DC Sources-Operating B 3.8.4 BASES (continued)
SURVEILLANCE      SR 3.8.4.1 and SR 3.8.4.2 REQUIREMENTS Verifying battery terminal voltage while on float charge for the batteries helps to ensure the effectiveness of the battery chargers, which support the ability of the batteries to perform their intended function. Float charge is the condition in which the charger is supplying the continuous charge required to overcome the internal losses of a battery and maintain the battery in a fully charged state while supplying the continuous steady state loads of the associated DC subsystem.
On float charge, battery cells will receive adequate current to optimally charge the battery. The voltage requirements are based on the nominal design voltage of the battery and are consistent with the minimum float voltage established by the battery manufacturer (2.20 Vpc times the number of connected cells or 132 V at the battery terminals for a 60 cell vital battery; 127.6 V at the battery terminals for a 58 cell DG battery). This voltage maintains the battery plates in a condition that supports maintaining the grid life. The 7 day Frequency is consistent with manufacturer recommendations.
SR 3.8.4.3 Verifying that for the vital batteries that the alternate feeder breakers to each required battery charger is open ensures that independence between the power trains is maintained. The 7-day Frequency is based on engineering judgement, is consistent with procedural controls governing breaker operation, and ensures correct breaker position.
SR 3.8.4.4 This SR demonstrates that the DG 125V DC distribution panel and associated charger are functioning properly, with all required circuit breakers closed and buses energized from normal power. The 7 day Frequency takes into account the redundant DG capability and other indications available in the control room that will alert the operator to system malfunctions.
(continued)
Watts Bar-Unit 1                            B 3.8-63                                  Revision XX
 
DC Sources-Operating B 3.8.4 BASES (continued)
SURVEILLANCE      SR 3.8.4.5 REQUIREMENTS This SR verifies the design capacity of the vital battery chargers. According to Regulatory Guide 1.32 (Ref. 5), the battery charger supply is recommended to be based on the largest combined demands of the various steady state loads and the charging capacity to restore the battery from the design minimum charge state to the fully charged state, irrespective of the status of the plant during these demand occurrences. The minimum required amperes and duration ensure that these requirements can be satisfied.
This SR provides two options. One option requires that each battery charger be capable of supplying 200 amps at the minimum established float voltage (132 V DC) for 4 hours. The ampere requirements are based on the output rating of the chargers. The voltage requirements are based on the charger voltage level after a response to a loss of AC power.
The other option requires that each vital battery charger be capable of recharging the battery after a service test coincident with supplying the largest coincident demands of the various continuous steady state loads (irrespective of the status of the plant during which these demands occur). This level of loading may not normally be available following the battery service test and will need to be supplemented with additional loads. The duration for this test may be longer than the charger sizing criteria since the battery recharge is affected by float voltage, temperature, and the exponential decay in charging current. The battery is recharged when the measured charging current is  2 amps.
The Surveillance Frequency is acceptable, given the plant conditions required to perform the test and the other administrative controls existing to ensure adequate charger performance during these 18 month intervals. In addition, this Frequency is intended to be consistent with expected fuel cycle lengths.
SR 3.8.4.6 This SR verifies the design capacity of the DG battery chargers. According to Regulatory Guide 1.32 (Ref. 5), the battery charger supply is recommended to be based on the largest combined demands of the various steady state loads and the charging capacity to restore the battery from the design minimum charge state to the fully charged state, irrespective of the status of the plant during these demand occurrences. The minimum required amperes and duration ensure that these requirements can be satisfied.
(continued)
Watts Bar-Unit 1                            B 3.8-62                                      Revision XX
 
DC Sources-Operating B 3.8.4 BASES SURVEILLANCE    SR 3.8.4.6 (continued)
REQUIREMENTS This SR provides two options. One option requires that each battery charger be capable of supplying 20 amps at the minimum established float voltage (127.6 V DC) for 4 hours. The ampere requirements are based on the output rating of the chargers. The voltage requirements are based on the charger voltage level after a response to a loss of AC power.
The other option requires that each vital battery charger be capable of recharging the battery after a service test coincident with supplying the largest coincident demands of the various continuous steady state loads (irrespective of the status of the plant during which these demands occur). This level of loading may not normally be available following the battery service test and will need to be supplemented with additional loads. The duration for this test may be longer than the charger sizing criteria since the battery recharge is affected by float voltage, temperature, and the exponential decay in charging current. The battery is recharged when the measured charging current is  1 amp.
The Surveillance Frequency is acceptable, given the administrative controls existing to ensure adequate charger performance during these 18 month intervals.
For the DG DC electrical subsystem, this Surveillance may be performed in MODES 1, 2, 3, or 4 in conjunction with LCO 3.8.1.B since the DG DC electrical power subsystem supplies loads only for the inoperable diesel generator and would not otherwise challenge safety systems supplied from vital electrical distribution systems. If available, the C-S DG and its associated DC electrical power subsystem may be substituted in accordance with LCO Note 2.
Additionally, credit may be taken for unplanned events that satisfy this SR.
Examples of unplanned events may include:
: 1)      Unexpected operational events which cause the equipment to perform the function specified by this Surveillance, for which adequate documentation of the required performance is available; and
: 2)      Post corrective maintenance testing that requires performance of this Surveillance in order to restore the component to OPERABLE, provided the maintenance was required, or performed in conjunction with maintenance required to maintain OPERABILITY or reliability.
SR 3.8.4.7 A battery service test is a special test of battery capability, as found, to satisfy the design requirements (battery duty cycle) of the DC electrical power system. The discharge rate and test length should correspond to worst case design duty cycle requirements based on References 8 and 10.
(continued)
Watts Bar-Unit 1                          B 3.8-64                                        Revision XX
 
DC Sources-Operating B 3.8.4 BASES SURVEILLANCE    SR 3.8.4.7 (continued)
REQUIREMENTS The Surveillance Frequency of 18 months is consistent with the recommendations of Regulatory Guide 1.32 (Ref. 5) and Regulatory Guide 1.129 (Ref. 9), which state that the battery service test should be performed during refueling operations or at some other outage, with intervals between tests, not to exceed 18 months.
This SR is modified by two Notes. Note 1 allows the performance of a modified performance discharge test in lieu of a service test.
The reason for Note 2 is that performing the Surveillance may perturb the vital electrical distribution system and challenge safety systems. However, this Surveillance may be performed in MODES l, 2, 3, or 4 provided that Vital Battery V is substituted in accordance with LCO Note l. For the DG DC electrical subsystem, this surveillance may be performed in MODES l, 2, 3, or 4 in conjunction with LCO 3.8.l.B since the supplied loads are only for the inoperable diesel generator and would not otherwise challenge safety system loads which are supplied from vital electrical distribution systems. If available, the C-S DG and its associated DC electrical power subsystem may be substituted in accordance with LCO Note 2. Additionally, credit may be taken for unplanned events that satisfy this SR. Examples of unplanned events may include:
: 1)      Unexpected operational events which cause the equipment to perform the function specified by this Surveillance, for which adequate documentation of the required performance is available; and
: 2)      Post corrective maintenance testing that requires performance of this Surveillance in order to restore the component to OPERABLE, provided the maintenance was required, or performed in conjunction with maintenance required to maintain OPERABILITY or reliability.
(continued)
Watts Bar-Unit 1                            B 3.8-65                                      Revision XX
 
DC Sources-Operating B 3.8.4 BASES (continued)
REFERENCES        1. Title 10, Code of Federal Regulations, Part 50, Appendix A, General Design Criterion 17, Electric Power System.
: 2. Regulatory Guide 1.6, Independence Between Redundant Standby (Onsite) Power Sources and Between Their Distribution Systems, U.S.
Nuclear Regulatory Commission, March 10, 1971.
: 3. IEEE-308-1971, IEEE Standard Criteria for Class 1E Power Systems for Nuclear Power Generating Stations, Institute of Electrical and Electronic Engineers.
: 4. Watts Bar FSAR, Section 8.3.2, DC Power System.
: 5. Regulatory Guide 1.32, Criteria for Safety-Related Electric Power Systems for Nuclear Power Plants, February 1977, U.S. Nuclear Regulatory Commission.
: 6. Watts Bar FSAR, Section 15, Accident Analysis and Section 6 Engineered Safety Features.
: 7. Regulatory Guide 1.93, Availability of Electric Power Sources, U.S.
Nuclear Regulatory Commission, December 1974.
: 8. TVA Calculation WBN EEB-MS-TI11-0003, 125 VDC Vital Battery and Charger Evaluation.
: 9. Regulatory Guide 1.129, Maintenance Testing and Replacement of Large Lead Storage Batteries for Generating Stations and Subsystems, U.S. Nuclear Regulatory Commission, February 1978.
: 10. TVA Calculation WBN EEB-MS-TI11-0062, "125 V DC Diesel Generator Control Power System Evaluation."
Watts Bar-Unit 1                      B 3.8-66                                    Revision XX
 
DC Sources - Shutdown B 3.8.5 B 3.8 ELECTRICAL POWER SYSTEMS B 3.8.5 DC Sources - Shutdown BASES BACKGROUND            A description of the DC sources is provided in the Bases for LCO 3.8.4, "DC Sources - Operating."
APPLICABLE            The initial conditions of Design Basis Accident and transient analyses in SAFETY ANALYSES      the FSAR, Section 6 (Ref. 1) and Section 15 (Ref. 1), assume that Engineered Safety Feature systems are OPERABLE. The vital DC electrical power system provides normal and emergency DC electrical power for the emergency auxiliaries, and control and switching during all MODES of operation.
The DG battery systems provide DC power for the DGs.
The OPERABILITY of the DC sources is consistent with the initial assumptions of the accident analyses and the requirements for the supported systems OPERABILITY.
The OPERABILITY of the minimum DC electrical power sources during MODES 5 and 6, and during movement of irradiated fuel assemblies ensures that:
: a.      The plant can be maintained in the shutdown or refueling condition for extended periods;
: b.      Sufficient instrumentation and control capability is available for monitoring and maintaining the plant status; and
: c.      Adequate DC electrical power is provided to mitigate events postulated during shutdown, such as a fuel handling accident.
The DC sources satisfy Criterion 3 of the NRC Policy Statement.
(continued)
Watts Bar-Unit 1                                B 3.8-70                                  Revision XX
 
DC Sources - Shutdown B 3.8.5 BASES (continued)
LCO              The 125V Vital DC electrical power subsystems, each vital subsystem channel consisting of a battery bank, associated battery charger, and the corresponding control equipment and interconnecting cabling within the channel; and the DG DC electrical power subsystems, each consisting of a battery, a battery charger, and the corresponding control equipment and interconnecting cabling, are required to be OPERABLE to support required subsystems of the distribution systems required OPERABLE by LCO 3.8.10, "Distribution Systems - Shutdown" and the required DGs required OPERABLE by LCO 3.8.2, "AC Sources-Shutdown." As a minimum, one vital DC electrical power subsystem (i.e.,
Channels I and III, or II and IV) and two DG DC electrical power subsystems (i.e.,
1A-A and 2A-A or 1B-B and 2B-B) shall be OPERABLE. This ensures the availability of sufficient DC electrical power sources to operate the plant in a safe manner and to mitigate the consequences of postulated events during shutdown (e.g., fuel handling accidents).
The LCO is modified by a Note. The Note indicates that Vital Battery V may be substituted for any of the required vital batteries. However, the fifth battery cannot be declared OPERABLE until it is connected electrically in place of another battery and it has satisfied applicable Surveillance Requirements.
APPLICABILITY    The DC electrical power sources required to be OPERABLE in MODES 5 and 6, and during movement of irradiated fuel assemblies, provide assurance that:
: a. Required features needed to mitigate a fuel handling accident are available; (continued)
Watts Bar-Unit 1                              B 3.8-71                                Revision XX
 
DC Sources - Shutdown B 3.8.5 BASES APPLICABILITY    b.        Required features necessary to mitigate the effects of events that can (continued)              lead to core damage during shutdown are available; and
: c.        Instrumentation and control capability is available for monitoring and maintaining the plant in a cold shutdown condition or refueling condition.
The DC electrical power requirements for MODES 1, 2, 3, and 4 are covered in LCO 3.8.4.
ACTIONS      A.1, A.2, and A.3 Condition A represents one subsystem with one or two battery charger(s) inoperable (e.g., the voltage limit of SR 3.8.4.1 is not maintained). The ACTIONS provide a tiered response that focuses on returning the battery to the fully charged state and restoring a fully qualified charger to OPERABLE status in a reasonable time period. Required Action A.1 requires that the battery terminal voltage be restored to greater than or equal to the minimum established float voltage within 2 hours. This time provides for returning the inoperable charger to OPERABLE status or providing an alternate means of restoring battery terminal voltage to greater than or equal to the minimum established float voltage.
Restoring the battery terminal voltage to greater than or equal to the minimum established float voltage provides good assurance that, within 12 hours, the battery will be restored to its fully charged condition (Required Action A.2) from any discharge that might have occurred due to the charger inoperability.
A discharged battery having terminal voltage of at least the minimum established float voltage indicates that the battery is on the exponential charging current portion (the second part) of its recharge cycle. The time to return a battery to its fully charged state under this condition is simply a function of the amount of the previous discharge and the recharge characteristic of the battery. Thus there is good assurance of fully recharging the battery within [12] hours, avoiding a premature shutdown with its own attendant risk.
If established battery terminal float voltage cannot be restored to greater than or equal to the minimum established float voltage within 2 hours, and the charger is not operating in the current-limiting mode, a faulty charger is indicated. A faulty charger that is incapable of maintaining established battery terminal float voltage does not provide assurance that it can revert to and operate properly in the current limit mode that is necessary during the recovery period following a battery discharge event that the DC system is designed for.
If the charger is operating in the current limit mode after 2 hours that is an indication that the battery is partially discharged and its capacity margins will be reduced. The time to return the battery to its fully charged condition in this case (continued)
Watts Bar-Unit 1                          B 3.8-72                                  Revision XX
 
