CNL-16-187, Response to Request for Additional Information Regarding Request to Revise Technical Specifications for Diesel Generator Completion Time Extension for Technical Specification 3.8.1, AC Sources - Operating

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Response to Request for Additional Information Regarding Request to Revise Technical Specifications for Diesel Generator Completion Time Extension for Technical Specification 3.8.1, AC Sources - Operating
ML16343A940
Person / Time
Site: Watts Bar  
Issue date: 12/08/2016
From: James Shea
Tennessee Valley Authority
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
CNL-16-187, TAC MF7147, TAC MF7148
Download: ML16343A940 (19)
v • d • e


Text

Tennessee Valley Authority, 1101 Market Street, Chattanooga, Tennessee 37402 CNL-16-187 December 8, 2016 10 CFR 50.90 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Watts Bar Nuclear Plant, Unit 1 Facility Operating License No. NPF-90 NRC Docket No. 50-390 Watts Bar Nuclear Plant, Unit 2 Facility Operating License No. NPF-96 NRC Docket No. 50-391

Subject:

Watts Bar Nuclear Plant Units 1 and 2 - Response to Request for Additional Information Regarding Request to Revise Technical Specifications for Diesel Generator Completion Time Extension for Technical Specification 3.8.1, AC Sources - Operating (TAC Nos. MF7147 and MF7148)

Reference:

1. TVA Letter to NRC, CNL-16-040, Revised Request for License Amendments - Diesel Generator Completion Time Extension for Technical Specification 3.8.1, AC Sources - Operating (TS-WBN-15-09), dated March 11, 2016 (ML16071A456)
2. TVA Letter to NRC, CNL-16-137, Watts Bar Nuclear Plant Units 1 and 2 -

Response to Request for Additional Information Regarding Request to Revise Technical Specifications for Diesel Generator Completion Time Extension for Technical Specification 3.8.1, AC Sources - Operating (TAC Nos. MF7147 and MF7148), dated October 13, 2016 (ML16287A656

3. TVA Letter to NRC, CNL-16-173, "Correction to Watts Bar Nuclear Plant Units 1 and 2 - Response to Request for Additional Information Regarding Request to Revise Technical Specifications for Diesel Generator Completion Time Extension for Technical Specification 3.8.1, AC Sources - Operating (TAC Nos. MF7147 AND MF7148), dated November 1, 2016 (ML16307A054)
4. NRC Electronic Mail to TVA, Watts Bar Units 1 and 2 DG Completion Time Extension LAR - Follow-up Questions Related to October 13, 2016, RAI response (MF7147 and MF7148), dated November 30, 2016

U.S. Nuclear Regulatory Commission CNL-16-187 Page 2 December 8, 2016 In Reference 1, Tennessee Valley Authority (TVA) submitted a request for an amendment to the Watts Bar Nuclear Plant (WBN) Units 1 and 2 Technical Specifications (TS) to revise TS 3.8.1, "AC Sources - Operating, "to extend the completion time for one inoperable diesel generator (DG) from 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to 14 days based on the availability of an alternate alternating current (AC) power source (i.e., a 6.9 kilovolt FLEX DG). In Reference 2, TVA provided a response to a Nuclear Regulatory Commission (NRC) request for additional information (RAI). In Reference 3, TVA provided a correction to the response provided in Reference 2. In Reference 4, the NRC provided TVA with supplemental RAls based on the NRC review of the responses provided in Reference 2. The enclosure to this letter provides the TVA responses to these supplemental RAls.

There are no new regulatory commitments provided in this submittal. These responses do not change the no significant hazards considerations determination contained in Reference 1.

Please address any questions regarding this response to Edward Schrull at 423-751-3850.

I declare under penalty of perjury that the foregoing is true and correct. Executed on this 8th day of December 2016.

