ML22300A188

License Amendment Request 10-Day Allowed Outage Time for Opposite Unit Auxiliary Feedwater Cross-Connect Capability Response to Request for Additional Information

ML22300A188
Person / Time
Site:	Surry
Issue date:	10/27/2022
From:	James Holloway Virginia Electric & Power Co (VEPCO)
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
22-306
Download: ML22300A188 (1)

Text

October 27, 2022 V IRGINIA E LEcrruc AND P OWER C O M PANY RICHMOND, VIRGINIA 2 3261 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555 VIRGINIA ELECTRIC AND POWER COMPANY SURRY POWER STATION UNITS 1 AND 2 LICENSE AMENDMENT REQUEST 10 CFR 50.90 Serial No.:

NRA/GDM:

Docket Nos.:

License Nos.:

22-306 R1 50-280 50-281 DPR-32 DPR-37 10-DAY ALLOWED OUTAGE TIME FOR OPPOSITE UNIT AUXILIARY FEEDWATER CROSS-CONNECT CAPABILITY RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION By letter dated June 20, 2022 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML22172A134), Virginia Electric and Power Company (Dominion Energy Virginia) requested an amendment to Facility Subsequent Renewed Operating License Numbers DPR-32 and DPR-37 in the form of a change to the Technical Specifications (TS) for Surry Power Station (SPS) Units 1 and 2.

The proposed change revises SPS TS 3.6.1.2 to include a 10-day Allowed Outage Time (AOT) for opposite unit Auxiliary Feedwater (AFW) cross-connect capability specific to when maintenance that would result in the inoperability of all three of the opposite unit's Auxiliary Feedwater (AFW) pumps is being performed. By letter dated August 8, 2022 (ADAMS Accession No. ML22220A216), Dominion Energy Virginia supplemented the proposed LAR to provide additional information in support of the NRC's acceptance review.

By email dated September 28, 2022, the SPS NRC Project Manager provided a request for additional information (RAI) to facilitate its review of the proposed LAR. Dominion Energy Virginia's response to the NRC RAI is provided in Attachment 1.

The information provided does not affect the conclusions of the no significant hazards consideration determination or the environmental assessment included in the June 20, 2022 LAR. Dominion Energy Virginia's request for NRC review and approval of the proposed LAR by April 30, 2023, with a 30-day implementation period is unchanged.

Serial No.22-306 Docket Nos. 50-280/281 RAI Response Page 2 of 3 If you have any further questions or require additional information, please contact Mr. Gary D. Miller at (804) 273-2771.

Respectfully,

~

James E. Holloway Vice President - Nuclear Engineering and Fleet Support Commitments contained in this letter: None Attachments:

1. Response to NRC Request for Additional Information

2. Revised Marked-up Proposed Technical Specifications Pages

3. Revised Typed Proposed Technical Specifications Pages COMMONWEAL TH OF VIRGINIA

)

)

COUNTY OF HENRICO

)

The foregoing document was acknowledged before me, in and for the County and Commonwealth aforesaid, today by Mr. James E. Holloway, who is Vice President -

Nuclear Engineering and Fleet Support, of Virginia Electric and Power Company. He has affirmed before me that he is duly authorized to execute and file the foregoing document in behalf of that company, and that the statements in the document are true to the best of his knowledge and belief.

Acknowledged before me this 21 th day of Oc:h>be -r

, 2022.

My Commission Expires: Jan':l,cml ?>lj 20'2.'i Kathryn Hill Barret Notary Public Commonwealth of Virginia Reg.No. 7905256 My Commission Expires January 31, 2024

¥<1ai&c 1J-:fdif)V)t Notary Public

cc:

U.S. Nuclear Regulatory Commission - Region II Marquis One Tower 245 Peachtree Center Avenue, NE Suite 1200 Atlanta, GA 30303-1257 Mr. L. John Klos NRC Project Manager - Surry U.S. Nuclear Regulatory Commission One White Flint North, Mail Stop 09 E-3 11555 Rockville Pike Rockville, MD 20852-2738 Mr. G. Edward Miller NRC Senior Project Manager - North Anna U.S. Nuclear Regulatory Commission One White Flint North, Mail Stop 09 E-3 11555 Rockville Pike Rockville, MD 20852-2738 NRG Senior Resident Inspector Surry Power Station State Health Commissioner Virginia Department of Health James Madison Building - 7th floor 109 Governor Street Suite 730 Richmond, VA 23219 Serial No.22-306 Docket Nos. 50-280/281 RAI Response Page 3 of 3 Serial No.22-306 Docket Nos. 50-280/281 RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION PROPOSED LICENSE AMENDMENT REQUEST 10-DA Y ALLOWED OUTAGE TIME FOR OPPOSITE UNIT AUXILIARY FEEDWATER CROSS-CONNECT CAPABILITY Virginia Electric and Power Company (Dominion Energy Virginia)

Surry Power Station Units 1 and 2

Serial No.22-306 Docket Nos. 50-280/281 RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION SURRY POWER STATION UNITS 1 AND 2

Background

By letter dated June 20, 2022 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML22172A134), Virginia Electric and Power Company (Dominion Energy Virginia) requested an amendment to Facility Subsequent Renewed Operating License Numbers DPR-32 and DPR-37 in the form of a change to the Technical Specifications (TS) for Surry Power Station (SPS) Units 1 and 2.

The proposed change revises SPS TS 3.6.1.2 to include a 10-day Allowed Outage Time (AOT) for opposite unit Auxiliary Feedwater (AFW) cross-connect capability specific to when maintenance that would result in the inoperability of all three of the opposite unit's Auxiliary Feedwater (AFW) pumps is being performed. By letter dated August 8, 2022 (ADAMS Accession No. ML22220A216), Dominion Energy Virginia supplemented the proposed LAR to provide additional information in support of the NRC's acceptance review. By email dated September 28, 2022, the NRC provided a request for additional information (RAI) to facilitate its review of the proposed LAR.

Dominion Energy Virginia's response to the NRC request for additional information is provided below.

NRC QUESTION APLB RA/ # 1 The Nuclear Regulatory Commission (NRG) has previously reviewed the Surry Power Station, Units 1 and 2, internal events, internal flooding, internal fire, and seismic probabilistic risk assessments (PRAs) for determining their acceptability to support the Surry Power Station, Units, 1 and 2, Title 10 Code of Federal Regulations (10 CFR) 50.69, "Risk-informed categorization and treatment of structures, systems and components for nuclear power reactors," license amendment request (LAR). The NRG issued its safety evaluation on December 8, 2020, Agencywide Documents Access and Management System (ADAMS) Accession No. ML20293A160.

The NRG staff concluded that the information was acceptable for that application. In this proposed LAR, the licensee referred to the aforementioned LAR for discussion on PRA technical adequacy. In Regulatory Guide (RG) 1.200, Revision 2, "An Approach for Determining the Technical Adequacy of Probabilistic Risk Assessment Results for Risk-Informed Activities," Regulatory Position 4.2 states that licensees are expected to address the need for the PRA model to represent the as-designed or as-built, as-operated plant.

Therefore, crediting previously reviewed analysis is appropriate as long as the previous technical conclusions reflect that the PRA model continues to reflect the as-built, as-operated plant for the current license amendment.

Describe upgrades made to the PRA models since the approval of the 10 CFR 50.69 LAR, and an evaluation of the impact to the current requested license amendment.

Page 1 of 6

Dominion Energy Response:

Serial No.22-306 Docket Nos. 50-280/281 Only one upgrade was made to the SPS PRA model since the approval of the 10 CFR 50.69 LAR.

This upgrade applied thermal hydraulic analysis from the GOTHIC containment analysis code to demonstrate the SPS containment would not be at risk of an overpressure failure in certain loss of coolant accident (LOCA) scenarios where the Modular Accident Analysis Program (MAAP) code predicted failure would occur. This model change had a significant impact on the plant risk profile, particularly Large Early Release Frequency (LERF) sequences caused by a small break LOCA.

