Part 21 Report - 1997-753

ACCESSION #: 9712190171 SIEMENS December 1, 1997 ABB Combustion Engineering Nuclear Operations PO Box 500 2000 Day Hill Road Windsor, CT 06095-0500 Attn: Jack R. Buckholz RE: Failed MDR Relays at Entergy Operations, Inc. Jack, ABB has forwarded three reports from Southwest Research Institute to Siemens Electromechanical Components pertaining to three failed MDR-7032 "medium" relays at Entergy Operations, Inc.'s Waterford 3 Nuclear Generating Station. Included in these reports are an analysis and a conclusion. Siemens Electromechanical Components agrees with the analysis contained in these reports, however, Siemens Electromechanical Components has reached a different conclusion based on its own analysis and testing. Siemens Electromechanical Components performed a number of temperature tests to determine if the Nye Nyogel 718B grease degrades for the possible temperature operations of these types of devices. Temperature testing of bearings shows both bearings are approximately the same temperature, A temperature test was conducted on the MDR-7068, the highest wattage of the suspected relays. With a 10% over voltage of 33.0 VDC, the bearing near the mounting base checked 58 Degrees C, and the bearing at the contact end checked 59 Degrees C Nye Nyogel 718B grease, is rated by the manufacturer for 260 Degrees C, The bearings operate 200 Degrees C below the manufacturer max rating. A weight loss test of the Nyogel grease is an on going test, After 696 hours at 150 Degrees C, there was only 1.312% weight loss. Siemens Electromechanical Components theory is the grease was contaminated by silicon dioxide fibers. To test this theory, relays were built using contaminated grease (test samples) and uncontaminated grease (control samples) in the bearings. Relays were cycled for 162,000 operations then left energized continuously for 48 hours at 65 Degrees C, The relays with uncontaminated grease still had fluid grease while the units with contaminated grease was a thick paste. The conclusions of these test shows that Nyogel grease does not degrade and cause the relay to bind. The results clearly show that the contaminated grease Is the root cause of the failure Page 1 Siemens Electromechanical Components, Inc. 200 South Richland Creek Drive Tel 812 386-1000 Princeton, IN 47671-0001 Fax 812 386-2430 SIEMENS Siemens Electromechanical Components did not analyze the failed relays at Waterford 3 because these units were not submitted to us. The amount of contamination that was within the relays is not known. Prior documented history Return Material Evaluation number 34017 (attachment one) had 4 MDR-170-1 relays recalled from ABB due to contamination within the relays, with date code of 9412. These 4 relays were the total order built for ABB. The contamination contained silicon dioxide fibers from contact ring insulator plates, flakes from the switch rings, and flakes of the coil epoxy. When silicon dioxide fiber is mixed in grease it becomes very abrasive, similar to lapping compound. This caused abnormal wear particles from the shaft and bearings. The grease then absorbs the wear particles and becomes too stiff for the relay to operate. Only the medium relays listed in attachment 2 are suspected to have this problem. There has been no reported failures on the small relays. The date codes of the suspected medium MDR relays are from 9317 to 9532. The reason 9317 is the suspected date codes is the start up date of the line after moving from Princeton, IN to Marion, KY. Date code 9532 is the initiation of a continuous improvement team. The team formalized housekeeping procedures and added an enclosed booth that isolated MDR final assembly from general production area preventing contamination. The relay listed in attachment 2 with the date codes 9317 to 9532 can be returned to the factory for inspection. Respectfully submitted, Dick Market Staff Technical Specialist Product Engineering Attachments: RME #34017 and #34406, and Part list of Potential Affected Devices. XC: Dan Smith, SEC Al Tessier, ABB