IR 05000327/1993035
| ML20057C291 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 09/16/1993 |
| From: | George Macdonald, Shymlock M NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML20057C289 | List: |
| References | |
| 50-327-93-35, 50-328-93-35, NUDOCS 9309280183 | |
| Download: ML20057C291 (3) | |
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UNITED STATES NUCLEAR REGULATORY COMMisslON i
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1D1 MARIETTA STREET, N.W.
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ATLANT A. GEORGI A 30323
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Report Nos.: 50-327/93-35 and 50-328/93-35 Licensee:
Tennessee Valley Authority
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6N 38A Lookout Place
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1101 Market Street Chattanooga, TN 37402-2801
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Docket Nos.: 50-327 and 50-328 License Nos.: DPR-77 and DPR-79 Facility Name: Sequoyah Units 1 and 2 Inspection Conducted: August 12 - 20, 1993
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Inspector:
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N' M' "23 Date Signed G. MacDonald
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Approved by:
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H. B. Shymlock/ Chief Date Signed Plant System Section Engineering Branch Division of Reactor Safety i
SUMMARY
Scope:
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This special announced inspection was performed to assess the lice.asee's
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balance of plant (BOP) equipment and systems. This inspection was a continuation of inspection 50-327,328/93-31 on selected B0P electrical
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systems. The licensee's overall backlog review process was reviewed, and l
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selected system walkdowns were performed.
Emergent electrical issues were reviewed on the following systems: main feedwater control, main generator,
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switchyard and transformers, 6900 volt electrical distribution, 480 volt
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electrical distribution, and low voltage electrical distribution.
Results:
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In the areas inspected, violations or deviations were not identified.
An Inspector Followup Item was identified on polyvinylchloride jacketed cables exuding plasticizer. (paragraph 3)
r An Inspector Followup Item was identified regarding B0P fuse control.
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(paragraph 4)
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9309280183 930917 PDR ADDCK 05000327 G
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l The licensee discovered timers with incorrect voltage ratings installed in the
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main turbine trip circuits. Corrective action to resolve this problem prior
to restart was adequate. (paragraph 5)
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The 2B Unit Station Service Transformer tripped while-the licensee was l
aligning the electrical distribution system to backfeed offsite power through
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the main transformers. The failure evaluation and corrective action for this
item were adequate. (paragraph 6)
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LER 92-018 was reviewed. Corrective actions were complete and LER 92-018 was closed. (paragraph 7)
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The licensee review of system backlog and prioritization of items for restart
was generally adequate for the systems reviewed. Emergent work was being l
reviewed in accordance with the licensee's restart program plan.
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Additional review of work status and report findings are scheduled prior to Sequoyah restart.
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REPORT DETAILS 1.
Persons Contacted Licensee Employees
- H. Anderson, Design Control Manager, Site Engineering
- J. Bajraszewski, Licensing Engineer
- J. Baumstark, Operations Manager
- C. Brimer, Project Engineering and Support Manager
- L. Bryant, Maintenance Manager
- M. Burzynski, Site Engineering Manager
- H. Cooper, Maintenance Program Manager
- R. Drake, Project Management / Controls Manager
- R. Driscoll, Site Quality Manager
- R. Fenech, Sequoyah Site Vice President
- T. Flippo, Site Support Manager
- D. Lundy, Technical Support Manager
- J. Haciejewski, Operations and Maintenance Manager K. Meade, Licensing Engineer
- M. Needham, Customer Group Operations and Maintenance Manager
- S. Poage, Quality Audit and Assessment Manager
- K. Powers, Plant Manager
- J. Proffitt, Licensing Engineer H. Rogers, Technical Support Program Manager
- R. Shell, Site Licensing Manager
- M. Skarzinski, Technical Programs and Performance Manager
- R. Thompson, Compliance Licensing Manager P. Trudel, Design Engineering Manager
- J. Ward, Engineering and Modifications Manager Other licensee employees contacted during this inspection included engineer, operators, craftsmen, and other plant personnel.