For the LAR application, the dominant risk scenario is a fire or a steam line break in the main steam valve house, where the operating unit's AFW pumps are located, combined with the unavailability of the AFW cross-connect, which leaves only the Beyond Design Basis (BDB)/FLEX AFW pumps to supply the AFW function.

Therefore, LOCA scenarios are not major contributors for this application, and the PRA upgrade doesn't impact the risk insights or the acceptability of this application. The SPS PRA model with this upgrade applied can continue to be used to effectively assess configuration risk associated with the proposed 10-day AOT for opposite unit AFW cross-connect capability.

NRC QUESTION APLB RA/ # 2 The Tier 3 requirement of RG 1. 177, Revision 2, "Plant-Specific, Risk-Informed Decisionmaking: Technical Specifications," stipulates that a licensee should develop a program that ensures that the risk impact of out of service equipment is appropriately evaluated prior to performing any maintenance activity. It is unclear to the NRG staff if any of the Surry Power Station PRA modeling (initiators and mitigation) is impacted by seasonal variations.

(ij Identify any initiators and/or basic events used in the configuration risk management model that can be impacted by seasonal variations in external hazards.

If any initiators or basic events are identified, justify why seasonal variation in these events cannot impact the proposed license amendment.

(ii)

As an alternative to part (i), identify basic event logic that can be impacted by seasonal variations and the limiting condition of operations that can be impacted and propose a mechanism to ensure that model logic impacted by seasonal variations are reflected in the PRA models used in the proposed license amendment prior to implementation.

Dominion Energy Response:

(i)

Impacts due to seasonal variations to risk are accounted for in the SPS Risk Monitor Model with Indirect Effects terms that can be selected to model configuration risk.

Page 2 of 6

Serial No.22-306 Docket Nos. 50-280/281 There are four Indirect Effects terms for seasonal variations within the Risk Monitor:

Abnormal Procedure 0-AP-10.18, (GRID INSTABILITY) o This term is used when operators enter procedure 0-AP-10.18, "Response to Grid Instability."

o The peak electricity demand environmental factor is modeled because offsite electrical power reliability can be challenged during periods of peak electricity demand. Hot weather conditions in the summer are most likely to result in peak electrical demand.

o This term increases initiating event %LOOP-GR which represents a grid related loss of offsite power.

Operating Procedure 0-OP-ZZ-021, (SEVERE COLD) o This term is used when operators enter procedure 0-OP-ZZ-021, "Severe Weather Preparation," in response to severe cold weather conditions.

o The severe cold environmental factor is modeled primarily as a concern to icing on the James River or at the Low-Level Intake Structure.

o This term increases basic events 1CW-TWS44PG-ALL-U1, 2CW-TWS44PG-ALL-U2, and 0FS-TWS88PG-ALL-U1-U2, which represent plugging of the Circulating Water (CW) traveling water screens and fish screens.

Operating Procedure 0-OP-ZZ-021 - (TORNADOES) o This term is used when operators enter procedure 0-OP-ZZ-021, "Severe Weather Preparation," for the potential of a tornado or hurricane to produce high winds on site.

o High winds from tornadoes or hurricanes have the potential to cause: (1) a loss of offsite power by impacting power lines or the grid, (2) transients caused by grid instabilities or equipment disabled by missiles, and (3) loss of CW caused by debris.

o This term increases the following events in the model:

Initiating event %LOOP-WR, which represents a weather-related loss of offsite power, Page 3 of 6

Serial No.22-306 Docket Nos. 50-280/281 Initiating events %U1-GPT and %U2-GPT, which represent plant transients, and Basic events 1CW-TWS44PG-ALL-U1, 2CW-TWS44PG-ALL-U2, and 0FS-TWS88PG-ALL-U1-U2, which represent plugging of the CW traveling water screens and fish screens.