DC Sources - Shutdown B 3.8.5 BASES ACTIONS          A.1, A.2, and A.3 (continued) is a function of the battery charger capacity, the amount of loads on the associated DC system, the amount of the previous discharge, and the recharge characteristic of the battery. The charge time can be extensive, and there is not adequate assurance that it can be recharged within 12 hours (Required Action A.2).
Required Action A.2 requires that the battery float current be verified as less than or equal to 2 amps. This indicates that, if the battery had been discharged as the result of the inoperable battery charger, it has now been fully recharged. If at the expiration of the initial 12 hour period the battery float current is not less than or equal to 2 amps this indicates there may be additional battery problems and the battery must be declared inoperable.
Required Action A.3 limits the restoration time for the inoperable battery charger to 7 days. This action is applicable if an alternate means of restoring battery terminal voltage to greater than or equal to the minimum established float voltage has been used (e.g., balance of plant non-Class 1E battery charger). The 7 day Completion Time reflects a reasonable time to effect restoration of the qualified battery charger to OPERABLE status.
B.1, B.2.1, B.2.2, B.2.3, and B.2.4 If two subsystems are required by LCO 3.8.10, the remaining subsystem with DC power available may be capable of supporting sufficient systems to allow continuation of CORE ALTERATIONS and fuel movement. By allowing the option to declare required features inoperable with the associated vital DC power source(s) inoperable, appropriate restrictions will be implemented in accordance with the affected required features LCO ACTIONS. In many instances, this option may involve undesired administrative efforts. Therefore, the allowance for sufficiently conservative actions is made (i.e., to suspend CORE ALTERATIONS, movement of irradiated fuel assemblies, and operations involving positive reactivity additions). The Required Action to suspend positive reactivity additions does not preclude actions to maintain or increase reactor vessel inventory, provided the required SDM is maintained.
Suspension of these activities shall not preclude completion of actions to establish a safe conservative condition. These actions minimize probability of the occurrence of postulated events. It is further required to immediately initiate action to restore the required vital DC electrical power subsystems and to continue this action until restoration is accomplished in order to provide the necessary DC electrical power to the plant safety systems.
(continued)
Watts Bar-Unit 1                            B 3.8-73                                    Revision XX
 
DC Sources - Shutdown B 3.8.5 BASES ACTIONS          B.1, B.2.1, B.2.2, B.2.3, and B.2.4 (continued)
The Completion Time of immediately is consistent with the required times for actions requiring prompt attention. The restoration of the required vital DC electrical power subsystems should be completed as quickly as possible in order to minimize the time during which the plant safety systems may be without sufficient power.
C.1 If the DG DC electrical power subsystem cannot be restored to OPERABLE status in the associated Completion Time, the associated DG may be incapable of performing its intended function and must be immediately declared inoperable.
This declaration also requires entry into applicable Conditions and Required Actions for an inoperable DG, LCO 3.8.2, "AC Sources-Shutdown."
SURVEILLANCE      SR 3.8.5.1 REQUIREMENTS SR 3.8.5.1 requires performance of all Surveillances required by SR 3.8.4.1 through SR 3.8.4.7. Therefore, see the corresponding Bases for LCO 3.8.4 for a discussion of each SR.
This SR is modified by a Note. The reason for the Note is to preclude requiring the OPERABLE DC sources from being discharged below their capability to provide the required power supply or otherwise rendered inoperable during the performance of SRs. It is the intent that these SRs must still be capable of being met, but actual performance is not required.
REFERENCES      1.        Watts Bar FSAR, Section 15, "Accident Analysis" and Section 6, "Engineered Safety Features."
: 2.        Watts Bar FSAR, Section 8.0, "Electric Power."
Watts Bar-Unit 1                            B 3.8-74                                Revision XX
 
Battery Parameters B 3.8.6 B 3.8 ELECTRICAL POWER SYSTEMS B 3.8.6 Battery Parameters BASES BACKGROUND            This LCO delineates the limits on battery float current as well as electrolyte temperature, level, and float voltage for the 125V vital DC electrical power subsystem and diesel generator (DG) batteries. A discussion of these batteries and their OPERABILITY requirements is provided in the Bases for LCO 3.8.4, "DC Sources - Operating," and LCO 3.8.5, "DC Sources - Shutdown." In addition to the limitations of this Specification, the Battery Monitoring and Maintenance Program also implements a program specified in Specification 5.7.2.22 for monitoring various battery parameters.
The battery cells are of flooded lead acid construction with a nominal specific gravity of 1.215. This specific gravity corresponds to an open circuit battery voltage of approximately 120 V for 60 cell battery (i.e., cell voltage of 2.063 volts per cell (Vpc)). The open circuit voltage is the voltage maintained when there is no charging or discharging. Optimal long term performance however, is obtained by maintaining a float voltage 2.20 to 2.25 Vpc. This provides adequate over-potential which limits the formation of lead sulfate and self discharge. The nominal float voltage of 2.22 Vpc corresponds to a total float voltage output of 133.2 V for a 60 cell battery as discussed in the FSAR, Chapter 8 (Ref. 3).
APPLICABLE            The initial conditions of Design Basis Accident (DBA) and transient analyses SAFETY                in the FSAR, Section 6 (Ref. 1) and Section 15 (Ref. 1), assume Engineered ANALYSES              Safety Feature systems are OPERABLE. The vital DC electrical power system provides normal and emergency DC electrical power for the emergency auxiliaries, and control and switching during all MODES of operation. The DG battery systems provide DC power for the DGs.
The OPERABILITY of the DC subsystems is consistent with the initial assumptions of the accident analyses and is based upon meeting the design basis of the plant. This includes maintaining at least one subsystem of DC sources OPERABLE during accident conditions, in the event of:
: a.      An assumed loss of all offsite AC power or all onsite AC power; and
: b.      A worst case single failure.
Battery parameters satisfy the Criterion 3 of the NRC Policy Statement.
(continued)
Watts Bar-Unit 1                                B 3.8-74                                  Revision XX
 
Battery Parameters B 3.8.6 BASES (continued)
LCO              Battery parameters must remain within acceptable limits to ensure availability of the required DC power to shut down the reactor and maintain it in a safe condition after an anticipated operational occurrence or a postulated DBA.
Battery parameter limits are conservatively established, allowing continued DC electrical system function even with limits not met. Additional preventative maintenance, testing, and monitoring performed in accordance with the Battery Monitoring and Maintenance Program is conducted as specified in Specification 5.7.2.22.
APPLICABILITY    The battery parameters are required solely for the support of the associated vital DC and DG DC electrical power subsystems. Therefore, battery parameter limits are only required when the DC power source is required to be OPERABLE.
Refer to the Applicability discussion in Bases for LCO 3.8.4 and LCO 3.8.5.
ACTIONS          A.1, A.2, and A.3 With one or more cells in one or more batteries in one vital DC subsystem
                  < 2.07 V, the battery cell is degraded. Within 2 hours verification of the required battery charger OPERABILITY is made by monitoring the battery terminal voltage (SR 3.8.4.1) and of the overall battery state of charge by monitoring the battery float charge current (SR 3.8.6.1). This assures that there is still sufficient battery capacity to perform the intended function. Therefore, the affected battery is not required to be considered inoperable solely as a result of one or more cells in one or more batteries < 2.07 V, and continued operation is permitted for a limited period up to 24 hours.
Since the Required Actions only specify "perform," a failure of SR 3.8.4.1 or SR 3.8.6.1 acceptance criteria does not result in this Required Action not met.
However, if one of the SRs is failed the appropriate Condition(s), depending on the cause of the failures, is entered. If SR 3.8.6.1 is failed then there is not assurance that there is still sufficient battery capacity to perform the intended function and the battery must be declared inoperable immediately.
B.1 and B.2 One or more batteries in one vital DC subsystem with float current > 2 amps indicates that a partial discharge of the battery capacity has occurred. This may be due to a temporary loss of a battery charger or possibly due to one or more battery cells in a low voltage condition reflecting some loss of capacity. Within 2 hours verification of the required battery charger OPERABILITY is made by monitoring the battery terminal voltage. If the terminal voltage is found to be less than the minimum established float voltage there are two possibilities, the battery charger is inoperable or is operating in the current limit mode. Condition A (continued)
Watts Bar-Unit 1                            B 3.8-75                                  Revision XX
 
Battery Parameters B 3.8.6 BASES ACTIONS          B.1 and B.2 (continued) addresses charger inoperability. If the charger is operating in the current limit mode after 2 hours that is an indication that the battery has been substantially discharged and likely cannot perform its required design functions. The time to return the battery to its fully charged condition in this case is a function of the battery charger capacity, the amount of loads on the associated DC system, the amount of the previous discharge, and the recharge characteristic of the battery.
The charge time can be extensive, and there is not adequate assurance that it can be recharged within 12 hours (Required Action B.2). The battery must therefore be declared inoperable.
If the float voltage is found to be satisfactory but there are one or more battery cells with float voltage less than 2.07 V, the associated "OR" statement in Condition H is applicable and the battery must be declared inoperable immediately. If float voltage is satisfactory and there are no cells less than 2.07 V there is good assurance that, within 12 hours, the battery will be restored to its fully charged condition (Required Action B.2) from any discharge that might have occurred due to a temporary loss of the battery charger.
A discharged battery with float voltage (the charger setpoint) across its terminals indicates that the battery is on the exponential charging current portion (the second part) of its recharge cycle. The time to return a battery to its fully charged state under this condition is simply a function of the amount of the previous discharge and the recharge characteristic of the battery. Thus there is good assurance of fully recharging the battery within 12 hours, avoiding a premature shutdown with its own attendant risk.
If the condition is due to one or more cells in a low voltage condition but still greater than 2.07 V and float voltage is found to be satisfactory, this is not indication of a substantially discharged battery and 12 hours is a reasonable time prior to declaring the battery inoperable.
Since Required Action B.1 only specifies "perform," a failure of SR 3.8.4.1 acceptance criteria does not result in the Required Action not met. However, if SR 3.8.4.1 is failed, the appropriate Condition(s), depending on the cause of the failure, is entered.
C.1, C.2, and C.3 With one or more cells in one or more batteries in one DG DC subsystem
                < 2.07 V, the battery cell is degraded. Within 2 hours verification of the required battery charger OPERABILITY is made by monitoring the battery terminal voltage (SR 3.8.4.2) and of the overall battery state of charge by monitoring the battery float charge current (SR 3.8.6.2). This assures that there is still sufficient battery capacity to perform the intended function.
(continued)
Watts Bar-Unit 1                            B 3.8-76                                    Revision XX
 
Battery Parameters B 3.8.6 BASES ACTIONS          C.1, C.2, and C.3 (continued)
Therefore, the affected battery is not required to be considered inoperable solely as a result of one or more cells in one or more batteries < 2.07 V, and continued operation is permitted for a limited period up to 24 hours.
Since the Required Actions only specify "perform," a failure of SR 3.8.4.2 or SR 3.8.6.2 acceptance criteria does not result in this Required Action not met.
However, if one of the SRs is failed the appropriate Condition(s), depending on the cause of the failures, is entered. If SR 3.8.6.2 is failed then there is not assurance that there is still sufficient battery capacity to perform the intended function and the battery must be declared inoperable immediately.
D.1 and D.2 One or more batteries in one DG DC subsystem with float current > 1 amps indicates that a partial discharge of the battery capacity has occurred. This may be due to a temporary loss of a battery charger or possibly due to one or more battery cells in a low voltage condition reflecting some loss of capacity. Within 2 hours verification of the required battery charger OPERABILITY is made by monitoring the battery terminal voltage. If the terminal voltage is found to be less than the minimum established float voltage there are two possibilities, the battery charger is inoperable or is operating in the current limit mode. Condition B addresses charger inoperability. If the charger is operating in the current limit mode after 2 hours that is an indication that the battery has been substantially discharged and likely cannot perform its required design functions. The time to return the battery to its fully charged condition in this case is a function of the battery charger capacity, the amount of loads on the associated DC system, the amount of the previous discharge, and the recharge characteristic of the battery.
The charge time can be extensive, and there is not adequate assurance that it can be recharged within 12 hours (Required Action D.2). The battery must therefore be declared inoperable.
If the float voltage is found to be satisfactory but there are one or more battery cells with float voltage less than 2.07 V, the associated "OR" statement in Condition H is applicable and the battery must be declared inoperable immediately. If float voltage is satisfactory and there are no cells less than 2.07 V there is good assurance that, within 12 hours, the battery will be restored to its fully charged condition (Required Action D.2) from any discharge that might have occurred due to a temporary loss of the battery charger.
A discharged battery with float voltage (the charger setpoint) across its terminals indicates that the battery is on the exponential charging current portion (the second part) of its recharge cycle. The time to return a battery to its fully charged state under this condition is simply a function of the amount of the previous discharge and the recharge characteristic of the battery. Thus there is good assurance of fully recharging the battery within 12 hours, avoiding a premature shutdown with its own attendant risk.
(continued)
Watts Bar-Unit 1                            B 3.8-77                                    Revision XX
 
Battery Parameters B 3.8.6 BASES ACTIONS          D.1 and D.2 (continued)
If the condition is due to one or more cells in a low voltage condition but still greater than 2.07 V and float voltage is found to be satisfactory, this is not indication of a substantially discharged battery and 12 hours is a reasonable time prior to declaring the battery inoperable.
Since Required Action D.1 only specifies "perform," a failure of SR 3.8.4.2 acceptance criteria does not result in the Required Action not met. However, if SR 3.8.4.2 is failed, the appropriate Condition(s), depending on the cause of the failure, is entered.
E.1, E.2, and E.3 With one or more required batteries in one vital DC subsystem or one DG battery with one or more cells electrolyte level above the top of the plates, but below the minimum established design limits, the battery still retains sufficient capacity to perform the intended function. Therefore, the affected battery is not required to be considered inoperable solely as a result of electrolyte level not met. Within 31 days the minimum established design limits for electrolyte level must be re-established.
With electrolyte level below the top of the plates there is a potential for dryout and plate degradation. Required Actions E.1 and E.2 address this potential (as well as provisions in Specification 5.7.2.22, Battery Monitoring and Maintenance Program). They are modified by a Note that indicates they are only applicable if electrolyte level is below the top of the plates. Within 8 hours level is required to be restored to above the top of the plates. The Required Action E.2 requirement to verify that there is no leakage by visual inspection and the Specification 5.7.2.22.b item to initiate action to equalize and test in accordance with manufacturer's recommendation. They are performed following the restoration of the electrolyte level to above the top of the plates. Based on the results of the manufacturer's recommended testing the battery(ies) may have to be declared inoperable and the affected cell(s) replaced.
F.1 With one or more batteries in one vital DC subsystem or one DG battery with pilot cell temperature less than the minimum established design limits, 12 hours is allowed to restore the temperature to within limits. A low electrolyte temperature limits the current and power available. Since the battery is sized with margin, while battery capacity is degraded, sufficient capacity exists to perform the intended function and the affected battery is not required to be considered inoperable solely as a result of the pilot cell temperature not met.
(continued)
Watts Bar-Unit 1                            B 3.8-78                                  Revision XX
 
