DCL-16-003, Notification of Full Compliance with Commission Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events

Notification of Full Compliance with Commission Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events

ML16005A638
Person / Time
Site:	Diablo Canyon
Issue date:	01/05/2016
From:	Welsch J Pacific Gas & Electric Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
DCL-16-003, EA-12-049, TAC MF0958, TAC MF0959, TAC MF0963, TAC MF0964
Download: ML16005A638 (21)

Text

Pacific Gas and Electric Company James M. Welsch Diablo Canyon Power Plant Site Vice President Mail Code 104/6 P. 0. Box 56 Avila Beach, CA 93424 January 05, 2016 805.545.3242 .

Internal: 691.3242 Fax: 805.545.4884 PG&E Letter DCL-16-003 U.S. Nuclear Regulatory Commission EA-12-049 ATTN: Document Control Desk 10 CFR 50.4 Washington, DC 20555-0001 Docket No. 50-275, OL-DPR-80 Diablo Canyon Unit 1 Pacific Gas and Electric Company's Notification of Full Compliance with Commission Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events (Order Nuniber EA-12-049) for Diablo Canyon Power Plant Unit 1

References:

1. NRC Order Number EA-12-049, "Issuance of Order to Modify Licenses With Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events," dated March 12, 2012 2 . . NRC Letter, from T. Brown, NRC to E. Halpin, PG&E, "Diablo Canyon Power Plant, Unit Nos. 1 and 2 - Report for the Onsite Audit Regarding Implementation of Mitigation Strategies and Reliable Spent Fuel Instrumentation Related to Orders EA-12-049 and EA-12-051 (TAC Nos.

MF0958, MF0959, MP0963, and MF0964)," October 30, 2015

Dear Commissioners and Staff:

On March 12, 2012, the Nuclear Regulatory Commission (NRC) issued Reference 1 to Pacific Gas and Electric Company (PG&E) directing PG&E to develop, implement, and maintain guidance and strategies to maintain or restore core cooling, containment, and spent fuel pool cooling capabilities in the event of a beyond-design-basis (BOB) external event. Specific requirements are outlined in Reference 1, Attachment 2.

Reference 1 requires full implementation of mitigation strategies for BOB external events no later than two refueling cycles after submittal of the Overall Integrated Plan or December 31, 2016, whichever comes first.

This letter provides notification that P&GE is in full compliance with Reference 1 for Diablo Canyon Power Plant Unit 1. Enclosure 1 to this letter provides a brief summary of the key elements associated with compliance to the order. Enclosure 2 A member of the STARS (Strategic Teaming and Resource Sharing) Alliance Callaway

• Diablo Canyon

• Palo Verde

• Wolf Creek

Document Control Desk PG&E Letter DCL-16-003 January 05, 2016 Page 2 to this letter provides a response for each of the open items identified within Reference 2.

PG&E is making no new or revised regulatory commitments (as defined by NEI 99-04).

If you have any questions, or require additional information, please contact Mr. Scott Maze at (805) 542-9591.

I declare under penalty of perjury that the foregoing is true and correct.

Executed on January 05, 2016.

Sincerely,

~* fV\. ~..O., J--

~es M. Welsch Site Vice President gwh2/50466122-7 Enclosures cc: Diablo Distribution cc:/enc: Tony Brown, NRC Project Manager Marc L. Dapas, NRC Region IV Administrator William M. Dean, NRC/NRR Director Siva P. Lingam, NRR Project Manager John P. Reynoso, Acting NRC Senior Resident Inspector A member of the STARS (Strategic Teaming and Resource Sharing) Alliance Callaway

• Diablo Canyon

• Palo Verde

• Wolf Creek

Enclosure 1 PG&E Letter DCL-16-003 Page 1 of 7 Pacific Gas and Electric Company's Summary of Compliance with Nuclear Regulatory Commission Order Regarding Mitigation Strategies for Beyond-Design-Basis Events (EA-12-049) for Diablo Canyon Power Plant Unit 1

1. Introduction Pacific Gas and Electric Company (PG&E) developed an overall integrated plan (OIP)

(Reference 2) to provide diverse and flexible coping (FLEX) strategies in response to Nuclear Regular Commission (NRC) Order EA-12-049, "Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events" (Reference 1). The OIP for Diablo Canyon Power Plant (DCPP) was submitted to the NRC on February 27, 2013 (Reference 2), and was supplemented by six-month status updates (References 3, 4, 5, 6, and 7) in accordance with Order EA-12-049.

PG&E achieved full compliance with Order EA-12-049 for DCPP Unit 1 on November 6, 2015. This date corresponds to the end of the second refueling outage for Unit 1 after submittal of the OIP (Reference 2) as required by Order EA-12-049. The information provided herein documents full compliance with Order EA-12-049 for DCPP Unit 1.

2. Open Item Resolution Issues from the NRC Interim Staff Evaluation (ISE) for FLEX (Reference 8) and audit report (Reference 9) have been addressed by PG&E.

The issues that were identified as open and pending in the NRC audit report (Reference 9) are listed below:

(1) ISE Open Item (ISE 01)- PG&E has no open or pending ISE Ols.

(2) ISE Confirmatory Items (ISE Cl) - ISE Cl 3.2.1.6.A (3) Audit Questions (AQ) /Audit Report Open/Pending Items/Safety Evaluation (SE) Items- AQ-12, SE-3, SE-5, SE-10, SE-11, and SE-17 A summary of the response to each of the open and pending issues is provided in . The open and pending items do not affect PG&E's compliance with Order EA-12-049 for DCPP Unit 1.

