IR 05000336/2020010

Temporary Instruction 2515/194 Inspection Report 05000336/2020010 and 05000423/2020010

ML20083F717
Person / Time
Site:	Millstone
Issue date:	03/20/2020
From:	Glenn Dentel Engineering Region 1 Branch 2
To:	Stoddard D Dominion Energy
Dentel G
References
IR 2020010
Download: ML20083F717 (9)

Text

March 20, 2020

SUBJECT:

MILLSTONE POWER STATION, UNITS 2 AND 3 - TEMPORARY INSTRUCTION 2515/194 INSPECTION REPORT 05000336/2020010 AND 05000423/2020010

Dear Mr. Stoddard:

On March 5, 2020, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at Millstone Power Station, Units 2 and 3 and discussed the results of this inspection with John Daugherty, Site Vice President 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, X /RA/

Signed by: Glenn T. Dentel Glenn T. Dentel, Chief Engineering Branch 2 Division of Reactor Safety Docket Nos. 05000336 and 05000423 License Nos. DPR-65 and NPF-49

Enclosure:

As stated

Inspection Report

Docket Numbers: 05000336 and 05000423 License Numbers: DPR-65 and NPF-49 Report Numbers: 05000336/2020010 and 05000423/2020010 Enterprise Identifier: I-2020-010-0015 Licensee: Dominion Energy Nuclear Connecticut, Inc.

Facility: Millstone Power Station, Units 2 and 3 Location: P.O. Box 128 Waterford, CT 06385 Inspection Dates: March 3, 2020 to March 5, 2020 Inspectors: L. Dumont, Reactor Inspector B. Pinson, Reactor Inspector Approved By: Glenn T. Dentel, Chief Engineering Branch 2 Division of Reactor Safety Enclosure

SUMMARY

The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees performance by conducting a Temporary Instruction 2515/194 Inspection at Millstone Power Station, Units 2 and 3, 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

The inspection was conducted using Temporary Instruction 2515/194 (ADAMS Accession No. ML17137A416), effective November 1, 2017. The inspectors reviewed the licensees implementation of the Nuclear Energy Institutes voluntary industry initiative in compliance with Commission guidance. The inspectors discussed Millstones open phase condition system design and ongoing implementation plans with plant staff. The inspectors reviewed licensee and vendor documentation, and performed system walkdowns to verify that the installed equipment was supported by the design documentation.

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 the Nuclear Energy Institute Voluntary Industry Initiative, (ADAMS Accession No. ML15075A454) dated March 16, 2015. This included reviewing how the licensee updated their licensing basis to reflect the need to protect against open phase conditions.

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) Dominion Energy Nuclear Connecticut, Inc., selected the open phase detection system designed and manufactured by Power System Sentinel Technologies, LLC, (PSSTech) as the design vendor for the open phase condition (OPC) system at Millstone Power Station. The open phase protection system is designed to protect the offsite power sources from a loss of phase condition.

The offsite electrical distribution system is functionally the same for both Millstone Unit 2 (MP2) and Unit 3 (MP3). At each unit the offsite power system includes the transmission system and the 345-kV switchyard. Included in the system are main generator step-up transformers (GSUs) and the reserve station service transformers (RSSTs) of both MP2 and MP3.

At the end of the inspection, the PSSTechs were in the "Detect" mode of operation.

The trip function was bypassed and will remain disabled on MP2 transformers, and will not be installed on the MP3 transformers. Dominion Energy Nuclear Connecticut, Inc. plans to pursue an alternate implementation method (i.e. risk based with manual actions) for Unit 2 and Unit 3 to comply with the open phase detection initiative.

INSPECTION RESULTS

Temporary Instruction 2515/194-03.01 - Voluntary Industry Initiative 2515/194 Based on discussions with licensee staff, review of design and testing documentation, and walkdowns of installed equipment, the inspectors had reasonable assurance that the licensee is appropriately implementing, with noted exceptions discussed below, the voluntary industry initiative at Millstone Power Station, Units 2 and 3. The inspectors determined that:

Detection, Alarms, and General Criteria

2. 03.01(a)(2) Detection circuits are sensitive enough to identify an OPC for credited loading

conditions (i.e., high and low loading).

3. 03.01(a)(3) OPC design and protective schemes minimize misoperation or spurious action

in the range of voltage unbalance normally expected in the transmission system that could cause separation from an operable off-site power source. In the design of the OPC system, multiple features have been added to prevent spurious trips of the system. Dominion Energy solutions demonstrated that the actuation circuit design does not result in lower overall plant operation reliability.

