IR 05000327/1989014

Insp Repts 50-327/89-14 & 50-328/89-14 on 890424-28. Violations Noted.Major Areas Inspected:Surveillance & Operational Records & Procedures.Discussions Held W/ Operations,Engineering & Transmissions Personnel

ML20247B015
Person / Time
Site:	Sequoyah
Issue date:	08/28/1989
From:	Donohew J, Harmon P, Marinos E, Paulitz F, Pierson R Office of Nuclear Reactor Regulation
To:
Shared Package
ML20247B004	List: IR 05000327/1989014 ML20247A998 ML20247B006
References
50-327-89-14, 50-328-89-14, NUDOCS 8909120308
Download: ML20247B015 (11)

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UNITED STATES NUCLEAR REGULATORY COMfAISSION

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.G E WASHINGTON, D. C. 20555

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..... UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF NUCLEAR REACTOR REGULATION TVA PROJECT DIVISION Report.Nos.: 50-327/89-14 and 50-328/89-14 Docket Nos.:- 50-327 and 50-328 Licensee: Tennessee Valley Authority 6N 38A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801 Facility Name: Sequoyah Units 1 and 2 Inspection At: Sequoyah fluclear Plant Site Scddy Daisy, Tennessee Inspection Conducted: April 24 - April 28, 1989 Inspectors

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E. Marinos Team Leader k

Chief, Reactor Operations Branch, TVA/TP/NRR Team Members: h N. Donohew Jr. , Project h

nager ' Datt b

Project Division, NRR C

N k F. P. Paulitz, ElectricaVEr(gineer ate Reactor Operations Branch, TVA/TP/NRR-(- kh N P. E. Harmon, Resident Inspector Date Sequoyah Nuclear Power Plant, TVAPD/NRR Approved by: ( - (-

R. C. 'ierson, Assistant Director h $dfM Date for Technical Programs TVA Projects Division Office of Nuclear Reactor Regulation 8909120308 890831 (

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SUMMARY Scope:

i This announced' team inspection was conducted by the NRC Headquarters staff and I one of Sequoyah's resident inspectors. The inspection effort was performed in the area of plant operations to evaluate the adequacy of procedures for managing overvoltage conditions at the Sequoyah site and to determine if these procedures were properly performed during the overvoltage condition that existed at the site on January 21, 1989. Also, Element Report (ER) 30202 was reviewed and a followup of the proposed corrective action was conducte Results:

Deficiencies were found in the management of an overvoltage event at the plant

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.and commitments to resolve discrepancies discussed in an Element Report had not been satisfie One violation was identified:

VIO 327/328/89-14-01, Failure to follow established procedures, on January 21, 1989, to correct the overvoltage condition on Unit 2 shutdown board No deviations were identifie Two inspector followup items were identified:

IFI 327/328/89-14-02. The change to the corrective action in the Element Report 30202 concerning equipment susceptibility to past overvoltage conditions. This change from test / analysis to a failure trend analysis is a concern to the inspector IFI 327/328/89-14-03. The Element Report 30202 lacks adequate analysis of the effects of the past overvoltage conditions on all affected plant equipmen Also, it did not identify the root cause of the overvoltage conditio The details of the violation and inspector followup items are discussed in Sectioit 6.0 of this inspection repor ,

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SPECIAL INSPECTION ELECTRICAL DISTRIBUTION SYSTEM OVERVOLTAGE TENNESSEE VALLEY AUTHORITY SEQUOYAH NUCLEAR PLANT UNITS 1 AND 2 1.0 PURPOSE This special inspection was conducted to ascertain (1) whether the Tennessee Valley Authority (TVA) has adequate design and administrative controls to prevent sustained overvoltage conditions on the Class IE electric systems at the Sequoyah Nuclear Plant and (2) whether TVA followed these procedures during the January 21, 1989 overvoltage condition. TVA Employee Concerns Special Program, Element Report (ER) 30202 was also reviewed to determine whether TVA adequately analyzed the effects of previous overvoltage conditions at Sequoyah and whether corrective actions proposed in the report were properly implemente .0 SCOPE This inspection included the review cf the following types of records and procedures, o Surveillance o Operational o Employee Concerns Special Program, Element Report 30202 The specific records and procedures reviewed are listed in Attachment During the inspection, discussions were held with personnel from the following areas:

o Operations o Engineering o Transmission and Customer Service The inspection covered the time period from January 21, 1989 to April 28, 198 The corrective actions regarding overvoltage identified in ER 30202 were scheduled for completion by December 22, 198 .0 PERSONS CONTACTED Persons contacted during this inspection are listed in Attachment .0 DOCUMENTS REVIEWED l