Enclosure 1 PG&E Letter DCL-16-003 Page 2 of 7

3. Milestone Schedule- Items Complete Completion Unit 1 FLEX Milestones Date Submit 20-day report Apr2012 Submit 60-day status report Oct 2012 Submit Overall Integrated Plan Feb 2013 Submit six-month status updates Update 1 Aug 2013 Update 2 Feb 2014 Update 3 Aug 2014 Update 4 Feb 2015 Update 5 Aug 2015 Modifications timeline Phase 1 Modifications

a. Design N/A

b. Equipment Procurement N/A

c. Installation N/A Phase 2 Modifications

a. Design 8/31/15

b. Large Equipment Procurement 12/31/14

c. Ancillary Equipment Procurement 10/27/15

d. Unit 1 Installation 11/6/15 Phase 3 Modifications

a. Design 2/28/15

b. Large Equipment Procurement 12/31/14 C. Ancillary Equipment Procurement 10/27/15

d. Unit 1 Installation 10/30/15 Procedure guidance implementation

a. Unit 1 Strategies 11/6/15

b. Unit 1 Maintenance 11/6/15

c. Unit 1 Testing 11/6/15 FLEX storage facilities

a. Primary Storage Facility 9/30/15

b. Secondary Storage Facility 10/27/15 Staffing analysis

a. Phase 1

1. Study Complete 3/29/13

2. NRC Submittal 4/30/13

b. Phase 2

a. Study Complete 5/27/15

b. NRC Submittal 5/27/15 Training completion for the strategies

a. Unit 1 11/6/15 National SAFER Response Center 2 (Phoenix) operational 8/28/14

Enclosure 1 PG&E Letter DCL-16-003 Page 3 of?

Completion Unit 1 FLEX Milestones Date Communications equipment implementation

a. Phase 1 12/31/13

b. Phase 2 10/27/15 Unit 1 Walk-throughs or Demonstrations 11/6/15 Unit 1 FLEX implementation complete 11/6/15

4. Order EA-12-049 Compliance Elements Summary The elements identified below for DCPP Unit 1 including the OIP (Reference 2), the six-month status updates (References 3, 4, 5, 6, and 7), and additional docketed correspondence demonstrate compliance with Order EA-12-049.

Strategies - Complete Strategy-related ISE open items, confirmatory items, or audit questions/audit report open items have been addressed as documented in Reference 9 or in Enclosure 2. DCPP Unit 1 strategies are in compliance with Order EA-12-049.

Modifications - Complete The modifications required to support the FLEX strategies for DCPP Unit 1 have been fully implemented in accordance with the station design control process.

Equipment- Procured and Maintenance and Testing- Complete The equipment required to implement the FLEX strategies for*DCPP Unit 1 has been procured, received at DCPP, initially tested, and performance verified in accordance with NEI 12-06, "Diverse and Flexible Coping Strategies (FLEX)

Implementation Guide," and is available for use.

Maintenance and testing will be conducted through the use of the DCPP Preventative Maintenance program such that equipment reliability is monitored and maintained.

Protected Storage- Complete The storage facilities required to implement the FLEX strategies for DCPP Unit 1 have been constructed and provide adequate protection from the applicable site hazards. The equipment required to implement the FLEX strategies for DCPP Unit 1 is stored in its protected configuration.

Enclosure 1 PG&E Letter DCL-16-003 Page 4 of 7 Procedures - Complete FLEX Support Guidelines (FSGs) for DCPP Unit 1 have been developed and integrated with existing procedures. The FSGs and applicable procedures have been verified and are available for use in accordance with the site procedure control program.

Training - Complete Training of personnel responsible for the mitigation of BOB external events at DCPP Unit 1 has been completed in accordance with accepted training processes as recommended in NEI 12-06, Section 11.6.

Staffing - Complete The PG&E Phase 1 Staffing Assessment (Reference 12) was completed in accordance with the 10 CFR 50.54(f) request for information with respect to Near-Term Task Force (NTTF) Recommendation 9.3 for Emergency Preparedness (Reference 11 ).

The PG&E Phase 2 Staffing Assessment (Reference 13) was completed in accordance with Reference 11.

Following the development of the FSGs, DCPP performed a revalidation of the Phase 2 Staffing Assessment to ensure the FLEX strategies could be implemented as written. Based on the revalidation, PG&E identified the following changes to the Phase 2 Staffing Assessment:

(1) added a task for an Industrial Fire Officer to block open control room and battery/charger and inverter room doors (2) changed the staffing to complete the task to take initial local control of the 10 percent steam dump valves from two to four nuclear operators (3) removed the Unit 2 balance of plant control operator task to isolate card ox. This task is not time sensitive and may be completed when offsite support is available.

Based on the task changes, PG&E concluded that the current minimum on-shift staff, as defined in the DCPP Emergency Plan, Section 5, "Organizational Control of Emergencies," Revision 4.15, remains sufficient to support the implementation of current DCPP procedures simultaneously for Units 1 and 2 with no collateral duties.

Enclosure 1 PG&E Letter DCL-16-003 Page 5 of 7 The Updated Phase 2 Staffing Assessment was provided to the NRC on October 28, 2015 (Reference 14).

National Strategic Alliance for FLEX Emergency Response (SAFER) Response Centers

-Complete PG&E has established a contract with Pooled Equipment Inventory Company (PEl Co) and has joined the National SAFER Team Equipment Committee for offsite facility coordination. PG&E confirmed that PEl Co is ready to support DCPP with Phase 3 equipment stored in the National SAFER Response Centers in accordance with the site-specific SAFER Response Plan.

Validation - Complete PG&E has completed validation testing of the FLEX strategies for DCPP Unit 1 in accordance with industry developed guidance. The validations assure that required tasks, manual actions and decisions for FLEX strategies are feasible and may be executed within the constraints identified in the OIP for Order EA-12-049.

