IR 05000295/1988005

Insp Repts 50-295/88-05 & 50-304/88-06 on 880115-0224.No Violations or Deviations Noted.Major Areas Inspected:Action on Previous Insp Findings,Summary of Operations,Operational Safety Verification,Lers & IE Bulletins

ML20150E875
Person / Time
Site:	Zion  File:ZionSolutions icon.png
Issue date:	03/25/1988
From:	Hinds J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
To:
Shared Package
ML20150E865	List: IR 05000295/1988005 ML20150E862
References
50-295-88-05, 50-295-88-5, 50-304-88-06, 50-304-88-6, IEB-84-02, IEB-84-2, IEIN-87-004, IEIN-87-008, IEIN-87-024, IEIN-87-034, IEIN-87-042, IEIN-87-047, IEIN-87-24, IEIN-87-34, IEIN-87-4, IEIN-87-42, IEIN-87-47, IEIN-87-8, NUDOCS 8804040142
Download: ML20150E875 (15)

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v V.S. NUCLEAR REGULATORY COMMISSION

REGION III

Report Nos. 50-295/88005(DRP);50-304/88006(DRP)

Docket Nos. 50-295; 50-304 License Nos. DPR-19; DPR-48 Licensee: Commonwealth Edison Company P. O. Box 767 Chicago, IL 60690 Facility Name: Zion Nuclear Power Station, Units 1 and 2 Inspection At: Zion, IL Inspection Conducted: January 15 through February 24, 1988 Inspectors: P. L. Eng D. J. Damon D. L. Shepard S. M. Hare T. D. Reidinger D. H. Oudinot Approved B .. Ni ds, b f OS.t s .86 Reactor Projects Section 1A Date Inspection Summary Inspection from January 15 through February 24, 1988 (Report Ne /87005(DRP); 50-304/87006(DRP))

Areas Inspected: Routine, unannounced resident inspection of licensee action on previous inspection findings; summary of operations; operational safety  !

verification and engineered safety feature (ESF) system walkdown; surveillance i observation; maintenance observation; licensee event reports (LERs); training; cold weather preparations; IE Bulletin 84-02; IEN 87-04; IEN 87-08; IEN 87-47; IEN 87-34; IEN 87-24; IEN 87-42; and site visit by Section Chie Results: Of the 17 areas inspected, no violations or deviations were identifie l l

8804040142 880325 PDR G

ADOCK 05000295 PDR

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DETAILS Persons Contacted G. Pliml, Station Manager

• E. Fuerst, Superintendent, Production

• T. Rieck, SuperinterJent, Services W. Kurth, Assistar.t Station Superintendent, Operations

• R. Johnson, Assistant Station Superintendent, Maintenance J. Gilmore, Assistant Station Superintendent, Planning R. Budowle, Assistant Station Superintendent, Technical Services N. Valos, Unit 2 Operating Engineer M. Carnahan, Unit 1 Operating Engineer R. Cascarano, Technical Staff Supervisor W. Stone, Regulatory Assurance Supervisor W. T'Niemi, Master Mechanic K. Depperschmidt, Master Electrician E. Campbell, Master Instrument Mechanic F. Tschakert, General Foreman, Instrument Maintenance

• R. Mika, Assistant Technical Staff Supervisor

• A. Broccolo, Assistant Operating Engineer

• T. Saksefski, Regulatory Assurance Engineer

• Smith, Security Administrator

• T. Vandevoort, Quality Assurance Supervisor

• J. Reiss, Field Engineering Supervisor And others of the licensee's staf * Indicates persons present at the exit intervie . Licensee Actions on Previous inspection Findings (92701, 92702) (Closed) Unresolved item (295/87015-03;304/87018-07): Control of deficiencies associated with the calibration of instruments used in containment type B and C leak testin The licensee has completed their corrective action to resolve this ite The procedures which implement the local leak rate test program TSS 15.6.10.C, E, and F have been revised to require preliminary and post test calibration of the subject Ashcroft pressure gaug The licensee's method of controlling pressure gauge calibration in addition to existing controls on rotometer calibration appears to be sufficient to ensure accurate and reliable leak rate test result This item is close (0 pen) Open item (295/80020-04;304/80021-04): Implement final fix to maintain adequate minimum flow through the Centrifugal Charging Pumps Following a secondary side High Energy Line Rupture as identi fied in IE Bulletin 80-18. The licensee performed interim modifications of equipment and procedures as a result of this IE Bulletin and in 1980 committed to a permanent modificatio _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