Respectfully, J. W. Shea Vice President, Nuclear Licensing

Enclosure:

Response to Watts Bar Nuclear Plant Units 1 and 2 Supplemental Request for Additional Information License Amendment Request to Revise Technical Specifications to Extend Inoperable Diesel Generator Completion Time Technical Specification 3.8.1, AC Sources - Operating (TAC Nos. MF7147 AND MF7148) cc (Enclosure):

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

Enclosure CNL-16-187 E-1 of 12 Response to Watts Bar Nuclear Plant Units 1 and 2 Supplemental Request for Additional Information License Amendment Request to Revise Technical Specifications to Extend Inoperable Diesel Generator Completion Time Technical Specification 3.8.1, AC Sources - Operating (TAC Nos. MF7147 AND MF7148)

Nuclear Regulatory Commission (NRC) Introduction The Tennessee Valley Authority (TVA) submitted a license amendment request (LAR) for Watts Bar Nuclear Plant (WBN) Units 1 and 2, by letter dated March 11, 2016 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML16071A456). The LAR proposed revision to Technical Specification (TS) 3.8.1, AC Sources - Operating, to extend the Completion Time (CT) for one inoperable Diesel Generator (DG) from 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to 14 days based upon the availability of a supplemental alternating current (ac) power source (i.e., a 6.9 kilovolt (kV) FLEX DG). TVA stated that the changes are requested to provide operational and maintenance flexibility. TVA stated that the proposed CT will allow sufficient time to perform planned maintenance activities that cannot be performed within a 72-hour CT.

By letter dated October 13, 2016 (ADAMS Accession No. ML16287A656), TVA provided responses to staff requests for additional information (RAIs) dated August 3, 2016. The staff has reviewed TVAs responses to the staffs RAIs and has identified draft supplemental requests for additional information as identified in the follow-up RAIs provided below.

NRC Request 1 TVA response to RAI No. 6 states (Reference Page E1-13): The timeline, based on plant procedures, for connecting the proposed 6.9 kV FLEX DG to the associated safety-related busses is shown on Figure 2, approximately 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />.

The staff requests additional information on the timeline to restore power to a 6.9 kV shutdown board from the FLEX DG, similar to the level of detail provided verbally to the staff during an October 14, 2016, teleconference to support TVAs request for a Notice of Enforcement Discretion (NOED). The NOED request was subsequently documented in TVAs letter dated October 18, 2016 (ADAMS Accession No. ML16292A827).

Tennessee Valley Authority (TVA) Response:

The requested additional information showing the timeline for restoring power to the 6.9 kilovolt (kV) and 480 volt (V) shutdown boards (SDBs) from the three (3) megawatt (MW)

FLEX diesel generator (DG) is provided in Table A to Attachment 1 to the enclosure. In accordance with the FLEX validation process validation plan OIP-8, "Restore Power to the 6.9 kV and 480V SD Boards from the 3 MW FLEX EDG," the task is assumed to start 0.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> into the event with a success criteria time limitation of 7.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />. The results of the validation process showed that the sum of the times measured during the validation process was 1.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />. With the addition of the task start time of 0.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />, the validation shows the FLEX 6.9 kV DG can repower the 6.9 kV SDBs in two hours. As shown in Table C to Attachment 1, the time of 50 minutes for subtask e, Strip 6.9 and 480V SD Bds., bounds the combined times of subtasks c and d that are performed in parallel with subtask e. Therefore, the times of subtasks c and d are not considered in the total time of two hours.

Enclosure CNL-16-187 E-2 of 12 NRC Request 2 The following pages of TVAs October 13, 2016, RAI response state that the FLEX DG will be connected within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> [Prior to 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />s], thus creating an inconsistency with the 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> timeline discussed in the follow-up Question 1 above. For example:

Page E1-8: Prior to 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, the 6.9 kV FLEX DG would be aligned to the Unit 1 6.9 kV SDB...

Page E1-8: Prior to 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, one or more 6.9 KV FLEX diesel(s) would be aligned to the Unit 2 6.9 kV SDB...