FLEX Program Document- Established The PG&E DCPP FLEX program document has been developed in accordance with the requirements of NEI 12-06.

5. References (1) NRC Order Number EA-12-049, "Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events," dated March 12, 2012 (2) PG&E Letter DCL-13-007, "Pacific Gas and Electric Company's Overall Integrated Plan in Response to March 12, 2012, Commission Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events (Order Number EA-12-049),"

dated February 27, 2013 (3) PG&E Letter DCL-13-081, "Pacific Gas and Electric Company's First Six-Month Status Report in Response to March 12, 2012, Commission Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events," dated August 22, 2013

Enclosure 1 PG&E Letter DCL-16-003 Page 6 of 7 (4) PG&E Letter DCL-14-014, "Pacific Gas and Electric Company's Second Six-Month Status Report in Response to March 12, 2012, Commission Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events (Order Number EA-12-049)," dated February 26, 2014 (5) PG&E Letter DCL-14-076, "Pacific Gas and Electric Company's Third Six-Month Status Report in Response to March 12, 2012, Commission Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events," dated August 21, 2014 (6) PG&E Letter DCL-15-026, "Pacific Gas and Electric Company's Fourth Six-Month Status Report in Response to March 12, 2012, Commission Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events," dated February 23, 2015 (7) PG&E Letter DCL-15-099, "Pacific Gas and Electric Company's Fifth Six-Month Status Report in Response to March 12, 2012, Commission Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events," dated August 26, 2015 (8) NRC Interim Staff Guidance, "Diablo Canyon Power Plant, Unit Nos. 1 and 2 - Interim Staff Evaluation Relating to Overall Integrated Plan in Response to Order EA-12-049 (Mitigation Strategies) (TAC Nos. MF0958 and MF0959)," dated February 3, 2014 (9) NRC Letter, from T. Brown, NRC to E. Halpin, PG&E, "Diablo Canyon Power Plant, Unit Nos. 1 and 2 - Report for the Onsite Audit Regarding Implementation of Mitigation Strategies and Reliable Spent Fuel Instrumentation Related to Orders EA-12-049 and EA-12-051 (TAC Nos.

MF0958, MF0959, MP0963, and MF0964)," October 30, 2015 (10) NEI12-06, "Diverse and Flexible Coping Strategies (FLEX)

Implementation Guide," Revision 0 (11) NRC Letter, "Request for Information Pursuant to Title 10 of the Code of Federal Regulations 50.54(f) Regarding Recommendations 2.1, 2.3, and 9.3, of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident," dated March 12, 2012 (12) PG&E Letter DCL-13-040, "Response to March 12. 2012, NRC 10 CFR 50.54(f) Request for Information Regarding Recommendation 9.3, Phase 1 Staffing Assessment," dated April 24, 2013

Enclosure 1 PG&E Letter DCL-16-003 Page 7 of 7 (13) PG&E Letter DCL-15-063, "Response to March 12, 2012, NRC 10 CFR 50.54(f) Request for Information Regarding Recommendation 9.3, of Phase 2 Staffing Assessment," dated May 27, 2015 (14) PG&E Letter DCL-15-117, "Response to March 12, 2012, NRC 10 CFR 50.54(f) Request for Information Regarding Recommendation 9.3, Resubmittal of Phase 2 Staffing Assessment," dated October 28, 2015

Enclosure 2 PG&E Letter DCL-16-003 Page 1 of 12 Pacific Gas and Electric Company's Response to Open Items for Diablo Canyon Power Plant Unit 1 This enclosure responds to NRC open items identified within the following audit report:

NRC Letter, from T. Brown, NRC to E. Halpin, PG&E, "Diablo Canyon Power Plant, Unit Nos. 1 and 2- Report for the Onsite Audit Regarding Implementation of Mitigation Strategies and Reliable Spent Fuel Instrumentation Related to Orders EA-12-049 and EA-12-051 (TAC Nos. MF0958, MF0959, MP0963, and MF0964)," October 30, 2015 NRC ISE C/3.2.1.6.A On pages 70 through 73 in the Integrated Plan, the licensee listed elapsed times and time constraints in different columns in Attachment 1A (sequence of events timeline).

The review determined that the times listed in the elapsed times column and the time constraint column often are the same and provide no margin between the elapsed time and the time constraint time. Provide clarification on how early a step must be begun to meet the time constraint, when the licensee actually expects to begin performing the step, and information on what margin exists for these critical actions, and whether the times can be reasonably met.

The staff requests that the licensee make available for audit the results of the timed FLEX validation and verification walk downs when complete. The report should provide clarification on how early a step must be begun to meet the time constraint, when the licensee actually expects to begin performing the step, and information on what margin exists for these critical actions, and whether the times can be reasonably met.

PG&E Response to NRC ISE Cl 3.2.1.6.A PG&E conducted validation of the Diablo Canyon Power Plant (DCPP) FLEX time sensitive actions (TSAs) in accordance with Attachment 1A in DCPP's Overall Integrated Plan (OIP) (Refer to PG&E Letter DCL-13-007, "Pacific Gas and Electric Company's Overall Integrated Plan in Response to March 12, 2012, Commission Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events (Order Number EA-12-049)," dated February 27, 2013).

The following FLEX TSAs provide the expected start time, duration, the FLEX time constraint and an estimate of the required manpower (reference "Diablo Canyon Power Plant Beyond Design Basis Validation of the FLEX Time Sensitive Actions, Unit 1,"

Revision 2, dated December 28, 2015).

