CNL-18-121, Response to Request for Additional Information Regarding Application to Modify Watts Bar Nuclear Plant, Units 1 and 2 Technical Specifications 3.8.9 Regarding Alternating Current (AC) Vital Buses (WBN-TS-17-19)

Response to Request for Additional Information Regarding Application to Modify Watts Bar Nuclear Plant, Units 1 and 2 Technical Specifications 3.8.9 Regarding Alternating Current (AC) Vital Buses (WBN-TS-17-19)

ML18313A214
Person / Time
Site:	Watts Bar
Issue date:	11/09/2018
From:	Henderson E Tennessee Valley Authority
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
CNL-18-121, EPID L-2018-LLA-0050
Download: ML18313A214 (18)

Text

Tennessee Valley Authority, 1101 Market Street, Chattanooga, Tennessee 37402 CNL-18-121 November 9, 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 NRC Docket No. 50-390 Watts Bar Nuclear Plant, Unit 2 Facility Operating License No. NPF-96 NRC Docket No. 50-391

Subject:

Response to Request for Additional Information Regarding Application to Modify Watts Bar Nuclear Plant, Units 1 and 2 Technical Specifications 3.8.9 Regarding Alternating Current (AC) Vital Buses (WBN-TS-17-19) (EPID L-2018-LLA-0050)

References:

1. TVA Letter to NRC, CNL-17-119, Application to Modify Watts Bar Nuclear Plant, Units 1 and 2 Technical Specifications 3.8.9 Regarding Alternating Current (AC) Vital Buses (WBN-TS-17-19), dated February 28, 2018 (ML18060A337)

2. NRC Electronic Mail to TVA, WATTS BAR Units 1 and 2 - Modify TS 3.8.9 Completion Time for Inoperable 120 VAC Vital Buses (L-2018-LLA-0050, dated September 26, 2018 (ML18270A236)

3. NRC Electronic Mail to TVA, RE: Extension for the RAI response on the 120V AC LAR, dated October 29, 2018 In Reference 1, Tennessee Valley Authority (TVA) submitted for Nuclear Regulatory Commission (NRC) approval, a request for an amendment to Facility Operating License Nos. NPF-90 and NPF-96 for Watts Bar Nuclear Plant (WBN) Units 1 and 2, respectively, to revise the WBN Units 1 and 2 Technical Specification (TS) 3.8.9 to add a new Condition C with an eight-hour completion for performing maintenance on the opposite units vital bus when the opposite unit is in Mode 5, Mode 6, or defueled.

In Reference 2, the Nuclear Regulatory Commission (NRC) transmitted a request for additional information (RAI) and requested a response by October 31, 2018. In Reference 3, the NRC granted an extension of the due date for the RAI response to November 9, 2018. Enclosure 1 to this letter provides the TVA response to the RAI.

U.S. Nuclear Regulatory Commission CNL-18-121 Page 2 November 9, 2018 As noted in Enclosure 1 to this letter, the response to EEOB RAl-1 requires a revision to the proposed changes to WBN Units 1 and 2 TS 3.8.9, "Distribution Systems - Operating," that were provided in Reference 1. Accordingly, Enclosure 2 to this letter provides the WBN Units 1 and 2 TS 3.8.9 pages marked up to show the proposed changes. Enclosure 3 to this letter provides the existing WBN Units 1 and 2 TS 3.8.9 pages retyped to show the changes incorporated. Enclosures 2 and 3 to this letter supersede the proposed WBN Units 1 and 2 TS 3.8.9 pages provided in Reference 1.

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

There are no new regulatory commitments associated with this submittal. Please address any questions regarding this request to Michael A. Brown at 423-751-3275.

I declare under penalty of perjury that the foregoing is true and correct. Executed on this 9th day of November 2018.