Page E1-12: Prior to 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, the FLEX DG would be aligned to the unpowered A train SDB.

Page E1-12: Prior to 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, the FLEX DG would be aligned to the unpowered 2B-B train SDB.

Please correct or clarify this inconsistency and confirm that the FLEX DG will be aligned to the appropriate shutdown bus within the 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> period discussed above and in previous communications.

TVA Response As noted in the TVA response to NRC Request 8 in the referenced letter, the WBN SBO coping duration is 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, after which an offsite power supply or another DG would be available to repower the batteries. The two-hour period discussed in the TVA response to NRC Request 1 is the time demonstrated by validation that the FLEX 6.9 kV DG can be aligned to the 6.9 kV SDBs. Therefore, there is no inconsistency regarding the two hours discussed in the TVA Response to NRC Request 1 and the four hours discussed in the above NRC Request 2.

As noted in the TVA Response to NRC Request 1, Attachment 1 to the enclosure provides the validation that the 6.9 kV FLEX DG could be aligned to the 6.9 kV SDBs within two hours.

NRC Request 3 Page E1-6 of the RAI responses states, This FSI implements FLEX strategies to place a 480 V FLEX DG in operation or to extend DC battery lifetime to 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. Extending battery lifetime is accomplished by performing a DC load shed within the first 90 minutes of the event if neither 480 V FLEX DGs can be initially placed in operation. If no 480 V FLEX DG is available when the 6.9 kV FLEX DG(s) are available, guidance is provided to power the 6.9 kV SDB(s) with the available 6.9 kV FLEX DG which would allow the 480 V SDB(s) to be energized from the 6.9 kV SDB.

Enclosure CNL-16-187 E-3 of 12 The proposed TS 3.8.1 mark-up pages do not identify the 480 V FLEX DG as a required source for the proposed LAR. Please confirm that the 480 V FLEX DGs are procedurally required to be connected to the station busses but are not credited for the purposes of this LAR, as alternate plans to load shed the DC system or connect the 6.9 kV DGs in a timely manner may be implemented in case of failure of the 480 V FLEX DGs.

TVA Response TVA confirms that the 480 V FLEX DGs are procedurally required to be connected to the station busses, but are not credited for the purposes of this license amendment request (LAR). The FLEX support instruction (FSI) 0-FSI-4, DC Bus Management/Load Shed and 480 V FLEX DG Alignment/Loading," provides direction to place the 480 V FLEX DG in operation and energize the vital batteries. Alternate guidance to load shed the DC system or connect the 6.9 kV FLEX DGs in a timely manner is provided in the event of a failure of the 480 V FLEX DGs to connect to the station busses. Therefore, the 480 V FLEX DGs are not credited for the purposes of this LAR because alternate plans to load shed the DC system or connect the 6.9 kV DGs in a timely manner may be implemented in the event of a failure of the 480 V FLEX DGs.

NRC Request 4 The staff also reviewed the information provided on page E1-9 of RAI responses and Table 3-1, 6.9 kV FLEX Diesel Generator Loads. Please provide the timeline of FLEX DG loads separately for each of the following scenarios, up to the time both units will be in cold shutdown. (Note: In the following scenarios, the staff assumes that a FLEX DG is connected to a 6.9 kV shutdown board/bus so that at least one train has a safety-related DG and a FLEX DG to provide cold shutdown of both units).

i. LOOP (both Units), when Unit 1 DG 1A-A (or 1B-B) is under maintenance, the redundant DG 1B-B (or 1A-A) fails to start (SBO Unit 1), and a Unit 2 DG 2A-A has a single failure.

ii. LOOP (both Units), SBO Unit 1, and a Unit 2 DG 2B-B has a single failure.

iii. LOOP (both Units), SBO Unit 2, and a Unit 1 DG 1A-A has a single failure.

iv. LOOP (both Units), SBO Unit 2, and a Unit 1 DG 1B-B has a single failure.

v. In addition to the major loads, provide details of any miscellaneous loads which are likely to be fed from the FLEX DG.

