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ACCESSION #: 9507170122 GENERAL INFORMATION or OTHER EVENT NUMBER: 29060 LICENSEE: LIMITORQUE CORPORATION NOTIFICATION DATE: 07/13/95 CITY: LYNCHBURG REGION: 2 NOTIFICATION TIME: 16:30 [ET] COUNTY: STATE: VA EVENT DATE: 07/13/95 LICENSE#: AGREEMENT: N EVENT TIME: 00:00[EDT] DOCKET: LAST UPDATE DATE: 07/13/95 NOTIFICATIONS NRC NOTIFIED BY: CHARLES HYLTON HQ OPS OFFICER: JOSEPH SEBROSKY VERN HODGE NRR EMERGENCY CLASS: NOT APPLICABLE 10 CFR SECTION: CCCC 21.21 UNSPECIFIED PARAGRAPH EVENT TEXT LIMITORQUE CORPORATION OF LYNCHBURG, VA REPORTED A POTENTIAL DEFECT IN SMB/SB/SBD-00 MOTOR OPERATED VALVE ACTUATORS IN ACCORDANCE WITH 10 CFR PART 21. LIMITORQUE DISCOVERED, THROUGH A NOTIFICATION FROM THE TVA, THE POSSIBILITY OF THE OUTSIDE CLUTCH TRIPPER BECOMING WEDGED AGAINST THE ACTUATOR HOUSING AND PREVENTING THE ACTUATOR SHIFTING TO ELECTRICAL FROM MANUAL OPERATION WHEN THE MOTOR IS ENERGIZED. LIMITORQUE CONTENDS THAT THIS CONDITION COULD BE REPORTABLE DEPENDING ON THE OPERATING PRACTICES OF THE LICENSEES, i.e. - A REPORTABLE CONDITION DOES NOT EXIST IF THE INDIVIDUAL LICENSEES PRACTICES ENSURE ACTUATOR ELECTRICAL (MOTOR) OPERATION VERIFICATION AFTER BEING IN THE MANUAL (HANDWHEEL) MODE. - THE POTENTIAL FOR A REPORTABLE CONDITION EXISTS IF THE INDIVIDUAL LICENSEES PRACTICES DO NOT ENSURE ACTUATOR (MOTOR) OPERATION VERIFICATION AFTER BEING IN THE MANUAL (HANDWHEEL) MODE. LIMITORQUE'S INVESTIGATION OF THE CONDITION SHOWS THAT SMB/SB/SBD-00 HOUSINGS HAVING A CAST DATE OF 1979 OR EARLIER MAY HAVE THE POTENTIAL FOR THIS WEDGING AND INSTALLATION OF A 'TRIPPER STOP' WILL PREVENT THE PROBLEM. SMB/SB/SBD-00 HOUSINGS HAVING A CAST DATE OF 1980 OR LATER WILL NOT HAVE THE POTENTIAL FOR THE PROBLEM. LIMITORQUE IS IN THE PROCESS OF MAKING A WRITTEN NOTIFICATION TO THE AFFECTED NUCLEAR UTILITIES OF THE PROBLEM. Limitorque Corporation July 12, 1995 Document Control Desk U.S. Nuclear Regulatory Commission Washington, D. C 20555 Pursuant to the requirements of Tide 10 of the Code of Federal Regulations Part 21, herein provided is notification of a potential defect in Limitorque SMB/SB/SBD-00 actuators. As detailed in the attached letter, this condition is dependent on the individual Licensee's internal operating practices that are used when declaring a motor operated valve operable for safety related services. Limitorque is making written notice to both the Commission and the affected Nuclear Utilities shown on the attached mailing list. Signed: Charles L. Hylton Vice President-Engineering WJM/lab Attachment cc: Part 21 Committee Members 10 CFR Part 21 - #55 Evaluation File Limitorque Corporation July 12, 1995 U.S. Nuclear Regulatory Commission Washington, DC 20555 ATTENTION: Document Control Desk REFERENCE: 1) Potential 10CFR 21 Condition 2) TVA Adverse Condition Report, Tracking No. WBPER950295 SUBJECT: Clutch Tripper Jam-up in SMB-00 Housing Please be advised that Limitorque Corporation has discovered, through the above notification from TVA, the, possibility of the outside clutch tripper (one of two trippers per assembly) becoming wedged against the actuator housing and preventing the actuator shifting to electrical from manual operation when the motor is energized. This creation could potentially be reportable depending on the operating practices of the licensee, i.e.: o a reportable condition does not exist if the individual licensee's practices ensure actuator electrical (motor) operation verification after being in the manual (handwheel) mode. o the potential for a reportable condition exists if the individual licensee's practices do not ensure actuator electrical (motor) operation verification after being in the manual (handwheel) mode. Limitorque Corporation P.O. Box 11318 5114 Woodall Road Lynchburg, VA 24506-1318 Tel. (804) 528-4400 FAX (8N) 845-9736 Page 2 July 12, 1995 Clutch Tripper Jam-up in SMB-00 Housing Identification of Basic Component The affected component is the housing of an SMB/SB/SBD-00 actuator that may cause the outside clutch tripper to become wedged and prevent the actuator from automatically shifting to the "motor operation position" from the "handwheel operation position" when the motor is energized - Exhibit F. Discovery Date Limitorque was notified by TVA of this condition on 05-26-95 and we completed our evaluation of affected equipment on July 6, 1995. Description of the Event When the actuator is in motor operation the two tripper cam continuously rotate - Exhibit F. If the actuator was