Action Items 1 to 10 are not considered to be FLEX TSAs because they are normal emergency operations actions defined in DCPP Emergency Operating Procedure (EOP)

ECA-0.0, "Loss of All Vital AC Power."

Enclosure 2 PG&E Letter DCL-16-003 Page 2 of 12 Action Item 11, Declare Extended Loss of Alternating Current (AC) Power: This action item is expected to begin within 34 minutes of the event. It is expected to take 1 minute to make the declaration based on the condition and the procedural actions that are to be taken to determine the condition is completed within 35 minutes. The time constraint on declaration is 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />. This provides 25 minutes of margin. This action to make the declaration has to start 59 minutes into the event in order to meet the time constraint.

The expected resource is one senior reactor operator.

Action Item 12, Deploy Control Room Portable Lighting: This is not a FLEX TSA.

However, the expected duration is 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />. The resource used is one person (non-operations) and a staging vehicle.

Action Item 13, Open doors to Control Room and Battery Charger/Inverter Room: This action item is expected to begin within 53 minutes of the event. It is expected to take 25 minutes to complete and is completed within 78 minutes. The original time constraint listed in the OIP is 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />; however, this time constraint has been revised to 1.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> (Refer to PG&E Calculation 9000041455-002-01). This change will be reflected in a future 6 month update. This provides 12 minutes of margin. This action has to start 65 minutes into the event in order to meet the time constraint. The expected resource is one person (non-operations).

Action Item 14, Request Assistance from the National Strategic Alliance for FLEX Emergency Response (SAFER) Response Center (NSRC): This action item is expected to begin within 53 minutes of the event. It is expected to take 1 minute to complete and is completed within 54 minutes. The time constraint is 1.25 hours2.893519e-4 days <br />0.00694 hours <br />4.133598e-5 weeks <br />9.5125e-6 months <br />. This provides 21 minutes of margin. This action has to start 74 minutes into the event in order to meet the time constraint. The expected resource is one senior reactor operator.

Action Item 15, Complete Vital Direct Current (DC) Battery Load Stripping: This action is expected to begin within 55 minutes of the event. It is expected to take 14 minutes to complete and is completed within 69 minutes. The time constraint is 1.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />. This provides 21 minutes of margin. This action has to start 76 minutes into the event in order to meet the time constraint. The expected resource is an operator.

Action Item 16, Initial Site Damage Assessment: This action would occur if one of the raw water reservoirs was taken out of service. Note that actions have been implemented to maintain the full reservoir when the other is taken out of service --

reference PG&E's Response to NRC SE Question SE-17. This action is expected to begin in less than an hour. It is expected to take 30 minutes to complete and is completed within 1.3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />. The time constraint is 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />. This provides 40 minutes of margin. This action has to start 1.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> into the event in order to meet the time constraint. The expected resource is an operator.

Enclosure 2 PG&E Letter DCL-16-003 Page 3 of 12 Action Item 17, Plant Access Assessment: This action is expected to begin in less than 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />. It is expected to take 0.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> to complete and is completed within 1.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />.

The time constraint is 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />. This provides 4.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> of margin. This action has to start 5.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> into the event in order to meet the time constraint. The expected resource is a security officer.

Action Item 18, Perform plant cooldown and depressurization: This action is expected begin within 28 minutes of the event (0.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />). It is expected to take 2.3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> to complete and is completed within 2.8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. The OIP time constraint is 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. This provides 9.2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> of margin. This action has to start 9.7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> into the event in order to meet the time constraint. The expected resource is the minimum on-shift control room staff.

Action Item 19, Deploy hoses to the spent fuel pool (SFP): This action is expected to begin close to the 6th hour of the event. It is expected to take 11 0 minutes to complete and is completed within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. The time constraint is 13 hours1.50463e-4 days <br />0.00361 hours <br />2.149471e-5 weeks <br />4.9465e-6 months <br />. This provides 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> of margin. This action has to start 11 hours1.273148e-4 days <br />0.00306 hours <br />1.818783e-5 weeks <br />4.1855e-6 months <br /> into the event in order to meet the time constraint. The expected resources are two nuclear operators.

Action Item 20, Align second vital battery and secure initial battery: This action is expected to begin at the 18th hour of the event. It is expected to take 8 minutes to complete and is completed within 18.1 hours1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />. The time constraint is 19.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />. This provides 1.4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> of margin. This action has to start 19.4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> into the event in order to meet the time constraint. The expected resource is a nuclear operator.

Action Item 21, Align 480 V generator and emergency reactor coolant system (ERCS) make-up pump from the boric acid storage tanks: This action is expected to begin at the 1Oth hour of the event. It is expected to take 5. 75 hours8.680556e-4 days <br />0.0208 hours <br />1.240079e-4 weeks <br />2.85375e-5 months <br /> to complete and is completed within 15.75 hours8.680556e-4 days <br />0.0208 hours <br />1.240079e-4 weeks <br />2.85375e-5 months <br />. The time constraint is 21 hours2.430556e-4 days <br />0.00583 hours <br />3.472222e-5 weeks <br />7.9905e-6 months <br />. This provides 5.25 hours2.893519e-4 days <br />0.00694 hours <br />4.133598e-5 weeks <br />9.5125e-6 months <br /> of margin. This action has to start 15.25 hours2.893519e-4 days <br />0.00694 hours <br />4.133598e-5 weeks <br />9.5125e-6 months <br /> into the event in order to meet the time constraint. The expected resources are four nuclear operators.