TVA Response The timeline of the FLEX DG loads for each of the above scenarios, up to the time both units will be in cold shutdown (CSD), is provided in Tables 1 through 4 to the enclosure. These tables represent the time for reaching CSD for the unit that experiences a station blackout (SBO).

Enclosure CNL-16-187 E-4 of 12 Each of the above scenarios is addressed as follows:

i. Refer to Table 1, Scenario I, Unit 1 SBO, 2B DG Operates ii. Refer to Table 2, Scenario II, Unit 1 SBO, 2A DG Operates iii. Refer to Table 3, Scenario III, Unit 2 SBO, 1B DG Operates iv. Refer to Table 4, Scenario IV, Unit 2 SBO, 1A DG Operates
v. The details of any miscellaneous loads that are likely to be fed from the FLEX DG are discussed below.

The governing FLEX procedures provide the flexibility to start miscellaneous loads provided that the 6.9 kV FLEX DG is monitored to ensure it is not overloaded. Only one unit accesses the available 6.9 kV FLEX DG, therefore there is margin beyond the normal design where both units are using power from the same 6.9 kV FLEX DG. The Technical Support Center (TSC) would be involved in analyzing 6.9 kV FLEX DG margin and recommending loads that should be restarted.

The below list of loads represents the most likely loads that would be considered for restart along with an explanation as to why they are likely to be started.

Normal battery charger (30 kilowatts (kW)) - If problems were encountered with operation of the FLEX 480 V DGs, then the normal battery charger could be aligned from the FLEX 6.9 kV DG. This will also power the emergency direct current (DC) lighting.

Motor driven auxiliary feedwater (MDAFW) pumps (450 kW each) - If problems were encountered in the turbine driven auxiliary feedwater (TDAFW) pump operation, the MDAFW pumps could be used. In the latter stages of cooldown, providing steam generator (SG) makeup with the TDAFW would not be possible due to low steam generator pressure. Only one MDAFW pump would be required to operate because the reactor coolant pump seals would have been cooled below temperatures associated with seal degradation.

Lower compartment coolers (54 kW each) - The lower compartment coolers could be started and stopped to control containment pressure and temperature.

Containment air return fans (75 kW each, only one would be run)- If problems were encountered restoring essential raw cooling water (ERCW) and normal containment coolers, the containment air return fans could be started and stopped to control containment pressure.

Reference TVA Letter to NRC, CNL-16-137, Watts Bar Nuclear Plant Units 1 and 2 - Response to Request for Additional Information Regarding Request to Revise Technical Specifications for Diesel Generator Completion Time Extension for Technical Specification 3.8.1, AC Sources -

Operating (TAC Nos. MF7147 and MF7148), dated October 13, 2016 (ML16287A656)

Enclosure CNL-16-187 E-5 of 12 Table 1 - Time for Reaching CSD for the Unit that has Experienced an SBO Scenario I Condition1, 2,3,4 U1 SBO, 2B DG operates KW Loading Remaining KW Capacity Common loads remaining on normal DG power F-B ERCW Pump H-B ERCW Pump B Auxiliary Air Compressor (AAC)

C-S Component Cooling System (CCS) Pump N/A N/A Flex DG loading sequence 6.9 kV power restored 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> (hrs)

N/A 3250 1st cool down plateau (420 degrees Fahrenheit (°F))