Documents reviewed during this inspection are listed in Attachment .0 BACKGROUND In August 1981, Sequoyah Unit 2 was in hot shutdown when the containment radiation monitors, 2-RE-90-106 and 2-RE-90-112, tripped on overcurrent and L L_-_ _ - - _ _ - - - _ - _

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were declared inoperable. The monitors were being supplied electrical power from a common station service transformer. Subsequently, it was determined that the tap settings on the common station service transformer were set too high. The settings were changed and manually set to reduce the voltage at the shutdown boards from 535 volts to 490 volts. Following reset, the transformer tap settings remained sufficiently high to ensure that anticipated low voltage conditions at the site would not adversely affect the performance of safety equipment. However, the lack of automatic adjustment in the transformer taps subjected safety equipment to unacceptable overvoltages when the grid voltage was significantly hig Employees at TVA raised concerns that equipment rated at 460 volts was being operated in excess of 580 volt TVA acknowledged the concern and submitted to the NRC, Employee Concern ER 30202, Revision 3, dated December 8, 1986, to address these concerns. TVA identified the root cause of the overvoltage condition as inadequate procedures and scheduled implementation of corrective actions, identified in EL 00202, by December 22, 198 On January 22, 1989 TVA informed the staff that diesel generator 2A-A had failed to meet the overvoltage limit expected during the performance of load rejection testing conducted on January 21, 1989. During this test, the voltage reached 8160 volts which was in excess of the maximum limit of 7866 volts specified in the Sequoyah Technical Specification It was TVA's determination, however, that thii overvoltage condition resulted from an unacceptably high pretest diesel and grid voltage (7400 volts) at the shutdown boards and, therefore, the test was invalid. Furthermore, TVA acknowledged that high grid voltage had persisted for some time and was expected to continue for a few more weeks and, therefore, retesting could not be performed until the voltage at the shutdown boards was near nornal (6900 volts), when large 1; ads (i.e., reactor coolant pumps) are reconnected to the unit boards. The staff was concerned about TVA's inability to correct long-term grid overvoltage conditions. This concern has resulted in the need for reevaluation of TVA's commitments made in response to specific employees concerns, regarding management of grid overvoltage conditions at Sequoya .0 FINDINGS I The findings of this inspection are based on the team's review of the following:

(1) Procedures to manage safety bus overvoltage at Sequoya (2) Actions taken during the Emergency Diesel Generator (EDG) testing of I January 21, 198 I (3) Element Report 3020 l 6.1 Procedures To Manage Safety Bus Overvoltage

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The inspection team held discussions with TVA's Operations personr31 to determine what procedures identify the acceptable voltage limiti for the shutdown boards, the action to be taken to reduce the voltage on the shutdown boards, and the time frame for the action to be taken. The procedures identified by Operations for managing overvoltage on safety

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busses were Surveillance Instruction SI-3, General Operating Instruction G01-6, and System Operating Instruction S0I-55-0M-26:

o The ER 30202 proposed a revision to SI-3 to provide proper guidance to operators. SI-3 was revised with Instruction Change Form (ICF)

No. 86-1120, approved September 4, 1986. This revision requires plant operators to notify the SRO if the voltage on the shutdown boards exceeds 7240 volts. However, the action to be taken by the SR0 following notification is not specified. The inspectors were informed that training is provided on both the recognition and the corrective actions to be taken to reduce overvoltag Surveillance Instruction SI-3, Revision 50, approved September 4, 1986, limits the maximum voltage on the 6900 volt Class 1E busses at 7240 volts and the 480 volt busses at 504 volts. Corrective action is required by SI-3 at 7260 volts and 508 volts, respectively, to reduce the voituge to nominal values. The same maximum voltage limits and corrective action were included in SI-3, Revision 68, approved August 23, 1988. This latest revision was in place on January 21, 198 The NRC staff inspectors confirmed from review of the records and discussions with the SR0 that no action was taken during January 21 and 22, 1989 when the overvoltage condition on the Unit 2 shutdown boards was present. Additionally, SI-3 requires that if the voltage exceeds 7260 volts, the SRO is to notify the lead electrical engineer (EE) in DNE at Sequoyah. The inspectors could not conclude that notification to EE-DNE was made on January 21 or 22,198 The SRC logs indicate that the notification was made on January 25, 1989 concerning the January 21 and 22,1989 event. Discussion with DNE staff confirmed that there were no written instructions for DNE per.sonnel to assist the SR0 during the even o General Operating Instruction G01-6, Revision 28, approved September 16, 1986, page 23, includes maximum voltage limits for normal operation at 7240 volt for the 6900 volt system and 504 volt for the 480 volt syste Corrective action is required by G01-6 at 7260 volts and 508 volts,