• Respectfully,

~¢<.t)h____

E. K. Henderson Director, Nuclear Regulatory Affairs

Enclosures:

1. Response to Request for Additional Information Regarding Application to Modify Watts Bar Nuclear Plant, Units 1 and 2 Technical Specifications 3.8.9 Regarding Alternating Current (AC) Vital Buses (WBN-TS-17-19) (EPI D L-2018-LLA-0050)

2. Proposed TS 3.8.9 Changes (Markups) for WBN Units 1 and 2

3. Proposed TS 3.8.9 Changes (Final Typed) for WBN Units 1 and 2 cc (see page 3) cc (Enclosures):

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

Enclosure 1 Response to Request for Additional Information Regarding Application to Modify Watts Bar Nuclear Plant, Units 1 and 2 Technical Specifications 3.8.9 Regarding Alternating Current (AC)

Vital Buses (WBN-TS-17-19) (EPID L-2018-LLA-0050)

By letter dated February 28, 2018 (Agencywide Documents Access management System (ADAMS) Accession No. ML18060A337), Tennessee Valley Authority (TVA, the licensee),

requested an amendment to Operating Licenses NPF-90 and NPF-96 for Watts Bar Nuclear Plant (WBN), Units 1 and 2. The proposed amendment would revise the Technical Specifications (TS) 3.8.9, Distribution Systems - Operating, with regard to the completion times (CTs) for restoring one or more inoperable alternate current (AC) vital bus(es) in one channel of the opposite unit to operable status. Specifically, the proposed changes would add to TS 3.8.9 one new Condition C with an eight-hour CT for performing maintenance on the opposite units AC vital bus when the opposite unit is in Modes 5-6 and defueled; and one new Condition D with a two-hour CT for restoring to operable status the opposite unit AC vital bus when it is inoperable for reasons other than planned maintenance.

The Electrical Engineering Operating Branch (EEOB) staff has determined that the following additional information is needed to complete the review of the WBN license amendment request (LAR).

Regulatory Requirements Title 10 of the Code of Federal Regulations (10 CFR) Part 50.36, Technical Specifications, requires, in part, that the operating license of a nuclear production facility include TS. 10 CFR 50.36 (c)(2) requires that the TS include limiting conditions for operation (LCOs) which are the lowest functional capability or performance levels of equipment required for safe operation of the facility. When an LCO of a nuclear reactor is not met, the licensee shall shut down the reactor or follow any remedial action permitted by the technical specifications until the condition can be met.

EEOB RAI - 1 The licensee proposed Conditions C and D that would be applicable when the AC vital bus(es) in the opposite unit are inoperable. The proposed Required Action C.1 for Condition C would require the restoration of the inoperable opposite unit AC vital bus to operable status within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> during planned maintenance of the opposite unit AC vital bus when the opposite unit is in Mode 5, 6, or defueled. The proposed Required Action D.1 for Condition D would require the restoration of the inoperable opposite unit AC vital bus(es) to operable status within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> and 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> from discovery of failure to meet LCO when the opposite unit AC vital bus is inoperable for reasons other than planned maintenance.

LAR Section 3.1, System Description of Electrical Power Distribution System states:

The AC sources for [the safety-related systems shared between the units] loads are supplied from A Train and B Train AC electrical power subsystems from either one or both units. Therefore, in addition to requiring the associated units AC electrical power subsystems to be operable, the opposite units AC electrical power subsystems supplying power to a required shared load are also required to be operable.

CNL-18-121 E1-1 of 6

Enclosure 1 The NRC staff notes that for the AC vital electrical power distribution system, the Train A consists of AC vital buses channels 1-I, 2-I, 1-III, and 2-III, and the Train B consists of AC vital buses channels 1-II, 2-II, 1-IV, and 2-IV. This makes a total of 8 channels of AC vital bus electrical power distribution subsystems for both Train A and Train B. In addition, the proposed Conditions C and D with associated Required Actions would imply that the operability of the AC vital buses in the opposite unit would be required by the operable units LCO 3.8.9 in Modes 1, 2, 3 and 4. However, the WBN current TS LCO 3.8.9 identifies only 4 channels of AC vital bus electrical power distribution subsystems to be operable for one unit (e.g., WBN-1) in Modes 1 - 4 and does not identify the AC vital bus electrical power distribution subsystems from the opposite unit (e.g., WBN-2).

10 CFR 50.36 (c)(2) requires the TS to include LCOs which are the lowest functional capability or performance levels of equipment required for safe operation of the facility. Since the opposite units channels of AC vital bus electrical power distribution subsystems supplying power to safety-related shared systems are required for the safe operation of the WBN units during Modes 1 - 4, as implied in Conditions C and D, LCO 3.8.9 would require 8 channels of AC vital bus electrical power distribution subsystems, for both Train A and B to be operable, instead of the 4 channels of AC vital bus electrical power distribution subsystems identified in the current LCO 3.8.9.

Provide a discussion that addresses this discrepancy.