Page 2 Siemens Electromechanical Components, Inc. 200 South Richland Creek Drive Tel 812 386-1000 Princeton, IN 47671-0001 Fax 812 386-2430 SIEMENS PROBLEM SOLVING AND RESOLUTION Problem No. Title: Date Opened: 9/18/96 Assigned To: 34017 Contacts frozen First Rev. MDR Line (1) Team Leader: Interim Problem Reported By: RME #: Mark Bryant Final Customer 34017 & 34406 Date 9/18/96 Responsibility M. Bryant (2) Describe Problem: Customer: ABB Combustion Engineering Nuclear Operations P.O. Box 500 M/S 9426-1936 Windsor, CT 06095-0500 Attn: Jack Buckholz Product: MDR-170-1 Date(s): 9412 (red) (S/N 514) Mfg. Plant: Marion Customer References: CE Order# 407112-01, CE Reference# 011-95823- 0040 Siemens References: RA# 9643077, Ack# 13745, PO# 407112 RME 32276 (S/N 513), RME 34406 (S/N 511 & 512) Reason For Customer Return: Contacts frozen Problem Identification/ Verification: Verified by Princeton Failure Analysis Lab, rotor remains bound in energized position without coil power. (2) Evaluation Date: 9/23/96 Responsibility: M. Bryant Black substance rolled up around the tip of the rotor shaft on the bottom bell. Substance is causing rotor to bind which prevents proper contact operation. (3) Containment & Interim Corrective Action(s): Date: 9/18/96 Responsibility: M. Bryant Contacted Sales to have Return Authorization issued for the remaining two MDR-170-1 units built for the original release in 1994. S/N 511 & 512. (RA 9643079 / RME 34406)) Due to the isolated nature MDR units presently in service or on the shelf. Siemens Electromechanical Components, Inc. Potter & Brumfield 200 South Richland Creek Drive Tel 812 386-1000 Products Division Princeton, IN 47671-0001 Fax 812 386-2430 13E163 06/04/96 Page 2 RME # 34017 (4.) Define & Verify Root Cause(Codes): Date: 12/18/96 Responsibility: M. Bryant Materials & Processes Lab has determined the cause for bound rotor was contamination of the bearing grease with glass particles and other debris (S/N 514). The contaminants reacted with the grease to form a black substance which would not allow the rotor to turn freely. The major components of the contamination were silicon from glass fibers found in the contact ring insulator plates and flakes of coil epoxy. These components are inherent to parts handling in the assembly area M&P Lab found similar contamination in S/N 511 & 512 although these units were still operable. S/N 513 returned in October '95, should also be considered to fall under this response (ref RA 9541066 / RME 32276) Exactly how such a quantity of contaminants could accumulate in these 4 relays is not known. Due to line improvements, layout changes and personnel turnover since 1994 it is difficult to identify a specific root cause for this isolated problem. M&P lab identification of the contaminants shows no indication this problem is related to the coil varnish outgassing problem which caused similar binding problems in the past (units built prior to date code 9024) Coils were gaged on the MDR line and found to be well within tolerance and in no way oversize. Document changes required Yes No N/A Date Changed Change Flow Diagram X Change Process FMEA X Change Design FMEA X Change Control Plan X Change Attribute Procedure X Routings X Drawings X Others X 13E163 06/04/96 RME # 34017 Page #3 (5.) Establish Corrective Action Plan Date: 1/8/97 Responsibility: M. Bryant While the source of the contamination to the motor assembly could not be definitely determined, the following improvements have occurred since the discrepant units were manufactured in 1994 - Enclosed booth built to isolate MDR final assembly stations from general production area to reduce contamination and noise levels - Added additional process step to fabrication of insulator plates Parts are tumbled following blanking operation in order to remove loose particles and fibers - Initiation of Continuous Improvement teams and successful QS9000 effort have resulted in formalized housekeeping procedures which mandate daily clean up by the operators. These have contributed greatly to improving general