ML20198F241
| ML20198F241 | |
| Person / Time | |
|---|---|
| Issue date: | 10/30/1985 |
| From: | Merschoff E, Naidu K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML20198F229 | List: |
| References | |
| REF-QA-99901024 99901024-85-01, 99901024-85-1, NUDOCS 8511140303 | |
| Download: ML20198F241 (5) | |
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ORGANIZATION: GENERAL ELECTRIC COMPANY GENERAL SWITCHGEAR DEPARTMENT CHAMBLEE. GEC RGIA REPORT INSPECTION INSPECTION NO.: 99901024/85-01 DATE(S): 6/19-20/85 ON-SITE HOURS: 10 CORRESPONDENCE ADDRESS: General Electric Company General Switchgear Department ATTN: Mr. J. Rider, Manager Switchgear Service 5134 Peach Tree Road Chamblee, Georgia 30341 ORGANIZATIONAL CONTACT: M. Austin, Service Supervisor TELEPHONE NUMBER: (404) 452-4800 PRINCIPAL PRODUCT: Repair and maintenance of 480 volt circuit breakers.
NUCLEAR INDUSTRY ACTIVITY: Less than 1%.
ASSIGNED INSPECTOR:
K. R. Naidu, Reactive Inspection Section (RIS) 10kW Date OTHER INSPECTOR (S): L. E. Foster, Region II APPROVED BY: .
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E. W. Merschoff/)flief, RIS, Vendor Program Branch Date INSPECTION BASES AND SCOPE:
A. BASES: 10 CFR Part 21 and 10 CFR 50 Appendix B.
B. SCOPE: Review of the Rancho Seco reactor trip circuit breaker records.
PLANT SITE APPLICABILITY: Rancho Seco (50-312).
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{ :- c ORGANIZATION: GENERAL ELECTRIC COMPANY GENERAL SWITCHGEAR DEPARTMENT CHAMBLEE, GEORGIA REPORT INSPECTION NO.: 99901024/85-01 RESULTS: PAGE 2 of 4 A. INSPECTION ISSUES On June 10, 1985, the Rancho Seco nuclear power plant notified the Nuclear Regulatory Commission (NRC) of an Unusual Occurrence (PNO-V-85-33A). During functional testing of the recently refurbished Reactor Trip Breakers (RTB) from the control room, one of the six RTBs failed to trip. The purpose of this inspection was to review the quality assurance records associated with recent refurbishment activities and obtain additional information to assist in evaluating the cause of failure.
B. BACKGROUND INFORMATION The NRC regulations require that the reactor trip systems on all commerical nuclear power reactors be single-failure proof and highly reliable. NUREG-1000 describes the generic implications of the Anticipated Transient Without Scram (ATWS) events which took place at the Salem nuclear power plant'on February 22 and 25, 1983. The NRC issued Generic Letter 83-28 dated July 8, 1983, which outlined the actions required to be taken by licensees of operating power plants, applicants for operating licenses, and construction permit holders, including maintenance of the RTBs.
Babcock & Wilcox (B&W), supplied the Nuclear Steam Supply System (NSSS) to Rancho Seco station. The RTBs are included within the scope of NSSS.
B&W had recently returned the Rancho Seco RTBs to General Electric Company (GE) for refurbishment. This refurbishment included replacement of the trip arm bearings and roller bearing latch assembly. After the refurbished RTBs were returned and installed at Rancho Seco, one of them failed to trip during a test.
C. INSPECTION FINDINGS AND OTHER COMMENTS
- 1. Review of Procurement Documents B&W issued Purchase Order (P0) 071 388 LP dated February 20, 1985 to GE, Atlanta, to supply the parts and services necessary to refurbish seven AK2-25 type circuit breakers which are being used as RTBs. Only six RTBs were shipped to GE.
The P0 required GE to perform the following:
- a. Stamp unique serial numbers on the RTBs.
b ., Perform an initial inspection and install new trip bearings and latch roller assemblies on the RTBs.
i a ORGANIZATION: GENERAL ELECTRIC COMPANY GENERAL SWITCHGEAR DEPARTMENT CHAMBLEE, GEORGIA REPORT INSPECTION N0.: 99901024/85-01 RESULTS: PAGE 3 of 4
- c. Notify B&W of any replacement parts required due to broken or missing parts. GE was to obtain B&W approval prior to replacement of parts or subsequent modification to the breakers.
- 2. Review of GE Documentation
- a. The GE documentation consisted of Work Orders (WO) for each breaker. The WO outlined the various steps to inspect the breakers and replace the trip arm bearings and roller bearing latch assemblies. The serial number of each breaker was entered on the WO to trace the work performed on the respective breaker.
The W0 provided space to identify the individuals who performed the work, including the dates the activities were performed.
Quality Control (QL/ inspectors signed and dated the various steps. The inspectors reviewed the W0s for all six breakers and determined that the work was performed and the QC inspectors reviewed and accepted the work as required.
- b. After the completion of work, the breakers were subjected to routine electrical tests. The test values were recorded on individual test data sheets. The test instruments used during the test are documented on GE data sheet GEZ-6058B-N to verify the validity of the calibration.
The inspectors reviewed the test data on all six breakers and identified no unacceptable results.
- c. Based on the above information GE issued a " Product Quality Certification" on each breaker to B&W.
- 3. Observation of Circuit Breaker Testing GE personnel used a specimen breaker which came in for repairs to demonstrate the following inspections and electrical tests performed on breakers,
- a. Inspections (1) At the undervoltage trip device, the clearance between the armature and the rivet was measured at the outer edges of the armature with a feeler guage.
(2) The trip shaft torque was measured with the circuit breaker open.
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.. e ORGANIZATION: GENERAL ELECTRIC COMPANY i GENERAL SWITCHGEAR DEPARTMENT !
i CHAMBLEE, GEORGIA REPORT INSPECTION N0.: 99901024/85-01 RESULTS: PAGE 4 of 4 (3) The trip shaft torque was measured with the circuit breaker closed.
(4) Four micrometer readings on bearing fit were taken'at 45 intervals on both the left and right hand sides of the trip shaft bearings.
(5) Micrometer readings of the outer race of the new bearings were taken.
- b. Electrical Tests (1) Megger tests on all phases with the circuit breaker in open and closed positions.
(2) Hi-Pot test on all auxiliary contacts.
(3) Ductor test (contact resistance) on all phases.
(4) Measuring the time to open the circuit breaker when actuated by the shunt trip and the under voltage trip.
(5) Voltage required for the undervoltage device to pickup.
(6) Voltage required for the undervoltage device to drop out.
- 4. Conclusion Review of the quality assurance records indicates that the Rancho Seco RTBs were in acceptable operating condition prior to shipment to B &.W Lynchburg, Virginia.
E. PERSONS CONTACTED M. Austin, Service Supervisor R. Rider, Quality Control Inspector F. EXIT INTERVIEW The inspectors met with individuals identified in Section E and discussed the scope and findings of the inspection. -