ML19262A247

Abnormal Occurrence 50-289/75-07:on 750317,problems Found W/Connector & Wiring on Engineered Safeguard Motor Control Center Units.Caused by Poor Workmanship During Mfg &/Or Installation.Connections Tightened & Wire Replaced

ML19262A247
Person / Time
Site:	Crane
Issue date:	04/02/1975
From:	Arnold R METROPOLITAN EDISON CO.
To:
References
GQL-0893, GQL-893, NUDOCS 7910260583
Download: ML19262A247 (7)

Text

.

NRCi TRIBUTION FOR PART SO DOCKE .1 ATE RI AL (TEMPORARY FORM)

CONTROL NO: 878 FILE: INCIDEPT PEPC'T FI'2 FROM: Metropolitan Edison Co. DATE OF DOC DATE REC'D LTR TWX RPT OTHER P.O. Box 542 Reading,Pa. U R.C. Arnold 4 9 7r A s_7s AG TO: ORIG CC OTHER SENT AEC PDR NRC 1 signed SENT LOCAL PDR CLASS UNCLASS PROPINFO INPUT NO CYS REC'D DOCKET NO:

EX 1 50-289 DESCRIPTION: ENCLOSU R ES:

Ltr. trans the following... Abnorm Occurr. fi 75-07, on 3-17-75, cancernini Connector and Wiring on Engineered Safe-guard Motor Control Center _ Units. . .

. . . . .s

~

PLANT NAME: Three Mile Island til FOR ACTION /INFORMATION vrp t :_,s BUTLER (L) SCHWENCE R (L) ZIEMANN (L) REG AN (E)

W/ Copies W/ Copics W/ Copies W/ Copies CLARK 'L) STOLZ (L) DICKER (E) /LE AR (L) w f r.n piet W/ Copies W/ Conies / W8 Con.es dan o (L) V A9SA! ! O f t i KNIGHTON (El SPELS W/ Copies W/ Copies W/ Copies W/ Copies KNIEL (L) PURPLE (L) YOUNGBLOOD (E)

W/ Copics .W/ Copies W/ Copies W/ Copies INTERNAL DISTRISUTION A/T IND

@G FU : 3 anGFDR TECH REVIEW

,,,, SC H R O E D E R

.DENTON LIC ASST R. DIGGS (L) _B R AITi.. AN f ~ PRIMES SALTZMAN 03C ROOM P 50GA MACCARY GAMMILL H. GE ARIN (L)

GOSSICK/ST AF F KNIGHT KASTN E R E. GOULSOURNE (L) MELTZ BALLARD P. KREUTZER (E) f CASE PAWLICKI SHAO SP ANG LE R J. LEE (L) PLANS GIAMBUSSO MCDONALD BOYD **p ST E L LO M. MAIGRET (L)

MOORE (L) ** , HOUSTON ENVIRO S. PEED (E) CHAPMAN

• • ,,,,N OV AK MULLER M. SERVICE (L) DUBE (Ltrl DEYOUNG (L) E. COUP E SKOVHOLT (L) f ROSS DICKER S. SHEPPARD (L)

KN:GHTON M. SLATER (E) PETERSON GOLLER (L) (Ltr) f IPPOLITO TEDESCO YOUNGBLOOD H. SMITH (L) HARTFIELD (2)

P. CO LLINS KLECKER DENISE LONG REGAN j S. TEETS (L)

LAIN AS PROJECT LDR/ G. F LLI AMS (E) EISENHUT REG OPR V. WILSON (L) . . WIGGINTON

/ FILE & REGION (2) . BENAROYA pT.R. WI LSON (;:) VOLLMER HAR LESS R. INGRAM (L) F. WILLIJ23 STEELE w:m:n -

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• EXTERNAL DISTRIBUTION

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POST OFFICE BOX 542 RE ADING, PENNSYLV ANI A 19603 TELEPHONE 215 - 929-3601 April 2, 1975 GQL 0593 Director Directorate of Reactor Licensing U.S. Nuclear Regulatory Commission Washington, D.C. 20555

Dear Sir:

Operating License DPR-50 Docket #50-289 The following abnormal occurrence is submitted in accordance with the Technical Specifications for Three Mile Island Nuclear S tation, Unit 1, and is being submitted at this time in accordance with the March 26, 1975, conversation between your office's Mr. D. Jaffe and our Mr.

