05000220/LER-2002-001, Kilovolt Offsite Power Inoperable Due to Low Voltage on Line 4 and Line 1 Out of Service

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Kilovolt Offsite Power Inoperable Due to Low Voltage on Line 4 and Line 1 Out of Service
ML030070699
Person / Time
Site: Nine Mile Point Constellation icon.png
Issue date: 12/27/2002
From: Hopkins L
Constellation Energy Group
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
NMP1L 1706 LER 02-001-00
Download: ML030070699 (5)
v • d • e


LER-2002-001, Kilovolt Offsite Power Inoperable Due to Low Voltage on Line 4 and Line 1 Out of Service
Event date:
Report date:
Reporting criterion: 10 CFR 50.73(a)(2)(v), Loss of Safety Function
10 CFR 50.73(a)(2)
10 CFR 50.73(a)(2)(x)
10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor
10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat
10 CFR 50.73(a)(2)(i)
10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded
10 CFR 50.73(a)(2)(viii)(B)
2202002001R00 - NRC Website
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text

P.O. Box 63 Lycoming, New York 13093 ConstlaW i

Energy Group Nine Mile Point Nuclear Station December 27, 2002 NMP1L 1706 United States Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555

Subject:

Nine Mile Point Unit 1 Docket No. 50-220; DPR-63 Licensee Event Report 02-00 1, "115 kilovolt Offsite Power Inoperable Due to Low Voltage on Line 4 and Line 1 Out of Service" Gentlemen:

In accordance with 10 CFR 50.73(a)(2)(v)(D), we are submitting Licensee Event Report 02-001, "115 kilovolt Offsite Power Inoperable Due to Low Voltage on Line 4 and Line 1 Out of Service."

Very truly yours, LUa va-,

Lawrence A. Hopkins Plant General Manager LAH/LE Attachment cc:

Mr. H. J. Miller, NRC Regional Administrator, Region I Mr. G. K. Hunegs, NRC Senior Resident Inspector

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 3150-0104 EXPIRES 7-31-2004

,1-200lj reverse for rctuisred number ok the NRC may not conduct or sponsor, and a person Is not required to respond to, the digits/characters for each block) nformation collection.____________

FACILITY NAME (1)

DOCKET NUMBER (2)

PAGE (3)

Nine Mile Point, Unit 1 05000220 1 OF 4

TITLE (4) 115 kilovolt Offsite Power Inoperable Due to Low Voltage on Line 4 and Line 1 Out of Service EVENT DATE (5)

LER NUMBER (6)

REPORT DATE (7)

OTHER FACITIES INVOLVED (B)

MO DAY YEAR YEAR SEQUENTIAL REV MO DAY YEAR FACILITYNAME DOCKET NUMBER NUMBER I

NO I

05000 11 01 2002 2002 -

001 -

00 12 27 2002 DOCKET NUMBER 05000 OPERATING 1

THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR j: (Check all that apply) (11)

MODE (9)

POWER

_20.2201 (b)

_ 20.2203(a)(3)(ii)

_ 50.73(a)(2)(i0(B) 50.73(a)(2)(a)(A)

LEVEL (10) 100 20.2201 (d) 20.2203(a)(4) 50.73(a)(2)(Iii) 50.73(a)(2)(x) 20.2203(a)(1) 50.36(c)(1)()(A_

50.73(aX2)(iv)(A) 73.71(a)(4) 20.2203(aX2)(D 50.36(c)(1)(li)(A) 50.73(a)(2)(v)(A) 73.71 (a)(5) 120.2203(a)(2)(ii) 50.36(c)(2) 50.73(a)(2)(v)(B)

OTHER 20.2203(a)(2)(lii) 50.46(a)(3)(i1) 50.73(a)(2)(v)(C) 20.2203(a)(2)(Iv) 50.73(a)(2)(i(A)

X 50.73(a)(2)(v)(D) 20.2203(a)(2)(v)

_ 50.73(a)(2)(D(B) 50.73(a)(2)(vii-20.2203(a)(2)(vi)

_ 50.73(a)(2)(i)(C) 50.73(a)(2)(viil)(A) 20.2203(a)(3)(i) 50.73(a)(2)(ii)(A) 50.73(a)(2)(viii)(B)

LICENSEE CONTACT FOR THIS LER (12)

NAME TELEPHONE NUMBER (Include Area Code)

R. G. Randall, Manager Engineering 315-349-2445 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)

CAiSEF SYSTEMI COMPONENT I MANU-Ft RETPORTABLE CUE SYSTEM COMPONEN MANU-REPORTABLE I

S FACTURER TO EPIX FAMTURER TO EPIX SUPPLEMENTAL REPORT EXPECTED (14)

EXPECTED MONTH DAY YEAR T SUBMISSION D ) X l

DATE (15) l l

ES- (iLecmlt XETDSBISO AE.