previously in manual operation, rotation of than cams will displace both tripper fingers from the tripper adjustment arm allowing the actuator to return to motor operation. The distance that the outside tripper will advance is a function of the rotary velocity of its respective cam at impact. This event may result in the outside tripper becoming wedged in She housing and preventing a return to motor operation. Nature of the Defect Our investigation of this condition shows: - a 1979 or earlier "cast date" housing may cause the outside clutch tripper to [illegible prints]. - during the 1979 or earlier time period, while performing the "routine bench testing" of actuators, Limitorque would occasionally experience similar occurrences to that reported by TVA on 05-26-95. When this condition occurred during the "routine bench test," Limitorque would hand grind the affected area of the housing to eliminate the material which was causing the wedging of the outside clutch tripper. - since this condition was discovered during the "routine bench test," and the affected housings were being hand ground to remove material to prevent wedging of the outside clutch tripper, it was presumed this condition had been Page 3 July 12, 1995 Clutch Tripper Jam-up in SMB-00 Housing corrected on the affected actuators prior to shipping from our facility. Limitorque Corporation Corrective Action The following is a list of modifications implemented by Limitorque to correct this condition: o prior to April 1979 - when the condition occurred during "routine bench test," material was removed by hand grinding the affected area of housing to prevent wedging. o April 1979 - instructions given for potential installation of tripper stop, 60-505-007-1 in the existing inventory of SMB/SB/SBD-00 housings - Exhibits B and G. Note: Our investigation was unable to produce records to show the number of units that had the tripper stops installed. o April 1979 - simultaneously a housing casting modification was implemented which added material to the housing casting. This modification inherently provided a positive stop for the outside clutch tripper to prevent potential wedging. This modification was made to subsequent orders of housing castings and eliminated the need for the installation of the tripper stop - Exhibit C. o September 1994 - re-designed the clutch end of the housing casting to eliminate a requirement for a machining operation in this area, which was required by the above modification, and still maintain the positive stop for the outside clutch tripper to prevent potential wedging - Exhibit D. Our investigation of this condition shows: o SMB/SB/SBD-00 housing having a "cast date" of 1979 or earlier may have the potential for this wedging and installation of the "tripper stop" will provide a positive stop for the outside clutch tripper and prevent the tripper from potentially becoming wedged against the actuator housing. o SMB/SB/SBD-00 housings having a "cast date" of 1980 or later will not have the potential for this wedging of the outside clutch tripper since it has had material added to the pad in the housing which will inherently prevent the tripper from becoming wedged against the actuator housing. Page 4 July 12, 1995 Clutch Tripper Jam-up in SMB-00 Housing Notes: Housings having a "cast date" of 1980 or later will have a Limitorque unit serial number of approximately 308000 or higher, also any serial number having an L-prefix followed by six digits will be in this category - example L365340. The serial number should not be the determining factor without "cast date" verifications. The "casting date" is located on the top side of the housing between the two conduit entries - Exhibit E. If "cast date" of housing cannot be determined, the geometry of the access hole on the clutch side of the housing will allow determination of pre and post 1980 housing castings. Refer to the following Exhibits for the geometrical difference of the access holes in the housing: [illegible Print] 1980 or later - Exhibit C or D Licensee/Customer Corrective Action o Review internal practices to verify if your individual operating practices ensure actuator electrical (motor) operation after being in the handwheel operation position prior to placing the motor operated valve into safety related service. If your internal practices do not ensure the above, then the verification of the return to actuator electrical (motor) operation is required. If this verification shows that the actuator has not