D . N . Gra ce .

(1) Report Number: A0 50-289/75-07 (2a) Report Date: April 2, 1975 (2b) Occurrence Date: March 17, 1975 (3) Facility : Three Mile Island Nuclear Station Unit 1 (4) Identification of Occurrence:

Title:

Connector and Wiring Problems on Engineered Safeguard Motor Control Center Units Type : An abnormal occurrence as defined by the Technical Specif-ications , paragraph 1.8d, in that the connector and wiring problems on Engineered Safeguards motor control center units could possibly threaten to cause portions of Engineered Safety systems to be incapable of performing intended functions .

(3) Conditions Prior to Occurrence:

Power: Core: 99%

Elec.: 867 E' (Gross) 1484 234

RC Flow: 139 x 106 lb/hr RC Pressure: 2150 psig RC Temp.: 580 F PRZR Level: 240 in.

PRZR Temp . : 6500F (6) Description of Occurrence:

On February 26, 1975, a situation regarding the reliability of Engineered Safeguards electrical circuits was reported as Nonroutine 30-Day Repo rt 75-01, and it was during investigations conducted in correction of this finding that additional problems were found and determined to constitute this abnormal occurrence. The initial March 17, 1975, telephone report of this occurrence noted that investigations had revealed 6 of 20 engineered safeguards motor control center units to have some type of wiring and/or connector problems. In addition to these problems, this report also addresses the results of additional inspections conducted through March 22, 1975. Specific descriptions of affected units, and respective associated components, results of inspections, and corrective actions , are given in the attached table.

(7) Designation of Apparent Cause of Occurrence:

The apparent cause of the occurrence is pcor workmanship daring the process of manuf acture and/or installation. This is primarily manifested in three areas : use of wire smaller than required in the manufacturer's specifications, poorly crimped lugs, and loosely-bolted electrical connections.

(8) Analysis of Occurrence:

lt is believed that the connector and wiring problems in the Engineered Safeguards motor control center units discovered in the inspections conducted through March 22, 1975, did not represent a threat to the health and safety of the public in that there was no evidence of overheating nor any indication of imminent f ailure related to these problems. Further, even in the event such a failure had occurred, sufficient redundancy existed to provide the necessary reactor core cooling, reactor building cooling, and isolation functions.

With regard to further operations prior to completion of an inspection program that is still in progress, it has been determined that this cccurrence does not threaten the health and safety of the public because of the redundancy that exists in safety systems, and the fact that two or more unit failures--for components in the same or related safety systems--would have to occur for the capability of safety systecs to be less than that assamed in the accident analyses ;

and the chances of this happening are considered to be highly unlikely.

1484 235

(9) ,

Corrective Action:

Immediate corrective actions have been taken as described in the attached table. It thould be noted that in some of the cases described therein, materials 1eed to be procurred prior to being able to remedy known deficiencies.

The Plant Operations Review Committee (PORC) met after the occurrence and recommended that when possible, deficiencies be continued to be corrected immediately upon discovery by tightening connections or replacing wire. PORC also recommended that

a. the inspection of all safety related units (except those requiring plant shutdown) be completed by April 18, 1975, and

b. the inspectien of all units in Engineered Safeguards Control Centers be completed and, if possible (i.e. barring material procurement problems) corrected by June 30, 1975.

The Station Superintendent concurred with PORC's findings, has taken steps to ensure PORC's recommendations are implemented, and in addition has directed that the use, type, calibration, and control of crimping tools be reviewed and, as may be found to be appropriate, administrative procedures be revised to include the results of this review.

(10) Failure Data:

a. Previous Failures: See Nonroutine 30-Day Report 75 -01

b. Equipment Identification:

ITE Imperial Corp.

480 V Motor Control Center Series 9600 Sincerely, R. C . 4hmold ~

Vice Pr'esident-Generation RCA: RSB :ccs cc: Office of Inspection and Enforcement, Region 1 U.S. Nuclear Regulatory Commission 631 Park Avenue King of Prussia, Pennsylvania 19406 File: 20.1.2 '7.7.3.5.1 1484 236

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