Battery Parameters B 3.8.6 BASES ACTIONS          G.1 (continued)
With one or more batteries in redundant vital DC subsystems with battery parameters not within limits there is not sufficient assurance that battery capacity has not been affected to the degree that the batteries can still perform their required function, given that redundant batteries are involved. With redundant batteries involved this potential could result in a total loss of function on multiple systems that rely upon the batteries. With more than one DG battery with battery parameters not within limits there is not sufficient assurance that battery capacity has not been affected to the degree that the batteries can still perform their required function.
The longer Completion Times specified for battery parameters on non-redundant batteries not within limits are therefore not appropriate, and the parameters must be restored to within limits on at least one subsystem within 2 hours.
H.1 With one or more batteries with any battery parameter outside the allowances of the Required Actions for Condition A, B, C, D, E, F, or G, sufficient capacity to supply the maximum expected load requirement is not assured and the corresponding battery must be declared inoperable. Additionally, discovering one or more vital DC batteries in one subsystem with one or more battery cells float voltage less than 2.07 V and float current greater than 2 amps, or one DG battery cells float voltage greater than or equal to 2.07 V and float current greater than 1 amp, indicates that the battery capacity may not be sufficient to perform the intended functions. The battery must therefore be declared inoperable immediately.
SURVEILLANCE    SR 3.8.6.1 and SR 3.8.6.2 REQUIREMENTS Verifying battery float current while on float charge is used to determine the state of charge of the battery. Float charge is the condition in which the charger is supplying the continuous charge required to overcome the internal losses of a battery and maintain the battery in a charged state. The equipment used to monitor float current must have the necessary accuracy and capability to measure electrical currents in the expected range. The float current requirements are based on the float current indicative of a charged battery. The 7 day Frequency is consistent with IEEE-450 (Ref. 2).
SR 3.8.6.1 is modified by a Note that states the float current requirement is not required to be met when battery terminal voltage is less than the minimum established float voltage of SR 3.8.4.1. When this float voltage is not maintained the Required Actions of LCO 3.8.4 ACTION A are being taken, which provide the necessary and appropriate verifications of the battery condition. Furthermore, the float current limit of 2 amps is established based on the nominal float voltage value and is not directly applicable when this voltage is not maintained.
(continued)
Watts Bar-Unit 1                            B 3.8-79                                    Revision XX
 
Battery Parameters B 3.8.6 BASES SURVEILLANCE    SR 3.8.6.1 and SR 3.8.6.2 (continued)
REQUIREMENTS SR 3.8.6.2 is modified by a Note that states the float current requirement is not required to be met when battery terminal voltage is less than the minimum established float voltage of SR 3.8.4.2. When this float voltage is not maintained the Required Actions of LCO 3.8.4 ACTION D are being taken, which provide the necessary and appropriate verifications of the battery condition. Furthermore, the float current limit of 1 amp is established based on the nominal float voltage value and is not directly applicable when this voltage is not maintained.
SR 3.8.6.3 and SR 3.8.6.6 Optimal long term battery performance is obtained by maintaining a float voltage greater than or equal to the minimum established design limits provided by the battery manufacturer, which corresponds to 132 V at the battery terminals, or 2.20 Vpc. This provides adequate overpotential, which limits the formation of lead sulfate and self discharge, which could eventually render the battery inoperable. Float voltages in this range or less, but greater than 2.07 Vpc, are addressed in Specification 5.7.2.22. SRs 3.8.6.3 and 3.8.6.6 require verification that the cell float voltages are equal to or greater than the short term absolute minimum voltage of 2.07 V. The Frequency for cell voltage verification every 31 days for pilot cell and 92 days for each connected cell is consistent with IEEE-450 (Ref. 2).
SR 3.8.6.4 The limit specified for electrolyte level ensures that the plates suffer no physical damage and maintains adequate electron transfer capability. The minimum design electrolyte level is the minimum level indication mark on the battery cell jar. The Frequency is consistent with IEEE-450 (Ref. 2).
SR 3.8.6.5 This Surveillance verifies that the pilot cell temperature is greater than or equal to the minimum established design limit (i.e., 60&deg;F for the vital batteries and 50&deg;F for the DG batteries). Pilot cell electrolyte temperature is maintained above this temperature to assure the battery can provide the required current and voltage to meet the design requirements. Temperatures lower than assumed in battery sizing calculations act to inhibit or reduce battery capacity. The Frequency is consistent with IEEE-450 (Ref. 2).
SR 3.8.6.7 A battery performance discharge test is a test of constant current capacity of a battery, normally done in the as found condition, after having been in service, to detect any change in the capacity determined by the acceptance test. The test is intended to determine overall battery degradation due to age and usage.
(continued)
Watts Bar-Unit 1                            B 3.8-80                                  Revision XX
 
Battery Parameters B 3.8.6 BASES SURVEILLANCE    SR 3.8.6.7 (continued)
REQUIREMENTS Either the battery performance discharge test or the modified performance discharge test is acceptable for satisfying SR 3.8.6.7; however, only the modified performance discharge test may be used to satisfy the battery service test requirements of SR 3.8.4.7.
A modified discharge test is a test of the battery capacity and its ability to provide a high rate, short duration load (usually the highest rate of the duty cycle). This will often confirm the battery's ability to meet the critical period of the load duty cycle, in addition to determining its percentage of rated capacity. Initial conditions for the modified performance discharge test should be identical to those specified for a service test.
It may consist of just two rates; for instance the one minute rate for the battery or the largest current load of the duty cycle, followed by the test rate employed for the performance test, both of which envelope the duty cycle of the service test.
Since the ampere-hours removed by a one minute discharge represents a very small portion of the battery capacity, the test rate can be changed to that for the performance test without compromising the results of the performance discharge test. The battery terminal voltage for the modified performance discharge test must remain above the minimum battery terminal voltage specified in the battery service test for the duration of time equal to that of the service test.
The acceptance criteria for this Surveillance are consistent with IEEE-450 (Ref. 2) and IEEE-485 (Ref. 4). These references recommend that the battery be replaced if its capacity is below 80% of the manufacturer's rating. A capacity of 80% shows that the battery rate of deterioration is increasing, even if there is ample capacity to meet the load requirements. Furthermore, the battery is sized to meet the assumed duty cycle loads when the battery design capacity reaches this 80% limit.
The Surveillance Frequency for this test is normally 60 months. If the battery shows degradation, or if the battery has reached 85% of its expected life and capacity is < 100% of the manufacturer's rating, the Surveillance Frequency is reduced to 12 months. However, if the battery shows no degradation but has reached 85% of its expected life, the Surveillance Frequency is only reduced to 24 months for batteries that retain capacity  100% of the manufacturer's ratings.
Degradation is indicated, according to IEEE-450 (Ref. 2), when the battery capacity drops by more than 10% relative to its capacity on the previous performance test or when it is  10% below the manufacturer's rating. These Frequencies are consistent with the recommendations in IEEE-450 (Ref. 2).
This SR is modified by a Note. The reason for the Note is that performing the Surveillance would perturb the electrical distribution system and challenge safety systems. Credit may be taken for unplanned events that satisfy this SR.
(continued)
Watts Bar-Unit 1                            B 3.8-81                                    Revision XX
 
Battery Parameters B 3.8.6 BASES REFERENCES      1. Watts Bar FSAR, Section 15, "Accident Analysis," and Section 6, "Engineered Safety Features."
: 2. IEEE-450-2002, "IEEE Recommended Practice for Maintenance, Testing, and Replacement of Vented Lead-Acid Batteries for Stationary Applications."
: 3. Watts Bar FSAR, Section 8, "Electric Power."
: 4. IEEE-485-1983, "IEEE Recommended Practice for Sizing Large Lead Storage Batteries for Generating Stations and Substations."
Watts Bar-Unit 1                    B 3.8-82                                Revision XX
 
WBN Unit 2 Clean Technical Specification and Bases CNL-18-118                    E3-145
 
DC Sources - Operating 3.8.4 3.8 ELECTRICAL POWER SYSTEMS 3.8.4 DC Sources - Operating LCO 3.8.4          The Train A and Train B vital DC electrical power subsystems and four Diesel Generator (DG) DC electrical power subsystems shall be OPERABLE.
                  ---------------------------------------------NOTE-------------------------------------------
Vital Battery V may be substituted for any of the required vital batteries.
APPLICABILITY:        MODES 1, 2, 3, and 4.
ACTIONS CONDITION                              REQUIRED ACTION                          COMPLETION TIME A. One or two required vital      A.1      Restore battery terminal                  2 hours battery charger(s) on                    voltage to greater than or one subsystem                            equal to the minimum inoperable.                              established float voltage.
AND A.2      Verify battery float current              Once per 12 hours 2 amps.
AND A.3      Restore vital battery                    7 days charger(s) to OPERABLE status.
B. One vital DC electrical        B.1      Restore vital DC electrical              2 hours power subsystem                          power subsystem to inoperable for reasons                    OPERABLE status.
other than Condition A.
(continued)
Watts Bar - Unit 2                                  3.8-21                                        Amendment XX
 
DC Sources - Operating 3.8.4 ACTIONS (continued)
CONDITION                REQUIRED ACTION              COMPLETION TIME C. Required Action and    C.1 Be in MODE 3.                6 hours Associated Completion Time of Condition A or  AND B not met.
C.2 Be in MODE 5.                36 hours D. One DG DC battery      D.1 Restore DG battery terminal  2 hours charger inoperable.        voltage to greater than or equal to the minimum established float voltage.
AND D.2 Verify battery float current  Once per 12 hours 1 amp.
AND D.3 Restore DG battery charger    72 hours to OPERABLE status.
E. One DG DC electrical    E.1 Restore DG DC electrical      2 hours power subsystem            power subsystem to inoperable for reasons      OPERABLE status.
other than Condition D.
F. Required Action and    F.1 Declare associated DG        Immediately associated Completion      inoperable.
Time of Condition D or E not met.
Watts Bar - Unit 2                    3.8-22                            Amendment XX
 
DC Sources - Operating 3.8.4 SURVEILLANCE REQUIREMENTS SURVEILLANCE                                      FREQUENCY SR 3.8.4.1        Verify vital battery terminal voltage is greater than or  7 days equal to the minimum established float voltage.
SR 3.8.4.2        Verify DG battery terminal voltage is greater than or      7 days equal to the minimum established float voltage.
SR 3.8.4.3        Verify for the vital batteries that the alternate feeder  7 days breakers to each required battery charger are open.
SR 3.8.4.4        Verify correct breaker alignment and indicated power      7 days availability for each DG 125 V DC distribution panel and associated battery charger SR 3.8.4.5        Verify each vital battery charger supplies  200 amps at greater than or equal to the minimum established float voltage for  4 hours.
OR Verify each vital battery charger can recharge the        18 months battery to the fully charged state within 36 hours 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.
(continued)
Watts Bar - Unit 2                              3.8-23                            Amendment XX
 
DC Sources - Operating 3.8.4 SURVEILLANCE REQUIREMENTS (continued)
SURVEILLANCE                                                  FREQUENCY SR 3.8.4.6        -------------------------------NOTE------------------------------
Credit may be taken for unplanned events that satisfy this SR.
Verify each DG battery charge supplies  20 amps at                    18 months greater than or equal to the minimum established float voltage for  4 hours.
OR Verify each DG battery charger can recharge the battery to the fully charged state within 24 hours 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.
SR 3.8.4.7        -------------------------------NOTES----------------------------
: 1. The modified performance discharge test in SR 3.8.6.7 may be performed in lieu of the service test in SR 3.8.4.7.
: 2. This Surveillance is not performed in MODE 1, 2, 3, or 4 for required vital batteries. Credit may be taken for unplanned events that satisfy this SR.
Verify battery capacity is adequate to supply, and                      18 months maintain in OPERABLE status, the required emergency loads and any connected nonsafety loads for the design duty cycle when subjected to a battery service test.
Watts Bar - Unit 2                                    3.8-24                                    Amendment XX
 
DC Sources - Shutdown 3.8.5 3.8 ELECTRICAL POWER SYSTEMS 3.8.5 DC Sources - Shutdown LCO 3.8.5            Vital DC and Diesel Generator (DG) DC electrical power subsystems shall be OPERABLE to support the DC electrical power distribution subsystem(s) required by LCO 3.8.10, "Distribution Systems - Shutdown" and to support the Diesel Generators (DGs) required by LCO 3.8.2, "AC Sources - Shutdown."
                      ---------------------------------------------NOTES------------------------------------------
Vital Battery V may be substituted for any of the required vital batteries.
APPLICABILITY:        MODES 5 and 6, During movement of irradiated fuel assemblies.
ACTIONS CONDITION                                REQUIRED ACTION                          COMPLETION TIME A. One or two required              A.1      Restore battery terminal                  2 hours vital battery charger(s)                  voltage to greater than or on one subsystem                          equal to the minimum inoperable.                                established float voltage.
AND                              AND The redundant                    A.2      Verify battery float current              Once per 12 hours subsystem vital battery                    2 amps.
and charger(s)
OPERABLE.                        AND A.3      Restore battery charger(s) to            7 days OPERABLE status.
(continued)
Watts Bar - Unit 2                                  3.8-26                                        Amendment XX
 
DC Sources - Shutdown 3.8.5 ACTIONS (continued)
CONDITION                      REQUIRED ACTION                COMPLETION TIME B. One or more required      B.1.1 Declare affected required      Immediately vital DC electrical power      feature(s) inoperable.
subsystems inoperable for reasons other than    OR Condition A.
B.2.1 Suspend CORE                  Immediately OR                              ALTERATIONS.
Required Actions and            AND associated Completion Time of Condition A not  B.2.2 Suspend movement of            Immediately met.                            irradiated fuel assemblies.
AND B.2.3 Initiate action to suspend    Immediately operations involving positive reactivity additions.
AND B.2.4 Initiate action to restore    Immediately required DC electrical power subsystems to OPERABLE status.
C. One required DG DC        C.1  Declare associated DG          Immediately electrical power                inoperable.
subsystem inoperable.
Watts Bar - Unit 2                        3.8-27                            Amendment XX
 
DC Sources - Shutdown 3.8.5 SURVEILLANCE REQUIREMENTS SURVEILLANCE                                                      FREQUENCY SR 3.8.5.1        -----------------------------NOTE-----------------------------
The following SRs are not required to be performed: SR 3.8.4.5, SR 3.8.4.6, and SR 3.8.4.7.
For DC sources required to be OPERABLE, the                        In accordance with following SRs are applicable:                                      applicable SRs SR 3.8.4.1        SR 3.8.4.5 SR 3.8.4.2        SR 3.8.4.6 SR 3.8.4.3        SR 3.8.4.7 SR 3.8.4.4 Watts Bar - Unit 2                              3.8-28                                      Amendment XX
 
