IR 05000220/2019014

Temporary Instruction Report 05000220/2019014 and 05000410/2019014

ML19344C980
Person / Time
Site:	Nine Mile Point
Issue date:	12/09/2019
From:	Glenn Dentel NRC Region 1
To:	Bryan Hanson Exelon Generation Co
References
IR 2019014
Download: ML19344C980 (9)

Text

ber 9, 2019

SUBJECT:

NINE MILE POINT NUCLEAR STATION, UNITS 1 AND 2 - TEMPORARY INSTRUCTION REPORT 05000220/2019014 AND 05000410/2019014

Dear Mr. Hanson:

On November 20, 2019, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at Nine Mile Point Nuclear Station, Units 1 and 2 and discussed the results of this inspection with Mr. Todd Tierney, Plant Manager 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,

/RA/

Glenn T. Dentel, Chief Engineering Branch 2 Division of Reactor Safety Docket Nos. 05000220 and 05000410 License Nos. DPR-63 and NPF-69 Enclosure:

As stated cc w/ encl: Distribution via LISTSERV

SUMMARY

The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees performance by conducting a Temporary Instruction at Nine Mile Point Nuclear Station, Units 1 and 2, 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 IPs with their attached revision histories are located on the public website at http://www.nrc.gov/reading-rm/doc-collections/insp-manual/inspection-procedure/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.

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) Exelon selected the open phase detection system designed and manufactured by Schweitzer Engineering Laboratories (SEL) as the design vendor for the open phase condition system at Nine Mile Point Nuclear Station. The open phase protection system is designed to protect the offsite power sources from a loss of phase condition.

Nine Mile Point Nuclear Station Unit 1 has two 115kV independent offsite power sources (Lines 1 and 4), which provide power to the station through breakers R10 and R40, and through Reserve Transformer 101N and Reserve Transformer 101S. Unit 2 has two 115kV independent offsite power sources (Lines 5 and 6),which provide power to the station through Reserve Transformer A, Reserve Transformer B, and the Auxiliary Boiler Transformer. SEL relays were installed to monitor, alarm, and provide a trip function on each of the 5 offsite power transformers, and for breakers R10 and R40. The relays are wired to provide annunciation and are configured to trip the associated power sources if a loss of phase condition is detected. The loss of phase detection relays include main control room annunciation and plant process computer alarms for relay trips, relay malfunction, and, in some cases, minimum loading conditions.

At the end of the inspection, the SEL system was in the alarm only mode of operation. The relay trip signals were isolated from the lockout relays by leaving test switches open. Exelon plans to pursue an alternate implementation method (i.e. risk based with manual actions) for Unit 1 and Unit 2 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 Exelon staff, review of design and testing documentation, and walkdowns of installed equipment, the inspectors had reasonable assurance that the Exelon is appropriately implementing, with noted exceptions discussed below, the voluntary industry initiative at Nine Mile Point Nuclear Station. The inspectors determined that:

Detection, Alarms and General Criteria 1. The open phase condition 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. Additionally, Exelon has demonstrated that the actuation circuit design does not result in lower overall plant operation reliability. 03.01(a)(3)2. No Class 1E circuits were being replaced with non-Class 1E circuits in this design.

03.01(a)(4)

Protective Actions Criteria 1. The identified offsite power sources are susceptible to an open phase condition and the licensee was implementing design changes to mitigate the effects. 03.01(b)(1)2. With an open phase condition present and no accident condition signal, Technical Specification Limiting Conditions for Operation would be maintained, important-to-safety equipment would not be damaged by the open phase condition, and shutdown safety would not be compromised. Exelon's open phase condition design solution added a set of additional tripping inputs in parallel with existing power isolation devices. These additional devices added a new tripping condition (open phase) to the previously analyzed electrical faults which result in isolation of the transformers. The credited plant response was unaffected and would be the same regardless of the conditions that generated the isolation of the transformers. 03.01(b)(2)

No findings were identified.

Detection, Alarms and General Criteria Exceptions 2515/194 03.01(a)(1) In general, open phase condition detection and alarming was adequately implemented at Nine Mile Point Nuclear Station. Inspectors noted one exception to this criteria.

During a system walkdown on November 18, 2019, inspectors identified that a test switch associated with the SEL relay for the 101N transformer was tagged in the open position. The test switch was opened on May 20, 2019, in response to nuisance alarms in the main control room associated with a minimum loading condition on the 101N transformer. Operators opened the test switch, believing that the plant process computer would still produce an alarm in the main control room. However, inspectors determined that with the test switch opened, no alarms would be received for any detected open phase condition for transformer 101N and that additional compensatory measures to monitor for these conditions should be in place. Inspectors did not identify any additional compensatory measures in place while the open phase condition alarm was bypassed for the 101N transformer. However, operators monitor transformer bus voltages every four hours and would have likely recognized an open phase condition. At the end of the inspection, additional compensatory measures were established, including taking additional transformer voltage and current readings at least once per shift. This issue was documented in their corrective action program as issue report 04298487.