2 hrs 45 min N/A 3250 Start additional ERCW pump 2 hrs 55 minutes (min) 600 2650 Start safety injection pump 3 hrs 15 min 300 2350 Start A AAC 3 hrs 15 min 15 2335 Start additional CCS pump 3 hrs 40 min 265 2070 Stop safety injection pump 4 hrs N/A 23705 Recommence cooldown 25°F/hr 4 hrs N/A 2370 Start spent fuel cooling pump 4 hrs 10 min 75 2295 2nd cool down plateau (350°F) 7 hrs N/A 2295 TSC decision to go to CSD 9 hrs N/A 2295 Start both MDAFW pumps 9 hrs 900 1395 Recommence cooldown 25°F/hr 9 hrs N/A 1395 Start residual heat removal pump 14 hrs 300 1095 Enter CSD 15 hrs N/A 1095 Stop both MDAFW pumps 15 hrs N/A 19955

Enclosure CNL-16-187 E-6 of 12 Notes: Additional loads that would be considered for restart are shown below. Sufficient capacity remains to power loads.

1. Normal battery charger (30 kW) - If problems were encountered with operation of the FLEX 480 V DGs, then the normal battery charger could be aligned from the FLEX 6.9 kV DG. This will also power the emergency DC lighting.
2. MDAFW pumps (450 kW each) - If problems were encountered in the TDAFW pump operation, the MDAFW pumps could be used. In the latter stages of cooldown, providing SG makeup with the TDAFW would not be possible due to low steam generator pressure. Only one MDAFW pump would be required to operate because the reactor coolant pump seals would have been cooled below temperatures associated with seal degradation.
3. Lower compartment coolers (54 kW each) - The lower compartment coolers could be started and stopped to control containment pressure and temperature.
4. Containment air return fans (75 kW each, only one would be run)- If problems were encountered restoring ERCW and normal containment coolers, the containment air return fans could be started and stopped to control containment pressure.
5. This is a gain in capacity by securing the pump(s).

Enclosure CNL-16-187 E-7 of 12 Table 2 - Time for Reaching CSD for the Unit that has Experienced an SBO Scenario II Condition1, 2,3,4 U1 SBO, 2A DG operates KW Loading Remaining KW Capacity Common loads remaining on normal DG power B-A ERCW Pump D-A ERCW Pump A AAC A-A Spent Fuel Colling (SFC) Pump N/A N/A Flex DG loading sequence 6.9 kV power restored 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> N/A 3250 1st cool down plateau (420°F) 2 hr 45 min N/A 3250 Start additional ERCW pump 2 hr 55 min 600 2650 Start safety injection pump 3 hr 15 min 300 2350 Start B AAC 3 hr 15 min 15 2335 Start CCS pump 3 hr 40 min 265 2070 Stop safety injection pump 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> N/A 23705 Recommence cooldown 25°F/hr 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> N/A 2370 Start SFC pump 4 hr 10 min 75 2295 2nd cool down plateau (350°F) 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> N/A 2295 TSC decision to go to CSD 9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br /> N/A 2295 Start both MDAFW pumps 9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br /> 900 1395 Recommence cooldown 25°F/hr 9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br /> N/A 1395 Start residual heat removal pump 14 hours1.62037e-4 days <br />0.00389 hours <br />2.314815e-5 weeks <br />5.327e-6 months <br /> 300 1095 Enter CSD 15 hours1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br /> N/A 1095 Stop both MDAFW pumps 15 hours1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br /> N/A 19955

Enclosure CNL-16-187 E-8 of 12 Notes: Additional loads that would be considered for restart are shown below. Sufficient capacity remains to power loads.

1. Normal battery charger (30 kW) - If problems were encountered with operation of the FLEX 480 V DGs, then the normal battery charger could be aligned from the FLEX 6.9 kV DG. This will also power the emergency DC lighting.
2. MDAFW pumps (450 kW each) - If problems were encountered in the TDAFW pump operation, the MDAFW pumps could be used. In the latter stages of cooldown, providing SG makeup with the TDAFW would not be possible due to low steam generator pressure. Only one MDAFW pump would be required to operate because the reactor coolant pump seals would have been cooled below temperatures associated with seal degradation.
3. Lower compartment coolers (54 kW each) - The lower compartment coolers could be started and stopped to control containment pressure and temperature.
4. Containment air return fans (75 kW each, only one would be run)- If problems were encountered restoring ERCW and normal containment coolers, the containment air return fans could be started and stopped to control containment pressure.
5. This is a gain in capacity by securing the pump(s).