Battery Parameters 3.8.6 3.8 ELECTRICAL POWER SYSTEMS 3.8.6 Battery Parameters LCO 3.8.6                    Battery parameters for Train A and Train B electrical power subsystem 125 V vital batteries and 125 V diesel generator (DG) batteries shall be within limits.
APPLICABILITY:              When associated DC electrical power subsystems and DGs are required to be OPERABLE.
ACTIONS
--------------------------------------------------------NOTE-------------------------------------------------------------
Separate Condition entry is allowed for each battery bank.
ACTIONS CONDITION                                  REQUIRED ACTION                          COMPLETION TIME A.        One or two required                A.1        Perform SR 3.8.4.1.                      2 hours vital battery(ies) on one subsystem with one or              AND more battery cells float voltage < 2.07 V.                  A.2        Perform SR 3.8.6.1.                      2 hours AND A.3        Restore affected cell voltage            24 hours 2.07 V.
B.        One or two required                B.1        Perform SR 3.8.4.1.                      2 hours vital battery(ies) on one subsystem with float              AND current > 2 amps.
B.2        Restore vital battery float              12 hours current to  2 amps.
(continued)
Watts Bar - Unit 2                                        3.8-29                                          Amendment XX
 
Battery Parameters 3.8.6 ACTIONS (continued)
CONDITION                              REQUIRED ACTION                      COMPLETION TIME C.        One DG battery with one          C.1        Perform SR 3.8.4.2.                2 hours or more battery cells float voltage < 2.07 V.          AND C.2        Perform SR 3.8.6.2.                2 hours AND C.3        Restore affected cell              24 hours voltage  2.07 V.
D.        One DG battery with              D.1        Perform SR 3.8.4.2.                2 hours float current > 1 amp.
AND D.2        Restore vital battery float        12 hours current to  1 amp.
----------------NOTE-------------------    ------------------NOTE-------------------
Required Action E.2 shall be                Required Actions E.1 and E.2 are completed if electrolyte level was          only applicable if electrolyte level below the top of plates.                    was below the top of plates.
E.        One or two required vital        E.1        Restore electrolyte level          8 hours battery(ies) on one                        to above top of plates.
subsystem with one or more cells electrolyte          AND level less than minimum established design              E.2        Verify no evidence of              12 hours limits.                                    leakage.
OR                              AND One DG battery with one          E.3        Restore electrolyte level          31 days or more cells electrolyte                  to greater than or equal to level less than minimum                    minimum established established design                          design limits.
limits.
(continued)
Watts Bar - Unit 2                                      3.8-30                                    Amendment XX
 
Battery Parameters 3.8.6 ACTIONS (continued)
CONDITION                  REQUIRED ACTION            COMPLETION TIME F. One or two required vital F.1  Restore battery pilot cell 12 hours battery(ies) on one            temperature to greater subsystem with pilot cell      than or equal to minimum electrolyte temperature        established design limits.
less than minimum established design limits.
OR One DG battery with pilot cell electrolyte temperature less than minimum established design limits.
G. One or more batteries in  G.1  Restore battery            2 hours redundant subsystems          parameters to within with battery parameters        limits.
not within limits.
OR More than one DG battery with battery parameters not within limits.
(continued)
Watts Bar - Unit 2                    3.8-31                            Amendment XX
 
Battery Parameters 3.8.6 (ACTIONS (continued)
CONDITION                  REQUIRED ACTION            COMPLETION TIME H. Required Action and      H.1 Declare associated battery Immediately associated Completion        inoperable.
Time of Condition A, B, C, D, E, F, or G not met.
OR One or two required vital battery(ies) on one subsystem with one or more battery cells float voltage < 2.07 V and float current > 2 amps.
OR One DG battery with one or more battery cells float voltage
      < 2.07 V and float current > 1 amp.
Watts Bar - Unit 2                    3.8-32                        Amendment XX
 
Battery Parameters 3.8.6 SURVEILLANCE REQUIREMENTS SURVEILLANCE                                                  FREQUENCY SR 3.8.6.1      -----------------------------NOTE----------------------------
Not required to be met when vital battery terminal voltage is less than the minimum established float voltage of SR 3.8.4.1.
Verify each vital battery float current is  2 amps.              7 days SR 3.8.6.2      -----------------------------NOTE----------------------------
Not required to be met when DG battery terminal voltage is less than the minimum established float voltage of SR 3.8.4.2.
Verify each DG battery float current is  1 amp.                  7 days SR 3.8.6.3      Verify each required vital battery and each DG                    31 days battery pilot cell float voltage is  2.07 V.
SR 3.8.6.4      Verify each required vital battery and each DG                    31 days battery connected cell electrolyte level is greater than or equal to minimum established design limits.
SR 3.8.6.5      Verify each required vital battery and each DG                    31 days battery pilot cell temperature is greater than or equal to minimum established design limits.
SR 3.8.6.6      Verify each required vital battery and each DG                    92 days battery connected cell float voltage is  2.07 V.
(continued)
Watts Bar-Unit 2                              3.8-33                                    Amendment XX
 
Battery Parameters 3.8.6 SURVEILLANCE REQUIREMENTS (continued)
SURVEILLANCE                                                  FREQUENCY SR 3.8.6.7      ------------------------------NOTES-------------------------
This Surveillance is not performed in MODE 1, 2, 3, or 4 for required vital batteries. Credit may be taken for unplanned events that satisfy this SR.
Verify battery capacity is  80% of the                          60 months manufacturer's rating when subjected to a performance discharge test or a modified                          AND performance discharge test.
12 months when battery shows degradation or has reached 85% of expected life with capacity <
100% of manufacturer's rating AND 24 months when battery has reached 85% of the expected life with capacity  100% of manufacturer's rating Watts Bar-Unit 2                              3.8-34                                      Amendment XX
 
Procedures, Programs, and Manuals 5.7 5.7 Procedures, Programs, and Manuals 5.7.2.22 Battery Monitoring and Maintenance Program This Program provides controls for battery restoration and maintenance. The program shall be in accordance with IEEE Standard (Std) 450-2002, "IEEE Recommended Practice for Maintenance, Testing, and Replacement of Vented Lead-Acid Batteries for Stationary Applications," as endorsed by Regulatory Guide 1.129, Revision 2 (RG), with RG exceptions and program provisions as identified below:
: a. The program allows the following RG 1.129, Revision 2 exceptions:
: 1. Battery temperature correction may be performed before or after conducting discharge tests.
: 2. RG 1.129, Regulatory Position 1, Subsection 2, "References," is not applicable to this program.
: 3. In lieu of RG 1.129, Regulatory Position 2, Subsection 5.2, "Inspections," the following shall be used: "Where reference is made to the pilot cell, pilot cell selection shall be based on the lowest voltage cell in the battery.
: 4. In Regulatory Guide 1.129, Regulatory Position 3, Subsection 5.4.1, "State of Charge Indicator," the following statements in paragraph (d) may be omitted: "When it has been recorded that the charging current has stabilized at the charging voltage for three consecutive hourly measurements, the battery is near full charge. These measurements shall be made after the initially high charging current decreases sharply and the battery voltage rises to approach the charger output voltage."
: 5. In lieu of RG 1.129, Regulatory Position 7, Subsection 7.6, "Restoration", the following may be used: "Following the test, record the float voltage of each cell of the string."
: b. The program shall include the following provisions:
: 1. Actions to restore battery cells with float voltage < 2.13 V;
: 2. Actions to determine whether the float voltage of the remaining battery cells is  2.13 V when the float voltage of a battery cell has been found to be < 2.13 V; Watts Bar-Unit 2                              5.0-29                                  Amendment XX
 
Procedures, Programs, and Manuals 5.7 5.7 Procedures, Programs, and Manuals 5.7.2.22 Battery Monitoring and Maintenance Program (continued)
: 3. Actions to equalize and test battery cells that had been discovered with electrolyte level below the top of the plates;
: 4. Limits on average electrolyte temperature, battery connection resistance, and battery terminal voltage; and
: 5. A requirement to obtain specific gravity readings of all cells at each discharge test, consistent with manufacturer recommendations.
Watts Bar-Unit 2                            5.0-30                                Amendment XX
 
DC Sources - Operating B 3.8.4 B 3.8 ELECTRICAL POWER SYSTEMS B 3.8.4 DC Sources - Operating BASES BACKGROUND          The station DC electrical power system provides the AC emergency power system with control power. It also provides both motive and control power to selected safety related equipment and preferred AC vital bus power (via inverters). As required by 10 CFR 50, Appendix A, GDC 17 (Ref. 1), the DC electrical power system is designed to have sufficient independence, redundancy, and testability to perform its safety functions, assuming a single failure. The DC electrical power system also conforms to the recommendations of Regulatory Guide 1.6 (Ref. 2) and IEEE-308 (Ref. 3).
125 V Vital DC Electrical Power Subsystem The vital 125 VDC electrical power system is a Class 1E system whose safety function is to provide control power for engineered safety features equipment, emergency lighting, vital inverters, and other safety related DC powered equipment for the entire unit. The system capacity is sufficient to supply these loads and any connected non-safety loads during normal operation and to permit safe shutdown and isolation of the reactor for the loss of all AC power condition. The system is designed to perform its safety function subject to a single failure.
The 125V DC vital power system is composed of the four channels (Channels I and III are associated with Train A and Channels II and IV are associated with Train B) and consists of four lead-acid-calcium batteries, eight battery chargers (including two pairs of spare chargers),
four distribution boards, battery racks, and the required cabling, instrumentation and protective features. Each channel is electrically and physically independent from the equipment of all other channels so that a single failure in one channel will not cause a failure in another channel.
Each channel consists of a battery charger which supplies normal DC power, a battery for emergency DC power, and a battery board which facilitates load grouping and provides circuit protection. These four channels are used to provide emergency power to the 120V AC vital power system which furnishes control power to the reactor protection system. No automatic connections are used between the four channels.
Battery boards I, II, III, and IV have a charger normally connected to them and also have manual access to a spare (backup) charger for use upon loss of the normal charger.
(continued)
Watts Bar - Unit 2                          B 3.8-53                                Revision XX
 
DC Sources - Operating B 3.8.4 BASES BACKGROUND        125 V Vital DC Electrical Power Subsystem (continued)
Additionally, battery boards I, II, III, and IV have manual access to the fifth vital battery system. The fifth 125V DC Vital Battery System is intended to serve as a replacement for any one of the four 125V DC vital batteries during their testing, maintenance, and outages with no loss of system reliability under any mode of operation.
Each of the vital DC electrical power subsystems provides the control power for its associated Class 1E AC power load group, 6.9 kV switchgear, and 480 V load centers. The vital DC electrical power subsystems also provide DC electrical power to the inverters, which in turn power the AC vital buses. Additionally, they power the emergency DC lighting system.
The vital DC power distribution system is described in more detail in Bases for LCO 3.8.9, Distribution System - Operating, and LCO 3.8.10, Distribution Systems - Shutdown.
Each 125 VDC vital battery is separately housed in a ventilated room apart from its charger and distribution centers, except for Vital Battery V.
Each subsystem is located in an area separated physically and electrically from the other subsystem to ensure that a single failure in one subsystem does not cause a failure in a redundant subsystem. There is no sharing between Class 1E subsystems, such as batteries, battery chargers, or distribution panels.
Each battery has adequate storage capacity to meet the duty cycle(s) discussed in the FSAR, Chapter 8 (Ref 4). The battery is designed with additional capacity above that required by the design duty cycle to allow for temperature variations and other factors.
The batteries for the vital DC electrical power subsystems are sized to produce required capacity at 80% of nameplate rating, corresponding to warranted capacity at end of life cycles, and the 100% design demand.
The minimum design voltage limit is 105 V.
(continued)
Watts Bar - Unit 2                        B 3.8-54                                  Revision XX
 
DC Sources - Operating B 3.8.4 BASES BACKGROUND        125 V Vital DC Electrical Power Subsystem (continued)
The battery cells are of flooded lead acid construction with a nominal specific gravity of 1.215. This specific gravity corresponds to an open circuit battery voltage of approximately 120 V for a 60 cell battery (i.e.,
cell voltage of 2.063 volts per cell (Vpc)). The open circuit voltage is the voltage maintained when there is no charging or discharging. Optimal long term performance however, is obtained by maintaining a float voltage 2.20 to 2.25 Vpc. This provides adequate over-potential, which limits the formation of lead sulfate and self discharge. The nominal float voltage of 2.22 Vpc corresponds to a total float voltage output of 133.2 V for a 60 cell battery as discussed in the FSAR, Chapter 8 (Ref. 4).
Each Vital DC electrical power subsystem battery charger has ample power output capacity for the steady state operation of connected loads required during normal operation, while at the same time maintaining its battery bank fully charged. Each battery charger also has sufficient excess capacity to restore the battery bank from the design minimum charge to its fully charged state within 12 hours (with accident loads being supplied) following a 30 minute AC power outage and in approximately 36 hours (while supplying normal steady state loads following a 2 hour AC power outage), (Ref. 5).
The battery charger is normally in the float-charge mode. Float-charge is the condition in which the charger is supplying the connected loads and the battery cells are receiving adequate current to optimally charge the battery. This assures the internal losses of a battery are overcome and the battery is maintained in a fully charged state.
When desired, the charger can be placed in the equalize mode. The equalize mode is at a higher voltage than the float mode and charging current is correspondingly higher. The battery charger is operated in the equalize mode after a battery discharge or for routine maintenance.
Following a battery discharge, the battery recharge characteristic accepts current at the current limit of the battery charger (if the discharge was significant, e.g., following a battery service test) until the battery terminal voltage approaches the charger voltage setpoint. Charging current then reduces exponentially during the remainder of the recharge cycle. Lead-calcium batteries have recharge efficiencies of greater than 95%, so once at least 105% of the ampere-hours discharged have been returned, the battery capacity would be restored to the same condition as it was prior to the discharge. This can be monitored by direct observation of the exponentially decaying charging current or by evaluating the amp-hours discharged from the battery and amp-hours returned to the battery.
(continued)
Watts Bar - Unit 2                          B 3.8-55                                  Revision XX
 
DC Sources - Operating B 3.8.4 BASES BACKGROUND        125 V Diesel Generator (DG) DC Electrical Power Subsystem (continued)
Control power for the DGs is provided by four DG battery systems, one per DG. Each system is comprised of a battery, a battery charger, distribution center, cabling, and cable ways. The DG 125V DC control power and field-flash circuits have power supplied from their respective 125V distribution panel. The normal supply of DC current is from the associated charger. The battery provides control and field-flash power when the charger is unavailable. The charger supplies the normal DC loads, maintains the battery in a fully charged condition, and recharges (480V AC available) the battery while supplying the required loads regardless of the status of the unit. The batteries are physically and electrically independent. The battery has sufficient capacity when fully charged to supply required loads for a minimum of four hours following a loss of normal power. Each battery is normally required to supply loads during the time interval between loss of normal feed to its charger and the receipt of emergency power to the charger from its respective DG.
APPLICABLE        The initial conditions of Design Basis Accident (DBA) and transient SAFETY            analyses in the FSAR, Section 6 (Ref. 6), and in the FSAR, Section 15 ANALYSES          (Ref. 6), assume that Engineered Safety Feature (ESF) systems are OPERABLE. The vital DC electrical power system provides normal and emergency DC electrical power for the emergency auxiliaries, and control and switching during all power for the emergency auxiliaries, and control and switching during all MODES of operation. The DG battery systems provide DC power for the DGs.
The OPERABILITY of the DC sources is consistent with the initial assumptions of the accident analyses and is based upon meeting the design basis of the plant. This includes maintaining the DC sources OPERABLE during accident conditions in the event of:
: a. An assumed loss of all offsite AC power or all onsite AC power; and
: b. A worst case single failure.
The DC sources satisfy Criterion 3 of 10 CFR 50.36(c)(2)(ii).
(continued)
Watts Bar - Unit 2                        B 3.8-56                                Revision XX
 
