DCL-19-088, Supplemental Information Response to NRC Request for Additional Information Regarding 'License Amendment Request 19-01, Proposed Changes to the Intake Structure Physical Security Classification'

Supplemental Information Response to NRC Request for Additional Information Regarding 'License Amendment Request 19-01, Proposed Changes to the Intake Structure Physical Security Classification'

ML19297H645
Person / Time
Site:	Diablo Canyon
Issue date:	10/24/2019
From:	Gerfen P Pacific Gas & Electric Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
DCL-19-088
Download: ML19297H645 (4)

Text

Pacific Gas and Electric Company*

Paul Garfan Diablo Canyon Power Plant Site Vice President Mail code 104/6/605 P.O. 80156 Avila Beach, CA 93424 805.545.4596 Internal: 691.4596 Fax: 805.545.4234 October 24, 2019 PG&E Letter DCL-19-088 U.S. Nuclear Regulatory Commission 10 CFR 50.90 ATTN: Document Control Desk Washington, DC 20555-0001 Docket No. 50-275, OL-DPR-80 Docket No. 50-323, OL-DPR-82 Diablo Canyon Units 1 and 2 Supplemental Information Response to NRC Request for Additional Information Regarding 'License Amendment Request 19-01, Proposed Changes to the Intake Structure Physical Security Classification'

References:

1. PG&E Letter DCL-19-008, "License Amendment Request 19-01, Proposed Changes to the Intake Structure Physical Security Classification," dated February 14, 2019

2. PG&E Letter DCL-19-075, "Response to NRC Request for Additional Information Regarding 'License Amendment Request 19-01, Proposed Changes to the Intake Structure Physical Security Classification,"' dated September 19, 2019

Dear Commissioners and Staff:

In Reference 1, Pacific Gas and Electric Company (PG&E) submitted a license amendment request to revise the intake structure physical security classification in the Diablo Canyon Power Plant Security Plan and Emergency Plan.

In Reference 2, the PG&E provided responses to a NRC Staff request for additional information (RAI). Based on a discussion with the NRC staff on October 15, 2019, PG&E is providing this supplemental information to provide additional details in response to NRC RAI RCB RAl-1 a.

The supplemental information is provided in the Enclosure to this letter.

The information in this supplement does not impact the significant hazards consideration evaluation contained in Reference 1.

A member of the STARS Alliance Callaway

• Diablo Canyon

• Palo Verde

• Wolf Creek

Document Control Desk PG&E Letter DCL-19-088 October 24, 2019 Page 2 PG&E makes no new or revised regulatory commitments (as defined by NEI 99-04) in this letter.

If you have any questions or require additional information, please contact Mr. Hossein Hamzehee, Regulatory Services Manager, at (805) 545-4720.

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

Executed on October 24, 2019.

Sin~,

Paul:;;:~

Site Vice President MJRM/4557 Enclosure cc: Diablo Distribution cc/enc:

Scott A. Morris, NRC Region IV Administrator Gonzalo L. Perez, Branch Chief, California Department of Public Health John P. Reynoso, Acting NRC Senior Resident Inspector Balwant K. Singal, NRC Senior Project Manager A member of the STARS Alliance Callaway

• Diablo Canyon

• Palo Verde

• Wolf Creek

PG&E Letter DCL-19-088 Enclosure Supplement to NRC RAI RCB RAl-1a

References:

1. PG&E Letter DCL-19-008, "License Amendment Request 19-01, Proposed Changes to the Intake Structure Physical Security Classification," dated February 14, 2019

2. PG&E Letter DCL-19-075, "Response to NRC Request for Additional Information Regarding 'License Amendment Request 19-01, Proposed Changes to the Intake Structure Physical Security Classification,"'

dated September 19, 2019 In Reference 1, Pacific Gas and Electric Company (PG&E) submitted a license amendment request (LAR) to revise the intake structure physical security classification in the Diablo Canyon Power Plant Security Plan and Emergency Plan.

In Reference 2, PG&E provided responses to a NRC Staff request for additional information (RAI).

PG&E's response to RCB RAl-1a included (in part) the following:

10 Percent Atmospheric Dump Valves: Each unit has 4 atmospheric dump valves (ADVs) that provide a method for cooling the unit to residual heat removal (RHR) entry conditions and maintaining decay heat removal in Mode 4 when steam generators are relied upon for heat removal. Assuming a loss of offsite power, each ADV is supplied with plant high-pressure nitrogen and has a dedicated backup air bottle system. The ADVs can be controlled from the Control Room.

Based on a discussion with the NRC staff on October 15, 2019, PG&E is providing additional information regarding the backup air capacity to operate the 10 percent ADVs.

Air to operate the 10 percent ADVs is normally supplied by instrument air supply.

In the event of loss of the normal instrument air supply, backup air/nitrogen function is first accomplished by the non-safety-related nitrogen system. The nitrogen system is comprised of nine (Unit 1) and six (Unit 2) high pressure nitrogen bottles which can be manually aligned to the low-pressure nitrogen system, and a low-pressure nitrogen supply tank which normally supplies the low-pressure nitrogen system. The nitrogen to operate the 10 percent ADVs is supplied from the low-pressure side of the nitrogen header.

In the event of loss of both the normal instrument air supply and the non-safety-related nitrogen system, a seismically qualified backup air system (bottled air) can be manually aligned from the Control Room. The ADVs can be controlled from the Control Room.

The ADVs can also be controlled locally. An additional backup air bottle is located near the 10 percent ADVs and can be aligned via local valves.

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PG&E Letter DCL-19-088 Enclosure The following figure shows the configuration of the normal instrument air, nitrogen system, and backup air/nitrogen supplies to the pressure control valve (PCV) associated with one of the 10 percent ADVs:

AIR SUPPLY AIIH- 1219 AIR -l- 12 19A

'INST CLASS IA N2 su_

PP_LY_, AIR

• l *l m~ AIR

• I

• 1223 AIR 3814 OPEt4 CLOSE Pl 320 STEAM OUMP l tlST. CLASS IC _J COt TROL SYSTEM 111ST. CLASS IA AIR*l

• 1227A AIR* l

• l229

_htisr. CLASS 11 L.!..J

__J FNST. CLASS IA A14N\JIC I ATOR INST. JNST.

CLASS II. CLASS 11

---

J AIR-1-4872 t ltlST CLASS I A PCV -20 PG&E calculations demonstrate that adequate compressed gas is available in the backup air system to provide 10 cycles over 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> per PCV with a minimum bottle pressure of 260 pounds per square inch gage (psig).

Technical Specification (TS) 3.7.4, "10 % Atmospheric Dump Valves (ADVs),"

Surveillance Requirement (SR) 3.7.4.3 ensures that the backup air bottle for each ADV has a pressure greater than or equal to 260 psig.

Administrative limits in PG&E Surveillance Procedure STP 1-1 B ensure that backup air bottles operating the ADVs have a pressure greater than or equal to 380 psig in order to satisfy TS 3.7.4, SR 3.7.4.3. Normally, pressure is maintained above 1000 psig.

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