ML20151J500

Part 21 & Deficiency Rept 88-02 Re Improper Mounting of Armature Button on Undervoltage Device Armature.Maint Procedure for CRD Trip Breaker Revised to Include Checks for Defects Discovered W/Undervoltage Device

ML20151J500
Person / Time
Site:	Rancho Seco
Issue date:	04/07/1988
From:	Andognini G, Rutter S SACRAMENTO MUNICIPAL UTILITY DISTRICT
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
References
REF-PT21-88, REF-PT21-88-036-000 88-02, 88-2, GCA-88-223, PT21-88-036-000, PT21-88-36, NUDOCS 8804210136
Download: ML20151J500 (4)

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F ACILITY NAME 0) pocalf NUMSER (2) P ACa t L 3a Rancho Seco Nuclear Generating Station o i s I o l_o 1 o ;3_t 312 y lorl0 3 1 )

10 CFR 21 Report 88-02: Manufacturing Defect on Model 2b%26b4 beneral t.ienric Undervoltage Devices EVENT DATE 15) LER NUMetR tel REPORT DATE in OTHtR f ACittfit $ INVOLVt0 ($1 Sto A6 MONTM DAY TEAR YEAR j a

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. . ,-. . ,,,,-n.~ nei In accordance with 10 CFR 21.21(b)(2). the Sacramento Municipal Utility District hereby submits a written report concerning a manufacturing defect on .

undervoltage devices supplied by General Electric Company. Philadelphia I Pennsylvania. The manufacturing defect is the armature "button" improperly (

mounted on the undervoltage device armature. This defect prevented proper  ;

operation of the Control Rod Drive (CRD) trip breakers. '

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0IO Ol2 0F 0 13 nxw- . .= w m w.nin Comoanv/ Facility In accordance with 10 CFR 21.21(b)(2), the Sacramento Municipal Utility District (SMUD) hereby submits a written report to document the defective manufacture of the undervoltage device (UVD) installed on the General Electric type AK2-25 Control Rod Drive (CRD) trip breakers.

Resoonsible Officer G. Carl Andognini, Chief Executive Officer, Nuclear is the responsible officer

< submitting this report.

Date Resoonsible Officer Received Information The Chief Executive Officer, Nuclear received information concerning the defect on April 7, 1988. The Chirf Executive Officer, Nuclear detennined that this defect should be reported under the provisions of 10 CFR 21 on April 7, 1988.

Basic Component Descriotion Specifications of the CR0 trip breaker with the UVD are:

Type: AK2-25-2 Model: None Voltage: 125V DC Serial No.: 224A3515-506CG-2 Specifications of the UVD with the defect are:

Type: Undervoltage Device Model: 269C282G2 Rating: ll5V 60 Hz Firm Supp1vina Basic Comoonent The firm that supplied the CRD trip breaker was:

General Electric Company Philade hia, Pennsylvania Rescriotion of the Defect and Substantial Safety Hazard That Could Hale _EfLen Coused On March 23, 1988, during the surveillance test of the CRD trip breakers, the

1. 3 DC CRD trip breaker failed to open when Reactor Protection System (RPS) channel D was tripped. The reactor was in hot shutdown and subtritical at the time of the event. A subsequent investigation on March 27, 1988, by SMUD technicians and vendor representatives disclosed that the armature "button" on the UVD was improperly mounted (not centered vertically) on the armature during the manufacture of the UVD (see drawing). Tnis allowed the possibility of the UVD trip paddle to become wedged against the UVD armature and prevent the UVD trip of the CRD trip breaker, pg==== .uacro.. o. . m m l

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LICENSEE EVENT REPORT (LER) TEXT COi4TINUATION amovto ove o mo-oix inP #E S 8 30 88 F LCIL i11 as Aug q t) DoCaliT kg;ugt e til L g g ,, g,,,g g , ,,, pggg ggi 94- " ett,' t' t'#,7:

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UfJOERVOLTAGE TRIP PADDLE UNDERVOLTAGE TRIP PADDLE

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h WY J ARMATURE BUTTori ARMATURE BUTTON UNACCEPTABLE Each group of safety control rods is held in the fully withdrawn position during re6ctor operation. When 12DV AC from RPS is removed from the breaker centrcls. the UVDs open the CRD trip breakers causing loss of power to the CRD n,tchanisms. This actfen releases the control rods which are pulled into the reacter core by genity. In addition to the UVDs, each CRD trip breaker has a 4 shunt trip device which provides a redundant means to open the CRD trip breakers. The r; hum trip 1evice couk trip the CRD trip breaker if the VVD failed to c::erate properly.

Ine CRD trip t'reakers wen supplied during initial plant construction. These l CRD tr10 breakers were refurbished by Babcock and Hilcox in 1985. Markings on t?e UVD indicate that the UVD in question was installed on the breaker when it i  ! was first manufactured by General Electric in 1973.

N. t #RLE LLOAl tl.rdLDLIV ? LCQ!!MD e D t s a t . R a n c h o S e c o Raccnc 5eco has s b AK2-25 CRD trip brea.*ers. These CRD trip breakers supply j power to the 55fety group CRDs.

Conef.ityLic.ticA On %rch 23,19ftB. The ChD trip breaker was removed from. service ind placed in QC quarantine. One the cause of the probic:n war de+,er. nines (en Mrch 27, 1988, erS CRD trip breaker was recoved f r aT. service tM inspected for & $1milar defect. No defs:is were found. The CRD tvip bred ars wrre then successfully surveillance tested.

The "raintenanc? prur;edure for t he CR0 ir 19 brealer has been rnised to include checks for the cef9ct disccvered witn the UVD arrature, l

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OsMu- $We SACRAMENTO MUNICIPAL UTILITY DISTRICT C P. O. Box 15830, Sacramento CA 95852-1830,'19'16) 452 3211 AN ELECTRIC SYSTEM SERVINQ'THEJ1EART OF CALIFORNIA

~ ' ' i - 0 p p GCA 88-223 APR C 71938 U. S. Nuclear Regulatory Commission Attn: J. B. Hartin, Regional Administrator Region V 1450 Maria Lane, Suite 210 Halnut Creek, CA 94596 Docket No. 50-312 Rancho Seco Nuclear Generating Station License No. DPR-54 10 CFR 21 REPORT 88-02: MANUFACTURING DEFECT ON H0 DEL 269C282G2 GENERAL ELECTRIC UNDERVOLTAGE DEVICES

Dear Mr. Hartin:

In accordance with 10 CFR 21.21(b)(2), the Sacramento Municipal Utility District hereby submits 10 CFR 21 Report 88-02.

Please contact me if you have any questions. Members of your staff with questions requiring additional information or clarification may contact Mr. Steve Rutter at (916) 452-3211, extension 4674.

Sincerely,

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'G[CarlAndog'nini Chief Executive Officer, Nuclear )

i Attachment I l

cc w/atch G. Kalman, NRC, Rockville (2)

A. D'Angelo, NRC, Rancho Seco J. B. Hartin (2)

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RANCHO SECO NUCLEAR GENERATING STATION ' 14440 Twin Cities Road, Herald, CA 95638-9799;(2o9) 333 2935