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l respectively, to reduce the voltage to nominal values. The same maximum '

voltage limits and corrective action were included in G01-6, Revision 49, approved January 20, 1988. This latest revision was in place on January 21, 198 l l

There were no instructions for actions to be taken when one unit is operating and the other unit is shut down with an overvoltage condition present, as was the case on January 21 and 22,1989. (Unit I was operating, Unit 2 was shut down). However, G01-6 provides specific j instructions to operators for actions to be taken to lower the shutdown board voltage in the event of an overvoltage condition in either the unit that is operating or when both units are shut dow J o System Operating Instruction 501-55-0M26, XX-55-26B, Revision 5, page 14, approved June 24, 1985, requires an alarm setpoint at 105%(7245 volts)

and also requires immediate action when the alarm sounds to reduce shutdown board voltage to nominal value (. _ _ - _ _ _ - - - . - . - - - . - - . - - - - - - - - - - -

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The inspection team discussed with an SRO the annunciator alarms available for alerting the operator of an overvoltage condition on the shutdown boards. The team was informed that there was a multi-purpose alarm that served to alert o down boards with regard to (perators of four conditions on the shut-1)

of direct current, and (4) lockout protectio It was also stated that during the. load rejection testing of EDG 2A-A on January 21, 1989, this annunciator alarm, would have alarmed on low voltage. Therefore, the ,

SRO stated that since (we) expected a low voltage alarm, the overvoltage j was not recognized. However, the inspection team's review of System {

Operating Instruction 501-55-0M-26, Alarm Response, approved July 24, j 1966, identified a dedicated high voltage alarm for the shutdown board J This annunciator alarm directs the operator to take corrective action to reduce voltage on the boards but specific guidance is not provided for reducing the voltag During the inspection TVA instituted a partial corrective action in Night Order No. 62, dated April 25, 1989. This night order required-compiiance with the voltage limits for the shutdown boards and indicated that Operations was aware that overvoltage on the shutdown boards should

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not be tolerated or allowed to continue. Additionally, the Lead Electrical Engincar, Sequoyah Engineering Projects, sent a memorandum to all Electrical Engineering supervisors, dated April 11, 1989, Subject: " Plant Overvoltage Condition Policy". This memorandum was reviewed by the inspection tea The inspection team concludes that the memorandum provides adequate guidance to EE engineer .2 Emergency Diesel Generator Testing of January 21, 1989 On January 19, 1989, Unit I was in Mode 1 and Unit 2 was shut down for the cycle 3 refueling outage. The Unit 2 Emergency Diesel Generator (EDG)

