IR 05000335/1993014
| ML17228A182 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie  |
| Issue date: | 06/07/1993 |
| From: | George Macdonald, Shymlock M NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML17228A181 | List: |
| References | |
| 50-335-93-14, 50-389-93-14, NUDOCS 9306160168 | |
| Download: ML17228A182 (8) | |
Text
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REGION II
101 MARIETTASTREET, N.IIII.
ATLANTA,GEORGIA 30323 Report Nos.:
50-335/93-14 and 50-389/93-14 Licensee:
Florida Power and Light Company 9250 West Flagler Street Miami, FL 33102 Docket Nos.:
50-335 and 50-389 Facility Name:
St. Lucie 1 and
Inspection Conducted:
May 10 - 14, 1993 Inspector:
.MacDona d
Approved by:
M. B.
Shyml
, Section Chief Plant Systems Section Engineering Branch Division of Reactor Safety License Nos.:
DPR-67 and NPF-16 g/r/gZ Date Signed Date Signed SUMMARY Scope:
This routine, announced inspection was conducted in the areas of Followup of Nonroutine Events and included a review of recent failures of General Electric (GE) type HFA latching relays and Asea Brown Boveri (ABB)/Westinghouse protective relays.
Results:
In the areas inspected, violations or deviations were not identified.
Three GE model HFA154 latching relays failed to latch during the recent Unit
integrated safeguards test.
Following these failures all safety related HFA latching relays were inspected in both units and several were found to require latch adjustment.
Periodic latch engagement inspections will be performed on all safety related HFA latching relays until the root cause of the failure can be determined and corrected or the relays are replaced.
An ABB/Westinghouse non-safety related overcurrent protective relay failed to operate during recent Unit 1 calibration testing.
The failure was due to contact contamination by material leaching from the internal cabinet wiring onto the relay.
The wiring was manufactured by Philadelphia Insulated Wire Co.
and had polyvinylchloride (PVC) insulation.
Following identification of this problem, the licensee inspected all Unit 1 protective relays manufactured by ABB/Westinghouse and discovered that PVC insulated internal cabinet wiring 9306i60i68 930609 PDR ADOCK 05000335
was also utilized in many of the safety related relays.
All relays in Unit
will be rewired or replaced.
Periodic inspections will be performed on the Unit 2 safety related relays until the next refueling outage when the relays will be rewired or replace REPORT DETAILS Persons Contacted Licensee Employees
- C. Burton, Operations Manager
- C. Davis, Protection and Control Superintendent
- B. Dawson, Maintenance Manager
- J. Dyer, guality Control Supervisor
- R. Englmeier, Site guality Manager
- J. Holt, Licensing Engineer
- A. Henocal, Mechanical Maintenance Department Head
- C. Pell, Service Manager
- S. Riviere, Electrical Maintenance Technical Support Engineer
- L. Rogers, Instrumentation and Control Department Supervisor
- D. Sager, Plant Vice President
- J. Scarola, Engineering Manager
- D. Wolf, Site Engineering Supervisor
- C. Wood, Assistant Operations Supervisor Other licensee employees contacted during this inspection included engineers and administrative personnel.
NRC Personnel
- S. Elrod, Senior Resident Inspector
- H. Scott, Resident Inspector
- Attended exit meeting.
Acronyms and abbreviations used throughout this report are listed in the last paragraph.
Followup of Failures of General Electric HFA Latching Relays Inspection Procedure (IP 92700)
Three safety related GE model HFA154 latching relays failed to latch during the recent Unit 1 loss of offsite power (LOOP) portion of the integrated safeguards test.
There were sixteen of these relays installed in Unit 1 and six installed in Unit 2.
The HFA relays were normally energized and electrically reset.
Once the relay's operate coil was energized, the relay latched and remain latched until the relay's reset coil was energized.
The relays were utilized as memory devices in the breaker control circuits for the ICW and CCW pumps in both units and for safety related fan motor circuits in Unit 1.
The failure of an HFA relay to latch would not affect normal start and stop functions.
The relay's function was to remember which loads were running prior to a LOOP.
Then when power was restored these loads would restart.
During an SIAS, required loads would start even if the HFA relay had failed to
latch.