Other organizations NRC Personnel
- C. Casto, Section Chief, Region II
- W. Holland, Senior Resident Inspector
- P. Kellogg, Section Chief, Region II
- A. Long, Resident Inspector
- S. Shaeffer, Resident Inspector
- M. Thomas, Reactor Inspector
- Denotes those individuals that attended the exit meeting.
Acronyms and abbreviations used throughout this report are listed in the last paragraph.
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2.
BOP Electrical Systems Review 2.1.
Main Feedwater Control System (System 46)
The function of the Main Feedwater Control System was to provide a signal to control Main Feedwater Pump Turbine speed in response to inputs from feedwater and steam header pressures and steam flow inputs from all four steam generators. The Main Feedwater control i
system preliminary system readiness review was complete through the Plant Manager's review.
i The inspector reviewed the MFW system backlog review notebook to determine if reliability significant work backlog items were classified as restart items (to be completed prior to restart).
The licensee had evaluated all backlogged items and the licensee's prioritization of work activities was adequate.
Emergent work items (new work activities identified after the backlog review process) were being reviewed and dispositioned in accordance with the licensee's restart program plan.
The inspector performed a MFW control system walkdown to ensure that significant system problems had been identified in the restart list and to determine if an acceptable material condition existed prior to plant restart. The inspector did not find material condition discrepancies which had not been identified by the licensee however, the MFW control system was not energized and the oil system was not pressurized.
Significant post restart work items included Unit 2 Foxboro 62H controller K1 relay replacement, Foxboro 62H controller replacement and overvoltage at the MFPT solenoids and relays.
The inspector reviewed the licensee's plant reliability study and determined that the significant reliability issues were addressed.
From the review of outstanding work / design items and the preliminary system walkdowns, the inspector considered that appropriate work items were scheduled to be completed prior to restart.
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2.2.
Main Generator Electrical (System 57)
The main generator system consists of the generator, exciter, voltage regulator and associated protective circuits and r
monitoring instrumentation. The Main Generator Electrical System
preliminary system readiness review was complete through the Plant
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Manager's review.
The inspector reviewed the Main Generator System backlog review notebook to determine if reliability significant work backlog items were classified as restart items. The licensee had evaluated the backlog items.
Emergent work was being reviewed and
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The significant reliability issues identified in the licensee's plant reliability study had been addressed.
j The inspector performed a walkdown of system 57 to ensure that significant problems had been identified in the restart list and to verify an acceptable material condition existed prior to plant restart.
The inspector did not find material condition
discrepancies which had not been identified by the licensee.
The final post maintenance testing for the generator automatic-voltage regulator will be performed during plant startup.
From the review of outstanding work / design items and the preliminary system walkdowns, the inspector considered that appropriate work items were completed or scheduled to be completed prior to restart.
2.3.
480 V Electrical Distribution System (System 201)
The system consisted of the safety related and the non-safety j
related 480 V switchgear and motor control centers (MCCs). The
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480 V Electrical Distribution System preliminary system readiness review was complete through the Plant Manager's review.
l The inspector reviewed the System 201 backlog review notebook to determine if reliability significant work backlog items were classified as restart items. The licensee had evaluated the l
backlog items and was reviewing emergent work items in accordance with the restart program plan. The prioritization of work activities was adequate. The inspector noted that the licensee's
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material condition walkdowns for system 201 were thorough. Many new work requests were included in the system backlog review notebook which had been written as a result of the system walkdown.
Problem evaluation repert SQPER930208 on Arrowhart MCC starter auxiliary switches was reviewed. The initial corrective action required inspection of all unit reliability related starters and inspection of 10% of remaining Arrowhart starters. However, the licensee had expand i their corrective action to include an
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inspection of all Arrowhart starter auxiliary switches.
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the inspection to include all Arrowhart starters was considered a positive step towards increasing Arrowhart MCC reliability.
The licensee had completed inspection of 411 of the 419 Arrowhart starters identified on motors required for Mode 4.
Ninety of the 411 starters inspected required cleaning of the starter auxiliary switches.
Licensee corrective actions on Arrowhart MCC starter auxiliary switches was adequate.
