05000461/LER-1997-006, :on 970219,lack of Coordination of 120 Volt non-safe Shutdown Circuit Breakers in Distribution Panels W/Shutdown Circuit Breakers Causes Plant to Be Outside Its Basis.Corrected Circuit Breaker Problems

:on 970219,lack of Coordination of 120 Volt non-safe Shutdown Circuit Breakers in Distribution Panels W/Shutdown Circuit Breakers Causes Plant to Be Outside Its Basis.Corrected Circuit Breaker Problems

ML20147F416
Person / Time
Site:	Clinton
Issue date:	03/20/1997
From:	Connell W, Tockstein D ILLINOIS POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-97-006, LER-97-6, U-602711, WC-150-97, NUDOCS 9703250077
Download: ML20147F416 (5)

LER-1997-006, on 970219,lack of Coordination of 120 Volt non-safe Shutdown Circuit Breakers in Distribution Panels W/Shutdown Circuit Breakers Causes Plant to Be Outside Its Basis.Corrected Circuit Breaker Problems

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(viii) 10 CFR 50.73(a)(2)(ii) 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(iv), System Actuation 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability
4611997006R00 - NRC Website

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Illinois Power Company m

Clinton Power Station P.O. Box 678 Clinton. IL 61727 Tel 217 935-5623 i

Fax 217 935-4632 r

Wilfred Connell E

NMS v'c

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P6WER 2$22o l

WC-150-97 t

March 20, 1997 1

Docket No. 50-461 10CFR50.73 t

Document Control Desk Nuclear Regulatory Commission

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Washington, D.C. 20535

Subject:

Clinton Power Station - Unit 1 l

Licensee Event Renort No. 97-006-00 t

Dear Madam or Sir:

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Enclosed is Licensee Event Report (LER) No. 97-006-00: Lack of Coordination

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of 120 Volt Non-Safe Shutdown Circuit Breakers in Distribution Panels with Safe j

i Shutdown Circuit Breakers Causes Plant to be Outside Its Design Basis. This report is

.being submitted in accordance with the requirements of 10CFR50.73.

Sincerely yours, j

$ k maad Wilfred Connell Vice President I

i MRS/krk I

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l Enclosure 1

cc:

NRC Clinton Licensing Project Manager 9

NRC Resident Office, V-690 Regional Administrator, Region Ill, USNRC l-Illinois Departinent of Nuclear Safety -

INPO Records Center 9703250077 970320 PDR ADOCK 05000461

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PDR

.E.E.N

NRC FORM 366 U.S.CUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO.3160 4104 (4-95)

ExpeRss 04i30/se ESTIMATED BURDEN PER RESPONSE TO COMPLY WATH THIS MANDATORY INFORMATION COLLECTION REOUEST: 50.0 HRS.

REPORTED LESSONS LICENSEE EVENT REPORT (LER)

LEARNED ARE WCORPORATED WTO THE UCENSNG PROCESS AND FED SACK TO INDUSTRY. FORWARD COMMENTS REGARDING BURDEN EST1 MATE TO THE INFORMATION AND RECORDS MANAGEMENT SRANCH (T e F331.

U.S.

NUCLEAR R3OULATORY COMMIS90N. WASHINGTON. DC 206664001. AND (See towerse for required number of TO THE PAPERWORK REDUCTION PROJECT (31504104). OFFICE OF dl tts/cherectors for each block)

MANAGEMENT AND BUDGET. WASHINGTON. DC 20603.

9 F AcaWTY NAME til DOCKET NUMast G)

PACE (33 Clinton Power Station 05000461 1OF4 TITLE (4)

Lcck of Coordination of 120 Volt Non-Safe Shutdown Circuit Breakers in Distribution Panels with Safe Shutdown Circuit Breakers Causes Plant to be Outside its Design Basis EVEf fT DATF f51 tER NUMRFR ffM REPO tT DATR f 71 OTHFR Facti fTIEBjQ( 3LVED (Pl MONTH DAY YEAR YEAR sEOULNTIAL REvlSON MONTH DAY YEAR FACIUTY N AME DOCKET NUMBER NUMB ER NUMBER None 05000 02 19 97 97 006 00 03 20 97

'* * " "^"'

None 05000 OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS oF 10 CFR 8: (Check one or more) (11)

MODE 19) 4 20.2201(b) 20.2203(a)(2)(v) 50.73(a)(2)(i) 50.73(a)(2)(viii)

POWER 20.2203(a)(1) 20.2203(a)(3)(i)

X 50.73(a)(2)(ii) 50.73(a)(2)(x)

