ML21356B721

Special Report 3-SR-2021-001-00

ML21356B721
Person / Time
Site:	Palo Verde
Issue date:	12/22/2021
From:	Rash B Arizona Public Service Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
102-08373-BJR/SPD 3-SR-2021-001-00
Download: ML21356B721 (3)

Text

TS 5.6.6 BRUCE J. RASH Vice President Nuclear Engineering/Regulatory Palo Verde Nuclear Generating Station 5801 S Wintersburg Road Tonopah, AZ 85354 Mail Station 7602 Tel 623 393 

102-08373-BJR/SPD December 2, 2021 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001

Subject:

Palo Verde Nuclear Generating Station (PVNGS) Unit 3 Docket No. STN 50-530 / License No. NPF 74 Special Report 3-SR-2021-001-00 Enclosed please find Special Report 3-SR-2021-001-00, which is prepared and submitted pursuant to PVNGS Technical Specifications 5.6.6, PAM Report. This report discusses the inoperability of the QualiILHG Safety Parameter Display System, that compriseV a portion of the post accident monitoring instrumentation.

,QDFFRUGDQFHZLWK&)5Fopies of this Special Report are being forwarded to WKHNuclear Regulatory Commission 15& 5HJLRQDO2IILFH15& Region IV and the 6enior 5esident ,nspector.

Arizona Public Service Company makes no commitments in this letter. If you have questions regarding this submittal, please contact Michael DiLorenzo, Department Leader, Regulatory Affairs, at (623) 393-3495.

Sincerely, Digitally signed by Rash, Bruce Rash, Bruce (Z77439)

DN: cn=Rash, Bruce (Z77439)

(Z77439) Date: 2021.12.22 10:01:42

-07'00' BJR/SPD Enclosure cc: S. A. Morris NRC Region IV Regional Administrator S. P. Lingam NRC NRR Project Manager for PVNGS L. N. Merker NRC Senior Resident Inspector for PVNGS A member of the STARS Alliance LLC Callaway

• Diablo Canyon

• Palo Verde

• Wolf Creek

Enclosure Palo Verde Nuclear Generating Station (PVNGS) Unit 3 Special Report 3-SR-2021-001-00 Qualified Safety Parameter Display System (QSPDS) Inoperable Reporting Requirement:

PVNGS Technical Specification (TS) 5.6.6, PAM Report, requires submittal of the report within 14days required by TS 3.3.10, Post Accident Monitoring (PAM) Instrumentation, Limited Condition for Operation (LCO) Condition B. The report shall outline the preplanned alternate method of monitoring, the cause of the inoperability, and the plans and schedule for restoring the instrumentation channels of the Function to OPERABLE status.

Initial Conditions:

On November 15, 2021, LCO 3.3.10 Condition A was entered when the B channel of the Unit 3 QSPDS was declared inoperable during the performance of the QSPDS Channel B calibration surveillance test in accordance with surveillance requirement 3.3.10.2. Condition A requires restoration of the required channel to an OPERABLE status within 30 days.

The post-accident monitoring functions that were affected by the inoperable channel (per Table 3.3.10-1) were:

• Reactor Vessel Water Level

• Core Exit Temperature Quadrants 1-4

• Reactor Coolant System Subcooling Margin Monitoring A failure of a power supply that occurred during the surveillance test did not allow the test to be completed. Condition B of LCO 3.3.10, for required action and associated completion time of Condition A not met, was entered at 09:36 Mountain Standard Time (MST) on December 15, 202. Condition B required immediate initiation of action required by TS 5.6.6.

Actions Taken:

KLOHWKH % FKDQQHOZDVLQRSHUDEOHWhe OPERABLE A channel of the QSPDS provided the primary method for post-accident monitoring. If both channels of the QSPDS became unavailable during actual accident conditions, the following existing procedures were in place to be used as alternate methods of monitoring for each of the affected functions:

Reactor Vessel Water Level:

The QSPDS Users Guide procedure provides a method for monitoring reactor vessel inventory with reactor vessel level monitoring system inoperable

Core Exit Temperatures The Flex Support Guidelines - Modes 1,2,3, or 4 procedure provides a method for obtaining core exit temperatures

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Enclosure Reactor Coolant System Subcooling Margin Monitoring The Determination of Subcooled Margin procedure provides guidance on calculating subcooled margin using various indicators of reactor coolant system temperature and pressure.

Channel A of the QSPDS remained OPERABLE and the alternate methods of monitoring remained available until the B channel of the QSPDS was repaired, tested, and returned to an OPERABLE status on December 15, 2021 at 13:58 MST.

Cause of the Inoperabilty:

7KHFDXVHRIWKHIDLOHG463'6FKDQQHOZDVDIDLOHGSRZHUVXSSO\Repair of the failed power supply was delayed due to equipment obsolescence issues and supply chain delays, causing the station to exceed the 30-day completion time of LCO 3.3.10, Condition A.

Plans and Schedule for Restoring the System to OPERABLE Status:

Channel B of the QSPDS ZDVrestored to an OPERABLE status as described above.

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