Also, all loads required to start following a LOOP, that may have an undetected HFA relay failure, have manual start capability from the control room.
There have been a number of recent failures of these relays in safety related applications at St. Lucie.
The inspector reviewed recent integrated safeguards test data and corrective actions for these failures.
During the 1990 Unit 2 integrated safeguards test, one HFA relay failure occurred on the 2B-ICW pump.
The failed HFA relay was replaced and the licensee satisfactorily completed all retesting.
During the 1991 Unit 1 integrated safeguards test, one HFA relay failure occurred on the lA-ICW pump.
The failed relay was replaced and retested.
The licensee inspected all latching HFA relays for proper latch engagement.
Three additional Unit 1 and one Unit 2 HFA relay were replaced as a result of inadequate latch engagement identified during the relay inspections.
The licensee sent two of the failed relays to GE for failure evaluation.
The failure evaluation indicated that the relays had inadequate latch clearance.
Latch clearance was controlled and adjusted by the number of shims installed below the latch mounting screw.
Root cause possibilities for the inadequate latch clearance were either incorrect adjustment during manufacture or incorrect adjustment following inspection or parts replacement.
The licensee performed a followup latch engagement inspection six months later and all HFA relays exhibited proper latch engagement.
During the 1993 Unit 1 integrated safeguards test, three HFA relay failures occurred on the 1A-ICW pump, the 1-HVE 3B reactor support cooling fan, and the 1-HVS 2B reactor cavity supply fan.
All three relays were replaced and tested satisfactorily.
A thorough disassembly and examination of one of the failed relays was performed to determine the root cause of its failure to latch.
Dimensions were taken and compared to those of a new relay.
Very insignificant differences were noted in dimensions which could affect latch clearance.
The armature plate was noted to be discolored and slightly cupped.
This was most likely due to heat.
The lower latch support plate was slightly deformed.
Prior to the disassembly, the relay was operated by hand and would only latch with excessive force applied to the armature plate.
The licensee could not conclusively determine the root cause of its failure to latch.
Two of the failed relays were sent to GE for.,failure evaluation.
After the three failures, the licensee performed a latch engagement inspection of all the safety related relays.
In addition to the three failed relays two Unit 1 and one Unit 2 relay required latch adjustment.
The relays were adjusted and tested satisfactorily.
The inspector visually examined the latch engagement of all the energized safety related HFA latching relays.
The inspector's findings agreed with the licensee's visual inspection results.
The inspector visually examined a disassembled relay and reviewed Maintenance Procedure No. 0960066 revision 5 " General Electric Type HFA
s.
Relay Testing and Set-Up Procedure".
The procedure was thorough and implemented the guidance of NRC Bulletin 88-03.
Despite the detailed inspection and set-up procedure, a
GE latching HFA relay which was installed in Unit 1 in October, 1991 failed to latch during the integrated safeguards test in April, 1993 (lA ICW).
The licensee did not perform any maintenance or inspections on the GE latching HFA relays with the exception of the functional checks during integrated safeguards testing.
NRC Bulletin 88-03 addressed inadequate latch engagement for GE latching HFA relays.
The bulletin indicated that relays with a date code prior to November, 1987 might exhibit inadequate latch engagement.
The three HFA relays which failed during the 1993 integrated safeguards test had date codes of July, 1991 or July, 1992.
The licensee identified corrective action for the relay failures which consisted of performing quarterly latch engagement inspections on all safety related latching HFA relays in both units.
The licensee was evaluating re'placement of the relays as a possible long term solution.
The periodic HFA relay latch engagement inspections will be performed until the root cause for the failures to latch can be determined and corrected or the relays are replaced.
The inspector concluded that the corrective action for the HFA relay failures was adequate.
This issue was being tracked by the licensee as Non Conformance Report (NCR). 1-797.
Followup of Failures of ABB/Westinghouse Protective Relays Inspection Procedure (IP 92700)
A Unit 1 non-safety related overcurrent protective relay (type C09)
failed to operate during calibration testing.
These relays are calibrated each refueling outage.
On this relay the instantaneous trip function failed to operate.
Inspection of the relay determined that the normally open instantaneous contacts were coated with a green substance.
The green substance dripped onto the contacts from terminal lugs on the ends of the relay internal cabinet wiring.