automatically shifted to the motor operation after being in the handwheel operation position; an instantaneous tap on the declutch lever should free the outside clutch tripper from the wedged condition and the actuator will then automatically shift to motor operation. Note: Do not fully depress the declutch lever when performing this process, just tap the declutch lever each time to free the outside clutch tripper from the wedged condition. Verification of the return to the electrical operating mode may be accomplished by rotating the handwheel and verifying that the handwheel is no longer in engagement with the clutch keys. It is not necessary to reposition the valve to accomplish this verification. Page 5 July 12, 1995 Clutch Tripper Jam-up in SUB-00 Housing It should be noted that Limitorque Corporation is not aware of other field reports relative to this issue. This would indicate that the likelihood of recurrence is minimal or that operation's personnel have been rectifying this problem. The potential for occurrence however, exists on an actuator that previously did not demonstrate this phenomenon, but has had the rotary speed of the worm shaft increased via a motor or motor gear VA changeout. Limitorque Corporation obtained an SMB-00 actuator of pre 1980 housing design. This actuator was subjected to testing in an attempt to duplicate the reported problem. "The actuator equipped with 37T motor pinion and 28T worm shaft gear and driven by an 1800 rpm 3 phase motor ( nearly equal to 2300 rpm @ worm shaft) was placed in manual mode and then electrically opened with no malfunction. This operational sequence was repeated over several cycles with no malfunction. The actuator was then fitted with a 3600 rpm 3 phase motor and a 43T motor pinion/22T worm shaft gear set (this gear set results in the highest worm shaft speed nearly equal to 6600 rpm). The previously mentioned operational sequence was duplicated and resulted in an instantaneous malfunction. The operational sequence was repeated and produced several subsequent malfunctions and eventually resulted in trouble fee operation. This was the result of the tripper duplicating the hand grinding of the casting material and eliminating the mechanical Interference which prevented any additional testing. o Contact Ms. Evelyn Crain, Nuclear Parts for the required number of tripper stops, #60-505-M7-1 for SMB/SB/SBD-00 housing having a "cast date" prior to 1980. These components will be furnished at no charge by Limitorque. Ms. Evelyn Crain cm be contacted by phone (804) 528-4400, Ext. 9847, or fax (804) 945-9736. The no charge order will include a Certificate of Compliance stating: o Parts supplied are provided in accordance with Limitorque's Quality Management System Manual. o Proper installation of these parts will not adversely affect any existing qualification of the actuators involved, Note: If additional statements are required on the Certificate of Compliance, then charges would be assessed to the order by Limitorque. Page 6 July 12, 1995 Clutch Tripper Jam-up in SMB-00 Housing Also, attached is Limitorque Drawing, #60-505-0057-1 and Installation. Instructions if the license/customer decides to fabricate the tripper stop. Any questions or clarifications regarding the above notification may be directed to Mr. Pat McQuillan, Nuclear/Special Projects Manager at (804) 528-4400, Ext. 9714, or fax (804) 845-9736. Signed, Charles L. Hylton Vice President - Engineering WJM/kls/lab Attachment(s) cc: Mr. J. J. Brennan Part 21 Notification File
Figures "EXHIBITS A, B, C, D, E, F, G"
INSTALLATION INSTRUCTIONS FOR TRIPPER STOP, 60-505-0057-1 References: L/C Bulletin SMBI-82 EXHIBITS A & B 1) Remove the electric motor in accordance with Limitorque Instructions, and Maintenance Manual, Bulletin SMBI-82. 2) If necessary, remove grease from the clutch cavity. 3) Remove the socket head screw and lockwasher that secures the tripper adjustment arm - see Exhibit A. 4) Install the tripper Mop with the 'L' toward the tripper fingers, the socket head screw and lockwasher removed in step (3). 5) The tripper stop should be positioned against the housing - see Exhibit B. Note: If necessary readjust clutch tripper adjustment arm per the instructions outlined in Bulletin SMBI-82. 6) Move the outer tripper finger toward the tripper stop to ensure that it hits the short leg of the 'L'. 7) Replace the grease and motor. 8) Declutch and verify that actuator automatically shifts to electrical (motor) operation. *** END OF DOCUMENT ***