TVA Response to EEOB RAI-1 WBN Units 1 and 2 TS 3.8.9 Bases include Table B 3.8.9-1, which identifies the required WBN 1 and 2 AC, direct current (DC), and vital AC buses for the Train A and Train B electrical power distribution subsystems. The required AC vital buses listed in WBN Units 1 and 2 TS Bases Table B 3.8.9-1 are vital buses 1-I, 2-I, 1-III, and 2-III (Train A) and vital buses 1-II, 2-II, 1-IV, and 2-IV (Train B). The current WBN Units 1 and 2 TS LCO 3.8.9 states, Train A and Train B AC, four channels of vital DC, and four channels of AC vital bus electrical power distribution subsystems shall be OPERABLE. This statement is inconsistent with the number of AC vital buses listed in TS Bases Table B 3.8.9-1.

The table provided in the response to EEOB RAI-2 indicates that AC vital channels 1-I and 1-II feed TS-required common equipment loads to the opposite unit when it is in operation.

Currently, there are no TS required common loads fed from AC vital channels 1-III, 1-IV, 2-I, 2-II, 2-III, and 2-IV. Therefore, when a unit is operating in Modes 1, 2, 3, or 4, the vital AC channels required to be operable includes the four associated units AC vital channels and the opposite unit AC vital channels that are required to support TS required common loads.

Requiring all eight AC vital channels for each unit to be operable exceeds the requirement to provide the lowest functional capability required for safe operation, however it provides flexibility to reassign loads between AC vital channels, if desired.

NUREG-1431, Revision 4, Standard Technical Specifications Westinghouse Plants, LCO 3.8.9 states, Train A and Train B AC, DC, and AC vital bus electrical power distribution subsystems shall be OPERABLE. NUREG-1431 does not specify the number of channels for the DC and AC vital bus electrical power distribution subsystems within the LCO statement. However, NUREG-1431, TS 3.8.9 Bases include a table that lists the required AC, DC, and vital AC distribution buses.

CNL-18-121 E1-2 of 6

Enclosure 1 Therefore, TVA proposes to revise WBN Units 1 and 2 TS LCO 3.8.9 to be consistent with NUREG-1431, Revision 4. This change will defer the details of the required DC and AC vital buses to Bases Table B 3.8.9-1. See Enclosures 2 and 3 for proposed changes to LCO 3.8.9.

As stated above, the WBN Unit 1 and Unit 2 TS Bases Table 3.8.9-1 currently requires eight AC vital channels to be operable for each unit, and therefore does not require a change.

The removal of these details from the TS is acceptable, because design detail information is not necessary to be included in the TS to provide adequate protection of public health and safety.

LCO 3.8.9 retains the requirement for the required electrical power distribution subsystems to be operable. In addition, this change is acceptable because the removed information will be adequately controlled in the TS Bases. The TS Bases Control Program controls changes to the TS Bases, requiring an evaluation of changes to ensure the TS Bases are properly controlled.

EEOB RAI-2 Table 1 of the LAR shows that the 120 V vital inverters are shared between the two units.

Note 8 of Table 1 indicates that the loads associated with the shared vital inverters 1-I, 2-I, 1-II, 2-II assigned to Unit 1 are provided in Table 2 of the LAR. Table 2 of the LAR provides the TS and CTs that are applicable to the safety-related common systems. All of the applicable common systems TS CTs are greater than the proposed 8-hour CT for Condition C. In addition, the LAR states that the safety-related common loads fed from the 120 V AC vital boards are encompassed by the common systems shown in Table 2.

The NRC staff notes that Table 1 provides no indication that there are common systems fed from the shared vital inverters 1-III, 2-III, 1-IV and 2-IV. Hence, the safety-related common loads provided in Table 2 of the LAR, which TS CTs are greater than the 8-hour CT proposed for Condition C, would be fed from the 120 V AC vital boards associated with the shared vital inverters 1-I, 2-I, 1-II, 2-II. But, the UFSAR Figure 8.1-3 shows that the shared vital inverters 1-III, 2-III, 1-IV and 2-IV supply power to the AC vital channels 1-III, 2-III, 1-IV and 2-IV, respectively.

Clarify whether the AC vital channels 1-III, 2-III, 1-IV and 2-IV are required to be operable to support common loads shared by the WBN Units 1 and 2. If so, provide the common systems that are fed from the AC vital channels 1-III, 2-III, 1-IV and 2-IV and the applicable TS CTs for these common systems.

