ML20086N998

Part 21 Rept Re Mdr Relays W/Potentially Damaged Internal Contact Arms

ML20086N998
Person / Time
Site:	San Onofre
Issue date:	07/21/1995
From:	Rosenblum R SOUTHERN CALIFORNIA EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
REF-PT21-95 NUDOCS 9507260097
Download: ML20086N998 (5)

Text

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. f [N Southem Calibmia Edison Company P. O. BOK a28 S AN CLEMENTE, CALWOMNea 92674 Os28 fleCH AftO M RO S E. N B LUM '"*"***

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July 21,1995 ,

U. S. Nuclear Regulatory Commission Document Control Desk Washington, D.C. 20555 l

Dear Sir.

Part 21 Report Potter & Brumfield (P&B) MOR Relays l

Subject:

San Onofre Nucl ear Generating Station, Units 2 and 3 l

Reference:

P&B Letter of June 28,1995 to SCE and other affected companies; "MOR Relays With Potentially Damaged intamal Contact Arms" This letter provides notification to the NRC concoming a defect found in P&B Model 5095 Motor Driven Relays (MDR). Since the vendor rupplies these relays as commercial grade items and they I are dedicated for Nuclear Service by SCE, this letter provides Edison's 10 CFR Part 21 report on the subject. The referenced letter provides P&B customer notification of possible improper reassembly of several different models of P&B relays. The improper reassembly involves intemally damaged (bent) contact arms that could adversely effect relay interrupt capability, dielectric capability, reliability and life expectancy. The problem is potentially applicable to any MDR relay retumed to P&B for rework or -

disassembly between March,1993 and March,1995.

The vendor / manufacturer findings are based on inspection and testing of several P&B Model 5095 MDR relays conducted at the SCE Commercia1 Grade laspection (CGI) Laboratory on June S 6,1995.

The defective contact arms could prevent the proper opening or closing of certain relay contacts and thus cause the relay to malfunction in a safety-related application depending on the design use of the relay. The enclosure to this letter provides the information available to SCE concoming the defect as specified by 10 CFR Part 21 reporting requirements.

If you have any further questions, please contact me.

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Sjncerely, l

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. Vice P es' ent, Engineering & Technical ScrAes Enclosure cc: L. J. Callan, Regional Administrator, NRC Region IV A. B. Beach, D; rector, Division of Reactor Projects, Region IV K. E. Perkins, Jr., Director, Walnut Creek Field Office, NRC Region IV J. A. Sloan, NRC Senin Resident inspector, San Onofre Units 2 and 3 M. B. Fields, NRC Pr> ject Manager, San Onofre Units 2 and 3 9507260097 950721 g PDR ADOCK 05000361 If S PDR i

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ENCLOSURE

.10 CFR Part 21 Report on P&B MDR Relays 1.' Name & address of notifier:

R. M. Rosenblum Vice President, Engineering & Technical Services Southem Califomia Edison Box 128 San Clemente, CA 92672

2. Facility name:

San Onofre Nuclear Generating Station, Units 2 & 3

3. Component supplier:

Potter & Brumfield inc. (A Siemens Co.)

Chapel Hill Road Marion. KY 42064

4. Nature of defect During initial commercial grade dedication of thirty-three Model 5095 MDR relays, excess epoxy was discovered in and around the stators of nine test sample relays. The entire batch of thirty-three relays (including ten which had been destructively tested at SONGS) were hand-carried back to the P&B factory in Marion, Kentucky for rework in November of 1993.

Following clean-up of the epoxy and reassembly of the twenty-three operable relays, normal testing was performed on each relay at the factory. Four relays failed the factory test and were not accepted by the attendant SONGS engineer.

' One of the nineteen relays retumed to SONGS failed the coil resistance check during acceptance testing and was rejected for safety related use. Seven of the remaining eighteen relays were subsequently installed in safety related systems at Units 2 and 3. Six went into the containment pressure sensing isolation lines at both units and one into the charging pump to regenerative heat exchanger isolation valve at Unit 3. Nine relays underwent destructively testing and two remain in stock under quarantine.

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. ENGRG/ TECH SVS Fax:714-368-1490 Jul 21 '95 17:45 P.03/04 i

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i Disassembly and close inspection of nine of the eighteen reworked Model 5095 P&B MDR relay at the San Onofre CGI t.ab revealed some bent contact arms in the relays. There are fourteen  ;

contact arms per relay and between three and seven arms were bent in each relay. It was determined that these arms had been bent during reassembly of the relays at P&B in November; of 1993. Extensive testing and examination of thirty-six P&B MDR relays has shown the def

• contact arms were restricted to the factory reworked relays.

The bent arms could conceivably cause a contact to fail to open or close whenever it changed ,

state or have inadequate interrupt capability because of an improper gap opening. Such failures j could,in tum, cause or prevent the proper operation of safety related equipment depending on i how the relay was designed into the system.  ;

5. Date defect discovered:

June 28,1996, wiicn P&B issued a notification letter to all MDR relay users that had returned '

relays for factory rework durin9 the time frame of March,1993 to March.1995. The reasse defect occurred at the new Marion facility following the P&B move from Princeton, Indiana.