2A-A Surveillance Test, SI-26.2A, was started at 1700 hours0.0197 days <br />0.472 hours <br />0.00281 weeks <br />6.4685e-4 months <br /> EDT on January 20, 1989, and load rejection was completed at 0600 hours0.00694 days <br />0.167 hours <br />9.920635e-4 weeks <br />2.283e-4 months <br /> EDT on January 21, 1989. High speed recorder (Visicorder) charts indicated the voltage at the start of the test to be 7400 volts. On January 22, 1989, the staff expressed 6 concern that the electrical equipment that was supplied power from the Unit 2 shutdown boards was being operated above its design limit i The inspection team's review of the results of test SI-26.2A, page 140, indicates that during the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> run of the EDG 2A-A test the voltage was 7400 volts for 13 hours1.50463e-4 days <br />0.00361 hours <br />2.149471e-5 weeks <br />4.9465e-6 months <br /> and 7300 volts for 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> at the shutdown board There was no indication that TVA took any corrective action from 0600 hours0.00694 days <br />0.167 hours <br />9.920635e-4 weeks <br />2.283e-4 months <br /> EDT on January 21 to 1219 hours0.0141 days <br />0.339 hours <br />0.00202 weeks <br />4.638295e-4 months <br /> EDT on January 22, 1989 to reduce the volt-age on Unit 2 shutdown boards to 7240 volts. The Sequence of Events submitted by TVA, for the NRC staff's review indicated that a voltage of 7110 volts was reached at 1900 hours0.022 days <br />0.528 hours <br />0.00314 weeks <br />7.2295e-4 months <br /> EDT on January 22, 1989. The record indicates that the Senior Reactor Operator (SR0) informed the Division of NuclearEngineering(DNE),ElectricalEngineeringBranch(EEB), electrical engineer at 1430 hours0.0166 days <br />0.397 hours <br />0.00236 weeks <br />5.44115e-4 months <br /> on January 25, 1989 that shutdown boards 2A and 28 were at 7300 volts. This voltage is greater than that allowed by SI-3, GOI-6 and S01-55-0M-2 This inadequate response to the overvoltage condition, which existed for about 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />, is considered a violation of Technical Specification 6. !. *

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foi not followin instructions SI-3, G01-6, and S01-55-0M-26, (Violation 327/328/89-14-01 .

6.3 Element Report 3020_2_

The inspection team reviewed Element Report 30202, Revision 3, dated December 8,1986 and determined that TVA did not address the effects of

- the past overvoltage conditions on all equipment affected by the over-voltage. The analysis for determining which plant electrical equipment was susceptible to past overvoltage conditions (SCR SQN EEB 86147, Calculation SQN-EPS-005, Attachment 2), was inadequate. The report omitted review of the effects of overvoltage on inverters, battery chargerc, motor-operated valve motors and their thermal overload protective devices and the interrupting capability of electrical switchgear. The staff considers this a failure to provide adequate evaluation of the effects of overvoltage on critical safety equipmen In Element Report 30202, TVA identified that it considered the root cause of the past overvoltage conditions "...the failure to include adequate operational requirements in SI-3 and the plant technical specifications for plant shutdown board voltage limits in accordance with the SQN FSAR and ANSI C84.1." The inspection team concludes that TVA has not identified the correct root cause for the overvoltage conditions that periodically appear at the site and, therefore, the corrective actions in ER 30202 do l not preclude repetition of the event. TVA's corrective actions, at best, attempt to mitigate the consequences of the overvoltage conditio The inspection team determined that the root cause for the unacceptable overvoltage condition at the Sequoyah site was a result of the following scenari The 480 shutdown boards are powered from the 6.9 Kv bus which is ultimately powered by the 161 KV offsite supply line. Each bus is tapped through a transformer to its supply. These tap settings were fixed and could not readily be change Plant personnel were concerned about maintaining the 480 V system sufficiently high to prevent spurious electrical transfer of station equipment to the diesel generator during some anticipated low voltage transients. As a result the 480 V to 6.9 Ky tap setting was set correspondingly high to allow more flexibility and to minimize the possi-bility of equipment transfer. Concurrently, offsite TVA transmission personnel were maintaining the 161 Kv line at 167.5 Kv (General Operating Instruction, GOI-6, Revision 28) to minimize transmission losses for economic considerations. When this high voltage setting, coupled with the high settings of the bus to bus taps occurred, the result was that shutdown boards were exposed to an overvoltage conditio Element Report 30202 also specifies that equipment susceptible to past over-voltage conditions be evaluated. SCR SQN EE8 86147, calculation SQN-EPS-005, Attachment 2, contains a list of devices and apparatus for Train IB (worst case) that should be reviewed by SQEP Electrical Section for susceptibility to overvoltage. All items on that list were reviewed by the licensee's electrical equipment specialist to identify those items that could be degraded by the prolonged exposure to overvoltage that existed while the units were shut down. This review was recorded in SQN-EPS-005, Attachment 3,