0-OP-ZZ-021 (T-STORMS) o This term is used when operators enter procedure 0-OP-ZZ-021 "Severe Weather Preparation" for the potential presence of thunderstorms on site.

o High winds and lightning strikes from thunderstorms can cause a plant trip or loss of offsite power; however, thunderstorms pose a lesser risk than tornadoes and hurricanes.

o This term increases the following events in the model:

Initiating events %LOOP-PC-U1 and %LOOP-PC-U2, which represent a plant-centered loss of offsite power, and Initiating events %U1-GPT and %U2-GPT, which represent plant transients.

As previously noted, the compensatory measures required to be in place prior to entering the 10-day AOT for opposite unit AFW cross-connect capability specify that weather conditions will be monitored and AFW maintenance affecting operability of the opposite unit cross-connect will not be scheduled if severe weather conditions are anticipated. The risk monitor terms described above will be used as-needed throughout the 10-day AOT period of AFW cross-connect unavailability to ensure risk insights reflect relevant considerations of seasonal variations.

Additional risk management actions will be identified and implemented, if needed, based on the risk impact of seasonal variation.

(ii)

Not applicable. See response to part (i).

NRC QUESTION APLB RA/# 3 Key principle five of RG 1. 17 4, Revision 3, An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant-Specific Changes to the Licensing Basis," specifies that the impact of a proposed risk-informed application should be monitored using performance management strategies. Furthermore, NRG staff position C. 3. 2 in RG 1. 177 for meeting principle five specifies that performance criteria should be established to assess degradation of operational safety over a period of time. It is Page 4 of 6

Serial No.22-306 Docket Nos. 50-280/281 unclear how the licensee's risk-informed process captures performance monitoring for the structures, systems, and components (SSCs) affected by the application.

Describe the approach or method used by Surry Power Station for SSC performance monitoring, as described in Regulatory Position C.3.2 of RG 1.177, for meeting the fifth key safety principle. In the description, include criteria (e.g., qualitative, or quantitative),

along with the appropriate risk metrics, and explain how the approach and criteria demonstrate the intent to monitor the potential degradation of SSCs.

Dominion Energy Response:

The impact of the proposed change will be monitored to ensure high levels of performance are maintained. The proposed AOT will limit individual instances of AFW cross-connect unavailability to 10 days when performing maintenance that would render the opposite unit's three AFW pumps inoperable.

This was determined to be reasonable and safe with the identified compensatory measures in place to mitigate risk. The Maintenance Rule, implemented in accordance with 10 CFR 50.65 and NEI 18-10 guidance, will ensure that maintenance appropriately balances reliability and availability of the systems, structures, and components (SSCs) related to the AFW cross-connect by tracking unavailability hours or by trending integrated risk.

PRA's Maintenance Rule input reflects the as-built plant and plant operating practices and assesses the quantitative results for Risk Reduction Worth (RRW), Fussell-Veseley (FV), Risk Achievement Worth (RAW), and Birnbaum importance measures for threshold acceptance of SSCs. As described in NEI 18-10, the Maintenance Rule Expert Panel will consider SSCs as potentially high safety significant if they meet any of the following criteria:

RRW > 1.005 (FV > 0.005)

RAW> 2.0 Birnbaum > 1 E-05/yr CDF or >1 E-06/yr LERF The Maintenance Rule Expert Panel will also consider the design basis, Technical Specifications requirements, and limitations in the PRA model when determining SSC safety significance. These actions, in conjunction with the corrective action program, will ensure any adverse trends in AFW availability or equipment reliability performance are promptly and effectively addressed.

NRC QUESTION APLB RA/ # 4 Section 3.2, "Compensatory Measures," of the LAR states that, "... Additional AFW system maintenance, including associated water sources, or changes in plant configuration that would result in a risk significant configuration will be precluded... " The licensee also presented compensatory measures with increased importance during the Page 5 of 6

Serial No.22-306 Docket Nos. 50-280/281 extended AFW outage period. If any of the identified SSCs, for example, emergency condensate makeup tank and BOB/FLEX high-capacity pump, become inoperable during the extended outage period, there is a potential that the configuration risk profile in the facility would exceed the acceptance criteria required for the requested outage period.