TVA Response to EEOB RAI-2 As noted in the referenced letter, TVA requested an LAR to revise the WBN Units 1 and 2 TS 3.8.9 to add a new Condition C to support maintenance of the 120-volt (V) AC vital buses when one unit is operating and the opposite unit is shutdown. Enclosure 1, Table 1, of the LAR provided a list of major safety-related systems powered from the AC electrical power distribution system. Table 1 showed the unit and train relationship of the overall electrical power to the listed safety-related systems, including the safety-related common systems shared between the units. Table 2 showed the Technical Specification applicable to the safety-related common systems. Table 1, Note 8 stated, The loads associated with the vital inverters apply to TS 3.3.7, 3.3.8, and 3.7.4, in Table 2. Note 8 was applied to 120 V Vital Inverters 1-I, 2-I, 1-II, and 2-II.

CNL-18-121 E1-3 of 6

Enclosure 1 During development of the response to EEOB RAI-2, TVA identified that the information provided in Enclosure 1, Table 1 to the LAR, required clarification. Specifically, Note 8 in , Table 1 to the LAR should have applied to inverters 1-I and 1-II. In addition, the list of TS associated with the shared loads fed from these inverters should have also included LCO 3.6.9, Emergency Gas Treatment System (EGTS), LCO 3.7.10, Control Room Emergency Ventilation System (CREVS), LCO 3.7.11, Control Room Emergency Air Temperature Control System (CREATCS), and 3.7.12, Auxiliary Building Gas Treatment System (ABGTS). Additionally, inoperable AC Vital channels 1-I and 1-II also affect the Auxiliary Air Control System (ACAS). ACAS is a non-TS support system that provides essential air to components in EGTS, ABGTS, CREVS, and CREATCS. In addition, ACAS also provides essential air to TS-required components associated with LCO 3.7.4, Atmospheric Dump Valves (ADV), and LCO 3.7.5, Auxiliary Feedwater System (AFW).

The following table indicates the TS required common equipment loads supplied by AC vital channels 1-I and 1-II when the opposite unit is in operation. Currently, there are no TS required common loads fed from AC vital channels 1-III, 1-IV, 2-I, 2-II, 2-III, and 2-IV.

AC Vital Opposite Unit LCO and CT with System loads Channel one train inoperable 1-I ACAS (affects ADVs, AFW, and systems below) LCOs 3.7.4 and 3.7.5 - 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> EGTS LCO 3.6.9 - 7 days ABGTS LCOs 3.3.8 and 3.7.12 - 7 days CREVS LCOs 3.3.7 and 3.7.10 - 7 days CREATCS LCO 3.7.11 - 30 days 1-II ACAS (affects ADVs, AFW, and systems below) LCOs 3.7.4 and 3.7.5 - 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> EGTS LCO 3.6.9 - 7 days ABGTS LCOs 3.3.8 and 3.7.12 - 7 days CREVS LCOs 3.3.7 and 3.7.10 - 7 days CREATCS LCO 3.7.11 - 30 days Reference TVA Letter to NRC, CNL-17-119, Application to Modify Watts Bar Nuclear Plant, Units 1 and 2 Technical Specifications 3.8.9 Regarding Alternating Current (AC) Vital Buses (WBN-TS 19), dated February 28, 2018 (ML18060A337)

EEOB RAI-3 The proposed TS Condition C would allow 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> to restore one opposite unit AC vital bus in one channel to operable status during planned maintenance of the opposite unit AC vital bus in Mode 5, Mode 6, or defueled. In addition, if the opposite units vital bus would be inoperable for reasons other than planned maintenance, the proposed new Condition D would require 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> for restoration of the inoperable opposite unit AC vital bus to operable status.

LAR Section 3.2.1, Assessment of Maintenance of the 120V AC Vital Buses, states:

With one unit operating, the proposed new Condition C establishes an eight-hour completion time when performing planned maintenance on the opposite units 120V AC vital buses when the opposite unit is in Modes 5 or 6 or defueled.

CNL-18-121 E1-4 of 6

Enclosure 1 LAR Section 3.2.3, Safety Assessment of the Proposed Technical Specification Changes, states the following as a justification for the proposed changes:

The opposite unit's AC vital buses are not as critical to the operating unit (fewer operating unit loads) as the operating unit's AC vital buses.