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" Susceptibility of 6.9 KV and 480 V Shutdown Boards' Electrical Devices to Prolonged Overvoltage Conditions". The following are the licensee's con-clusions from the review:

o Voltage transformers and control transformers should be included in a test-analysis program to determine the effect of overvnitag o Power and distribution transformers should be tested for dielectric strength and for signs of degradation of the solid ir.sulatio o Undervoltage Relays may have been affected by 116% overvoltag o Sturter (contactor) coils should be reviewed for possible patterns of failure, o Electronic circuits should be examined for possible problem For equipment evaluated as susceptible to overvoltage, Element Report 30202 required review of maintenance records to determine if this equipment required excessive maintenance. The report also required that a sample of the susceptible equipment be tested to determine if its insulation had been unacceptably degraded. No evidence, however, was given to the inspection team that these TVA actions were carried out. The inspection team reviewed a memorandum from W. S. Raughly to M. R. Sedlacik dated December 23, 1988, Subject: Sequoyah Nuclear Plant (SQN) - SCR-SQNEEB86147 - Employee Concern 302.02 - SQN Overvoltage Stres This memorandum states, "We have completed our evaluation of electrical items and have not identified equipment degradation that is directly attributable to overvoltage stress" and that there was no equipment degradation "directly attributable" to overvoltage conditions. The inspection team was not provided with documentation that supports this claim. The memorandum recommends a failure trend analysis, to be conducted in the future, instead of the test / analysis recommended in the Element Report. This change in corrective action is considered an item of concern to the inspectors

[IFI(327/328/89-14-02)].

Element Report 30202 is inadequate because. (1) it lacks adequate analysis of the effects of the past overvoltage on all affected plant equipment, and (2) it does not identify the root cause of the overvoltage conditio The inadequary of Element Report 30202 discussed above is considered an item of concern to the inspectors [lFI (327/328/89-14-03)].

7.0 EXIT INTERVIEW The inspection scope and findings were summarized on April 26 and April 28, 1989, with those persons indicated in Attachment 1. The inspectors described the areas inspected and discussed in detail the inspection findings. The licensee acknowledged the inspection findings and did not identify as proprietary any of the material reviewed by the inspectors during the inspection.

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ATTACHMENT 1 PERSONS CONTACTED Licensee Employees J. Arnett, Specialist NE-EE-CS

• 1. A. Burzese, Protection Service Manager

1. M. Burzynski, Site Licensing Manager

• L. Bush, Unit OPS Manager

1. W. Byrd, Project Control & Financial Manager

1. M. Cooper, Compliance / License Supervisor

1. S. Crowe, Site Quality NQA Manager

'#L. Ellis, Employee Concern'Special Project Manager S. Franks, Technical Support Manager E. Gibson, Engineering Transmission Operator

• 1. B. Harvey, Engineering Assurance

• 1. J. Holland, Corrective Action Program Manager

1. J. Kearney, QA Surveillance Supervisor

• 1. J. Long, Engineering Plant Suppor #W. Lovelace Operation Service Manager

• B. McDowell, QA NQA&E Auditor

• 1. D. Moore, Engineering Technical Support System

• Nicely, Electrical Engineer M. Riden, Engineering Assurance NE-EA H. Rogers, Plant Support Superintendent

• 1. M. Sedlacik, Lead Electrical Engineer

1. S. Smith, Sequoyah Plant Manager

• S. Spencer, Engineer, NLRA

• 1. D. Stewart, ASOS, OPS, SR0 R. Tallent, Transmission Operation Manager

1. P. Trudel, NE Engineer, Project P. Wallace, SQN Programs Manager

• A. Wilkey, QA Audit NQA&E Manager Nuclear Regulatory Commission

1. K. Jenison, Senior Resident Inspector

• Persons present at the Pre-Exit Meeting April 26, 1989

1. Persons present at the Exit Meeting April 28, 1989

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ATTACHMENT 2 DOCUMENTS REVIEWED General Operating Instruction, " Apparatus Operations," G01-6, Revision 49, dated January 30, 1988 and Revision 28 dated September 16, 198 Surveillance Instruction, " Daily, Weekly and Monthly Logs," SI-3, Revision 70, dated March 23, 1989, Revision 53, dated April 9,1987 and Revision 50, dated November 5, 198 System Operating Instruction, " Annunciator Response," S01-55-0M26/XA-55-26B, Revision 5, dated June 24, 1985, XA-55-26A, "6900V SD BD 1A-A Overvoltage,"

page 14 Revision 4; XA-55-268, "6900V SD BD 1B-B Overvoltage," page 14 Revision 5; XA-55-26C, "6900V SD BD 1A-A Overvoltage," page 14, Revision 5; and XA-55-26D, "6900V SD BD Overvoltage," page 14, Revision System Operating Instruction " Annunciator Response," S0I-55-1M1/XA-55-1B,