The inspector performed a walkdown of system 201 to ensure that significant problems had been identified in the restart list and to verify an acceptable material condition existed prior to plant
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restart. The 480 V Westinghouse switchgear material condition was considered acceptable. The significant issues identified in the licensee's reliability study were addressed. The inspector did not find significant material condition discrepancies which had not been identified by the licensee.
From the review of outstanding work / design items and the preliminary system walkdowns, the inspector considered that
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restart.
2.4.
6900 V Electrical Distribution System (System 202)
System 202 consisted of the 6900 V start boards, unit boards, shutdown boards, common boards and cooling tower boards. The 6900 V Electrical Distribution System preliminary system readiness review was complete through the Plant Manager's review.
The inspector reviewed the System 202 backlog review notebook to i
determine if reliability significant work backlog items were j
classified as restart items. The licensee had evaluated the
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backlog items.
Emergent work items were being reviewed in accordance with the restart program plan. The prioritization of work activities was adequate.
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Inspection Report 50-327,328/93-26 described a concern regarding incorrect wiring of replacement cts. The licensee conducted an
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incident investigation of the issue. The licensee will verify that all replacement cts are properly wired prior to plant restart. Seven unit board compartments still required CT phasing checks.
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The inspector performed a walkdown of system 201 to ensure that significant problems had been identified in the restart list and to verify an acceptable material condition existed prior to plant restart. The inspector did not find material condition
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discrepancies which had not been identified by the licensee. The inspector noted many new work requests in the system 202 backlog
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review notebook which indicated that the licensee's walkdowns were thorough.
From the review of outstanding work / design items and the preliminary system walkdowns, the inspector considered that approptiate work items were scheduled to be completed prior to restart.
2.5.
Transformers and Switchyard (System 241)
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System 241 consists of the main transformers, unit auxiliary transformers, common station service transformers, the 161 kV switchyard components, the 500 kV switchyard components, and
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monitoring and protective instrumentation.
System 241 preliminary i
readiness review was only complete through the system engineer signoff.
The inspector reviewed the System 241 backlog review notebook to determine if reliability significant work backlog items were classified as restart items. The licensee had evaluated the backlog items.
Emergent work items were being evaluated in accordance with the licensee's restart program plan.
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prioritization of the work activities was adequate. The inspector noted that many new work requests had been added to system 241
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backlog review notebook indicating that the licensee's system l
walkdowns were thorough.
The inspector had previously identified that backlog review evaluations for customer group protective relay calibrations and certain customer group switchyard routine testing and routine
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preventive maintenance activities were inadequate. The inspector i
reviewed the revised evaluations and determined that the work activities had been individually evaluated and that the significant items were properly classified.
The prioritization of these activities was adequate.
Items identified in the licensee's reliability study which had caused plant transients had been i
addressed or were scheduled as restart items.
From the review of outstanding work / design items and the preliminary system walkdowns, the inspector considered that appropriate work items were scheduled to be completed prior to
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restart.
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2.6.
Low Voltage AC and DC Distribution System (System 250)
System 250 consisted of the vital 125 VDC batteries, battery chargers, inverters, and the 250 VDC station batteries, battery chargers, and inverters. The Low Voltage AC and DC Distribution System was complete through the Plant Manager's review of preliminary system readiness.
The items identified in the licensee's reliability study which had caused plant transients had been corrected or were scheduled as restart items.
The inspector reviewed the System 250 backlog review notebook to determine if reliability significant work backlog items were classified as restart items. The licensee had evaluated the backlog items._ Emergent work items were being evaluated in accordance with the licensee's restart program plan.
A major item for system 250 was the age and material condition of the vital and station batteries.
Both station batteries and vital batteries 1 through 4 were nearing their 20 year life. The inspector reviewed the test results of the last discharge test for all the station and vital batteries. All test results indicated i
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greater than 90 %.
The material condition of the station
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batteries was considered marginal. Several individual cells had
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been replaced. Several cells were exhibiting electrolyte seepage from the cell top joints.