The NRC staff notes that the opposite units AC vital buses are required to power the safety-related common systems that are shared with the operating unit, and the impact of not having the common systems required by the operating unit during entry into Condition C is not clearly discussed in the LAR. To allow the NRC staff to evaluate the technical adequacy of the 8-hour CT for Condition C based on the above statements, provide the following information:

a- Explain why the opposite unit's AC vital buses are considered as not as critical to the operating unit as the operating unit's AC vital buses.

b- Provide a discussion about the impact of having one opposite unit AC vital bus in one channel inoperable (proposed Condition C) on the operating units safety-related systems and its response if the following conditions would occur:

• The worst case design basis event in the operating unit

• The worst case design basis event concurrent with the failure of another AC vital bus in the operating unit. If there would be a potential loss of safety functions, provide a discussion of the compensatory measures, equipment alignment, and procedures that are or will be in place to address the potential consequences to the operating unit.

TVA Response to EEOB RAI-3

a. The proposal to allow an opposite units vital AC bus to be inoperable for eight hours with the opposite unit in Mode 5, Mode 6, or defueled will allow for the performance of maintenance that will ensure continued system reliability. The proposed completion time of eight hours takes into account that the opposite units AC vital buses only feed shared systems associated with the operating unit and that the shared systems are fully redundant, as indicated in Enclosure 1, Table 1 to the referenced letter. In addition, as indicated in the response to EEOB RAI-2, the proposed completion time of eight hours for an inoperable AC vital bus is bounded by the completion time for each common load that would be affected when AC vital channel 1-I or 1-II is inoperable. Currently, there are no TS required common loads fed from AC vital channels 1-III, 1-IV, 2-I, 2-II, 2-III, and 2-IV.

b. As shown in Enclosure 1, Table 1, to the referenced letter (as revised by the response to EEOB RAI-2 above), the loads powered from an opposite unit AC vital bus consist of systems common to both units. There are no common system loads powered across the units, such that a loss of an operating unit AC vital channel during maintenance on a shutdown units AC vital channel would result in a loss of safety function. However, when either AC vital channel 1-I or 1-II is inoperable for maintenance, one train of ACAS is inoperable, thereby affecting the operability of one train of CREVS, CREATCS, EGTS, ABGTS, ADV and AFW on the operating unit.

The worst case design basis event is a loss of coolant accident. If a loss of a Unit 2 AC vital channel on the opposite train were to occur during the maintenance window (eight hours), a loss of safety function could occur for each of the above systems.

CNL-18-121 E1-5 of 6

Enclosure 1 The potential for occurrence of the above scenario is mitigated by the following:

• During maintenance on AC vital channel 1-I or 1-II, the respective opposite train AC vital channels will be protected for the operating unit by site-specific administrative barriers (e.g., signage) in accordance with site and corporate procedures.

• The maintenance activity on AC vital channels results in loss of the seismic qualification of the 120V AC vital panel while the panel cover is removed. During maintenance on the AC vital channels, the 120 V AC vital panel under maintenance will be continuously manned and can be restored to an operable status, if a seismic event or design basis event occurs.

In addition, the 120V AC vital panels are supplied by inverters that are uninterruptible power supplies. The system incorporates features that serve to increase the overall reliability.

Each channel has access to four power sources: two 480V AC sources, a 125V DC source, and a 120V AC regulated transformer bypass source. There are two unit inverters and a spare inverter for each channel capable of receiving power from either the 480V AC source or the 125V DC source. Each inverter has an auctioneered solid-state transfer switch between the 480V AC and 125V DC sources. The unit inverter output has an automatic make-before-break solid-state transfer to the regulated bypass source in the event of inverter failure or overload. An automatically synchronized manual transfer between the output of the inverter and the 120V AC regulated transformer bypass source and between the unit inverter system output and the spare inverter is provided, so that the inverters may be taken out of service for maintenance without interrupting power to the loads. The current limiting feature of the inverter provides self-protection from load faults. The inverters and instrumentation power boards are monitored to alert the operator of abnormalities. The distribution bus is sectionalized with coordinated fuses to prevent losing the entire board due to failure of a single branch circuit breaker. Therefore, the occurrence of a loss of an additional AC vital channel during an 8-hour maintenance activity on AC vital channels 1-I or 1-II is unlikely.