Enclosure CNL-16-187 E-9 of 12 Table 3 - Time for Reaching CSD for the Unit that has Experienced an SBO Scenario III Condition1, 2,3,4 U2 SBO, 1B DG operates KW Loading Remaining KW Capacity Common loads remaining on normal DG power E-B ERCW Pump G-B ERCW Pump B Station Air Compressor B-B SFC Pump N/A N/A Flex DG loading sequence 6.9 kV power restored 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> N/A 3250 1st cool down plateau (420°F) 2 hr 45 min N/A 3250 Start additional ERCW pump 2 hr 55 min 600 2650 Start safety injection pump 3 hr 15 min 300 2350 Start A and B AACs 3 hr 15 min 30 2320 Start CCS pump 3 hr 40 min 265 2055 Stop safety injection pump 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> N/A 23555 Recommence Cooldown 25°F/hr 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> N/A 2355 Start SFC pump 4 hr 10 min 75 2280 2nd cool down plateau (350°F) 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> N/A 2280 TSC decision to go to CSD 9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br /> N/A 2280 Start both MDAFW pumps 9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br /> 900 1380 Recommence cooldown 25°F/hr 9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br /> N/A 1380 Start residual heat removal pump 14 hours1.62037e-4 days <br />0.00389 hours <br />2.314815e-5 weeks <br />5.327e-6 months <br /> 300 1080 Enter CSD 15 hours1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br /> N/A 1080 Stop both MDAFW pumps 15 hours1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br /> N/A 19805

Enclosure CNL-16-187 E-10 of 12 Notes: Additional loads that would be considered for restart are shown below. Sufficient capacity remains to power loads.

1. Normal battery charger (30 kW) - If problems were encountered with operation of the FLEX 480 V DGs, then the normal battery charger could be aligned from the FLEX 6.9 kV DG. This will also power the emergency DC lighting.
2. MDAFW pumps (450 kW each) - If problems were encountered in the TDAFW pump operation, the MDAFW pumps could be used. In the latter stages of cooldown, providing SG makeup with the TDAFW would not be possible due to low steam generator pressure. Only one MDAFW pump would be required to operate because the reactor coolant pump seals would have been cooled below temperatures associated with seal degradation.
3. Lower compartment coolers (54 kW each) - The lower compartment coolers could be started and stopped to control containment pressure and temperature.
4. Containment air return fans (75 kW each, only one would be run)- If problems were encountered restoring ERCW and normal containment coolers, the containment air return fans could be started and stopped to control containment pressure.
5. This is a gain in capacity by securing the pump(s).

Enclosure CNL-16-187 E-11 of 12 Table 4 - Time for Reaching CSD for the Unit that has Experienced an SBO Scenario IV Condition1, 2,3,4 U2 SBO, 1A DG operates KW Loading Remaining KW Capacity Common loads remaining on normal DG power

  • A-A ERCW Pump C-A ERCW Pump A Station Air Compressor N/A N/A Flex DG loading sequence 6.9 kV power restored 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> N/A 3250 1st cool down plateau (420°F) 2 hr 45 min N/A 3250 Start additional ERCW pump 2 hr 55 min 600 2650 Start safety injection pump 3 hr 15 min 300 2350 Start A and B AACs 3 hr 15 min 30 2320 Start CCS pump 3 hr 40 min 265 2055 Stop safety injection pump 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> N/A 23555 Recommence Cooldown 25°F/hr 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> N/A 2355 Start SFC pump 4 hr 10 min 75 2280 2nd cool down plateau (350°F) 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> N/A 2280 TSC decision to go to CSD 9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br /> N/A 2280 Start both MDAFW pumps 9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br /> 900 1380 Recommence cooldown 25°F/hr 9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br /> N/A 1380 Start residual heat removal pump 14 hours1.62037e-4 days <br />0.00389 hours <br />2.314815e-5 weeks <br />5.327e-6 months <br /> 300 1080 Enter CSD 15 hours1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br /> N/A 1080 Stop both MDAFW pumps 15 hours1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br /> N/A 19805