XIN ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines) (16)

At 1508 hours0.0175 days <br />0.419 hours <br />0.00249 weeks <br />5.73794e-4 months <br /> on November 1, 2002, with 115 kilovolt (kV) Line 1 out of service to support emergency repair activities being performed on Line 2, National Grid Power Control (NGPC) notified the Nine Mile Point Unit 1 (NMP1) control room staff that a low contingency voltage alarm had been received for 115 kV Line 4. When Line 1 was removed from service, NMP1 entered action statement 3.6.3 of the Technical Specifications, requiring restoration of Line 1 within seven days or commence a plant shutdown. Upon notification of the low contingency voltage alarm, NMP1 operators declared Line 4 Inoperable and proceeded with Action statement 3.6.3 of the Technical Specifications for both 115 kV lines inoperable. With 115 kV offsite power inoperable, both emergency diesel generators were started and aligned to power emergency buses, as required by procedure. At 2310 hours0.0267 days <br />0.642 hours <br />0.00382 weeks <br />8.78955e-4 months <br />, Line 1 was restored to service and the low contingency voltage alarm cleared. With both 115 kV lines operable, NMP1 exited 3.6.3 action statement of the Technical Specifications.

The cause of the event was inadequate validation and verification of the administrative process governing the interface between NMP1 and NGPC for maintaining 115 kV voltage. This led to weaknesses in the process. For example, there was no formal administrative process identified for taking Line 1 out of service. Contributing causes include insufficient training, inadequate administrative controls, and the design of Line 4, which can require actions to boost voltage when Line 1 is out of service.

Corrective actions include implementing additional training, procedure modifications, and modifications to provide voltage control when Line 1 is out of service and Line 4 is supporting the 115 kV bus.

NRC FORM 366 (1.2001)

I NRCFOIM366A U.S.NUCLEARREGULATORYCOMMISSION (1-2001)

LICENSEE EVENT REPORT (LER)

FACILITY NAME (1)

DOCKET (2)

LER NUMBER (6)

PAGE (3)

NUME 2

Nine Mile Point, Unit 1 05000220 YEAR SEQUENTIAL REVISION 2

OF 4

NUMBER NUMBER 2002 001 00

NARRATIVE

(if mre space Is required, use additional c of NRC Form 3664) (17)

I. Description of Event

On November 1, 2002, at 0901 hours0.0104 days <br />0.25 hours <br />0.00149 weeks <br />3.428305e-4 months <br />, National Grid Power Control (NGPC) notified Nine Mile Point Unit 1 (NMP1) that a fault had occurred on 115 kV Line 2, the fault had been isolated, and the 115 kV grid was stable. At 1208 hours0.014 days <br />0.336 hours <br />0.002 weeks <br />4.59644e-4 months <br />, NGPC notified NMP1 that 115 kV Line 1 needed to be removed from service for approximately 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> to allow repair of a damaged insulator on Line 2. The removal from service was needed for personnel safety considerations because of the Line 1 proximity to Line 2. Line 1 and Line 4 provide 115 kV offsite power to NMP1.

At approximately 1430 hours0.0166 days <br />0.397 hours <br />0.00236 weeks <br />5.44115e-4 months <br />, a NGPC engineer ran the 115 kV grid voltage estimator program to obtain an estimation of the impact of removing Line 1 on the Line 4 voltage. The estimator program Is a computer program that is used to predict voltage and other grid parameters given various conditions. One of the outputs of the program is contingency voltage, which is the projected 115 kV system voltage for the specified conditions. A contingency voltage value less than 111.8 kV, the low contingency voltage alarm setpoint on Line 4, is assumed to actuate the Degraded Voltage Relays (DVR) at NMP1 which result in separating the emergency buses from the 115 kV supply. The conditions used for the estimator program run at 1430 were: Line 1 out of service, a plant trip at NMPI with a Loss of Coolant Accident (LOCA),

and Emergency Core Cooling System equipment needed to mitigate the LOCA supplied from the 115 kV system. This generated a contingency voltage below the low contingency voltage alarm setpoint for Line 4.