Therefore:

(0 Describe the licensee's plan to address any potential outages of the SSCs identified, as a part of the RG 1. 177 Tier 2 evaluation.

(ii)

Alternatively, propose a mechanism that avoids a risk-significant configuration from an outage of the SSCs mentioned in LAR.

(iii)

In the affected TS 3.6.4.l.2, reference the document that contains the list of all compensatory measures, explicitly making them requirements.

Dominion Energy Response:

(i)

Several compensatory actions identified in this application rely on the availability of key components to backup safety functions if needed. The proposed 10-day AOT will not be entered without these compensatory measures in place, including the prestaging of a BOB/FLEX AFW pump. For the BOB equipment, there are multiple pumps in each role available in the onsite BOB equipment storage building at SPS, and even more equivalent pumps available at North Anna Power Station that could be transported to SPS and deployed if needed.

There are also procedural restrictions for having more than one of three BOB/FLEX pumps out of service at a time.

Similarly, there are diverse and redundant FLEX qualified water sources available to provide AFW supply, including both units' Emergency Condensate Storage Tanks (ECSTs), the Emergency Condensate Makeup Tank (ECMT), and the BOB High-Capacity Pump, which can essentially draw water from the CW Discharge Canal indefinitely. Additional backup water sources are also available in the unlikely event they would be needed (e.g., Condensate Storage Tanks, Fire Protection Tanks)

The high degree of redundancy of equipment and water sources and the existing procedural requirements will ensure availability is maintained for key SSCs relied upon in the compensatory measures and the Tier 2 evaluation.

(ii)

Not applicable. See response to part (i).

(iii) The proposed change to SPS TS 3.6.1.2 to incorporate a 10-day Allowed Outage Time for opposite unit AFW cross-connect capability for the specific purpose of performing maintenance related to the operability of all three of the opposite unit's auxiliary feedwater pumps has been revised to include a specific reference to the compensatory measures included in the LAR dated June 20, 2022 (ADAMS Accession No. ML22172A134). The revised marked-up and typed proposed TS pages are provided in Attachments 2 and 3, respectively, and supersede in their entirety those provided in the June 20, 2022 LAR.

Page 6 of 6 Serial No.22-306 Docket Nos. 50-280/281 REVISED MARKED-UP PROPOSED TECHNICAL SPECIFICATIONS PAGES Virginia Electric and Power Company (Dominion Energy Virginia)

Surry Power Station Units 1 and 2

TS 3.6-4a L,..

0223 06 ~

I. The requirements of Specification 3.6.C.4 above concerning the opposite unit's auxiliary feedwater pumps; the associated redundant flowpaths, including piping, headers, valves, and control board indication; the cross-connect piping from the opposite unit; and the protected condensate storage tank may be modified to allow the following components to be inoperable, provided immediate attention is directed to making repairs. Automatic initiation instrumentation associated with the opposite unit's auxiliary feed water pumps need not be OPERABLE.

I. One of the opposite unit's flowpaths or two of the opposite unit's auxiliary feedwater pumps may be inoperable for a period not to exceed 14 days.

2. Both of the opposite unit's flowpaths; the opposite unit's protected condensate ~

storage tank; the cross-connect piping from the opposite unit; or three of the opposite unit's,,,.a..... u_,,.xi_*1_i __ ________ _.,...,,,,.....,.._... -...,,.-* *.,..........................,,.-..-

___,,,.......,,.-..,........,...-..,r-~. For e spec1 1c purp the operability of all three of the opposi erable for a pe

,._.._.,..._..,.........,..._...,...__,.._..,.............,..__,..__.,,._,,_"'--"'--"'--"'--,..__.___,"--"'-"'~~~~~ ~

3. A train of the opposite unit's emergency power system as required by Section 3.6.C.4.c above may be inoperable for a period not to exceed 14 days; if

~

this train's inoperability is related to a diesel fuel oil path, one diesel fuel oil path ~

may be "inoperable" for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> provided the other flowpath is proven OPERABLE; if after 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, the inoperable flowpath cannot be restored to service, the diesel shall be considered "inoperable." During this 14 day period, the following limitations apply:

a.