LEVEL (10) 000 20.2203(a)(2)(0 20.2203(a)(3)(io 50.73(a)(2)(iii) 73.71 A

^

20.2203(a)(2Hi0 20.2203(a)(4) 50.73(a)(2)(iv)

OTHER E-20.2203(a)(2)(iii) 50.36(C)(1) 50.73(a)(2)(v)

Specify in Abstract below k$'<

or in NRC Form 366A 20.2203(e)(2)(iv) 50.36(c)(2) 50.73(a)(2)(vii) iICFNRFF CONTACT FOR THIS LD 1171 NAME TELEPHONE NUMBER pnclude Area Cedel D. G. Tockstein, Engineer (217) 935-8881, Extension 4080 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)

CAUSE

SYSTEM COMPONENT MANUFACTURER REPORTABLE

CAUSE

SYSTEM COMPONENT MANUFACTURER REPORTABLE To NPROS TO NPRDS e

M*

i ML SUPPLEMENTAL REPORT EXPECTED (14)

EXPECTED MONTH DAY YEAR SusMISSION DATE (15)

X YES NO 05 30 97 (if yes, Complete EXPECTED SUBMISSION DATE).

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

On February 19, 1997, the plant was in Mode 4 (Cold Shutdown) and reactor coolant temperature was being maintained between 95 and 105 degrees Fahrenheit, reactor pressure was atmospheric. An engineer discovered that there was a circuit breaker coordination problem between 120 volt circuit breakers and safety related 480 volt circuit breakers that supply 120 volt distribution panels. This is contrary to the design basis of the plant which requires that the 120 volt circuit breakers be coordinated with the 480 volt supply circuit breaker to the 120 volt distribution panel on electrical distribution systems that contain safe shutdown and non-safe shutdown equipment. The cause of this event is still under review. Design information is still under review to determine the number of occurrences of this condition.

NRC FORM 366 (4-951

,U.S. NUCLEAR REGULATORY COMMISSION I& 93)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME fil DOCKET LER NUMBER (G)

PAGE (3)

YEAR SEQUENTIAL REV @ON NUMBER NUMBE R Clinton Power Station 05000461 97 006 00 2

OF 4

4 TEXT (11 more space is required, use additional copies of NRC Form 366A) til)

DESCRIPTION OF EVENT

On February 19, 1997, the plant was in Mode 4 (Cold Shutdown) and reactor (RCT] coolant i

temperature was being maintained in a band of 95 to 105 degrees Fahrenheit, reactor pressure was atmospheric.

An engineer was reviewing calculation 19-AI-62 to determine what effect changing a distribution transformer [XFMR] would have on circuit breaker [52] coordination as part of development of a plant modification. The review of this calculation revealed that a potential problem existed with circuit breaker coordination in safety related distribution panels (PL]. The problem identified that an instantaneous overcurrent on a non-safe shutdown circuit supplied by a 120 volt, 2 or 3 pole, 20 or 30 ampere ITE model BQ circuit breaker in a 120 volt distribution panel with a 15 KVA supply transformer could potentially cause the 480 volt supply circuit breaker to the 120 volt distribution panel to trip off before the 120 volt load circuit breaker would trip.

It was determined that this could occur if the 480 volt supply circuit breaker to the 120 volt distribution panel is a 480 volt, 30 ampere ITE model HE revision 3, 1976, or revision 4, 1985.

It was also determined that such a miscoordination could occur if the 480 volt supply circuit breaker to the 120 volt distribution panel breaker is a 480 volt, 30 ampere, ITE model HE, revision 5.

Tripping of the 480 volt supply circuit breaker to the 120 volt distribution panel would cause the loss of all of the loads supplied by the affected 120 volt distribution panel.

This is contrary to the design basis of the plant, described in the Updated Safety Analysis Report Appendix F section 1.5, which requires that the 120 volt circuit breaker for ncn-safe shutdown equipment trip before the 480 volt supply circuit breaker to the 120 volt distribution panel on electrical distribution systems [ED] that contain safe shutdown equipment.

The above condition was identified on condition report 1-97-02-179.

The immediate action for the condition report was to walk down and review the Division I and III electrical distribution system and identify if this condition existed on either of these electrical distribution systems since they were both considered operable at the time.

An immediate walkdown of the Division II electrical distribution system was not required because it was not operable when this condition was identified.

During the walkdown of the 120 volt distribution pancis, on February 19, 1997, at about 2000 hours0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br /> an engineer and electrical maintenance technician discovered that auxiliary building MCC 1A1, LAP 72E, 120 volt distribution panel circuit 1 contained an ITE model BQ 3 pole 30 ampere circuit breaker in a 120 volt distribution panel supplied by a 480 volt ITE model HE, 30 ampere, revision 3, 1976 or revision 4, 1985. This 120 volt circuit supplies power to Operations Department radio equipment [FI).