Reference TVA Letter to NRC, CNL-17-119, Application to Modify Watts Bar Nuclear Plant, Units 1 and 2 Technical Specifications 3.8.9 Regarding Alternating Current (AC) Vital Buses (WBN-TS-17-19), dated February 28, 2018 (ML18060A337)

CNL-18-121 E1-6 of 6

Enclosure 2 Proposed TS 3.8.9 Changes (Markups) for WBN Units 1 and 2 CNL-18-121

Distribution Systems-Operating 3.8.9 3.8 ELECTRICAL POWER SYSTEMS 3.8.9 Distribution Systems - Operating LCO 3.8.9 Train A and Train B AC, four channels of vital DC, and four channels of AC vital bus electrical power distribution subsystems shall be OPERABLE.

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

ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME A. One or more AC electrical A.1 Restore AC electrical power 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> power distribution distribution subsystem to subsystems inoperable. OPERABLE status. AND 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> from discovery of failure to meet LCO B. One or more Unit 1 AC B.1 Restore AC vital bus(es) to 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> vital buses in one channel OPERABLE status.

inoperable. AND 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> from discovery of failure to meet LCO

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NOTES-----------------

1. Only applicable during planned maintenance of a Unit 2 AC vital bus.

2. Only applicable when Unit 2 is in MODE 5, MODE 6 or defueled.

---

C. One Unit 2 AC vital bus in C.1 Restore the Unit 2 AC vital bus 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> one channel inoperable. to OPERABLE status.

(continued)

Watts Bar-Unit 1 3.8-41 Amendment XX

Distribution Systems-Operating 3.8.9 ACTIONS (continued)

CONDITION REQUIRED ACTION COMPLETION TIME D. One or more Unit 2 AC vital D.1 Restore the Unit 2 AC vital 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> buses in one channel bus(es) to OPERABLE status.

inoperable for reasons AND other than Condition C.

16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> from discovery of failure to meet LCO CE. One or more vital DC CE.1 Restore DC electrical power 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> electrical power distribution distribution bus to OPERABLE buses inoperable. status. AND 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> from discovery of failure to meet LCO DF. Required Action and DF.1 Be in MODE 3. 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> associated Completion Time not met. AND DF.2 Be in MODE 5. 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> EG. Two trains with one or EG.1 Enter LCO 3.0.3. Immediately more inoperable distribution subsystems that result in a loss of safety function.

SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.8.9.1 Verify correct breaker alignments and voltage to 7 days required AC, vital DC, and AC vital bus electrical power distribution subsystems.

Watts Bar-Unit 1 3.8-42 Amendment XX

Distribution Systems - Operating 3.8.9 3.8 ELECTRICAL POWER SYSTEMS 3.8.9 Distribution Systems - Operating LCO 3.8.9 Train A and Train B AC, four channels of vital DC, and four channels of AC vital bus electrical power distribution subsystems shall be OPERABLE.

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

ACTIONS COMPLETION CONDITION REQUIRED ACTION TIME A. One or more AC A.1 Restore AC electrical power 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> electrical power distribution subsystem to distribution subsystems OPERABLE status. AND inoperable.

16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> from discovery of failure to meet LCO B. One or more Unit 2 AC B.1 Restore AC vital bus(es) to 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> vital buses in one OPERABLE status.

channel inoperable. AND 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> from discovery of failure to meet LCO

---

NOTES--------------

1. Only applicable during planned maintenance of a Unit 1 AC vital bus.

2. Only applicable when Unit 1 is in MODE 5, MODE 6 or defueled.

---

C. One Unit 1 AC vital bus C.1 Restore the Unit 1 AC vital 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> in one channel bus to OPERABLE status.

inoperable.

(continued)

Watts Bar - Unit 2 3.8-37 Amendment XX

Distribution Systems - Operating 3.8.9 ACTIONS (continued)

CONDITION REQUIRED ACTION COMPLETION TIME D. One or more Unit 1 AC D.1 Restore the Unit 1 AC vital 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> vital buses in one bus(es) to OPERABLE channel inoperable for status. AND reasons other than Condition C. 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> from discovery of failure to meet LCO C.E. One or more vital DC CE.1 Restore DC electrical power 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> electrical power distribution bus to distribution buses OPERABLE status. AND inoperable.

16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> from discovery of failure to meet LCO D.F.Required Action and DF.1 Be in MODE 3. 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> associated Completion Time not met. AND DF.2 Be in MODE 5. 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> E.G. Two trains with one EG.1 Enter LCO 3.0.3. Immediately or more inoperable distribution subsystems that result in a loss of safety function.

SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.8.9.1 Verify correct breaker alignments and voltage to 7 days required AC, vital DC, and AC vital bus electrical power distribution subsystems.