If the off site power source becomes unable to energize the opposite unit's OPERABLE train, operation may continue provided its associated emergency diesel generator is energizing the OPERABLE train.

b.

If the opposite unit's OPERABLE train's emergency diesel generator becomes unavailable, operation may continue for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> provided the offsite power source is energizing the opposite unit's OPERABLE train.

Amendment Nos. 246 an:d 245

TS 3.6-5a 02 23 06 restore operability of one inoperable pump or of the inoperable component or instrumentation in one flowpath. With such a loss of auxiliary feed water capability, the unit is in a seriously degraded condition. In this condition, the unit should not be perturbed by any action, including a power change, which could result in a plant transient or trip. The seriousness of this condition requires that action be taken immediately to restore eperability, where immediately means the required action should be pursued without delay and in a controlled manner. Under these circumstances, Specification 3.0.1 and all other required actions directing mode changes are suspended until one inoperable pump or the inoperable component or instrumentation in one flowpath is restored to operable status, because taking those actions could place the unit in a less safe condition.

~

!INSERT 2 In the event of complete loss of electrical power to the station, residual heat removal would continue to be assured by the availability of either the turbine driven auxiliary feedwater pump or /

one of the motor driven auxiliary feedwater pumps and the 110,000-gallon protected condensate storage tank.

In the event of a fire or high energy line break which would render the auxiliary feedwater pumps inoperable on the affected unit, residual heat removal would continue to be assured by the availability of either the turbine driven auxiliary feedwater pump or one of the motor driven /

auxiliary feedwater pumps from the opposite unit. A minimum of two auxiliary feedwater pumps are required to be operable* on the opposite unit to ensure compliance with the design basis accident analysis assumptions, in that auxiliary feedwater can be delivered via the cross-connect, even if a single active failure results in the loss of one of the two pumps. In addition, the requirement for operability of the opposite unit's emergency power system is to ensure that auxiliary feedwater from the opposite unit can be supplied via the cross-connect in the event of a common-mode failure of all auxiliary feedwater pumps in the affected unit due to a high energy line break in the main steam valve house. Without this requirement, a single failure (such as loss of the shared backup diesel generator) could result in loss of power to the opposite unit's emergency buses in the event of a loss of offsite power, thereby rendering the cross-connect inoperable. The longer allowed outage time for the opposite unit's emergency power system is based on the low probability of a high energy line break in the main steam valve house coincident with a loss of offsite power.

• excluding automatic initiation instrumentation Amendment Nos. 246 e.t1:cl 245

INSERT 1 {TS 3.6.1.2 Footnote)

Serial No.22-306 Docket Nos. 50-280/281

• The compensatory measures identified in the letter from Virginia Electric and Power Company to the US NRG dated June 20, 2022 (ADAMS Accession No. ML22172A134) and listed in the TS 3.6 Basis are required to be in place whenever the 10-day Allowed Outage Time is entered.

INSERT 2 {TS 3.6 Basis)

Due to the occasional need to perform periodic maintenance on common AFW components that would render all three AFW pumps on the opposite unit inoperable, e.g., the AFW pumps' full flow recirculation piping or the protected condensate storage tank, a 10-day allowed outage time is provided for opposite unit AFW cross-connect capability.

The 10-day allowed outage time is supported by a risk analysis that demonstrates the associated risk is acceptably small for both GDF and LERF with considerable margin remaining. When entering the 10-day allowed outage time for the specific purpose of performing maintenance related to the operability of all three of the opposite unit's auxiliary feedwater pumps, the following compensatory measures are required to be in place:

Additional AFW system maintenance, including associated water sources, or changes in plant configuration that would result in a risk significant configuration will be precluded; Weather conditions will be monitored and AFW maintenance affecting operability of the opposite unit cross-connect will not be scheduled if severe weather conditions are anticipated; The steam-driven AFW pump will be controlled as "Protected Equipment";

The Technical Requirements Manual compensatory actions to address 10 CFR 50.65 (a)(4) fire risk related to AFW cross-connect unavailability, which include periodic walkdowns in relevant fire areas, will be taken; and The BOB/FLEX AFW pump will be pre-staged to provide AFW defense-in-depth comparable to the AFW cross-connect.