The inspector performed a walkdown of the system to ensure that significant problems had been identified in the restart list and to verify an acceptable material condition existed prior to plant i
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restart. The inspector did not find material condition discrepancies which had not been identified by the licensee.
l From tee review of outstanding work / design items and the preliminary system walkdowns, the inspector considered that
appropriate work items were scheduled to be completed prior to J
restart.
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Polyvinylchloride (PVC) Jacketed Cable PER SQPER931556 The inspector reviewed SQPER931556 which described the condition of an oily substance exuding from PVC jacketed cable. The licensee initially discovered the problem on cables in the Turbine Building Vent Boards and Turbine Building MOV Boards. SQPER931556 was initiated on July 16, 1993 and was classified as a post restart PER. On July 26, 1993, the licensee discovered exuding cables in the safety related EDG Auxiliary MCCs. SQPER931556 was revised to revision 1 and was now classified as a restart PER.
The licensee sent samples of the exuding substance and pieces of the
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affected cables to an independent laboratory for testing and analysis.
The preliminary laboratory results indicated that the material was a plasticizer added to the cable jacket during cable fabrication. To date the oily substance has been noted on cables in the Turbine Building, EDG Building, Auxiliary Building, Cooling Tower Boards, and Condensate Demineralizer Boards.
The licensee determined that five vendors supplied PVC jacketed cable to Sequoyah. PVC jacketed cables are used in medium voltage power, low voltage power, control, and instrumentation applications. During system walkdowns, the licensee identified several instances of oily cables supplied by Triangle / Plastic Wire Corporation (PWC), and one example was identified of an oily cable supplied by Essex Corporation.
At the time of this inspection, only samples of the plasticizer / cable supplied by PWC have been analyzed. The inspector reviewed the preliminary laboratory report which indicated that the material was plasticizer added to the cable jacket. The report also indicated that the plasticizer exhibited a high dielectric strength and was classified as an insulator. The plasticizer was exuding from the cable jacket and had no affect on cable insulating properties.
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The licensee developed corrective action for SQPER931556 and presented the plan to the Management Review Committee. The inspector attended the meeting and noted that the scope of planned corrective action was to evaluate all PVC jacketed cable.
The licensee planned to develop a procedure for evaluating the cabling and end devices which utilized PVC jacketed cabling.
The overall corrective action plan will be evaluated prior to restart. This issue has been identified as Inspector Followup Item 93-35-01 "PVC Cables Exuding Plasticizer".
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Fuse Control Several recent PERs have been initiated regarding fuse control.
SQPE9.930333 identified problems with improperly installed FLAS5 indicating fuses.
The improperly installed fuse would prevent the annunciation from working if the fuse cleared.
Some of the identified improperly installed fuses were in safety related applications.
The inspector examined several cabinets containing the FLAS5 fuses and noted an example of an improperly installed fuse. The licensee classified the PER as restart. The corrective action for the PER was reviewed and was considered adequate. The corrective actioa called for a 100% fuse verification prior to restart.
SQPER931561, SQPER931565, and SQPER930342 identified problems with fuse labelling and fuses not matching the installed labels.
Some of the instrument rack fuses were not labelled. There were also problems identified with the use of non-permanent labels. The licensee had initiated an incident investigation to addresses the issue of labelling, including fuse labels.
Inspection report 50-327,328/93-31 identified problems with B0P fuse control in the 480 V BOP MCCs. The licensee has performed fuse checks during the system 201 walkdown and indicated that 60 fuse discrepancies were noted for the approximately 3000 fuses which were inspected. Most of the discrepancies were fuses of the correct amperage but from a different manufacturer or type.
The inspector reviewed the plant reliability study and did not find any evidence that incorrect fuses have led to plant transients. The licensee indicated that they had established a project to review and upgrade BOP fuse control.
The item was identified as Master Issue List item MIL 91080 and was indicated as a post restart item.
Plant operation with B0P fuse control problems represented some plant reliability risk, however the available data indicated that the risk was low.
This item has been identified as Inspector Followup Item 93-35-01
"B0P Fuse Control".