6. Componentlocation:

Seven of eighteen retumed relays were subsequently installed in safety-related systems of the SONGS plants. Three in Unit 2 (2HV-0352C,2HV-0352D & 2HY9200) and four in Unit 3 (3HV- l 0352A, B, C & D).

The most limiting application for these seven MDR relays is in the control circuits of Valcor j solenoid valves which isolate containment pressure transmitter sensing line , at Units 2 & 3. Thi solenoid valves are normally open and remain open during accident conditions inside the containment. These valves are only required to close in order to isolate a sensing line failure or loss of pressure boundary in the transmitter.

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7. Corrective actions: \

The two spare Model 5095 relays nave been quarantined and the seven installed relays will b replaced per NCR 95030035 at the earliest opportunity following procurement of replacemen The next production run for this type of relay is scheduled for late August 1995. SCE will sen engineer familiar with past MDR relay problemn to the Marion facility to oversee assembl testing of the relays as part of the procurement package. )

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- 6. Other pertinent information:

l The seven installed PAB MDR relays at SONGS remain operable as highlighted in NCR That evaluation is based on positive dedication testing response, system design use, 95030035. '

successfulinstallation post-maintenance testing and past operating experience with other used in this type application. ,

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POWER REACTOR ,

EVENT NUMBER: 29096 FACILITY: SAN ONOFRE REGION: 4 NOTIFICATION DATE: 07/21/95 UNIT: [] [2] (3) STATE: CA NOTIFICATION TIME: 20:45 [ET]

RX. TYPE: [1] W-3 -LP, [2] CE, [3] CE EVENT DATE: 07/21/95 EVENT TIME: 00:00[PDT]

NRC NOTIFIED BY: RILEY LAST UPDATE DATE: 07/21/95 HQ OPS OFFICER: TIM McGINTY NOTIFICATIONS EMERGENCY CLASS: NOT APPLICABLE 10 CFR SECTION:

CCCC 21.21 UNSPECIFIED PARAGRAPH UNIT SCRAM CODE RX CRIT INIT PWR INIT RX MODE CURR PWR CURR RX MODE 2 N Y 100 POWER OPERATION 100 POWER OPERATION 3 N Y 83 POWER OPERATION 83 POWER OPERATION EVENT TEXT SAN ONOFRE PROVIDED A PART 21 REPORT REGARDING POTTER & BRUMFIELD (P&B)

.MODEL-5095 MOTOR-DRIVEN RELAYS (MDR). SAN ONOFRE WAS NOTIFIED BY P&B OF POSSIBLE IMPROPER RE-ASSEMBLY OF SEVERAL DIFFERENT MODELS OF P&B RELAYS, THE IMPROPER RE-ASSEMBLY INVOLVES INTERNALLY DAMAGED (BENT) CONTACT ARMS THAT COULD ADVERSELY EFFECT RELAY INTERRUPT CAPABILITY, DIELECTRIC CAPABILITY, RELIABILITY, AND LIFE EXPECTANCY. THE PROBLEM IS POTENTIALLY APPLICABLE TO ANY MDR RELAY RETURNED TO P&B FOR REWORK OR DISASSEMBLY BETWEEN MARCH 1993 AND MARCH 1995.

POTTER & BRUMFIELD INC. (A SEIMENS CO.) IS LOCATED IN MARION, KY. SEVEN OF EIGHTEEN RELAYS RETURNED FROM P&B TO SONGS WERE SUBSEQUENTLY INSTALLED IN SAFETY-RELATED SYSTEMS OF THE SONGS PLANTS. THE MOST LIMITING APPLICATION OF THESE SEVEN MDR RELAYS IS IN THE CONTROL CIRCUITS OF VALCOR SOLENOID VALVES WHICH ISOLATE CONTAINMENT PRESSURE TRANSMITTER SENSING LINES AT UNITS 2 AND 3. THE SOLENOID VALVES ARE NORMALLY OPEN AND REMAIN OPEN DURING ACCIDENT CONDITIONS INSIDE THE CONTAINMENT. THESE VALVES ARE ONLY REQUIRED TO CLOSE IN ORDER TO ISOLATE A SENSING LINE FAILURE OR LOSS OF PRESSURE BOUNDARY IN THE TRANSMITTER. THE SEVEN INSTALLED RELAYS WILL BE REPLACED AT THE EARLIEST OPPORTUNITY FOLLOWING PROCUREMENT OF REPLACEMENTS.

THE SEVEN INSTALLED P&B MDR RELAYS AT SONGS REMAIN OPERABLE AT THIS TIME BASED ON POSITIVE DEDICATION TESTING RESPONSE, SYSTEM DESIGN USE, SUCCESSFUL INSTALLATION POST-MAINTENANCE TESTING, AND PAST OPERATING EXPERIENCE WITH OTHER RELAYS USED IN THIS TYPE APPLICATION.

THE HOO FORWARDED THE PART 21 NOTIFICATION TO VERN HODGE.

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