Serial No.22-306 Docket Nos. 50-280/281 REVISED TYPED PROPOSED TECHNICAL SPECIFICATIONS PAGES Virginia Electric and Power Company (Dominion Energy Virginia)

Surry Power Station Units 1 and 2

TS 3.6-4a I. The requirements of Specification 3.6.C.4 above concerning the opposite unit's auxiliary feedwater pumps; the associated redundant flowpaths, including piping, headers, valves, and control board indication; the cross-connect piping from the opposite unit; and the protected condensate storage tank may be modified to allow the following components to be inoperable, provided immediate attention is directed to making repairs. Automatic initiation instrumentation associated with the opposite unit's auxiliary feedwater pumps need not be OPERABLE.

1. One of the opposite unit's flowpaths or two of the opposite unit's auxiliary feedwater pumps may be inoperable for a period not to exceed 14 days.

2. Both of the opposite unit's flowpaths; the opposite unit's protected condensate storage tank; the cross-connect piping from the opposite unit; or three of the opposite unit's auxiliary feedwater pumps may be inoperable for a period not to exceed 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. For the specific purpose of performing maintenance related to the operability of all three of the opposite unit's auxiliary feedwater pumps, these components may be inoperable for a period not to exceed 10 days.*

3. A train of the opposite unit's emergency power system as required by Section 3.6.C.4.c above may be inoperable for a period not to exceed 14 days; if this train' s inoperability is related to a diesel fuel oil path, one diesel fuel oil path may be "inoperable" for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> provided the other flowpath is proven OPERABLE; if after 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, the inoperable flowpath cannot be restored to service, the diesel shall be considered "inoperable." During this 14 day period, the following limitations apply:

a.

If the offsite power source becomes unable to energize the opposite unit's OPERABLE train, operation may continue provided its associated emergency diesel generator is energizing the OPERABLE train.

• The compensatory measures identified in the letter from Virginia Electric and Power Company to the US NRC dated June 20, 2022 (ADAMS Accession No. ML22172A134) and listed in the TS 3.6 Basis are required to be in place whenever the 10-day Allowed Outage Time is entered.

Amendment Nos.

TS 3.6-4b

b.

If the opposite unit's OPERABLE train's emergency diesel generator becomes unavailable, operation may continue for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> provided the offsite power source is energizing the opposite unit's OPERABLE train.

c.

Return of the originally inoperable train to OPERABLE status allows the second inoperable train to revert to the 14 day limitation.

If the above requirements are not met, be in HOT SHUTDOWN within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and be less than 350°F and 450 psig within the following 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

J. The requirements of Specification 3.6.C.2 above may be modified to allow utilization of protected condensate storage tank water with the auxiliary feedwater pumps provided the water level is maintained above 60,000 gallons, sufficient replenishment water is available in the 300,000 gallon condensate storage tank, and replenishment of the protected condensate storage tank is commenced within two hours after the cessation of protected condensate storage tank water consumption.

Amendment Nos.

TS 3.6-5a restore operability of one inoperable pump or of the inoperable component or instrumentation in one flowpath. With such a loss of auxiliary feedwater capability, the unit is in a seriously degraded condition. In this condition, the unit should not be perturbed by any action, including a power change, which could result in a plant transient or trip. The seriousness of this condition requires that action be taken immediately to restore operability, where immediately means the required action should be pursued without delay and in a controlled manner. Under these circumstances, Specification 3.0.1 and all other required actions directing mode changes are suspended until one inoperable pump or the inoperable component or instrumentation in one flowpath is restored to operable status, because taking those actions could place the unit in a less safe condition.