4. 03.01(a)(4) No class 1E circuits were replaced with non class 1E circuits during installation

of the open phase detection system.

Protective Actions Criteria

1. 03.01(b)(1) An OPC detection system was installed on the high voltage side of the MP2

GSU transformer and the MP2 RSST. Additionally, an OPC detection system was installed on the MP3 GSU transformer and the MP3 RSST "A" to mitigate the effects of an OPC.

2. 03.01(b)(2) With an OPC present and no accident condition signal, the open phase design

would not adversely affect the function of important-to-safety systems, structures, or components. The licensees OPC design solution added three PSSTech systems on the high side of the MP2 GSU and RSST and the MP3 GSU and RSST. The credited plant response was unaffected and would be the same regardless of the conditions that generated the lockout of the transformer.

No findings were identified.

Detection, Alarms, and General Criteria Exceptions 2515/194 03.01(a)(5) Neither MP2 and MP3 UFSAR were updated at the time of the inspection to describe the design features of the OPC detection system. This was documented in CR-1142660 and was identified during the self-assessment conducted prior to the start of the inspection under PIR1135211. The licensee provided to the inspectors the proposed changes to the licensing basis that discussed the system requirements related to the effects of, and protection for, any OPC design vulnerability.

Protective Actions Exceptions 2515/194 03.01(b)(3) The inspectors determined that with an OPC and an accident condition signal present, the open phase detection system would not adversely affect the function of the load shedding and sequencing system to provide a means of disconnecting and sequencing of loads on the safety related buses. The open phase protection trip circuit was installed on MP2 transformers; however, the trip function was bypassed and will remain disabled on MP2 transformers, and will not be installed on the MP3 transformers as a result of the licensee deciding to implement the risk informed guidance of NEI 19-02, Revision 3. As such, the OPC equipment on both units were not placed in the trip mode of operation.

03.01(b)(4) At the time of this inspection, the licensee had not established documentation for periodic tests, calibrations, setpoint verifications, or inspection procedures associated with the PSSTech equipment.

EXIT MEETINGS AND DEBRIEFS

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

• On March 5, 2020, the inspectors presented the Temporary Instruction 2515/194 Inspection results to John Daugherty, Site Vice President and other members of the licensee staff.

DOCUMENTS REVIEWED

Inspection Type Designation Description or Title Revision or

Procedure Date

2515/194 Calculations MP2-ENG-EMTP- MP2 Open Phase Condition Modeling Analysis 1

04446E2

MP2-ENG-EMTP- MP2 Open Phase Condition EMTP Time Delay Limit Analysis

04447E2

MP3-ENG-EMTP- MP3 Open Phase Condition Time Delay Limit Analysis 1

04547E3

MP3-ENG-EMTP- MP3 Open Phase Condition Modeling and Analysis 1

04548E3

Corrective Action CR1136741

Documents CR1136786

CR1142281

CR1142285

CR1142530

Corrective Action CR1142660

Documents

Resulting from

Inspection

Drawings 1700156-E- Generator Transformer (15G-2U) Final Trip & Coast Down 0

203-32005

1700156-E- Generator Transformer (15G-2U) Final Trip and Generator 1

20332005-B Coast Down

203-30001 Main Single Line Diagram 48

212-30001 Main One Line / Phasing Diagram PWR Distr Sys Composite 27

Engineering MP2-17-00156 MP2 Open Phase Condition Detection System (Protection 5

Changes Phase)

MP3-17-00157 MP3 Open Phase Condition Detection System (Protection 4

Phase)

Miscellaneous Open Phase Protection System Unit 3 GSU Online 12/12/2017

Commissioning Test

Unit 3 Plant Equipment Round - Outside 2/28/2020 -

3/3/2020

Millstone Switchyard Inspection 2/21/2020

Inspection Type Designation Description or Title Revision or

Procedure Date

Unit 2 Outside Rounds 2/28/2020 -

3/3/2020

Open Phase Protection System Unit 3 RSST Online 12/12/2017

Commissioning Test

Unit 2 Control 2/28/2020

Room Weekly

Checks

Unit 3 Mode 1-4 2/29/2020

Weekly Control

Room Rounds

Procedures 1-8 RSST Open Phase 014

2-1 Main XFMR Open Phase 016

3-9 RSST Open Phase Sys Trouble 014

5-1 Main XFMR Phase Sys Trouble 016

BA-47 Main XFMR Open Phase 003

BB-47 Main XFRM Open Phase Sys Trouble 002

CA-48 RSST Open Phase 003

CB-48 RSST Open Phase Sys Trouble 001

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