Action Item 22, Transfer turbine driven auxiliary feedwater (TDAFW) Pump Suction to 0-1 Fire Water Storage Tank: This action is expected to begin at the 17th hour of the event. It is expected to take 20 minutes to complete and is completed within 17.3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />. The time constraint is 20 hours2.314815e-4 days <br />0.00556 hours <br />3.306878e-5 weeks <br />7.61e-6 months <br />. This provides 2.7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> of margin. This action has to start 19.7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> into the event in order to meet the time constraint. The expected resource is a nuclear operator.

Action Item 23, Complete FLEX Deployment Damage Assessment: This action is expected to begin within 88 minutes of the start of the event. It is expected to take 1.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> to complete and is completed within 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />. The time constraint is 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

This provides 21 hours2.430556e-4 days <br />0.00583 hours <br />3.472222e-5 weeks <br />7.9905e-6 months <br /> of margin. This action has to start 22.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> into the event in order to meet the time constraint. The expected resources are three nuclear operators.

Enclosure 2 PG&E Letter DCL-16-003 Page 4 of 12 Action Item 24, 480 V Generator Repower Battery Charger: This action is expected to begin at the 16th hour of the event. It is expected to take 5.1 hours1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> to complete and is completed within 21.1 hours1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />. The time constraint is 28 hours3.240741e-4 days <br />0.00778 hours <br />4.62963e-5 weeks <br />1.0654e-5 months <br />. This provides 6.9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br /> of margin. This action has to start 22.9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br /> into the event in order to meet the time constraint. The expected resources are one nuclear operator, a person (non-operations) and a tow vehicle.

Action Item 25, Emergency Auxiliary Feedwater (EAFW) and Raw Water Reservoir (RWR) Equipment in Service: These actions are expected to begin at the 24th hour of the event. It is expected to take 3.2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> to place EAFW in service and 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> to place RWR in service. These actions are expected to be completed concurrently and are completed within 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />. The time constraint to place the equipment in service is 39.9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br />. This provides 9.9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br /> of margin. This action has to start 33.9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br /> into the event in order to meet the time constraint. The expected resources are three nuclear operators, eight people (non-operations) and two tow vehicles.

Action Item 26, Align ERCS pump suction to refueling water storage tank (RWST): This action is expected to begin at the 24th hour of the event. It is expected to take 3.4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> to complete and is completed within 27.4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />. The time constraint is 44 hours5.092593e-4 days <br />0.0122 hours <br />7.275132e-5 weeks <br />1.6742e-5 months <br />.

This provides 16.6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> of margin. This action has to start 40.6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> into the event in order to meet the time constraint. The expected resources are one nuclear operator, a person (non-operations) and a tow vehicle.

Action Item 27, Align flexible hoses to RWR Supply Header for SFP Cooling: This action is expected to occur at the 24th hour of the event. It is expected to take 2.2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> to complete and is completed within 26.2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />. The time constraint is 67 hours7.75463e-4 days <br />0.0186 hours <br />1.107804e-4 weeks <br />2.54935e-5 months <br />.

This provides 40.8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> of margin. This action has to start 64.8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> into the event in order to meet the time constraint. The expected resources are one nuclear operator, a person (non-operations) and a tow vehicle.

Action Item 28, Establish Alternate Fuel Supply: This action is expected to occur after the 24th hour of the event. It is expected to take 15 minutes to coordinate with an offsite contractor to bring fuel to DCPP. The time constraint is less than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. This action has to start 71.75 hours8.680556e-4 days <br />0.0208 hours <br />1.240079e-4 weeks <br />2.85375e-5 months <br /> into the event in order to meet the time constraint.

Action Item 29, Align 4160 V NSRC Generators: This action is expected to occur after the ?2nd hour of the event. It is expected to take 26.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> to complete and is completed within 98.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />. The time constraint is 121 hours0.0014 days <br />0.0336 hours <br />2.000661e-4 weeks <br />4.60405e-5 months <br />. This provides 22.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> of margin. This action has to start 94.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> into the event in order to meet the time constraint. The expected resources are several nuclear operators, NSRC technicians, electricians and tow vehicle.

Action Item 30, Align emergency auxiliary saltwater (ASW) Pump: This action is expected to occur after the ?2nd hour of the event. It is expected to take 11.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> to complete and is completed within 83.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />. The time constraint is 121 hours0.0014 days <br />0.0336 hours <br />2.000661e-4 weeks <br />4.60405e-5 months <br />. This

Enclosure 2 PG&E Letter DCL-16-003 Page 5 of 12 provides 37.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> of margin. This action has to start 109.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> into the event in order to meet the time constraint. The expected resources are several personnel (including operations), a crane, a crane operator and two vehicles.

NRC Audit Question (AQ) #12 Open Item 3.1.1.38- The licensee's plan for the development of mitigating strategies with respect to the procedural interfaces did not address Guidelines 2 and 3 in Section 5.3.3 of NEI12-06 for seismic hazards. These guidelines are associated with large internal flooding sources that are not seismically robust and do not require ac power and the use of ac power to mitigate ground water in critical locations, respectively.

Describe how the DCPP will meet the guidance in NEI12-06, Section 5.3.3, Guidelines 2 and 3.

The staff requests that the licensee make available for audit the internal flooding evaluation when complete.

PG&E Response to AQ #12 (1) NEI 12-06, Section 5.3.3, Guideline 2: "Consideration should be given to the impacts from large internal flooding sources that are not seismically robust and do not require ac power (e.g., gravity drainage from lake or cooling basins for nonsafety-related cooling water systems)."

Evaluation of large internal flooding sources that are not seismically robust and do not require ac power is provided in the Staging and Deployment Walkdown Report, Revision 2, which is provided in Certrec Inspection Management System (IMS). Additional discussions evaluating internal flooding sources that could impact FLEX pathways and time-sensitive action pathways are documented in the corrective action program in Notifications 50801874 and 50801366.

