IR 05000528/2021015

Temporary Instruction 2515/194 Report 05000528/2021015 and 05000529/2021015 and 05000530/2021015

ML21293A339
Person / Time
Site:	Palo Verde
Issue date:	10/27/2021
From:	Nick Taylor NRC Region 4
To:	Lacal M Arizona Public Service Co
References
IR 2021015
Download: ML21293A339 (8)

Text

October 27, 2021

SUBJECT:

PALO VERDE NUCLEAR GENERATING STATION - TEMPORARY INSTRUCTION 2515/194 REPORT 05000528/2021015 AND 05000529/2021015 AND 05000530/2021015

Dear Ms. Lacal:

On September 20, 2021, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at Palo Verde Nuclear Generating Station. On September 21, 2021, the NRC inspectors discussed the results of this inspection with Mr. Bruce Rash, Vice President Nuclear Engineering / Regulatory and other members of your staff. The results of this inspection are documented in the enclosed report.

No findings or violations of more than minor significance were identified during this inspection.

This letter, its enclosure, and your response (if any) will be made available for public inspection and copying at http://www.nrc.gov/reading-rm/adams.html and at the NRC Public Document Room in accordance with Title 10 of the Code of Federal Regulations 2.390, Public Inspections, Exemptions, Requests for Withholding.

Sincerely, Nicholas H. Taylor, Chief Engineering Branch 2 Division of Reactor Safety

Docket Nos. 05000528 and 05000529 and 05000530 License Nos. NPF-41 and NPF-51 and NPF-74

Enclosure:

As stated

Inspection Report

Docket Numbers:

05000528, 05000529 and 05000530

License Numbers:

NPF-41, NPF-51 and NPF-74

Report Numbers:

05000528/2021015, 05000529/2021015 and 05000530/2021015

Licensee:

Arizona Public Service Company

Facility:

Palo Verde Nuclear Generating Station

Location:

Tonopah, Arizona

Inspection Dates:

September 13, 2021 to September 17, 2021

Inspectors:

S. Makor, Reactor Inspector

R. Deese, Senior Reactor Analyst

Approved By:

Nicholas H. Taylor, Chief

Engineering Branch 2

Division of Reactor Safety

SUMMARY

The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees performance by conducting a Temporary Instruction 2515/194 at Palo Verde Nuclear Generating Station, in accordance with the Reactor Oversight Process. The Reactor Oversight Process is the NRCs program for overseeing the safe operation of commercial nuclear power reactors. Refer to https://www.nrc.gov/reactors/operating/oversight.html for more information.

List of Findings and Violations

No findings or violations of more than minor significance were identified.

Additional Tracking Items

None.

INSPECTION SCOPES

Inspections were conducted using the appropriate portions of the inspection procedures (IPs) in effect at the beginning of the inspection unless otherwise noted. Currently approved TIs with their attached revision histories are located on the public website at https://www.nrc.gov/reading-rm/doc-collections/insp-manual/temp-instructions/index.html.

Samples were declared complete when the IP requirements most appropriate to the inspection activity were met consistent with Inspection Manual Chapter (IMC) 2515, Light-Water Reactor Inspection Program - Operations Phase. The inspectors reviewed selected procedures and records, observed activities, and interviewed personnel to assess licensee performance and compliance with Commission rules and regulations, license conditions, site procedures, and standards. Starting on March 20, 2020, in response to the National Emergency declared by the President of the United States on the public health risks of the coronavirus (COVID-19),inspectors were directed to begin telework. In addition, regional baseline inspections were evaluated to determine if all or a portion of the objectives and requirements stated in the IP could be performed remotely. If the inspections could be performed remotely, they were conducted per the applicable TI. In some cases, portions of an TI were completed remotely and on site. The inspections documented below met the objectives and requirements for completion of the TI.