This 120 volt distribution panel is fed by a 15 KVA transformer, and the distribution panel contains safe shutdown equipment.

The engineer immediately informed the Operations Shift Supervisor of this condition. The Operations Shift Supervisor declared the Division I electrical distribution system inoperable and took the actions required by Technical Specification 3.8.10.

At 2137 hours0.0247 days <br />0.594 hours <br />0.00353 weeks <br />8.131285e-4 months <br /> auxiliary building MCC 1Al, LAP 72E, 120 volt distribution panel circuit 1 was opened.

Openirg the two series circuit breakers on circuit 1 eliminated the potential for a fault cor.dition on that circuit to trip the auxiliary building MCC 120 volt distribution panel.

NRC FORM 36CA t4-9M

U.S. NUCLEAR REGULATORY COMMISSION W9%

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACIUTY NAME f11 DOCKET LER NUMBER (G)

PAGEf3)

YEAR SEQUENTIAL REV'S80N ER NUMBER Clinton Power Station 05000461 97 006 00 3

OF 4

TEXT Ut more space is required, use additional copies of NRC Form 366A) (17)

At 2314 hours0.0268 days <br />0.643 hours <br />0.00383 weeks <br />8.80477e-4 months <br /> a tag out was approved to ensure that circuit 1 circuit breakers are maintained in the open position until the circuit breaker coordination problem can be resolved.

A field walkdown of the Division II electrical distribution system determined that auxiliary building MCC 1B1, LAP 75E, 120 volt distribution panel circuit 1, which serves the Maintenance Department radios, has the same problem as the problem discovered on auxiliary building MCC 1A1, LAP 72E.

However, the associated circuit breakers were not opened because Division II was not operable and therefore proper circuit breaker coordination was not required. An entry was made in the Limiting Condition for Operation log for the Division II electrical distribution system to note that the problem with circuit breaker coordination on the Division II system must be resolved prior to declaring it operabl Review of the drawings for the Division III electrical distribution system showed that the same problem identified with the Division I and II electrical distribution system could not occur on Division III due to the use of different circuit breaker models or different transformers.

Illinois Power is continuing to review the electrical distribution scheme at Clinton Power Station to determine if there are any additional cases of failing to properly coordinate 120 volt distribution panel circuit breakers with the 480 volt supply circuit breakers to the 120 volt distribution panels that feed safe shutdown and non-safe shutdown required equipment.

No automatic or manually initiated safety system responses were necessary to place the plant in a safe and stable condition. No equipment or components were inoperable at the start of this event to the extent that their inoperable condition contributed to this event.

CAUSE OF THE EVENT \\ CORRECTIVE ACTION The cause of the failure to properly coordinate 120 volt distribution panel circuit i

breakers with the 480 volt supply circuit breakers to the 120 volt distribution panels is still under investigation. The corrective actions for this event will be determined after the cause of this event is identified. Corrective actions have been taken to mitigate circuit breaker coordination problems discovered during the investigation of this event.

Circuit breaker coordination information is still being reviewed to identify any further instances of a lack of circuit breaker coordination between 120 volt distribution panel circuit breakers and 480 volt supply circuit breakers to the 120 volt distribution panels that feed safe shutdown and non-safe shutdown required equipment. This review will be complete prior to the plant entering Mode 2 (Startup).

Illinois Power expects to issue a l

revision to this licensee event report identifying the cause of the event, corrective action, an assesstaent of safety consequences and implications of the event and similar event discussion by May 30, 1997.

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U.O. NUCLEAR REOULATORY COMMISSION NRC FORM 3SSA 84-96)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION sanw nry== m new- - 1 esaau---

im pans m WM YEAR SEoUENTIAL psm wtsunrn Clinton Power Station 05000461 97 006 00 4

OF 4

TEKT ttf more space is required, use additional copies of NRC Form 366A) (17)

ANALYSIS OF THE EVENT

This event is reportable under the provisions of 10CFR50.73(a)(2)(ii) due to the plant being in a condition outside of its design basis.

l An assessment of the safety consequences and implications of this event has not yet been completed. This information will be provided in a revision to this report.

It is believed that the circuit breaker coordination problems described in this report have

[

xisted since initial plant licensing, r

ADDITIONAL INFORMATION

I No equipment or components failed during this event.

l Previous similar event information will be provided in a revision to this report.

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For further information on regarding this event contact D. G. Tockstein Engineer-Nuclear Station Engineering at (217) 935-8881, extension 4080.

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