03.01(a)(2) For cases in which automatic detection was not possible in very low or no loading conditions when the offsite power transformers are in a standby mode, inspectors determined that automatic detection would occur as soon as loads were transferred to the standby source. However, Exelon determined that additional shiftly surveillances were needed to adequately monitor and detect an open phase condition while in a very low or no loading condition. This was identified during an Exelon self-assessment performed prior to the inspection and documented in issue report 04296560.

03.01(a)(5) Exelon had neither updated the Nine Mile Point Unit 1 Updated Final Safety Analysis Report (UFSAR) nor the Unit 2 Updated Safety Analysis Report (USAR) to discuss the design features and analyses related to the effects of, and protection for, any open phase condition design vulnerability. The Unit 2 USAR did include a listing of the added open phase condition relays, without further system or analysis description. This was identified during an Exelon self-assessment performed prior to the inspection and documented in issue report 04296560.

Protective Actions Exceptions 2515/194 03.01(b)(3) Inspectors determined that with an open phase condition 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. Automatic detection of an open phase condition has been installed, but the automatic actuation of the system has been bypassed. Exelons operating procedures, once detection has occurred, would allow operators to diagnose the condition and transfer the required loads to the non-affected offsite source, or the onsite emergency power source. A loss of voltage caused by isolation of offsite sources due to an open phase condition does not have an adverse effect on the availability of the non-affected offsite sources, or to the onsite emergency power sources. The bypass of the automatic isolation was identified during an Exelon self-assessment performed prior to the inspection and documented in issue report 04296567.

03.01(b)(4) Relay setpoints associated with the open phase detection scheme were verified and validated as part of acceptance factory testing, and as part of the system monitoring period. Preventative maintenance testing and periodic calibrations were developed for some aspects of the open phase detection system for Unit 1 systems, but none had been developed for Unit 2 systems. This was identified during an Exelon self-assessment performed prior to the inspection and documented in issue report

EXIT MEETINGS AND DEBRIEFS

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

• On November 20, 2019, the inspectors presented the Temporary Instruction results to Mr. Todd Tierney, Plant Manager and other members of the licensee staff.

DOCUMENTS REVIEWED

Inspection Type Designation Description or Title Revision or

Procedure Date

2515/194 Calculations 115kV- NMP1 Open Phase EMTP Analysis Revision

OPENPHASE- 0000

STUDY

115kV- NMP1 Open Phase LOCA Analysis Revision

OPENPHASELOCA- 0000

STUDY

115KV- Unit 1 XF-101N and XF-101S Relay Settings for Open Revision

OPENPHASEXFMR- Phase 0000

SP

EC-204 NMP2 Open Phase EMTP Analysis Revision

0000

EC-205 NMP2 Open Phase LOCA Analysis Revision

0000

EC-208 Unit 2 SEL-487E Relay Settings Revision

0000

EC-209 NMP2 Open Phase Alternate Offsite Source Analysis Revision

0000

Corrective Action 04015088

Documents 04296556

250274

296554

250274

296560

292365

Corrective Action 04298477 Door C288-1 Failed to Latch on First Closure

Documents 04298484 Discrepancies Noted with Unit 1 and Unit 2 Open Phase

Resulting from Relay (clocks)

Inspection 04298487 N1-OP-033A Procedure Discrepancy Identified

298493 Scriba Yard Relay Data Historian UPS in Alarm

Engineering ECP-14-000340 Unit 1 Open Phase Relaying for Transformers XF-101S Revision

Changes and XF-101N 0001

ECP-14-000922 NMP2 Open Phase Detection System Implementation Revision

Inspection Type Designation Description or Title Revision or

Procedure Date

(Scriba Transformers) 0002

ECP-15-000297 Open Phase Detection System Implementation (NMP2 Revision

Transformers) 0002

ECP-16-000021 Unit 1 Open Phase Detection Implementation (115 kV Line Revision

1. 1 (BKR-R10) and 115 kV Line #4 (BKR-R40)) 0001

ECP-17-000507 NMP Unit 1 & 2 - Open Phase Algorithm and OPD Relay Revision

Setting Change Modification 0000

ECP-17-000507 NMP Unit 1 & 2 - Open Phase Algorithm and OPD Relay Revision

Setting Change Modification 0001

Miscellaneous AR 04289767 NRC Open Phase Inspection TI 2515/194 Self- 10/22/2019

Assessment

N1-PM-S1 NMP1 Control Room Parameter Monitoring 11/19/2019

(Compensatory Measures) for OPC 101N

NMP1 LER 05-004 Operation Prohibited by Technical Specification due to 02/17/2006

Unrevealed Inoperability of One Off-site Power Source

PCRS-18-01100 Update to N1-OP-033A 05/28/2018

Tag ACPS NMP-U1 ACPS to Maintain Configuration of Open Phase Mod Knife 11/18/2019

19-055 Switch (P&ID C34857C, Sht 2)

Procedures N1-ARP-A8 Control Room Panel A8 Revision

01500

N1-OP-033A 115kV System Revision

03300

N2-ARP-852600 2CEC*PNL852 Series 600 Alarm Response Procedures Revision

01100

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