OTHER ACTIVITIES

- TEMPORARY INSTRUCTIONS, INFREQUENT AND ABNORMAL

2515/194 - Inspection of the Licensees Implementation of Industry Initiative Associated With the Open Phase Condition Design Vulnerabilities In Electric Power Systems (NRC Bulletin 2012-01)

The inspectors reviewed the licensees implementation of Revision 3 to the Nuclear Energy Institute Industry Initiative on Open Phase Condition, (ADAMS Accession No. ML19163A176)dated June 6, 2019. This review included the licensee's application of risk screening techniques to determine that the risk associated with an open phase condition (OPC) event is significantly reduced through the implementation of detection circuits and the use of operator manual actions in lieu of automatic trip functions. The inspectors also reviewed the updates to the PVNGS licensing basis to reflect the need to protect against open phase conditions.

Sections 03.01.a, Detection, Alarms and General Criteria, and 03.01.b, Protective Actions, were previously inspected and documented in Inspection Report (ADAMS Accession No.

ML18103A157) 05000528; -529; -530/2018010 with noted exceptions. Because the licensee has chosen to demonstrate compliance with Revision 3 of the Open Phase Condition Initiative using the Risk Informed Evaluation Method in lieu of the designs automatic protective functions, section 03.01.c, Use of Risk-Informed Evaluation Method is inspected in this report.

Inspection of the Licensees Implementation of Industry Initiative Associated With the Open Phase Condition Design Vulnerabilities In Electric Power Systems (NRC Bulletin 2012-01) (1 Sample)

(1) Inspection of the Licensees Implementation of Industry Initiative Associated With the Open Phase Condition Design Vulnerabilities in Electric Power Systems (NRC

Bulletin 2012-01) (1 Sample)

Arizona Public Service (APS) Company selected the open phase detection system designed and manufactured by Power System Sentinel Technologies, LLC, (PSSTech) as the design vendor for the Palo Verde Nuclear Generating Station (PVNGS). The licensee had installed an Open Phase Protection (OPP) on each Start-up transformer (SUT) that detects an Open Phase Condition (OPC) on the high voltage side of its applicable transformer from the offsite 525 kV transmission system. In total, the licensee installed six PSSTech open phase detection systems on three transformers.

The open phase condition equipment was installed on the SUTs AE-NAN-X01, AE-NAN-X02, and AE-NAN-X03 which provide power to station busses, including the stations six engineered safety feature (ESF) busses.

Each ESF bus is fed from a separate SUT connected to a common switchyard supplied by eight 525 kV offsite transmission lines. Each SUT is equipped with four windings: a primary, a tertiary and two secondary to transform 525 kV power into 13.8 kV power. During normal operations, each unit generates and delivers power to the 525-kV transmission system via the main generator through the Unit Auxiliary Transformer. The SUTs are normally lightly loaded, and the generator trip initiates a fast bus transfer of the non-1E loads to the SUT.

As part of the licensees implementation of Revision 3 to the open phase initiative, the licensee used contractor services to model and evaluate the effects of open phase conditions (OPCs) on the PVNGS electrical distribution system and ESF/PRA-credited loads. The inspectors reviewed the contractors report and assumptions and discussed the system distribution behavior under various open-phase scenarios with licensee staff.

Based on the licensees analysis, PVNGS decided to not credit recovery and not enable the trip function.

INSPECTION RESULTS

Observation: Temporary Instruction 2515/194-03.01 - Voluntary Industry Initiative 2515/194 Based on discussions with PVNGS staff, review of design and testing documentation, and walkdowns of installed equipment, the inspectors had reasonable assurance that APS is appropriately implementing the voluntary industry initiative at PVNGS.

The inspectors verified the following criteria:

Detection, Alarms and General Criteria

2. [03.01(a)(2)] The team determined that detection circuits were sensitive enough to identify

an open phase condition for all credited loading conditions.

3. [03.01(a)(4)] No Class 1E circuits were being replaced with non-Class 1E circuits in this

design.

4. [03.01(a)(5)] The Final Safety Analysis Report was updated to discuss the features and

analyses related to the effects of any open phase condition design vulnerability.