Enclosure CNL-16-187 E-12 of 12 Notes: Additional loads that would be considered for restart are shown below. Sufficient capacity remains to power loads.

1. Normal battery charger (30 kW) - If problems were encountered with operation of the FLEX 480 V DGs, then the normal battery charger could be aligned from the FLEX 6.9 kV DG. This will also power the emergency DC lighting.
2. MDAFW pumps (450 kW each) - If problems were encountered in the TDAFW pump operation, the MDAFW pumps could be used. In the latter stages of cooldown, providing SG makeup with the TDAFW would not be possible due to low steam generator pressure. Only one MDAFW pump would be required to operate because the reactor coolant pump seals would have been cooled below temperatures associated with seal degradation.
3. Lower compartment coolers (54 kW each) - The lower compartment coolers could be started and stopped to control containment pressure and temperature.
4. Containment air return fans (75 kW each, only one would be run)- If problems were encountered restoring ERCW and normal containment coolers, the containment air return fans could be started and stopped to control containment pressure.
5. This is a gain in capacity by securing the pump(s).

CNL-16-187 A1-1 of 5 Watts Bar Nuclear Plant FLEX (Beyond Design Basis) Validation Process, Validation Plan OIP-8 Restore Power to the 6.9 kV Shutdown Boards from the 3 MW FLEX DG

FLEX (BEYOND DESIGN BASIS)

VALIDATION PROCESS Validation Plan No.: OIP-8 Table A - Validated Item Results Item: #8 5HVWRUH3RZHUWR.9DQG9

6'%RDUGVIURPWKH0:)/(;('*

Level:

A B

C Time Constraint:

8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> ACTION ITEM #

FROM OIP ATTACHMENT 1A TASK START TIME TIME CONSTRAINT SUCCESS CRITERIA (TIME CONSTRAINT MINUS START TIME)

RESULTS (SUM OF TIMES MEASURED DURING VALIDATION PROCESS) 8 Restore power to 6.9KV Shutdown Boards.

T=0.5 HRS Y

7.5 HRS 1.5 1.5 HR HRSS Margin = 6 hrs CNL-16-187 A1-2 of 5

FLEX (BEYOND DESIGN BASIS)

VALIDATION PROCESS Validation Plan No.: OIP-8 Table C - Validation Performance Action Item #: 8 Task: 5HVWRUH3RZHUWR.9DQG96'%RDUGVIURPWKH0:

)/(;('*

Controlling Procedure 0-FSI-5.02, 5.03, 5.04 NOTE: Non-controlling parallel results have been shaded SUBTASK NO.

SUBTASKS TO COMPLETE TASK FROM TABLE A METHOD RESOURCES RESULTS a.

Declare ELAP Longest time allowed by ECA-0.0 SRO 30 min b.

Recall NAUO to MCR and assign task Walkthrough 1 UO 3 NAUOs 15 min c.

MCR handswitch alignments.

Walkthrough 1 UO

    • 9 min, 51 sec d.

Align Kirk Keys and startup the 3 MW EDG Walkthrough 1 NAUO

    • 37 min, 21 sec e.

Strip 6.9 and 480V SD Bds.

Walkthrough 2 NAUO 50 min f.

Restore Power to 6.9 KV and 480V SD Bds Walkthrough 1 UO 2 NAUOs 8 min, 9 sec

    • Performed in parallel with NAUO boardroom breaker alignments (subtask No. e. above) which take much longer, thus this time is not factored into the final time required.