DC Sources - Operating B 3.8.4 BASES (continued)
LCO                Two 125V vital DC electrical power subsystems (Train A and Train B),
each vital subsystem consisting of two channels. Each channel consisting of a battery bank, associated battery charger and the corresponding control equipment and interconnecting cabling supplying power to the associated DC bus within the channel; and four DG DC electrical power subsystems each consisting of a battery, a dual battery charger assembly, and the corresponding control equipment and interconnecting cabling are required to be OPERABLE to ensure the availability of the required power to shut down the reactor and maintain it in a safe condition after an anticipated operational occurrence (A00) or a postulated DBA. Loss of any DC electrical power subsystem does not prevent the minimum safety function from being performed (Ref. 4).
An OPERABLE vital DC electrical power subsystem requires all required batteries and respective chargers to be operating and connected to the associated DC buses.
The LCO is modified by one Note. The Note indicates that Vital Battery V may be substituted for any of the required vital batteries. However, the fifth battery cannot be declared OPERABLE until it is connected electrically in place of another battery and it has satisfied applicable Surveillance Requirements.
APPLICABILITY      The vital DC electrical power sources and DG DC electrical power sources are required to be OPERABLE in MODES 1, 2, 3, and 4 to ensure safe plant operation and to ensure that:
: a. Acceptable fuel design limits and reactor coolant pressure boundary limits are not exceeded as a result of AOs or abnormal transients; and
: b. Adequate core cooling is provided, and containment integrity and other vital functions are maintained in the event of a postulated DBA.
The DC electrical power requirements for MODES 5 and 6 are addressed in the Bases for LCO 3.8.5, DC Sources - Shutdown.
(continued)
Watts Bar - Unit 2                          B 3.8-57                                Revision XX
 
DC Sources - Operating B 3.8.4 BASES (continued)
ACTIONS            A.1, A.2, and A.3 Condition A represents one vital DC subsystem with one or two battery chargers inoperable (e.g., the voltage limit of SR 3.8.4.1 is not maintained). The ACTIONS provide a tiered response that focuses on returning the battery to the fully charged state and restoring a fully qualified charger to OPERABLE status in a reasonable time period.
Required Action A.1 requires that the battery terminal voltage be restored to greater than or equal to the minimum established float voltage within 2 hours. This time provides for returning the inoperable charger to OPERABLE status or providing an alternate means of restoring battery terminal voltage to greater than or equal to the minimum established float voltage. Restoring the battery terminal voltage to greater than or equal to the minimum established float voltage provides good assurance that, within 12 hours, the battery will be restored to its fully charged condition (Required Action A.2) from any discharge that might have occurred due to the charger inoperability.
A discharged battery having terminal voltage of at least the minimum established float voltage indicates that the battery is on the exponential charging current portion (the second part) of its recharge cycle. The time to return a battery to its fully charged state under this condition is simply a function of the amount of the previous discharge and the recharge characteristic of the battery. Thus there is good assurance of fully recharging the battery within 12 hours, avoiding a premature shutdown with its own attendant risk.
If established battery terminal float voltage cannot be restored to greater than or equal to the minimum established float voltage within 2 hours, and the charger is not operating in the current-limiting mode, a faulty charger is indicated. A faulty charger that is incapable of maintaining established battery terminal float voltage does not provide assurance that it can revert to and operate properly in the current limit mode that is necessary during the recovery period following a battery discharge event that the DC system is designed for.
If the charger is operating in the current limit mode after 2 hours that is an indication that the battery is partially discharged and its capacity margins will be reduced. The time to return the battery to its fully charged condition in this case is a function of the battery charger capacity, the amount of loads on the associated DC system, the amount of the previous discharge, and the recharge characteristic of the battery. The charge time can be extensive, and there is not adequate assurance that it can be recharged within 12 hours (Required Action A.2).
Required Action A.2 requires that the battery float current be verified as less than or equal to 2 amps. This indicates that, if the battery had been discharged as the result of the inoperable battery charger, it is now fully capable of supplying the maximum expected load requirement.
(continued)
Watts Bar - Unit 2                        B 3.8-58                                  Revision XX
 
DC Sources - Operating B 3.8.4 BASES (continued)
ACTIONS            A.1, A.2, and A.3 (continued)
The 2 amp value is based on returning the battery to 98% charge and assumes a 2% design margin for the battery. If at the expiration of the initial 12 hour period the battery float current is not less than or equal to 2 amps this indicates there may be additional battery problems and the battery must be declared inoperable.
Required Action A.3 limits the restoration time for the inoperable battery charger to 7 days. This action is applicable if an alternate means of restoring battery terminal voltage to greater than or equal to the minimum established float voltage has been used (e.g., balance of plant non-Class 1E battery charger). The 7 day Completion Time reflects a reasonable time to effect restoration of the qualified battery charger to OPERABLE status.
B.1 Condition B represents one vital DC electrical power subsystem with a loss of ability to completely respond to an event, and a potential loss of ability to remain energized during normal operation. It is, therefore, imperative that the operator's attention focus on stabilizing the plant, minimizing the potential for complete loss of DC power to the affected subsystem. The 2 hour limit is consistent with the allowed time for an inoperable DC distribution subsystem.
If one of the required vital DC electrical power subsystems is inoperable for reasons other than Condition A (e.g., inoperable battery charger and associated inoperable battery), the remaining vital DC electrical power subsystem has the capacity to support a safe shutdown and to mitigate an accident condition. Since a subsequent worst case single failure of the OPERABLE subsystem could, however, result in the loss of the minimum necessary vital DC electrical power subsystems to mitigate a worst-case accident, continued power operation should not exceed 2 hours. The 2 hour Completion Time is based on Regulatory Guide 1.93 (Ref. 7) and reflects a reasonable time to assess plant status as a function of the inoperable vital DC electrical power subsystem and, if the vital DC electrical power subsystem is not restored to OPERABLE status, to prepare to effect an orderly and safe plant shutdown.
(continued)
Watts Bar - Unit 2                        B 3.8-59                                  Revision XX
 
DC Sources - Operating B 3.8.4 BASES ACTIONS            C,1 and C.2 (continued)
If the inoperable vital DC electrical power subsystem cannot be restored to OPERABLE status within the required Completion Time, the plant must be brought to a MODE in which the LCO does not apply. To achieve this status, the plant must be brought to at least MODE 3 within 6 hours and to MODE 5 within 36 hours. The allowed Completion Times are reasonable, based on operating experience, to reach the required plant conditions from full power conditions in an orderly manner and without challenging plant systems. The Completion Time to bring the plant to MODE 5 is consistent with the time required in Regulatory Guide 1.93 (Ref. 7).
D.1, D.2, and D.3 Condition D represents one DG DC subsystem with one battery charger inoperable (e.g., the voltage limit of SR 3.8.4.1 is not maintained). The ACTIONS provide a tiered response that focuses on returning the battery to the fully charged state and restoring a fully qualified charger to OPERABLE status in a reasonable time period. Required Action D.1 requires that the battery terminal voltage be restored to greater than or equal to the minimum established float voltage within 2 hours. This time provides for returning the inoperable charger to OPERABLE status or providing an alternate means of restoring battery terminal voltage to greater than or equal to the minimum established float voltage.
Restoring the battery terminal voltage to greater than or equal to the minimum established float voltage provides good assurance that, within 12 hours, the battery will be restored to its fully charged condition (Required Action D.2) from any discharge that might have occurred due to the charger inoperability.
A discharged battery having terminal voltage of at least the minimum established float voltage indicates that the battery is on the exponential charging current portion (the second part) of its recharge cycle. The time to return a battery to its fully charged state under this condition is simply a function of the amount of the previous discharge and the recharge characteristic of the battery. Thus there is good assurance of fully recharging the battery within 12 hours, avoiding a premature shutdown with its own attendant risk.
If established battery terminal float voltage cannot be restored to greater than or equal to the minimum established float voltage within 2 hours, and the charger is not operating in the current-limiting mode, a faulty charger is indicated. A faulty charger that is incapable of maintaining established battery terminal float voltage does not provide assurance that it can revert to and operate properly in the current limit mode that is necessary during the recovery period following a battery discharge event that the DG DC system is designed for.
(continued)
Watts Bar - Unit 2                        B 3.8-60                                  Revision XX
 
DC Sources - Operating B 3.8.4 BASES ACTIONS            D.1, D.2, and D.3 (continued)
If the charger is operating in the current limit mode after 2 hours that is an indication that the battery is partially discharged and its capacity margins will be reduced. The time to return the battery to its fully charged condition in this case is a function of the battery charger capacity, the amount of loads on the associated DC system, the amount of the previous discharge, and the recharge characteristic of the battery. The charge time can be extensive, and there is not adequate assurance that it can be recharged within 12 hours (Required Action D.2).
Required Action D.2 requires that the battery float current be verified as less than or equal to 1 amp. This indicates that, if the battery had been discharged as the result of the inoperable battery charger, it is now fully capable of supplying the maximum expected load requirement. The 1 amp value is based on returning the battery to 98% charge and assumes a 2% design margin for the battery. If at the expiration of the initial 12 hour period the battery float current is not less than or equal to 1 amp this indicates there may be additional battery problems and the battery must be declared inoperable.
Required Action D.3 limits the restoration time for the inoperable battery charger to 72 hours. The 72 hour Completion Time reflects a reasonable time to effect restoration of the qualified battery charger to OPERABLE status.
E.1 Condition E represents one DG with a loss of ability to completely respond to an event. Since a subsequent single failure on the opposite train could result in a situation where the required ESF function is not assured, continued power operation should not exceed 2 hours. The 2 hour time limit is consistent with the allowed time for an inoperable vital DC electrical power subsystem.
F.1 If the DG DC electrical power subsystem cannot be restored to OPERABLE status in the associated Completion Time, the associated DG may be incapable of performing its intended function and must be immediately declared inoperable. This declaration also requires entry into applicable Conditions and Required Actions for an inoperable DG, LCO 3.8.1, "AC Sources-Operating."
(continued)
Watts Bar - Unit 2                        B 3.8-61                                  Revision XX
 
DC Sources - Operating B 3.8.4 BASES (continued)
SURVEILLANCE      SR 3.8.4.1 and SR 3.8.4.2 REQUIREMENTS Verifying battery terminal voltage while on float charge for the batteries helps to ensure the effectiveness of the battery chargers, which support the ability of the batteries to perform their intended function. Float charge is the condition in which the charger is supplying the continuous charge required to overcome the internal losses of a battery and maintain the battery in a fully charged state while supplying the continuous steady state loads of the associated DC subsystem. On float charge, battery cells will receive adequate current to optimally charge the battery. The voltage requirements are based on the nominal design voltage of the battery and are consistent with the minimum float voltage established by the battery manufacturer (2.20 Vpc times the number of connected cells or 132 V at the battery terminals for a 60 cell vital battery; 127.6 V at the battery terminals for a 58 cell DG battery). This voltage maintains the battery plates in a condition that supports maintaining the grid life. The 7 day Frequency is consistent with manufacturer recommendations.
SR 3.8.4.3 Verifying that for the vital batteries that the alternate feeder breakers to each required battery charger is open ensures that independence between the power trains is maintained. The 7 day Frequency is based on engineering judgment, is consistent with procedural controls governing breaker operation, and ensures correct breaker position.
SR 3.8.4.4 This SR demonstrates that the DG 125V DC distribution panel and associated charger are functioning properly, with all required circuit breakers closed and buses energized from normal power. The 7 day Frequency takes into account the redundant DG capability and other indications available in the control room that will alert the operator to system malfunctions.
SR 3.8.4.5 This SR verifies the design capacity of the vital battery chargers.
According to Regulatory Guide 1.32 (Ref. 5), the battery charger supply is recommended to be based on the largest combined demands of the various steady state loads and the charging capacity to restore the battery from the design minimum charge state to the fully charged state, irrespective of the status of the plant during these demand occurrences.
The minimum required amperes and duration ensure that these requirements can be satisfied.
(continued)
Watts Bar - Unit 2                        B 3.8-62                                  Revision XX
 
DC Sources - Operating B 3.8.4 BASES SURVEILLANCE      SR 3.8.4.5 (continued)
REQUIREMENTS This SR provides two options. One option requires that each battery charger be capable of supplying 200 amps at the minimum established float voltage (132 V DC) for 4 hours. The ampere requirements are based on the output rating of the chargers. The voltage requirements are based on the charger voltage level after a response to a loss of AC power.
The other option requires that each vital battery charger be capable of recharging the battery after a service test coincident with supplying the largest coincident demands of the various continuous steady state loads (irrespective of the status of the plant during which these demands occur). This level of loading may not normally be available following the battery service test and will need to be supplemented with additional loads. The duration for this test may be longer than the charger sizing criteria since the battery recharge is affected by float voltage, temperature, and the exponential decay in charging current. The battery is recharged when the measured charging current is  2 amps.
The Surveillance Frequency is acceptable, given the plant conditions required to perform the test and the other administrative controls existing to ensure adequate charger performance during these 18 month intervals.
In addition, this Frequency is intended to be consistent with expected fuel cycle lengths.
SR 3.8.4.6 This SR verifies the design capacity of the DG battery chargers.
According to Regulatory Guide 1.32 (Ref. 5), the battery charger supply is recommended to be based on the largest combined demands of the various steady state loads and the charging capacity to restore the battery from the design minimum charge state to the fully charged state, irrespective of the status of the plant during these demand occurrences. The minimum required amperes and duration ensure that these requirements can be satisfied.
This SR provides two options. One option requires that each battery charger be capable of supplying 20 amps at the minimum established float voltage (127.6 V DC) for 4 hours. The ampere requirements are based on the output rating of the chargers. The voltage requirements are based on the charger voltage level after a response to a loss of AC power.
(continued)
Watts Bar - Unit 2                        B 3.8-63                                  Revision XX
 