Electronic copies of the Notifications are provided in Certrec IMS. Conclusions provided in these evaluations include:

(a) FLEX staging routes and staging areas are not located in areas susceptible to internal flooding. Staging areas were evaluated for interactions with failed tanks and broken pipes.

(b) FLEX deployment routes and connection points exist in Areas GE and GW at elevations 100 and 115 feet. Structures, systems, and components (SSCs) that are not restrained per Hosgri seismic criteria were assumed to fail across the deployment paths. Water levels resulting from a large internal flooding source do not prohibit the successful deployment of any FLEX strategy or the ability to tie into a FLEX connection point.

Enclosure 2 PG&E Letter DCL-16-003 Page 6 of 12 (2) NEI 12-06, Section 5.3.3, Guideline 3: "For sites that use ac power to mitigate ground water in critical locations, a strategy to remove this water will be required."

Groundwater mitigation is not required at the DCPP site because DCPP does not experience ground water intrusion into any safety-related facilities. Therefore, ac power is not required.

NRC Safety Evaluation (SE) Question SE-3 The licensee should confirm that there is at least one connection point for FLEX equipment requiring access via routes only through seismically robust structures JAW with NE/12-06, Section 5.3.2.

The staff requests the licensee make available for audit a discussion that addresses the seismic design of:

1) Maintenance shop area (area where 275 kW generator cables will be routed)

2) Admin building/tunnel where 4160 V NSRC Generator is expected to be staged

3) Catwalk near ADVs (units 1 and 2)

The discussion should demonstrate that at least one connection point, for each required FLEX strategy connection, is in a robust structure, and also that any hose and cable deployment path, or area where operator actions are required, also go through seismically robust structures. The discussion should also justify having a single staging area and cable routing for Phase 2 and 3 electrical generators.

PG&E Response to NRC SE Question SE-3 All FLEX connection points are within the auxiliary building, turbine building, and fuel handling building or in the ASW vacuum breaker vaults. These structures have been evaluated to the Final Safety Analysis Report (FSAR) Update-described seismic criteria.

The deployment paths used to route the cables, hoses, etc. from staged equipment to connection points with permanent plant equipment are also within these structures and identified accordingly in the Staging and Deployment Walkdown Report, Revision 2, which is provided in Certrec IMS. Therefore, all deployment routes and connection points are within seismically robust structures in accordance with NEI 12-06, Section 5.3.2. Note that the Staging and Deployment Walkdown Report, *Revision 2, assumes that all doors that are installed in a facility or structure evaluated to the Hosgri seismic criteria will have limited deflection and remain operable considering the seismic qualification of the structure.

The FLEX hose and cable deployment, staging pathways, and time-sensitive operator action pathways have been identified and evaluated for seismic and flooding interaction potential in the Staging and Deployment Walkdown Report. The Staging and

Enclosure 2 PG&E Letter DCL-16-003 Page 7 of 12 Deployment Walkdown Report confirms that all FLEX connection points are within seismically robust structures that have been evaluated to the FSAR Update-described seismic criteria. The Staging and Deployment Walkdown Report also demonstrates that the staging area and cable routing paths for all FLEX strategies have been evaluated and will be available for FLEX implementation following a beyond-design-bases external events (BDBEE).

The following provides a discussion that addresses the seismic design of the maintenance shop area, administrative building/tunnel where 4160 V NSRC generator is expected-to be staged, and the catwalk near the Units 1 and 2 atmospheric dump valves (ADVs).

(1) Maintenance shop area (area where 275 kW generator cables will be routed)

The maintenance/machine shop area is located inside the turbine building, which is seismically qualified to the FSAR Update-described seismic criteria. The crane bay portion of this area has been identified as an acceptable area where the FLEX 275 kW generator load center and cables would likely be staged and then routed further through the turbine building to their connection points as shown in Figure 20A, Attachment 11.1 (page 35), of the Staging and Deployment Walkdown Report. The deployment path for routing the generator cables is identified and evaluated in the Staging and Deployment Walkdown Report. Note that there are numerous alternate pathways available for the response personnel to route cables inside the turbine building to the FLEX connection points.

(2) Admin building/tunnel where 4160 V NSRC Generator is expected to be staged The 4160 V NSRC generator is not required to be staged directly underneath the bridge structure connecting the administration building to the turbine building .

The staging of FLEX equipment at this location is west of the bridge structure at the southwest corner of the turbine building as shown in Attachment 11.2 of the Staging and Deployment Walkdown Report. In addition to the evaluated staging routes, there are numerous alternative staging pathways around the administration and security buildings that could be utilized if the bridge structure were to fail. Furthermore, the Staging and Deployment Walkdown Report indicates that the FLEX debris removal equipment would be available to clear failed architectural components required for routing Phase 2 or Phase 3 equipment through or around the area should the need arise after initial debris removal activities have been completed.

(3) Catwalk near ADVs (Units 1 and 2)

Attachment 11.13 of the Staging and Deployment Walkdown Report and Notification 50801366, which is provided in Certrec IMS, provides the evaluation of pathways required for FLEX response TSAs. The evaluation considers the

Enclosure 2 PG&E Letter DCL-16-003 Page 8 of 12 internal and external BDBEE hazards (i.e., seismic and flooding) that could impact the ability of plant personnel to complete the DCPP FLEX response TSAs. The various TSA pathways required to access the 10 percent ADVs are specifically identified and evaluated in the Staging and Deployment Walkdown Report. Note that the containment pipe way structure is safety-related, seismically qualified, and design class I and the associated platform grating, i.e.,

the catwalk near the ADVs, has been evaluated in the Staging and Deployment Walkdown Report for each of the applicable TSA pathways.