"6900V SD BD; Failure or Bus / Norm Feeder Undervoltage or Overvoltage, IA-A " pages 12 & 13, Revision 4; IB-B, pages 14 & 15 Revision 4; S01-55-2M1/XA-551B, 2A-A, pages 12 & 13, Revisions 5 & 6, 2B-B, pages 14 & 15, Revision Surveillance Instruction, " Relay 590AT,59DBT&590CT 6.9KV SD BD 2A-A Under-voltage Calibration Check," SI-235, pages 46 & 47, Revision 10, Calibration dated February 27, 198 Surveillance Instruction, " Diesel Generator 2A Test," SI-26.2A, page 140, data sheet 6.12, Diesel Generator 24 Hour Test Run, dated January 21, 198 Operations Switchyard Section Instruction Letter:

o SWYD-3, " Operation of Sequoyah Nuclear Plant 500-kv and 161-kv Switchyards," Revision 0, dated December 2, 198 o SWYD-13, "Sequoyah Nuclear Plant, Operations Switchyard Section Instruction Letter, General for Generating Plant," Revision 0, dated December 2, 198 o SWYD-15. " Emergency Operating Instructions for 500kv and 161 kv Switchyards," Revision 0, dated December 2,198 o SWYD-18, " Plant Voltage Schedule " Revision 1, dated October 17, 198 Procedure No. N7701, " Abnormal Voltage Conditions on Safety-Related Auxiliary Power Systems," Revision 0, dated September 27, 198 Standard Practice SQ039, "Sequoyah Nuclear Plant - AC Auxiliary Power System ,

Operating Instructions and Transformer Voltage Settings," Revision 2, l dated February 7, 198 l l

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Employee Concern Special Program, Volume 3, Operation Category, Part'

30200. Subcategory Electrical and Communication, Sequoyah Element Report 30302 "Five Percent Low Voltage Problem," Revision 3, dated December 8,198 Significant Condition Report, SCR SQNEEB86147, "Overvoltage", Revision 0

' Memorandum from J. G. Dewease, TVA, to J. M. Ballentine, TVA, "AC Auxiliary Power System Transfer Taps," dated March 31, 198 Memorandum from M. N. Sprouse, TVA, to H. J. Green, TVA, "AC Auxiliary Power System 161kv Grid," dated June 1, 198 Memorandum from J. G. Dewease, TVA, to J. M. 8allentine. TVA, "AC Auxiliary Power System Plant / Grid Interface Operability Matrix," dated June 23, 198 Memorandum from W. A. Doyle, TVA, to E. L. Eichelberger, TVA, " Transfer-Tap Settings," dated January 13, 198 Memorandum from W. A. Doyle, TVA, to E. L. Eichelberger, TVA, "Transfar Tap Settings," dated February 1,198 Memorandum from M. N. Sprouse, TVA, to H. J. Green, TVA, " Plant / Grid Interface Restrict." dated February 16, 198 Memorandum from H. L. Abercrombie, TVA, to C. C. Mason, TVA, " Plant / Grid Interface Restrict," dated June 19, 198 Memorandum from J. A. Coffey, TVA, to R. W. Cantrell, TVA, " Plant / Grid Interface Restrict," dated March 8,198 Memorandum from A. A.' Burzese, TVA, to H. Gardner, TVA, " Transfer Tap Setting," dated October 23, 198 Memorandum from J. M. McGriff, TVA, to M. R. Sedlacik, TVA, " Employee Concern 30202 SQN Overvoltage Stress," dated December 23, 198 Memcrandum from M. R. Sedlacik, TVA, to All EE Supervisors, "SQN Plant Overvoltage Condition Policy," dated April 11, 198 Memorandum from R. L. Tallent. TVA, to F. R. Horne, TVA, "161 kV System Operation," dated April 27, 198 Memorandum from SRO, TVA, to All R0, TVA, " Night Order No. 62, " Voltage Limits 6.9KV SD BD"," dated April 25, 198 L___-______-_-_-_-_