DC Sources - Operating B 3.8.4 BASES SURVEILLANCE      SR 3.8.4.6 (continued)
REQUIREMENTS The other option requires that each vital battery charger be capable of recharging the battery after a service test coincident with supplying the largest coincident demands of the various continuous steady state loads (irrespective of the status of the plant during which these demands occur). This level of loading may not normally be available following the battery service test and will need to be supplemented with additional loads. The duration for this test may be longer than the charger sizing criteria since the battery recharge is affected by float voltage, temperature, and the exponential decay in charging current. The battery is recharged when the measured charging current is  1 amp.
The Surveillance Frequency is acceptable, given the administrative controls existing to ensure adequate charger performance during these 18 month intervals.
For the DG DC electrical subsystem, this Surveillance may be performed in MODES 1, 2, 3, or 4 in conjunction with LCO 3.8.1.B since the DG DC electrical power subsystem supplies loads only for the inoperable diesel generator and would not otherwise challenge safety systems supplied from vital electrical distribution systems. Additionally, credit may be taken for unplanned events that satisfy this SR. Examples of unplanned events may include:
: 1)      Unexpected operational events which cause the equipment to perform the function specified by this Surveillance, for which adequate documentation of the required performance is available; and
: 2)      Post corrective maintenance testing that requires performance of this Surveillance in order to restore the component to OPERABLE, provided the maintenance was required, or performed in conjunction with maintenance required to maintain OPERABILITY or reliability.
SR 3.8.4.7 A battery service test is a special test of battery capability, as found, to satisfy the design requirements (battery duty cycle) of the DC electrical power system. The discharge rate and test length should correspond to worst case design duty cycle requirements based on References 8 and 10.
The Surveillance Frequency of 18 months is consistent with the recommendations of Regulatory Guide 1.32 (Ref. 5) and Regulatory Guide 1.129 (Ref. 9), which state that the battery service test should be (continued)
Watts Bar - Unit 2                          B 3.8-64                                  Revision XX
 
DC Sources - Operating B 3.8.4 BASES SURVEILLANCE      SR 3.8.4.7 (continued)
REQUIREMENTS performed during refueling operations or at some other outage, with intervals between tests, not to exceed 18 months.
This SR is modified by two Notes. Note 1 allows the performance of a modified performance discharge test in lieu of a service test.
The reason for Note 2 is that performing the Surveillance may perturb the vital electrical distribution system and challenge safety systems.
However, this Surveillance may be performed in MODES 1, 2, 3, or 4 provided that Vital Battery V is substituted in accordance with LCO Note
: 1. For the DG DC electrical subsystem, this surveillance may be performed in MODES 1, 2, 3, or 4 in conjunction with LCO 3.8.1.B since the supplied loads are only for the inoperable diesel generator and would not otherwise challenge safety system loads which are supplied from vital electrical distribution systems. Additionally, credit may be taken for unplanned events that satisfy this SR. Examples of unplanned events may include:
: 1)      Unexpected operational events which cause the equipment to perform the function specified by this Surveillance, for which adequate documentation of the required performance is available; and
: 2)      Post corrective maintenance testing that requires performance of this Surveillance in order to restore the component to OPERABLE, provided the maintenance was required, or performed in conjunction with maintenance required to maintain OPERABILITY or reliability.
(continued)
Watts Bar - Unit 2                          B 3.8-65                                Revision XX
 
DC Sources - Operating B 3.8.4 BASES REFERENCES          1. Title 10, Code of Federal Regulations, Part 50, Appendix A, General Design Criterion 17, Electric Power System.
: 2. Regulatory Guide 1.6, Independence Between Redundant Standby (Onsite) Power Sources and Between Their Distribution Systems, U.S. Nuclear Regulatory Commission, March 10, 1971.
: 3. IEEE-308-1971, IEEE Standard Criteria for Class 1E Power Systems for Nuclear Power Generating Stations, Institute of Electrical and Electronic Engineers.
: 4. Watts Bar FSAR, Section 8.3.2, DC Power System.
: 5. Regulatory Guide 1.32, Criteria for Safety-Related Electric Power Systems for Nuclear Power Plants, February 1977, U.S. Nuclear Regulatory Commission.
: 6. Watts Bar FSAR, Section 15, Accident Analysis and Section 6 Engineered Safety Features.
: 7. Regulatory Guide 1.93, Availability of Electric Power Sources, U.S. Nuclear Regulatory Commission, December 1974.
: 8. TVA Calculation EDQ00023620070003, 125V DC Vital Battery System Analysis
: 9. Regulatory Guide 1.129, Maintenance Testing and Replacement of Large Lead Storage Batteries for Generating Stations and Subsystems, U.S. Nuclear Regulatory Commission, February 1978.
: 10. TVA Calculation WBN EEB-EDQ00023620070003, 125V DC Vital Battery System Analysis.
Watts Bar - Unit 2                    B 3.8-66                                Revision XX
 
DC Sources - Shutdown B 3.8.5 B 3.8 ELECTRICAL POWER SYSTEMS B 3.8.5 DC Sources - Shutdown BASES BACKGROUND          A description of the DC sources is provided in the Bases for LCO 3.8.4, DC Sources - Operating.
APPLICABLE          The initial conditions of Design Basis Accident and transient analyses in SAFETY              the FSAR, Section 6 (Ref. 1) and Section 15 (Ref. 1), assume that ANALYSES            Engineered Safety Feature systems are OPERABLE. The vital DC electrical power system provides normal and emergency DC electrical power for the emergency auxiliaries, and control and switching during all MODES of operation. The DG battery systems provide DC power for the DGs.
The OPERABILITY of the DC sources is consistent with the initial assumptions of the accident analyses and the requirements for the supported systems OPERABILITY.
The OPERABILITY of the minimum DC electrical power sources during MODES 5 and 6, and during movement of irradiated fuel assemblies ensures that:
: a. The plant can be maintained in the shutdown or refueling condition for extended periods;
: b. Sufficient instrumentation and control capability is available for monitoring and maintaining the plant status; and
: c. Adequate DC electrical power is provided to mitigate events postulated during shutdown, such as a fuel handling accident.
The DC sources satisfy Criterion 3 of 10 CFR 50.36(c)(2)(ii).
(continued)
Watts Bar - Unit 2                        B 3.8-68                                Revision XX
 
DC Sources - Shutdown B 3.8.5 BASES (continued)
LCO                The 125V Vital DC electrical power subsystems, each vital subsystem channel consisting of a battery bank, associated battery charger, and the corresponding control equipment and interconnecting cabling within the channel; and the DG DC electrical power subsystems, each consisting of a battery, a battery charger, and the corresponding control equipment and interconnecting cabling, are required to be OPERABLE to support required subsystems of the distribution systems required OPERABLE by LCO 3.8.10, Distribution Systems - Shutdown and the required DGs required OPERABLE by LCO 3.8.2, AC Sources - Shutdown. As a minimum, one vital DC electrical power subsystem (i.e., Channels I and III, or II and IV) and two DG DC electrical power subsystems (i.e., 1A-A and 2A-A or 1B-B and 2B-B) shall be OPERABLE. This ensures the availability of sufficient DC electrical power sources to operate the plant in a safe manner and to mitigate the consequences of postulated events during shutdown (e.g., fuel handling accidents).
The LCO is modified by one Note. The Note indicates that Vital Battery V may be substituted for any of the required vital batteries. However, the fifth battery cannot be declared OPERABLE until it is connected electrically in place of another battery and it has satisfied applicable Surveillance Requirements.
APPLICABILITY      The DC electrical power sources required to be OPERABLE in MODES 5 and 6, and during movement of irradiated fuel assemblies, provide assurance that:
: a. Required features needed to mitigate a fuel handling accident are available;
: b. Required features necessary to mitigate the effects of events that can lead to core damage during shutdown are available; and
: c. Instrumentation and control capability is available for monitoring and maintaining the plant in a cold shutdown condition or refueling condition.
The DC electrical power requirements for MODES 1, 2, 3, and 4 are covered in LCO 3.8.4.
(continued)
Watts Bar - Unit 2                          B 3.8-69                                Revision XX
 
DC Sources - Shutdown B 3.8.5 BASES (continued)
ACTIONS            A.1, A.2, and A.3 Condition A represents one subsystem with one or two battery charger(s) inoperable (e.g., the voltage limit of SR 3.8.4.1 is not maintained). The ACTIONS provide a tiered response that focuses on returning the battery to the fully charged state and restoring a fully qualified charger to OPERABLE status in a reasonable time period. Required Action A.1 requires that the battery terminal voltage be restored to greater than or equal to the minimum established float voltage within 2 hours. This time provides for returning the inoperable charger to OPERABLE status or providing an alternate means of restoring battery terminal voltage to greater than or equal to the minimum established float voltage. Restoring the battery terminal voltage to greater than or equal to the minimum established float voltage provides good assurance that, within 12 hours, the battery will be restored to its fully charged condition (Required Action A.2) from any discharge that might have occurred due to the charger inoperability.
A discharged battery having terminal voltage of at least the minimum established float voltage indicates that the battery is on the exponential charging current portion (the second part) of its recharge cycle. The time to return a battery to its fully charged state under this condition is simply a function of the amount of the previous discharge and the recharge characteristic of the battery. Thus there is good assurance of fully recharging the battery within [12] hours, avoiding a premature shutdown with its own attendant risk.
If established battery terminal float voltage cannot be restored to greater than or equal to the minimum established float voltage within 2 hours, and the charger is not operating in the current-limiting mode, a faulty charger is indicated. A faulty charger that is incapable of maintaining established battery terminal float voltage does not provide assurance that it can revert to and operate properly in the current limit mode that is necessary during the recovery period following a battery discharge event that the DC system is designed for.
If the charger is operating in the current limit mode after 2 hours that is an indication that the battery is partially discharged and its capacity margins will be reduced. The time to return the battery to its fully charged condition in this case is a function of the battery charger capacity, the amount of loads on the associated DC system, the amount of the previous discharge, and the recharge characteristic of the battery. The charge time can be extensive, and there is not adequate assurance that it can be recharged within 12 hours (Required Action A.2).
Required Action A.2 requires that the battery float current be verified as less than or equal to 2 amps. This indicates that, if the battery had been discharged as the result of the inoperable battery charger, it has now Watts Bar - Unit 2                        B 3.8-70                                  Revision XX
 
DC Sources - Shutdown B 3.8.5 BASES (continued)
ACTIONS            A.1, A.2, and A.3 (continued) been fully recharged. If at the expiration of the initial 12 hour period the battery float current is not less than or equal to 2 amps this indicates there may be additional battery problems and the battery must be declared inoperable.
Required Action A.3 limits the restoration time for the inoperable battery charger to 7 days. This action is applicable if an alternate means of restoring battery terminal voltage to greater than or equal to the minimum established float voltage has been used (e.g., balance of plant non-Class 1E battery charger). The 7 day Completion Time reflects a reasonable time to effect restoration of the qualified battery charger to OPERABLE status.
B.1, B.2.1, B.2.2, B.2.3, and B.2.4 If two subsystems are required by LCO 3.8.10, the remaining subsystem with DC power available may be capable of supporting sufficient systems to allow continuation of CORE ALTERATIONS and fuel movement. By allowing the option to declare required features inoperable with the associated vital DC power source(s) inoperable, appropriate restrictions will be implemented in accordance with the affected required features LCO ACTIONS. In many instances, this option may involve undesired administrative efforts. Therefore, the allowance for sufficiently conservative actions is made (i.e., to suspend CORE ALTERATIONS, movement of irradiated fuel assemblies, and operations involving positive reactivity additions). The Required Action to suspend positive reactivity additions does not preclude actions to maintain or increase reactor vessel inventory, provided the required SDM is maintained.
Suspension of these activities shall not preclude completion of actions to establish a safe conservative condition. These actions minimize probability of the occurrence of postulated events. It is further required to immediately initiate action to restore the required vital DC electrical power subsystems and to continue this action until restoration is accomplished in order to provide the necessary DC electrical power to the plant safety systems.
The Completion Time of immediately is consistent with the required times for actions requiring prompt attention. The restoration of the required vital DC electrical power subsystems should be completed as quickly as possible in order to minimize the time during which the plant safety systems may be without sufficient power.
Watts Bar - Unit 2                        B 3.8-71                                  Revision XX
 
DC Sources - Shutdown B 3.8.5 BASES (continued)
ACTIONS            C.1 If one or more DG DC electrical power subsystem cannot be restored to OPERABLE status in the associated Completion Time, the associated DG may be incapable of performing its intended function and must be immediately declared inoperable. This declaration also requires entry into applicable Conditions and Required Actions for an inoperable DG, LCO 3.8.2, AC Sources - Shutdown.
SURVEILLANCE      SR 3.8.5.1 REQUIREMENTS SR 3.8.5.1 requires performance of all Surveillances required by SR 3.8.4.1 through SR 3.8.4.7. Therefore, see the corresponding Bases for LCO 3.8.4 for a discussion of each SR.
This SR is modified by a Note. The reason for the Note is to preclude requiring the OPERABLE DC sources from being discharged below their capability to provide the required power supply or otherwise rendered inoperable during the performance of SRs. It is the intent that these SRs must still be capable of being met, but actual performance is not required.
REFERENCES        1. Watts Bar FSAR, Section 15, Accident Analysis and Section 6, Engineered Safety Features.
: 2. Watts Bar FSAR, Section 8.0, Electric Power.
Watts Bar - Unit 2                        B 3.8-72                                Revision XX
 
Battery Parameters B 3.8.6 B 3.8 ELECTRICAL POWER SYSTEMS B 3.8.6 Battery Parameters BASES BACKGROUND          This LCO delineates the limits on battery float current, electrolyte temperature, electrolyte level, and float voltage for the 125V vital DC electrical power subsystem and the diesel generator (DG) batteries. A discussion of these batteries and their OPERABILITY requirements is provided in the Bases for LCO 3.8.4, DC Sources - Operating, and LCO 3.8.5, DC Sources - Shutdown. In addition to the limitations of this Specification, the Battery Monitoring and Maintenance Program also implements a program specified in Specification 5.7.2.22 for monitoring various battery parameters.
The battery cells are of flooded lead acid construction with a nominal specific gravity of 1.215. This specific gravity corresponds to an open circuit battery voltage of approximately 120 V for 60 cell battery (i.e., cell voltage of 2.063 volts per cell (Vpc)). The open circuit voltage is the voltage maintained when there is no charging or discharging. Optimal long term performance however, is obtained by maintaining a float voltage 2.20 to 2.25 Vpc. This provides adequate over-potential which limits the formation of lead sulfate and self discharge. The nominal float voltage of 2.22 Vpc corresponds to a total float voltage output of 133.2 V for a 60 cell battery as discussed in the FSAR, Chapter 8 (Ref. 3).
APPLICABLE          The initial conditions of Design Basis Accident (DBA) and transient SAFETY              analyses in the FSAR, Section 6 (Ref. 1) and Section 15 (Ref. 1), assume ANALYSES            Engineered Safety Feature systems are OPERABLE. The vital DC electrical power system provides normal and emergency DC electrical power for the emergency auxiliaries, and control and switching during all MODES of operation. The DG battery systems provide DC power for the DGs.
The OPERABILITY of the DC subsystems is consistent with the initial assumptions of the accident analyses and is based upon meeting the design basis of the plant. This includes maintaining at least one subsystem of DC sources OPERABLE during accident conditions, in the event of:
: a. An assumed loss of all offsite AC power or all onsite AC power; and
: b. A worst case single failure.
Battery parameters satisfy the Criterion 3 of 10 CFR 50.36(c)(2)(ii).
(continued)
Watts Bar - Unit 2                          B 3.8-72                                  Revision XX
 