NRC SE Question SE-5 (RVL/S availability) Technical report WCAP-17792-P makes recommendations regarding the timing for providing RCS makeup based on level indications in the reactor vessel. However, these systems were not included as recommended instrumentation in NEI 12-06 and, hence, did not typically appear in licensee's integrated plans. Please clarify whether a system such as the reactor vessel/eve/ instrumentation system (RVL/S) or reactor vessel/eve/ measurement system (RVLMS) will be available during an ELAP event. If such as system will not be available, please provide clarification as to how reactor operators will determine when to provide RCS makeup and provide justification for the intended strategy.

The staff noted that RVL/S is not available after the initial battery load shed is complete.

It will be repowered at approximately 20 hours2.314815e-4 days <br />0.00556 hours <br />3.306878e-5 weeks <br />7.61e-6 months <br /> when the FLEX DGs are set up and two of the three unit batteries are repowered. Once the RCS shrinks out of the pressurizer, there will be no indication of RCS level available to plant operators.

The staff requests the licensee make available for audit a discussion of how RCS level indication will be available to plant operators during an ELAP.

PG&E Response to NRC SE Question SE-5 PG&E has revised the load shedding strategy so that all of the pertinent inputs to reactor vessel level instrumentation system (RVLIS) remain energized during Phase 1 coping following a BDBEE. Calculation 90000041771-000-00 evaluated the batteries in this load shedding strategy, which shows the batteries are capable of maintaining adequate voltage beyond 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. This strategy has been reflected in the Implementing Procedure FSG-04, "ELAP DC Bus Load Shed and Management."

NRC SE Question SE-10 Identify whether the FLEX strategy involves entry into the containment building. If containment entry is planned, please provide justification that it can be carried out in a safe and effective manner under ELAP conditions.

Enclosure 2 PG&E Letter DCL-16-003 Page 9 of 12 The staff requests that the licensee make available for audit a justification that a containment entry can be carried out in a safe and effective manner under ELAP conditions.

PG&E Response to NRC SE Question SE-1 0 DCPP FLEX strategy does not involve entry into the containment.

From NEI 12-06, the plants electrical distribution system remains available following a BDBEE, provided they are protected consistent with current station design. In addition, portable equipment may be provided if it is reasonably protected from applicable external hazards and has predetermined hookup strategies with appropriate procedures and guidance.

These conditions are to be completely satisfied to enable the residual heat removal (RHR) and accumulator isolation valves located in containment to be powered by a FLEX portable generator, switchgear, hookup cabling, and the intact electrical Class 1E distribution system. In the phase 3 coping period where off site portable equipment is used to enhance the capabilities to safety shutdown or maintain the plant in a shutdown condition, the DCPP OIP is to energize 4160 V Bus G (or alternatively Bus H). The energized 4160 V Bus, will then energize 480 V Bus G (or alternatively Bus H), and the RHR and accumulator valves normally supplied by that bus. For those valves whose normally supply is from either Bus For H (or alternatively Bus For G), a predetermined hookup strategy has been evaluated in engineering calculation 9000041768-000-00 and would be implemented by procedure FSG-45, "Supplying Power to Sl Accumulator and RHR Valves." This procedure and onsite portable equipment will repower the remaining valves through the use of a breaker feed off 480 V Bus G (alternatively Bus H).

The hookup strategy maintains the normal control and indication for each valve as designed under normal plant operation. Since the valves to be are 3-phase, 480 V Limitorque valves, the hookup strategy will require the verification of proper phasing, prior to energizing the valves. This will be achieved by maintaining consistent cable orientation through the use of color coded interconnecting cables, and also hooking up and testing the phase rotation by bumping a ventilation fan on the same bus as the containment valve(s). In addition, protection setpoints have been reviewed to ensure that the supplying breaker and cables do not result in an inadvertent trip on overcurrent or inrush of the valve motor. The RHR Inlet Valves 8701 and 8702 have associated with their control scheme, temperature and pressure interlocks to protect the valves.

These interlocks can be enabled by closing the associated 125 V instrument ac breakers associated with their vital battery, or they could be bypassed with a jumper in a local control panel and the control room operator verifying through control board instrumentation that the temperature and pressure is within limits prior to opening the valves.

Enclosure 2 PG&E Letter DCL-16-003 Page 10 of 12 Based on the above analysis and procedure, the RHR inlet valves and accumulator isolation valves can be operated electrically, and no entry into containment is necessary for these valves.

NRC SE Question SE-11 The licensee needs to confirm that the temperature and pressure within containment, other areas within the plant (i.e., electrical switchgear room), and AD V rooms will not exceed the qualification of electrical equipment that is being relied upon as part of the FLEX strategy. The licensee needs to ensure that the qualification of the required electrical equipment remains bounding during the entire duration of the event (i.e.,

indefinitely).

The staff noted that the licensee's calculation implies that doors should be open at t= 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> into the event (same time as ELAP is declared). The calculation also assumes that loads are shed from the inverters at t= 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />.

The staff requests that the licensee make available for audit documentation that describes the design qualification of the equipment and the expected room temperatures for the following areas: containment, switchgear rooms, battery charger/inverter rooms, battery rooms, and control room. The documentation should also clarify the sequence of events (e.g. time to open doors as necessary) and confirm that the assumptions of the analyses are correct.

PG&E Response to NRC SE SE-11 EOP ECA-0.0, Step 24 directs operators to start opening doors in the auxiliary building and auxiliary feedwater (AFW) pump room. As discussed in PG&E's response to Interim Staff Evaluation (ISE) Cl 3.2.1.6.A, Action Item 13, these doors will be blocked open within the required time constraint.