Watts Bar - Unit 2 3.8-38 Amendment XX

Enclosure 3 Proposed TS 3.8.9 Changes (Final Typed) for WBN Units 1 and 2 CNL-18-121

Distribution Systems-Operating 3.8.9 3.8 ELECTRICAL POWER SYSTEMS 3.8.9 Distribution Systems - Operating LCO 3.8.9 Train A and Train B AC, vital DC, and AC vital bus electrical power distribution subsystems shall be OPERABLE.

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

ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME A. One or more AC electrical A.1 Restore AC electrical power 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> power distribution distribution subsystem to subsystems inoperable. OPERABLE status. AND 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> from discovery of failure to meet LCO B. One or more Unit 1 AC B.1 Restore AC vital bus(es) to 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> vital buses in one channel OPERABLE status.

inoperable. AND 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> from discovery of failure to meet LCO

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NOTES-----------------

1. Only applicable during planned maintenance of a Unit 2 AC vital bus.

2. Only applicable when Unit 2 is in MODE 5, MODE 6 or defueled.

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C. One Unit 2 AC vital bus in C.1 Restore the Unit 2 AC vital bus 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> one channel inoperable. to OPERABLE status.

(continued)

Watts Bar-Unit 1 3.8-41 Amendment XX

Distribution Systems-Operating 3.8.9 ACTIONS (continued)

CONDITION REQUIRED ACTION COMPLETION TIME D. One or more Unit 2 AC vital D.1 Restore the Unit 2 AC vital 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> buses in one channel bus(es) to OPERABLE status.

inoperable for reasons AND other than Condition C.

16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> from discovery of failure to meet LCO E. One or more vital DC E.1 Restore DC electrical power 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> electrical power distribution distribution bus to OPERABLE buses inoperable. status. AND 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> from discovery of failure to meet LCO F. Required Action and F.1 Be in MODE 3. 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> associated Completion Time not met. AND F.2 Be in MODE 5. 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> G. Two trains with one or G.1 Enter LCO 3.0.3. Immediately more inoperable distribution subsystems that result in a loss of safety function.

SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.8.9.1 Verify correct breaker alignments and voltage to 7 days required AC, vital DC, and AC vital bus electrical power distribution subsystems.

Watts Bar-Unit 1 3.8-42 Amendment XX

Distribution Systems - Operating 3.8.9 3.8 ELECTRICAL POWER SYSTEMS 3.8.9 Distribution Systems - Operating LCO 3.8.9 Train A and Train B AC, vital DC, and AC vital bus electrical power distribution subsystems shall be OPERABLE.

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

ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME A. One or more AC A.1 Restore AC electrical 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> electrical power power distribution distribution subsystems subsystem to OPERABLE AND inoperable. status.

16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> from discovery of failure to meet LCO B. One or more Unit 2 AC B.1 Restore AC vital bus(es) 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> vital buses in one to OPERABLE status.

channel inoperable. AND 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> from discovery of failure to meet LCO

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NOTES--------------

1. Only applicable during planned maintenance of a Unit 1 AC vital bus.

2. Only applicable when Unit 1 is in MODE 5, MODE 6 or defueled.

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C. One Unit 1 AC vital bus C.1 Restore the Unit 1 AC vital 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> in one channel bus to OPERABLE status.

inoperable.

(continued)

Watts Bar - Unit 2 3.8-37 Amendment XX

Distribution Systems - Operating 3.8.9 ACTIONS (continued)

CONDITION REQUIRED ACTION COMPLETION TIME D. One or more Unit 1 AC D.1 Restore the Unit 1 AC vital 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> vital buses in one bus(es) to OPERABLE channel inoperable for status. AND reasons other than Condition C. 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> from discovery of failure to meet LCO E. One or more vital DC E.1 Restore DC electrical power 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> electrical power distribution bus to distribution buses OPERABLE status. AND inoperable.

16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> from discovery of failure to meet LCO F. Required Action and F.1 Be in MODE 3. 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> associated Completion Time not met. AND F.2 Be in MODE 5. 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> G. Two trains with one or G.1 Enter LCO 3.0.3. Immediately more inoperable distribution subsystems that result in a loss of safety function.

SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.8.9.1 Verify correct breaker alignments and voltage to 7 days required AC, vital DC, and AC vital bus electrical power distribution subsystems.

Watts Bar - Unit 2 3.8-38 Amendment XX