Battery Parameters B 3.8.6 BASES (continued)
LCO                Battery parameters must remain within acceptable limits to ensure availability of the required DC power to shut down the reactor and maintain it in a safe condition after an anticipated operational occurrence or a postulated DBA. Battery parameter limits are conservatively established, allowing continued DC electrical system function even with limits not met. Additional preventative maintenance, testing, and monitoring performed in accordance with the Battery Monitoring and Maintenance Program is conducted as specified in Specification 5.7.2.22.
APPLICABILITY      The battery parameters are required solely for the support of the associated vital DC and DG DC electrical power subsystems. Therefore, battery parameter limits are only required when the DC power source is required to be OPERABLE. Refer to the Applicability discussion in Bases for LCO 3.8.4 and LCO 3.8.5.
ACTIONS            A.1, A.2, and A.3 With one or more cells in one or more batteries in one vital DC subsystem
                  < 2.07 V, the battery cell is degraded. Within 2 hours verification of the required battery charger OPERABILITY is made by monitoring the battery terminal voltage (SR 3.8.4.1) and of the overall battery state of charge by monitoring the battery float charge current (SR 3.8.6.1). This assures that there is still sufficient battery capacity to perform the intended function.
Therefore, the affected battery is not required to be considered inoperable solely as a result of one or more cells in one or more batteries < 2.07 V, and continued operation is permitted for a limited period up to 24 hours.
Since the Required Actions only specify "perform," a failure of SR 3.8.4.1 or SR 3.8.6.1 acceptance criteria does not result in this Required Action not met. However, if one of the SRs is failed the appropriate Condition(s),
depending on the cause of the failures, is entered. If SR 3.8.6.1 is failed then there is not assurance that there is still sufficient battery capacity to perform the intended function and the battery must be declared inoperable immediately.
B.1 and B.2 One or more batteries in one vital DC subsystem with float current
                  > 2 amps indicates that a partial discharge of the battery capacity has occurred. This may be due to a temporary loss of a battery charger or possibly due to one or more battery cells in a low voltage condition reflecting some loss of capacity. Within 2 hours verification of the required battery charger OPERABILITY is made by monitoring the battery terminal voltage. If the terminal voltage is found to be less than the minimum established float voltage there are two possibilities, the battery charger is inoperable or is operating in the current limit mode. Condition A (continued)
Watts Bar - Unit 2                          B 3.8-73                                Revision XX
 
Battery Parameters B 3.8.6 BASES ACTIONS            B.1 and B.2 (continued) addresses charger inoperability. If the charger is operating in the current limit mode after 2 hours that is an indication that the battery has been substantially discharged and likely cannot perform its required design functions. The time to return the battery to its fully charged condition in this case is a function of the battery charger capacity, the amount of loads on the associated DC system, the amount of the previous discharge, and the recharge characteristic of the battery. The charge time can be extensive, and there is not adequate assurance that it can be recharged within 12 hours (Required Action B.2). The battery must therefore be declared inoperable.
If the float voltage is found to be satisfactory but there are one or more battery cells with float voltage less than 2.07 V, the associated "OR" statement in Condition H is applicable and the battery must be declared inoperable immediately. If float voltage is satisfactory and there are no cells less than 2.07 V there is good assurance that, within 12 hours, the battery will be restored to its fully charged condition (Required Action B.2) from any discharge that might have occurred due to a temporary loss of the battery charger.
A discharged battery with float voltage (the charger setpoint) across its terminals indicates that the battery is on the exponential charging current portion (the second part) of its recharge cycle. The time to return a battery to its fully charged state under this condition is simply a function of the amount of the previous discharge and the recharge characteristic of the battery. Thus there is good assurance of fully recharging the battery within 12 hours, avoiding a premature shutdown with its own attendant risk.
If the condition is due to one or more cells in a low voltage condition but still greater than 2.07 V and float voltage is found to be satisfactory, this is not indication of a substantially discharged battery and 12 hours is a reasonable time prior to declaring the battery inoperable.
Since Required Action B.1 only specifies "perform," a failure of SR 3.8.4.1 acceptance criteria does not result in the Required Action not met.
However, if SR 3.8.4.1 is failed, the appropriate Condition(s), depending on the cause of the failure, is entered.
(continued)
Watts Bar - Unit 2                          B 3.8-74                                Revision XX
 
Battery Parameters B 3.8.6 BASES ACTIONS            C.1, C.2, and C.3 With one or more cells in one or more batteries in one DG DC subsystem
                  < 2.07 V, the battery cell is degraded. Within 2 hours verification of the required battery charger OPERABILITY is made by monitoring the battery terminal voltage (SR 3.8.4.2) and of the overall battery state of charge by monitoring the battery float charge current (SR 3.8.6.2). This assures that there is still sufficient battery capacity to perform the intended function.
Therefore, the affected battery is not required to be considered inoperable solely as a result of one or more cells in one or more batteries < 2.07 V, and continued operation is permitted for a limited period up to 24 hours.
Since the Required Actions only specify "perform," a failure of SR 3.8.4.2 or SR 3.8.6.2 acceptance criteria does not result in this Required Action not met. However, if one of the SRs is failed the appropriate Condition(s),
depending on the cause of the failures, is entered. If SR 3.8.6.2 is failed then there is not assurance that there is still sufficient battery capacity to perform the intended function and the battery must be declared inoperable immediately.
D.1 and D.2 One or more batteries in one DG DC subsystem with float current
                  > 1 amps indicates that a partial discharge of the battery capacity has occurred. This may be due to a temporary loss of a battery charger or possibly due to one or more battery cells in a low voltage condition reflecting some loss of capacity. Within 2 hours verification of the required battery charger OPERABILITY is made by monitoring the battery terminal voltage. If the terminal voltage is found to be less than the minimum established float voltage there are two possibilities, the battery charger is inoperable or is operating in the current limit mode. Condition B addresses charger inoperability. If the charger is operating in the current limit mode after 2 hours that is an indication that the battery has been substantially discharged and likely cannot perform its required design functions. The time to return the battery to its fully charged condition in this case is a function of the battery charger capacity, the amount of loads on the associated DC system, the amount of the previous discharge, and the recharge characteristic of the battery. The charge time can be extensive, and there is not adequate assurance that it can be recharged within 12 hours (Required Action D.2). The battery must therefore be declared inoperable.
If the float voltage is found to be satisfactory but there are one or more battery cells with float voltage less than 2.07 V, the associated "OR" statement in Condition H is applicable and the battery must be declared inoperable immediately. If float voltage is satisfactory and there are no (continued)
Watts Bar - Unit 2                          B 3.8-75                                Revision XX
 
Battery Parameters B 3.8.6 BASES ACTIONS            D.1 and D.2 (continued) cells less than 2.07 V there is good assurance that, within 12 hours, the battery will be restored to its fully charged condition (Required Action D.2) from any discharge that might have occurred due to a temporary loss of the battery charger.
A discharged battery with float voltage (the charger setpoint) across its terminals indicates that the battery is on the exponential charging current portion (the second part) of its recharge cycle. The time to return a battery to its fully charged state under this condition is simply a function of the amount of the previous discharge and the recharge characteristic of the battery. Thus there is good assurance of fully recharging the battery within 12 hours, avoiding a premature shutdown with its own attendant risk.
If the condition is due to one or more cells in a low voltage condition but still greater than 2.07 V and float voltage is found to be satisfactory, this is not indication of a substantially discharged battery and 12 hours is a reasonable time prior to declaring the battery inoperable.
Since Required Action D.1 only specifies "perform," a failure of SR 3.8.4.2 acceptance criteria does not result in the Required Action not met.
However, if SR 3.8.4.2 is failed, the appropriate Condition(s), depending on the cause of the failure, is entered.
E.1, E.2, and E.3 With one or more required batteries in one vital DC subsystem or one DG battery with one or more cells electrolyte level above the top of the plates, but below the minimum established design limits, the battery still retains sufficient capacity to perform the intended function. Therefore, the affected battery is not required to be considered inoperable solely as a result of electrolyte level not met. Within 31 days the minimum established design limits for electrolyte level must be re-established.
With electrolyte level below the top of the plates there is a potential for dryout and plate degradation. Required Actions E.1 and E.2 address this potential (as well as provisions in Specification 5.7.2.22, Battery Monitoring and Maintenance Program). They are modified by a Note that indicates they are only applicable if electrolyte level is below the top of the plates. Within 8 hours level is required to be restored to above the top of the plates. The Required Action E.2 requirement to verify that there is no leakage by visual inspection and the Specification 5.7.2.22.b item to initiate action to equalize and test in accordance with manufacturer's recommendation. They are performed following the restoration of the electrolyte level to above the top of the plates. Based on the results of the manufacturer's recommended testing the battery(ies) may have to be declared inoperable and the affected cell(s) replaced.
(continued)
Watts Bar - Unit 2                        B 3.8-76                                  Revision XX
 
Battery Parameters B 3.8.6 BASES ACTIONS            F.1 (continued)
With one or more batteries in one vital DC subsystem or one DG battery with pilot cell temperature less than the minimum established design limits, 12 hours is allowed to restore the temperature to within limits. A low electrolyte temperature limits the current and power available. Since the battery is sized with margin, while battery capacity is degraded, sufficient capacity exists to perform the intended function and the affected battery is not required to be considered inoperable solely as a result of the pilot cell temperature not met.
G.1 With one or more batteries in redundant vital DC subsystems with battery parameters not within limits there is not sufficient assurance that battery capacity has not been affected to the degree that the batteries can still perform their required function, given that redundant batteries are involved. With redundant batteries involved this potential could result in a total loss of function on multiple systems that rely upon the batteries. With more than one DG battery with battery parameters not within limits there is not sufficient assurance that battery capacity has not been affected to the degree that the batteries can still perform their required function.
The longer Completion Times specified for battery parameters on non-redundant batteries not within limits are therefore not appropriate, and the parameters must be restored to within limits on at least one subsystem within 2 hours.
H.1 With one or more batteries with any battery parameter outside the allowances of the Required Actions for Condition A, B, C, D, E, F, or G, sufficient capacity to supply the maximum expected load requirement is not assured and the corresponding battery must be declared inoperable.
Additionally, discovering one or more vital DC batteries in one subsystem with one or more battery cells float voltage less than 2.07 V and float current greater than 2 amps, or one DG battery cells float voltage greater than or equal to 2.07 V and float current greater than 1 amp, indicates that the battery capacity may not be sufficient to perform the intended functions. The battery must therefore be declared inoperable immediately.
(continued)
Watts Bar - Unit 2                        B 3.8-77                                Revision XX
 
Battery Parameters B 3.8.6 BASES SURVEILLANCE      SR 3.8.6.1 and SR 3.8.6.2 REQUIREMENTS Verifying battery float current while on float charge is used to determine the state of charge of the battery. Float charge is the condition in which the charger is supplying the continuous charge required to overcome the internal losses of a battery and maintain the battery in a charged state.
The equipment used to monitor float current must have the necessary accuracy and capability to measure electrical currents in the expected range. The float current requirements are based on the float current indicative of a charged battery. The 7 day Frequency is consistent with IEEE-450 (Ref. 2).
SR 3.8.6.1 is modified by a Note that states the float current requirement is not required to be met when battery terminal voltage is less than the minimum established float voltage of SR 3.8.4.1. When this float voltage is not maintained the Required Actions of LCO 3.8.4 ACTION A are being taken, which provide the necessary and appropriate verifications of the battery condition. Furthermore, the float current limit of 2 amps is established based on the nominal float voltage value and is not directly applicable when this voltage is not maintained.
SR 3.8.6.2 is modified by a Note that states the float current requirement is not required to be met when battery terminal voltage is less than the minimum established float voltage of SR 3.8.4.2. When this float voltage is not maintained the Required Actions of LCO 3.8.4 ACTION D are being taken, which provide the necessary and appropriate verifications of the battery condition. Furthermore, the float current limit of 1 amp is established based on the nominal float voltage value and is not directly applicable when this voltage is not maintained.
SR 3.8.6.3 and SR 3.8.6.6 Optimal long term battery performance is obtained by maintaining a float voltage greater than or equal to the minimum established design limits provided by the battery manufacturer, which corresponds to 132 V at the battery terminals, or 2.20 Vpc. This provides adequate overpotential, which limits the formation of lead sulfate and self discharge, which could eventually render the battery inoperable. Float voltages in this range or less, but greater than 2.07 Vpc, are addressed in Specification 5.7.2.22.
SRs 3.8.6.3 and 3.8.6.6 require verification that the cell float voltages are equal to or greater than the short term absolute minimum voltage of 2.07 V. The Frequency for cell voltage verification every 31 days for pilot cell and 92 days for each connected cell is consistent with IEEE-450 (Ref.
2).
(continued)
Watts Bar - Unit 2                        B 3.8-78                                  Revision XX
 
Battery Parameters B 3.8.6 BASES SURVEILLANCE      SR 3.8.6.4 REQUIREMENTS (continued)        The limit specified for electrolyte level ensures that the plates suffer no physical damage and maintains adequate electron transfer capability. The minimum design electrolyte level is the minimum level indication mark on the battery cell jar. The Frequency is consistent with IEEE-450 (Ref. 2).
SR 3.8.6.5 This Surveillance verifies that the pilot cell temperature is greater than or equal to the minimum established design limit (i.e., 60&deg;F for vital batteries and 50&deg;F for DG batteries). Pilot cell electrolyte temperature is maintained above this temperature to assure the battery can provide the required current and voltage to meet the design requirements. Temperatures lower than assumed in battery sizing calculations act to inhibit or reduce battery capacity. The Frequency is consistent with IEEE-450 (Ref. 2).
SR 3.8.6.7 A battery performance discharge test is a test of constant current capacity of a battery, normally done in the as found condition, after having been in service, to detect any change in the capacity determined by the acceptance test. The test is intended to determine overall battery degradation due to age and usage.
Either the battery performance discharge test or the modified performance discharge test is acceptable for satisfying SR 3.8.6.7; however, only the modified performance discharge test may be used to satisfy the battery service test requirements of SR 3.8.4.7.
A modified discharge test is a test of the battery capacity and its ability to provide a high rate, short duration load (usually the highest rate of the duty cycle). This will often confirm the battery's ability to meet the critical period of the load duty cycle, in addition to determining its percentage of rated capacity. Initial conditions for the modified performance discharge test should be identical to those specified for a service test.
It may consist of just two rates; for instance the one minute rate for the battery or the largest current load of the duty cycle, followed by the test rate employed for the performance test, both of which envelope the duty cycle of the service test. Since the ampere-hours removed by a one minute discharge represents a very small portion of the battery capacity, the test rate can be changed to that for the performance test without compromising the results of the performance discharge test. The battery terminal voltage for the modified performance discharge test must remain above the minimum battery terminal voltage specified in the battery service test for the duration of time equal to that of the service test.
(continued)
Watts Bar - Unit 2                        B 3.8-79                                  Revision XX
 