production area cleanliness - Continuous improvement teams have also worked to significantly reduce the inventory level of parts and sub assemblies stacked on the production line and in the Stockroom The reduced inventory levels result in more of a JIT system which limits the opportunity for contamination to the subassemblies A review of the present MDR production for further potential sources of contamination showed the following problem areas: - The assembly operators maintained a small cup of grease at each assembly station and used a toothpick to apply a dab of grease from the cup to the bearing surfaces. The grease cups were uncovered and would collect contamination on the surface of the grease supply. These cups were replaced with plastic syringes which seal off the grease supply from any contaminants (eff 9640, 10/1/96) - No instructions existed to prevent the operators from beginning assembly of a unit and then later setting it aside to work on a different unit, The possibility existed for a partially assembled unit to collect contaminants on a greased bearing surface. Operators have been instructed to ensure any partially assembled units are properly covered when it becomes necessary to put them aside or they are to complete the unit to the point of sealing the motor assembly Grease is to be removed from any questionable units and fresh grease applied. Instructions reflecting these requirements are in process to be added to MDR Engineering Specifications (eff. 9640) Existing assembly instructions require each motor assembly be blown out with de-ionized air in order to remove any contamination prior to capping the motor assembly with the too end bell. It is felt that the present MDR assembly methods, process controls and housekeeping measures are adequate to preclude further occurrence of this problem. (6.) Implement & Verify Corrective Action(s): Date: 1/8/97 Responsibility: M. Bryant - 5 piece MDR sample taken from present MDR production and examined for contamination, No contaminated motor assemblies were found. - 6 MDR units successfully completed mechanical life testing to 500,000 operations @ 5 ops./min. on 12/22/95 This is submitted as an indication of the reliability of recent production. Date Implemented Date Verified: Verified By: 10/1/96 1/8/97 M. Bryant Document changes required Yes No N/A Date Changed Change Flow Diagram X Change Process FMEA X Change Design FMEA X Change Control Plan X Change Attribute Procedure X Routings X Drawings X Others X 13E163 06/04/96 RME # 34017 Page #4 (7) Actions to Prevent Recurrence: Date: 1/8/97 Responsibility M. Bryant Actions taken are applicable to all MDR part numbers (8.) Congratulate/Team Members: Date: 1/8/97 Responsibility M. Bryant Distribution Mike Carnahan Gale Maxwell Michael Goldhacker Don Deel Dick Market Ed Wagner Karen Greenwall Jack Buckholtz ABB (FAX) Document changes required Yes No N/A Date Changed Change Flow Diagram X Change Process FMEA X Change Design FMEA X Change Control Plan X Change Attribute Procedure X Routings X Drawings X Others X 13E163 06/04/96 SIEMENS Part List of Potential Affected Devices With Date Codes of 9317 to 9532 MDR-141-1 MDR-6054 MDR-7033-SCE-0 MDR-141-1-SCE-2 MDR-6059 MDR-7034 MDR-141-2 MDR-6050 MDR-7034-SCE-0 MDR-142-1 MDR-6054 MDR-7033-SCE-1 MDR-167-1 MDR-6069 MDR-7036 MDR-170-1 MDR-45074 MDR-7045 MDR-170-1-SCE-2 MDR-6100 MDR-7048 MDR-170-2 MDR-6101 MDR-7052 MDR-172-1 MDR-66-4 MDR-7056 MDR-173-1 MDR-7020 MDR-7059 MDR-6007 MDR-7025 MDR-7067 MDR-6019 MDR-7029 MDR-7068 MDR-6041 MDR-7032 MDR-7069 MDR-60150 MDR-7032-SCE-0 MDR-7033 Attachment 2 Siemens Electromechanical Components, Inc. 200 South Richland, Creek Drive Tel 812 386 1000 Princeton, IN 47671-0001 Fax 812 386 2430 SIEMENS Siemens Electromechanical Components, Inc. Fax To: From: Company: Department: Department: Fax: (502) 965-1212 Fax: Telephone: Telephone: Date: Pgs. to follow: Message Potter & Brumfield Products Division 726 Chapel Hill Road Marion, KY 42064 502.965.3193 *** END OF DOCUMENT ***

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