5. [03.01(a)(6)] The open phase condition detection and alarm components are maintained

in accordance with Arizona Public Service Company procedures or maintenance program, and periodic tests, calibrations setpoint verifications or inspections (as applicable) have been established. The open phase equipment is covered under the licensees maintenance rule requirements.

Use of Risk-Informed Evaluation Method

1. [03.01(c)(1)] The plant configuration matched the changes made to the probabilistic risk

assessment model to address an open phase condition, and the logic of the probabilistic risk assessment model changes is sound.

2. [03.01(c)(2)] The procedures which validate that the open phase condition alarm would

identify the proper indication to validate the open phase conditions at all possible locations.

3. [03.01(c)(3)] Observations associated with procedure(s) and operator actions required to

respond to an open phase condition alarm and potential equipment trip matched the Human Reliability

4. [03.01(c)(4)] Assumptions listed in the NEI 19-02 Appendix A evaluation and the

sensitivity analyses listed in Section 5 of the evaluation were verified.

5. [03.01(c)(5)] Assumptions, procedures, operator actions, and Arizona Public Service

Company analyses specified above are consistent with the plant-specific design and licensing basis, including:

a. Initiating events considered in the analysis b. Boundary conditions specified in Attachment 1 of the NEI Voluntary Industry Initiative, Revision 3 c. Operating procedures for steps taken to recover equipment from the effects of open phase conditions (or use of alternate equipment) was appropriate.

d. Where recovery was assumed in the probabilistic risk assessment analysis for tripped electric equipment, restoration of the equipment was based on analyses that demonstrate that automatic isolation trips didnt not result in equipment damage.

No findings or exceptions were identified.

EXIT MEETINGS AND DEBRIEFS

The inspectors verified no proprietary information was retained or documented in this report.

• On September 21, 2021, the inspectors presented the Temporary Instruction 2515/194 results to Mr. Bruce Rash, Vice President Nuclear Engineering / Regulatory and other members of the licensee staff.

DOCUMENTS REVIEWED

Inspection

Procedure

Type

Designation

Description or Title

Revision or

Date

2515/194

Corrective Action

Documents

21-10239, 21-09803, 21-10368, 21-10509

Engineering

Changes

2015-00400

Implement changes per DMWO 441244 - Installing

OPP cabinets in Start-up yard

10/19/2018

Engineering

Evaluations

13-NS-B061

Event Tree Study

17-12228-001

An evaluation was performed to determine the type

and frequency of Preventative Maintenance (PM) for

Open Phase Protection (OPP) cabinets and their

Heating, Ventilation, and Air Conditioning (HVAC)

units.

11/16/2020

EE 20-02937-037

Perform a risk assessment in accordance with

81DP-0CC15 and NEI 19-02

09/05/2021

Miscellaneous

13-NS-BS061

At-Power PRA Event Trees and Success Criteria

2015-00401

OPP Non-Class 1E OPP Protection Settings

AE-NAN-C10A

Non-Class 1E Neutral Over -Current Relay

Protecting Start-Up Transformer AE-NAN-X01 from

"Open Phase" Conditions

06/21/2018

AENANC10A*AC*ELECON HVAC OPP cabinets

11/13/2020

CDF Cutset Report 1

OPIS Automatic Trip Function Enabled

09/15/2021

CDF Cutset Report 2

OPIS Automatic Trip Disabled

09/15/2021

CDF Cutset Report 3

Differences - Trip Enabled versus Disabled

09/15/2021

E003-00138

Open Phase Protection (OPP) System Operating

and Maintenance Manual

0.0.1

E003-00205

PSSTech Open Phase Protection System -

Preventative Maintenance Guide

0.0.1

IEGR-DD-184

Open Phase Protection (OPP System)

Procedures

40AL-9MA01

Transformer Trouble Alarm Responses

40AL-9MA01

Transformer Trouble Alarm Responses (TAPA)

49a

40DP-9OPA9

Outside Area Operator Logs

19