Battery Parameters B 3.8.6 BASES SURVEILLANCE      SR 3.8.6.7 (continued)
REQUIREMENTS The acceptance criteria for this Surveillance are consistent with IEEE-450 (Ref. 2) and IEEE-485 (Ref. 4). These references recommend that the battery be replaced if its capacity is below 80% of the manufacturer's rating. A capacity of 80% shows that the battery rate of deterioration is increasing, even if there is ample capacity to meet the load requirements.
Furthermore, the battery is sized to meet the assumed duty cycle loads when the battery design capacity reaches this 80% limit.
The Surveillance Frequency for this test is normally 60 months. If the battery shows degradation, or if the battery has reached 85% of its expected life and capacity is < 100% of the manufacturer's rating, the Surveillance Frequency is reduced to 12 months. However, if the battery shows no degradation but has reached 85% of its expected life, the Surveillance Frequency is only reduced to 24 months for batteries that retain capacity  100% of the manufacturer's ratings. Degradation is indicated, according to IEEE-450 (Ref. 2), when the battery capacity drops by more than 10% relative to its capacity on the previous performance test or when it is  10% below the manufacturer's rating.
These Frequencies are consistent with the recommendations in IEEE-450 (Ref. 2).
This SR is modified by a Note. The reason for the Note is that performing the Surveillance would perturb the electrical distribution system and challenge safety systems. Credit may be taken for unplanned events that satisfy this SR.
REFERENCES        1. Watts Bar FSAR, Section 15, Accident Analysis, and Section 6, Engineered Safety Features.
: 2. IEEE-450-2002, "IEEE Recommended Practice for Maintenance, Testing, and Replacement of Vented Lead-Acid Batteries for Stationary Applications."
: 3. Watts Bar FSAR, Section 8, Electric Power.
: 4. IEEE-485-1983, "IEEE Recommended Practice for Sizing Large Lead Storage Batteries for Generating Stations and Substations."
Watts Bar - Unit 2                        B 3.8-80                                Revision XX
 
Enclosure 4 Regulatory Commitments Commitment                                    Due Date/Event TVA commits to include in the FSAR a requirement to              Prior to implementation of maintain a 2 percent design margin for the vital batteries        the approved TSTF-500 which corresponds to a 2 amp float current value being used      license amendment as an indication that the battery is at least 98 percent charged.
TVA commits to include in the FSAR a requirement to              Prior to implementation of maintain a 2 percent design margin for the DG batteries          the approved TSTF-500 which corresponds to a 1 amp float current value being used      license amendment as an indication that the battery is at least 98 percent charged.
TVA commits that the licensee-controlled program, required        Prior to implementation of and described in TS Section 5.7, Programs, Programs, and        the approved TSTF-500 Manuals, and titled, Battery Monitoring and Maintenance        license amendment Program, will require verification of the selection of the pilot cell or cells when performing SR 3.8.6.5.
TVA commits to a licensee-controlled program that will            Prior to implementation of require the availability of a means to charge the batteries that  the approved TSTF-500 is capable of being supplied power from a power source that      license amendment is independent of the offsite power supply.
TVA commits to verify that the equipment that will be used to    Prior to implementation of monitor float current under SR 3.8.6.1 and SR 3.8.6.2 will        the approved TSTF-500 have the necessary accuracy and capability to measure            license amendment electrical currents in the expected range. Additionally, TVA commits to verify that the minimum required procedural time to measure battery float current will be 30 seconds or as recommended by the float current measurement instrument manufacturer.
TVA commits to relocating the monitoring of battery              Prior to implementation of parameters (i.e., specific gravity, electrolyte level, cell      the approved TSTF-500 temperature, float voltage, connection resistance, and            license amendment physical condition) to the licensee-controlled program, required and described in TS Section 5.7, Programs, Programs, and Manuals, and titled the Battery Monitoring and Maintenance Program.
CNL-18-118                                        E4-1
 
Enclosure 4 Regulatory Commitments Commitment                                  Due Date/Event TVA commits to revising the FSAR to include the following:    Prior to implementation of the approved TSTF-500 How a 2 percent design margin for the vital batteries license amendment corresponds to a 2 amp float current value indicating that the battery is at least 98 percent charged.
How a 2 percent design margin for the DG batteries corresponds to a 1 amp float current value indicating that the battery is at least 98 percent charged.
How long term battery performance is obtained by maintaining a float voltage greater than or equal to the minimum established design limits provided by the battery manufacturer.
How the batteries are sized with correction margins that include temperature and aging and how these margins are maintained.
The minimum established design limit for battery terminal float voltage.
The minimum established design limit for electrolyte level.
The minimum established design limit for electrolyte temperature.
How each battery is designed with additional capacity above that required by the design duty cycles to allow for temperature variations and other factors.
Normal DC system operation i.e., powered from the battery chargers with the batteries floating on the system, and with a loss of normal power to the battery charger.
The minimum requirements for the alternate means (i.e.,
spare battery charger) that are used to obtain an extended battery charger CT.
CNL-18-118                                    E4-2
 
Enclosure 5 Letters from Battery Manufacturers Verifying the Acceptability of Using Float Current Monitoring CNL-18-118                      E5-1
 
CDTECHNOLOGIES, INC.
P o w er            Solutions 1400 Union Meeting Road Blue Bell, PA 19422 Phone: (215) 775-1306 Fax: (215) 619-7887 Sent via Email to: rnballard@tva.gov February 23, 2018 Ms. Regina Ballard Tennessee Valley Authority
 
==Subject:==
Watts Bar Nuclear Plant - Using Float Current for State of Charge
 
==Dear Regina:==
 
In regards to the C&D battery models KCR and LCUN in safety related (Class 1-E) applications at Watts Bar, it is acceptable to use float current monitoring instead of specific gravity monitoring as a reliable and accurate indication of the state of charge of the battery. This relationship remains valid for the life of these batteries.
For technical basis, please reference IEEE 450-2010, Annex A.2, which indicates in part:
A.2 Stabilized charging current used to determine a fully charged condition The pattern of charging current delivered by a conventiona l voltage-regulated charger after a discharge is the most accurate method for detem1ining the state of charge. As the cells approach full charge, the battery voltage rises to approach the charger output vo ltage, and the charging current decreases. When the charging current has stabilized at the charging vo ltage for three consecutive hourly measurements , the battery is near full charge. The expected charging current range applicable to each model may be verified by test or in consultation with the manufacturer.
I hope that this information meets your needs. If you require any additional information, please contact me.
: Regards, Kristen Jamison Nuclear Applications Engineer C&D Technologies, Inc.
 
CDTECHNOLOGIES, INC.
Power          Solutions 1400 Union Meeting Road Blue Bell, PA 19422 Phone: (215) 775-1314 Fax: (215) 619-7887 Sent via Email to: tcwalker@tva.gov May 30, 2013 Mr. Tim Walker Watts Bar Nuclear Plant Tennessee Valley Authority
 
==Subject:==
Use of Float Current to Determine Operability Revision of Letter dated February 22, 2013
 
==Dear Tim:==
 
The following statements are based on a battery temperature of 77F.
For the LCUN-33 batteries, when the float current drops to less than or equal to 2 amps, the battery would have been at least 98% recharged.
For the KCR-7 batteries, when the float current drops to less than or equal to 1 amp, the battery would have been at least 98% recharged.
This relationship will not change as the batteries age.
These values of float current are also valid if the float voltage has been adjusted to compensate for battery temperatures that are above or below 77F. See C&Ds Installation and Operating Manual (RS-1476) at the following link for recommended temperature compensation factors.
http://cdtechno.com/pdf/ref/rs_1476_0610.pdf I hope that this information meets your needs. If you require any additional information, please contact me.
: Regards, Larry A. Carson Nuclear Product Manager C&D Technologies, Inc.
 
Enclosure 6 Evaluation of an Extended Completion Time for Technical Specification 3.8.4, Required Action A.3 The Vital 125 volt (V) DC Control Power System is a Class 1E DC electrical power system that provides control power to the emergency alternating current (AC) power system. The 125 V DC vital control power system is composed of four channels (Channels I, II, III, and IV) in two trains (Channels I and III in Train A and Channels II and IV in Train B), which are shared by both WBN Units 1 and 2. Each channel consists of a battery charger that supplies normal DC power, a battery for emergency DC power, and a battery board that facilitates load grouping and provides circuit protection.
Vital Battery Boards I, II, III, and IV have manual access to two spare (backup) chargers for use upon loss of the normal charger. Each pair of spare chargers is mechanically interlocked such that only one charger in each pair can be utilized at a time. Additionally, Vital Battery Boards I, II, III, and IV have manual access to a fifth 125V DC Vital Battery System, and is intended to serve as a replacement for any one of the four 125V DC vital batteries during testing, maintenance, and outages with no loss of system reliability under any mode of operation.
During normal operation the DC load is powered from the battery chargers with the batteries floating on the system. In case of loss of normal power to the battery charger, the DC load is automatically powered from the station batteries.
Each battery is separately housed in a ventilated room apart from its charger and distribution centers. Each subsystem is located in an area separated physically and electrically from the other subsystem to ensure that a single failure in one subsystem does not cause a failure in a redundant subsystem. There is no sharing of dedicated components between redundant Class 1E subsystems, such as batteries, battery chargers, or distribution panels.
With the batteries in the fully charged condition, the system has the capacity to supply the required loads for a minimum of four hours with a loss of all AC power. Each battery is designed with additional capacity above that required by the design duty cycles to allow for temperature variations and other factors.
Each DC electrical power subsystem battery charger has ample power output capacity for the steady state operation of connected loads required during normal operation, while at the same time maintaining its battery bank fully charged. Each battery charger also has sufficient excess capacity to restore the battery from the design minimum charge to its fully charged state while supplying normal steady state loads.
Each battery charger is normally in the float-charge mode. Float-charge is the condition in which the charger is supplying the connected loads and the battery cells are receiving adequate current to optimally charge the battery. The purpose of the float-charge is to overcome the internal losses of the battery such that the battery is maintained in a fully charged state.
The normal supply of DC current to the vital battery boards is from the battery charger in each channel. Each charger maintains a float voltage of approximately 135 volts on the associated battery board with the battery connected to the board and is capable of maintaining 140 volts during an equalizing charge period (all loads can tolerate the 140 volt equalizing voltage). The charger supplies normal steady state DC load demand on the battery board and maintains the battery in a charged state. Normal recharging of the battery from the design discharged condition can be accomplished in approximately 12 hours (with accident loads being supplied) following a 30 minute AC power outage and in approximately 36 hours (with normal loads being CNL-18-118                                      E6-1
 
Enclosure 6 Evaluation of an Extended Completion Time for Technical Specification 3.8.4, Required Action A.3 supplied) following a 4-hour AC power outage. The battery chargers, including the spare chargers if in service, are automatically loaded on the diesel generators for a loss of offsite power event. Two pairs of spare chargers are available for the four channels (two each for two channels). Each spare charger can be connected to either of its two assigned channels.
AC power for each charger is derived from the station auxiliary power system via two 480V AC 3-phase circuits which are physically and electrically independent. Each circuit has access to a preferred (offsite) and a standby (onsite) source. If the normal circuit supplying a charger is unavailable, the alternate circuit is selected by a manual transfer. The transfer switches are mechanically interlocked to prevent closing switches in a manner to parallel both feeds. The alternate 480V feeder breakers are verified open in accordance with the TSs. Each charger is equipped with a DC voltmeter, DC ammeter, and charger abnormal alarm. Malfunction of a charger is annunciated in the Main Control Room. Upon loss of normal power to a charger, each may be energized from the standby power system.
Chargers I, II, III, IV, and V are solid-state type devices that convert a 3-phase 480V AC input to a nominal 125V DC output having a rated capacity of 200 amperes. Over this output current range, the DC output voltage will vary no more than +/-1.0% for a supply voltage amplitude variation of +/- 7.5% and frequency variation of +/- 2.0%.
The operational features of the chargers include:
(1)    float and equalize modes of operation, (2)    output voltage adjustable over the range of 125 to 140 volts, (3)    a current limit feature which limits continuous overload operation to 125% of rated output, (4)    protective devices which prevent a failed charger from discharging its associated battery and protect the charger from external overloads, (5)    metering and alarm circuits to monitor the charger output, (6)    parallel operation capability, and (7)    high voltage cutout function that will trip the output breaker in the event there is an over-voltage condition.
The chargers normally operate in the float mode at 135V for Batteries I-IV and 139.5V for Battery V. The maximum equalizing voltage for batteries I-IV is 140V when connected to the distribution system. The system configuration, using substitution of Battery V, permits off-line equalization at higher than normal values.
Onsite Standby Diesel Generator System The Standby Diesel Generator (SDG) system serves as the plant emergency standby alternating current (AC) power source. It is designed, installed and tested to requirements necessary to assure its availability. Its sole purpose is for emergency power in case of a loss of offsite power.
The WBN SDG system consists of four self-contained, water-cooled, automatic starting, diesel engine driven, stationary electric generators. Two diesel generators (DGs) powering the same load group (i.e., both 1A and 2A, or both 1B and 2B) are required to mitigate a design basis event (DBE). Redundancy for single failure is provided by maintaining four DGs in ready condition for automatic start.
CNL-18-118                                        E6-2
 
Enclosure 6 Evaluation of an Extended Completion Time for Technical Specification 3.8.4, Required Action A.3 Each DG consists of two 16-cylinder engines directly connected to a common 6.9 kV generator with exciter. Each DG is capable of starting and accelerating to rated speed within 10 seconds to provide power to the needed engineered safety features and shutdown loads. Each DG has a "continuous" and "short time" rating of 4400kW-5500 kVA and 4840kW-6050 kVA, respectively.
CNL-18-118                                    E6-3}}

Latest revision as of 08:56, 5 January 2025

Application to Revise Technical Specifications Regarding DC Electrical Systems TStf-500, Revision 2, DC Electrical Rewrite - Update to TSTF-360 (WBN-TS-18-09)
ML18334A389
Person / Time
Site: Watts Bar  Tennessee Valley Authority icon.png
Issue date: 11/29/2018
From: Henderson E
Tennessee Valley Authority
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
CNL-18-118, WBN-TS-18-09
Download: ML18334A389 (225)
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