Aggregate:

      • Rounded up
      • 2 hr 2 hr CNL-16-187 A1-3 of 5

FLEX (BEYOND DESIGN BASIS)

VALIDATION PROCESS Table D - Other Considerations (if needed) x The validation assumed that this activity would be performed by minimum on staff personnel prior to any augmented staff reporting to the site.

x The time constraint for this activity is 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. This time was derived from the potential need to begin boron injection at 9.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> (See Table D of action OIP-9 for discussion). An additional hour is subtracted to allow margin for performing breaker and valve alignments prior to starting the Safety Injection Pump. An additional 30 minutes is subtracted to allow margin for alignment and start of the HP Pump should the SIP fail to operate. Reference Calculation WBN-OSG4-188, EOP Setpoints Verification Calculation for additional information.

x The time validation results for restoring power to 6.9KV and 480V Shutdown Boards is 103 minutes and 9 seconds (1.85 hours9.837963e-4 days <br />0.0236 hours <br />1.405423e-4 weeks <br />3.23425e-5 months <br />). Multiple timed walk downs were conducted, and the longest obtained time was used for this estimate. This estimate was rounded up to 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> for use in the general timeline.

x This activity is assumed to start at T+45 minutes from ELAP. This is based on: allowing 30 minutes for official declaration of ELAP, allowing time for previous dispatch of personnel to start 480V FLEX EDGs and allowing 15 minutes for recall and dispatch of personnel. At the time of direction, NAUOs will be available in Turbine Building due to previous recall to combat plant trip.

CNL-16-187 A1-4 of 5

FLEX (BEYOND DESIGN BASIS)

VALIDATION PROCESS NOTE: Refer to Appendix A for Performance Attributes that are applicable for the task/subtask being validated.

Table E - Performance Attributes CONSIDERATION OF PERFORMANCE ATTRIBUTES (5HVWRUH3RZHUWR.9DQG96'%RDUGV)

Special Equipment There is no special equipment required to complete this task. FLEX equipment required to complete this task are the 3MW FLEX EDGs and associated distribution system. Other equipment operated is permanently installed plant equipment located in protected structures.

Complexity This task is not complex and is within the existing skill set of NAUOs.

Cues and Indications This activity will be directed by FSI-5.01 upon declaration of an ELAP.

Special Fitness Issues No special fitness issues beyond those required to stand duty as a NAUO.

Environmental Factors and Accessibility Most alignments are performed completely inside the Auxiliary Building, specifically the electrical board room areas The areas are provided with DC lighting, both App R battery packs and LED lights powered by the vital batteries.

This activity requires travel to the Diesel building and the FLEX Equipment Storage Building. Travel will be by foot and no debris removal is anticipated to be required. If NAUO does not have flashlight, one can be obtained from either the 729 fire cage or the App R locker on Aux building El 737. Battery backed lighting is installed in the EDG buildings. The FLEX building has stored battery light packs that may be utilized.

Communications MCR recall of NAUO from field and field communications by radio.

Special Considerations None Table F - Conclusions Restore Power to 6.9 KV and 480V SD Boards can be accomplished within 103 min and 9 sec (1.85 hours9.837963e-4 days <br />0.0236 hours <br />1.405423e-4 weeks <br />3.23425e-5 months <br />) from the loss of station power. For use in the general timeline, this estimate has been rounded up to 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />.

Performance attributes have been reviewed per Table E and no significant challenges were identified.

The validation efforts resulted in margin judged sufficient to account for potential challenges and impacts. 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> of margin are available to perform this task.

Table G - References and Supporting Documentation 0-FSI-5.02, 6900V FLEX DG Startup and Alignment 0-FSI-5.03, 6.9kv and 480V SD Bd Alignment 0-FSI-5.04, 6900V FLEX DG Plant Equipment Loading CNL-16-187 A1-5 of 5

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