The engineer informed the NGPC operators that the voltage would likely go low, and reviewed Policy 4.42, Nine Mile Point 1 & 2 and Fitzpatrick Post Contingency Voltage Alarm, with the operators to familiarize them with their required actions. The engineer knew that NMP1 would be required to enter an Action statement requiring a plant shutdown to commence within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> unless either 115 kV Line 1 or 115 kV Line 4 were restored. He also knew that the NMP1 operators had a procedural process that would be followed under those conditions. Furthermore, he believed that Line 1 and Line 4 would likely be restored by 2400 hours0.0278 days <br />0.667 hours <br />0.00397 weeks <br />9.132e-4 months <br /> on November 1, well before the end of the 24-hour Action statement.

The NGPC engineer did not realize the impact on NMP1 station operators, or the overall increased risk. He also did not realize the implications of a planned 115 kV outage versus an unexpected and unplanned outage. As a result, NGPC operators did not inform the NMP1 operators that removing Line 1 from service would likely result in receipt of a low contingency voltage alarm for Line 4. Consequently, NMP1 operators did not realize that removing Line 1 from service for corrective maintenance on Line 2 would result in entry into an unplanned 24-hour Action statement.

At 1501 hours0.0174 days <br />0.417 hours <br />0.00248 weeks <br />5.711305e-4 months <br />, Line 1 was removed from service and NMP1 entered Action statement 3.6.3 of Technical Specifications, which requires restoration of Line 1 within seven days or commence a plant shutdown. At 1508 hours0.0175 days <br />0.419 hours <br />0.00249 weeks <br />5.73794e-4 months <br />, NMP1 was notified by NGPC that a low contingency voltage alarm was received for LIne 4. NMP1 declared Line 4 Inoperable and entered the Action statement 3.6.3 of Technical Specifications requiring restoration of Line 1 or Line 4 within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or commence a plant shutdown. With 115 kV offsite power inoperable, in accordance with plant procedures, NMP1 started activities to place both emergency diesels on their respective emergency buses and separate from the 115 kV system. At 1639 hours0.019 days <br />0.455 hours <br />0.00271 weeks <br />6.236395e-4 months <br />, emergency diesel generator EDG-1 02 was running and powering its associated emergency bus. At 1757 hours0.0203 days <br />0.488 hours <br />0.00291 weeks <br />6.685385e-4 months <br />, emergency diesel generator EDG-103 was running and powering its associated emergency bus.

At 2310 hours0.0267 days <br />0.642 hours <br />0.00382 weeks <br />8.78955e-4 months <br />, Line i was returned to service and the low contingency voltage alarm cleared on Line 4. With both 115 kV lines operable, NMP1 exited Action statement 3.6.3 of the Technical Specifications.

I (if more space Is required, use additional copies of (ff more space Is required, use additional copies of NRC Formn 366A) (17)

IV. Corrective Actions

1.

NGPC revised their Policy 4.42, Nine Mile Point 1 & 2 and Fitzpatrick Post Contingency Voltage Alarm, to include NGPC operator actions when it Is expected that future system conditions may bring in the low contingency voltage alarm.

2.

NMP1 implemented an interim checklist for communication between NMP1 and NGPC, to be used when removing Line 1 from service.

3.

Training will be provided for NGPC operators and support engineers on low voltage contingencies for Nine Mile Point Unit 1 and Unit 2, and the impact of line outages to risk.

4.

NMPNS procedures will be modified to address communications that are needed with NGPC whenever NGPC notifies NMP1 that a 115 kV line needs to be taken out of service. These procedure changes will be verified and validated by a joint meeting of NMP1 engineering, operations, and work control personnel, and NGPC engineering and operations personnel.

5.

Continued training will be established to reinforce the design and communications issues.

6.

A modification will be implemented that provides effective voltage control for the 115 kV system when Line 1 is out of service and Line 4 is supporting the 115 kV bus.

V. Additional Information

A. Failed Components:

None

B. Previous similar events

Licensee Event Report (LER)01-002, "115 kilovolt Une 4 Inoperable due to Inadequate Analysis of Design Change," describes the event that resulted in creation of the administrative process for interfacing between NMP1 and NGPC, providing training for NMP1 and NGPC personnel, and modification of procedures. These actions should have prevented the event described in LER 02-001.

C. Identification of components referred to In this Licensee Event Report:

Components IEEE 805 System ID IEEE 803A Function 115 kV Offsite Power FK N/A Emergency Diesel Generators EK DG Emergency Core Cooling Systems BM N/A Emergency Cooling System BL N/A High Pressure Coolant Injection BJ N/A Relay EK 27 Alarm FK EA Condenser BL COND

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