The green substance was leaching out of. the wiring, which was identified as polyvinylchloride (PVC) insulation, manufactured by Philadelphia Insulated Wire.
The Protection and Control Systems Group wrote Discrepant Field Condition No. 93-0001 identifying the concern.
Quality Control (QC)
Report no.
E93-092 was written to Electrical Maintenance who wrote NCR 1-780 to Engineering.
The scope of the concern was PVC internal wiring in ABB/Westinghouse relays.
The relays in which the PVC wiring was identified were model C0-7, model C0-9, model KC-4, model CON-5, model CV-2, and model CVE.
These protective relays were utilized in the safety related 4. 16kV switchgear and the non-safety related 4.16 and 6.9kV switchgear.
The licensee performed an inspection of all the ABB/Westinghouse protective relays and found that many of the relays were contaminated with the same green substance.
Host Unit 1 relays which had the green substance contamination had 1970 date codes.
The licensee contracted with the
relay vendor, ABB Power TIED Company Inc, Relay Division to rewire the relays.
The vendor brought factory stock and performed the relay repairs onsite.
All relays which had the PVC insulated wire were rewired except for certain relays whose configuration did not support rewiring. These relays were replaced or will be replaced when replacement relays are available.
The safety related relays were rewired by the vendor, ABB Power T&D, working under the ABB Combustion Engineering guality Assurance Program.
The replacement wiring had cross linked polyethylene insulation.
The new wiring was identified as Surprenant Mire and Cable CSA type CL-1251 XLPE 600V.
The safety related relays were disassembled, cleaned, rewired then tested.
The inspector reviewed the controlling procedures and selected gA certificates and found them to be adequate.
The relay coils were replaced because the coil lead wiring could not be identified and could possibly have been PVC insulation.
The inspector witnessed the repair and testing of several relays.
The work was performed in accordance with the controlling documents and the inspector determined that the repairs were acceptable.
The licensee also performed a
separate relay functional test and a calibration test prior to installing the relays.
The inspector reviewed the corrective action for the Unit 1 safety related protective relays.
Of the 85 safety related protective relays in Unit 1, 80 were rewired, three were acceptable as is (non-PVC insulation),
and two will be replaced as soon as replacement relays are available.
The two relays to be replaced had PVC insulation but could not be rewired due to coil configuration.
They were utilized as EDG loss of field relays and were not part of the EDG protection scheme used during emergency operation.
The inspector examined the safety related protective relays in Unit 1 and verified that all relays had been rewired or did not contain PVC insulation except for the EDG loss of field relays.
Corrective action for Unit 1 was adequate.
The inspector examined all the Unit 2 safety related relays.
Hany of the relays had PVC insulation, however no evidence of the green substance coming from the wires was found.
Host of the Unit 2 relays had 1975 date codes.
No PVC contamination on Unit 1 relays was noted during the previous relay calibrations conducted during the Unit
1991 outage.
This indicated that the PVC breakdown phenomena was likely time dependent.
The Unit 2 relays had less time in service than the Unit
relays.
The licensee corrective action for the Unit 2 safety related relays was to perform periodic quarterly inspections until the next Unit 2 refueling outage when the relays will be rewired or replaced.
The inspector determined that corrective action for Unit 2 was adequate.
This issue was being tracked by the licensee as NCR 1-780.
The inspection scope and results were summarized on Hay 14, 1993, with those persons indicated in paragraph 1.
The inspector described the areas inspected and discussed in detail the inspection findings.
Dissenting comments were not received from the licensee.
Proprietary information is not contained in this repor Acronyms and Abbreviations ABB CCW CSA EDG GE HVA HVE HVS ICW IP kV LOOP NCR NRC PVC QA QC SIAS T&D V
XLPE Asea Brown Boveri Component Cooling Water Canadian Standards Association Emergency Diesel Generator General Electric Heating Ventilation and Air Conditioning Heating Ventilation Exhaust Heating Ventilation Supply Intake Cooling Water Inspection Procedure Kilovolt Loss of Offsite Power Non Conformance Report Nuclear Regulatory Commission Polyvinylchloride Quality Assurance Quality Control Safety Injection Actuation System Transmission and Distribution Volts Cross Linked Polyethylene