The following describes the design qualification of the equipment and the expected room temperatures by areas:

Containment Calculation DCA 9000041684-000-00 (Legacy FLEX-011) was performed by Westinghouse for the DCPP extended loss of ac power (ELAP) containment environmental analysis. Section 2.1 of the calculation shows the maximum containment temperature is 271 oF (133°C) in all compartments in containment. The electrical equipment required to be available in containment are the RHR Inlet Valves (8701 and 8702) and Accumulator Isolation Valves (8808A, B, C, and D). These valves are Limitorque SMB-1 and SMB-3 respectively, and in accordance with DCPP EQ File IH07 Revision 8, "Limitorque Valve Actuators," SCEW # IH07-1, these valve operators are qualified to an environment of up to 356°F (180°C).

Enclosure 2 PG&E Letter DCL-16-003 Page 11 of 12 Auxiliary Building Switchgear Rooms: There is no temperature sensitive electrical equipment relied upon for FLEX in the switchgear rooms .

Battery Rooms and Battery Charger/Inverter Rooms: DCPP Calculation 9000041455, Part 002, Version 01, "GOTHIC Evaluation of Heat Removal thought Natural Convection in the Battery Charger/Inverter Room, Battery Room, Cable Spreading Room and Control Room," evaluates the battery and battery charger/inverter rooms and the opening of doors to create a natural circulation flow path for cooling. The calculation assumes load shedding of the batteries occurs within 1.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />, and that the required doors will be opened in 1.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />. The maximum temperatures in the battery and charger/inverter rooms are calculated at 114 oF and 119oF respectively, which are below the maximum equipment qualification temperatures of 120°F and 122°F.

Control Room and Cable Spreading Room:

Control Room and Cable Spreading Room: DCPP Calculation 9000041455, Part 002, Version 01 evaluates the control room and cable spreading room and the opening of doors to create a natural circulation flow path for cooling. The results indicate the maximum temperature in the cable spreading room to be 111 oF and the control room to be 109°F. Based on the requirements for the control room in Equipment Control Guideline (ECG) 23.5, "Plant Systems- Control Room Ventilation System (CRVS)," a temperature limit of 120oF is acceptable. This temperature limit also applies to the cable spreading room, as the equipment required to operate in this room is similar to the equipment required within the control room.

The results of DCPP Calculation 9000041455, Part 002, Version 01, indicate that no forced cooling is necessary for up 'to 7 days for all above evaluated rooms in the auxiliary building . It is expected that some plant ventilation can be reestablished after the 4 kV FLEX generator sets from the NSRC are installed. Additional cooling with fans and portable generators stored in the FLEX storage facilities are also available to be deployed within this time frame if necessary.

NRC SE Question SE-17 500kV Line Interference:

The staff noted that the licensee's ability to deploy FLEX equipment could be impacted if 500kV power lines fall across the deployment paths following a beyond-design-basis external event. The staff requests that the licensee make available for audit a discussion of the plans for addressing downed power lines and justification that 500 kV line interference will not impact the ability of the licensee to successfully implement its FLEX strategies.

Enclosure 2 PG&E Letter DCL-16-003 Page 12 of 12 The staff noted that the licensee's ability to deploy FLEX equipment could be impacted if 500kV power lines fall across the deployment paths following a beyond-design-basis external event. The staff requests that the licensee make available for audit a discussion of the plans for addressing downed power lines and justification that 500 kV line interference will not impact the ability of the licensee to successfully implement its FLEX strategies.

PG&E Response to NRC SE Question SE-17 PG&E performed an assessment of potential debris that could fall in a seismic event and affect FLEX deployment paths. The assessment is documented in the Staging and Deployment Walkdown Report, Revision 2, which is provided in Certrec IMS. The 500 kV transmission lines and towers were identified in this study, as well as any other structures, systems, or components that could potentially block the routes. This study shows that the 500 kV towers are seismically evaluated to Hosgri criteria and are not expected to fall in a seismic event. However, the 500 kV transmission lines have not been evaluated and could potentially affect the deployment paths leading to the 115-foot elevation radiologically controlled area (RCA) staging location, the raw water reservoirs, and the secondary storage facility. Access to the primary storage facility (Building 113) would not be affected, and debris removal equipment is provided in this facility to remove any potential debris, including the transmission lines. While the transmission lines are expected to not be energized, PG&E has conservatively assumed that they cannot be cut or traversed until they are adequately grounded due to potential personnel safety concerns. Therefore, the required grounding equipment is stored in the primary storage facility. Procedures are in place to require appropriately trained personnel to arrive onsite 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> after the event to ground the transmission lines if needed (Reference PG&E Operating Procedure OP J-2:VIII, "Guidelines for Reliable Transmission Service for DCPP," Revision 26; Attachment #3- GCC System Dispatch Instruction 0-23, "Operating Instructions for Reliable Transmission Service to DCPP," Revision 22, dated June 17, 2015; Attachment 3, Page 27 of 63).

The timing of grounding the 500 kV lines, as well as the timing associated with the debris removal strategy has been evaluated by the Staging and Deployment Walkdown Report, which shows that there is adequate time to access all required locations and implement the strategies with margin (Refer to PG&E's response to ISE Cl 3.2.1.6.A).

The RWR has two sections, one of which is normally isolated at the RWR with adequate water volume to support FLEX requirements. In support of RWR maintenance activities which could drain down one RWR section, PG&E implements Operating Procedure OP F-3:V, "Raw Water- Remove from Service", to maintain the minimum quantity of water in the other RWR section for support of FLEX. As a result, even if the 500 kV lines come down, after grounding and debris removal, the water volume would still remain and the FLEX strategies can be implemented.