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Main Turbine Trip Circuit Timers SQPER930335 The licensee discovered a 120 V solid state relay timer on Westinghouse relay CLOGR in the main turbine trip circuit.
The circuit is a 250 VDC circuit and should utilize a 250 VDC rated timer. The timer was not safety related. The electrical shop personnel discovered the
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discrepancy while performing relay inspections. The timer was on a
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relay which provided a turbine trip on a main turbine oil tank low level condition.
The licensee performed a complete inspection of all Westinghouse relay
cabinets comparing the field timer to the drawings and discovered a total of three 120 V timers installed in 250 VDC applications.
None of the three timers were in safety related applications. The inspector examined several of the relay cabinets and observed the incorrect
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timers. The timers and associated wiring appeared to be original equipment. Review of licensee maintenance records did not indicate that
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the relays or timers had been changed. The licensee did not calibrate the timer or test the relay. The only testing of the relay was during initial plant preoperational testing.
The licensee classified SQPER930335 as a restart PER. The inspector reviewed the corrective action which consisted of performing a 100 %
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timers.
The corrective action was considered adequate.
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Unit Station Service Transformer 2B Trip SQPER930406 On August 15, 1993 while attempting to backfeed power through Unit 2 main bank transformers Unit Station Service Transformer 2B tripped by differential relay 2B87S.
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The licensee performed an evaluation of the cause of the relay operation and concluded that the differential relay operated due to transformer inrush current. High inrush current was due to the rapid application of voltage due to the backfeed operation. When the transformer is in the
generating mode the voltage is brought up along with the generator. The t
transformer does not normally see a rapid voltage application and high inrush currents. The relay is not equipped with harmonic restraint which prevents tripping on inrush. A similar event had occurred on a different USST during a previous backfeed operation.
The licensee completed tests to verify that there had been no damage to the transformer. All test results indicated that there was no damage to
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the transformer. The corrective action was to issue relay setting sheets to change the pickup settings for the differential relays when a backfeed condition exists. The TVA Corporate Customer Group performed i
an evaluation to verify that the increased relay settings still provided protection for fault conditions.
The inspector concluded that the i
licensee corrective actions for SQPER930406 were adequate.
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Licensee Event Report 92-018 The inspector reviewed LER 92-018 which described a reactor trip as_a result of a high steam generator level condition caused by a failure of
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the feedwater regulating valve controller auto / manual transfer rela r
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Failures in the plant air systems caused poor operation of the air operated valves and a failure of the controller auto / manual transfer relay prevented manual control.
The inspector reviewed the corrective actions. The auto / manual transfer relays in the controllers were replaced. The licensee inspected and cleaned the air receivers. The inspector reviewed the work documents for replacement of the auto / manual transfer relays in the Foxboro controllers and the work documents for the air receiver inspection and cleaning.
Corrective actions identified in the LER were considered appropriate and were complete. LER 92-018 is closed.
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Exit Interview The inspection scope and results were summarized on August 20, 1993, with those persons indicated in paragraph 1.
The inspector described l
the areas inspected and discussed in detail the inspection findings and
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open items as indicated below. Dissenting comments were not received
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from the licensee. Proprietary information is not contained in this report.
IFI 50-327,328/93-35-01, PVC Cables Exuding Plasticizer l
(paragraph 3).
i IFI 50-327,328/93-35-02, B0P Fuse Control (paragraph 4).
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Acronyms and Abbreviations
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BOP Balance of Plant CSST Common Station Service Transformer CT Current Transformer i
'EDG Emergency Diesel Generator EDS Electrical Distribution System
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IFI Inspector Followup Item kV Kilovolt LER Licensee Event Report
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MCC Motor Control Center MFP Main Feedwater Pump MFPT Main Feedwater Pump Turbine
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MFW Main Feedwater MOV Motor Operated Valve PER Problem Evaluation Report PWC Plastic Wire Corporation SqPER Sequoyah Problem Evaluation, Report j
TVA Tennessee Valley Authority USST Unit Station Service Transformer V
Volts Alternating Current VDC Volts Direct Current