Due to the occasional need to perform maintenance on common AFW components that would render all three AFW pumps on the opposite unit inoperable, e.g., the AFW pumps' full flow recirculation piping or the protected condensate storage tank, a IO-day allowed outage time is provided for opposite unit AFW cross-connect capability. The 10-day allowed outage time is supported by a risk analysis that demonstrates the associated risk is acceptably small for both CDP and LERF with considerable margin remaining. When entering the IO-day allowed outage time for the specific purpose of performing maintenance related to the operability of all three of the opposite unit's auxiliary feedwater pumps, the following compensatory measures are required to be in place:

• Additional AFW system maintenance, including associated water sources, or changes in plant configuration that would result in a risk significant configuration will be precluded;

• Weather conditions will be monitored and AFW maintenance affecting operability of the opposite unit cross-connect will not be scheduled if severe weather conditions are anticipated;

• The steam-driven AFW pump will be controlled as "Protected Equipment";

• The Technical Requirements Manual compensatory actions to address 10 CFR 50.65 (a)(4) fire risk related to AFW cross-connect unavailability, which include periodic walkdowns in relevant fire areas, will be taken; and

• The BDB/FLEX AFW pump will be pre-staged to provide AFW defense-in-depth comparable to the AFW cross-connect.

Amendment Nos.

TS 3.6-5b In the event of complete loss of electrical power to the station, residual heat removal would continue to be assured by the availability of either the turbine driven auxiliary feedwater pump or one of the motor driven auxiliary feedwater pumps and the 110,000-gallon protected condensate storage tank.

In the event of a fire or high energy line break which would render the auxiliary feedwater pumps inoperable on the affected unit, residual heat removal would continue to be assured by the availability of either the turbine driven auxiliary feedwater pump or one of the motor driven auxiliary feedwater pumps from the opposite unit. A minimum of two auxiliary feedwater pumps are required to be operable* on the opposite unit to ensure compliance with the design basis accident analysis assumptions, in that auxiliary feedwater can be delivered via the cross-connect, even if a single active failure results in the loss of one of the two pumps. In addition, the requirement for operability of the opposite unit's emergency power system is to ensure that auxiliary feedwater from the opposite unit can be supplied via the cross-connect in the event of a common-mode failure of all auxiliary feedwater pumps in the affected unit due to a high energy line break in the main steam valve house. Without this requirement, a single failure (such as loss of the shared backup diesel generator) could result in loss of power to the opposite unit's emergency buses in the event of a loss of offsite power, thereby rendering the cross-connect inoperable. The longer allowed outage time for the opposite unit's emergency power system is based on the low probability of a high energy line break in the main steam valve house coincident with a loss of offsite power.

The specified minimum water volume in the 110,000-gallon protected condensate storage tank is sufficient for 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> of residual heat removal following a reactor trip and loss of all offsite electrical power. If the protected condensate storage tank level is reduced to 60,000 gallons, the immediately available replenishment water in the 300,000-gallon condensate tank can be gravity-fed to the protected tank if required for residual heat removal. An alternate supply of feedwater to the auxiliary feedwater pump suctions is also available from the Fire Protection System Main in the auxiliary feedwater pump cubicle.

• excluding automatic initiation instrumentation Amendment Nos.

TS 3.6-Sc The five main steam code safety valves associated with each steam generator have a total combined capacity of 3,842,454 pounds per hour at their individual relieving pressure; the total combined capacity of all fifteen main steam code safety valves is 11,527,362 pounds per hour.

The maximum steam flow at full power is approximately 11,444,000 pounds per hour. The combined capacity of the safety valves required by Specification 3.6 always exceeds the total steam flow corresponding to the maximum steady state power than can be obtained during three reactor coolant loop operation.

The availability of the auxiliary feedwater pumps, the protected condensate storage tank, and the main steam line safety valves adequately assures that sufficient residual heat removal capability will be available when required.

The limit on steam generator secondary side iodine-131 activity is based on limiting the dose at the site boundary following a postulated steam line break accident to the Regulatory Guide 1.183 limits. The accident analysis assumes the release of the entire contents of the faulted steam generator to the atmosphere.

Amendment Nos.