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As of this inspection period, the licensee has still not completed their review of the interim modifications made in 1980 to determine if they are adequate for a permanent modification. The inspector indicated to the licensee that the completion of their work on this

~ item should be expedite This item remains open pending determination of whether the interim modification is an appropriate permanent fi (Closed) Violation (295/82020-08;304/82018-09): Rescinded Violation on failure to submit a 30 Day Report on a missed Technical Specification surveillance test. This violation was contested by the licensee and subsequently rescinded by the NRC in January,198 This item was inadvertently left open and is hereby close The missed surveillance was the direct result of an inadequate procedure revision which deleted the requirement for a surveillance tes The licensee was requested to respond to the NRC, outlining how future procedure revisions would not delete technical specification surveillance requirement The licensee responded in February 1983, and stated that procedure ZAP 5-51-4, "Procedural Control and Approval," assured that procedure revisions were reviewed by management to ensure that commitments and required surveillances were not inadvertently delete !

d. (Closed) Open Item (295/82028-01;304/82025-01): Part 21 Report by ITT Barton on defective electronic pressure transmitters which f

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experience thermal non-repeatability problems. The licensee has indicated that the Barton transmitters affected by this notice have been inspected by a Westinghouse technical representativ The Westinghouse representative indicated that the adjustment potentiometer which made the transmitters subject to thermal non-repeatability is encased in plastic which makes these i transmitters not susceptible to this proble During this inspection period, the licensee's PWR Engineering department provided a memorandum from W. H. Koester to P. E. Hull ;

dated November 1, 1983, which states that Westinghouse had '

detemined that some instrument set points would be affected; however, the only significant instrument which was affected was the pressurizer pressure transmitter. The licensee stated that Zion does not use a Barton instrument for this purpose and that the Part 21 was not applicable to Zion station. This item is closed, e. (Closed) Unresolved item (295/87010-01; 304/87013-01): Inclusion of specific requirements in purchase orders for austenitic stainless steel. The Division of Reactor Safety has elected to administratively close this item as stated in a memorandum from N. Chrissotimos to C. Norelius, dated January 14, 198 .

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. (Closed) Open item (295/84012-01; 304/84012-02)

Disable component cooling water surge tank vent valve in the open position te prevent tank overpressurization. The licensee has determined that the subject valves would be locked in the open position. The inspector verified the valve's locked open status and verified that procedure PT-41, "Locked Valve Audit," included these valves in the checklis This item is close During the revjew of this item, the inspector noted that the control room did not have a current revision of PT-41, "Locked Valve Audit" in the control room "consumable" file drawer. This procedure which was dated October 3, 1987, was revised on January 5, 1988. When the inspector looked into the file on February 12, 1988, the October revision had not been update The licensee is required by their procedures to ensure all procedure revisions are placed into the controlled copies within 30 days. The inspector and the licensee performed an audit of the control room consumable procedure file had no other old revisions. No additional procedures were located that exceeded the 30 day time limit. This is therefore considered an isolated incident and no enforcement action will be take (Closed) Open item (295/84023-02): Seismic analysis of boric acid transfer pump motor repair. The motor that had been repaired was replaced on April 16, 1985. The inspector noted that field installation of the boric acid transfer pump 1A was essentially identical to that of the other boric acid transfer pumps with the exception that stronger bolts were used to secure the pump to its pedestal. This item is close (Closed) Open Item (295/83026-04; 304/83027-05): The calculated feedwater flow to the steam generator under accident conditions may I not meet the volumetric flow rate assumptions of the accident analysis. An analysis was performed by Westinghouse and furnished '

to the licensee on March 13, 1984. This analysis indicated that the Zion Auxiliary Feedwater system meets the accident analysis assumptions in its present configuration. This item is close The inspector reviewed a letter dated March 30, 1984, from the responsible SNED engineer to the Plant Manage This letter recomended that the reanalysis information be included in the next update of the Zion FSAR. Discussions with the Regulatory Assurance Supervisor indicated that this recommended revision to the FSAR has not yet been performed but would be included in the next FSAR update. Revision of the FSAR to include the pertinent information will be tracked as an open item (295/88005-01; 304/88006-01).

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. Summary of Operations Unit 1 The unit operated at power levels of up to 93% power throughout the inspection period until February 24, 1988, when the reactor tripped from 49% power. The unit is currently being brought to cold shutdown for the scheduled refueling outage. On January 30, the unit broke the Commonwealth Edison record of 259 days for consecutive days on lin Unit 2 The unit operated at power levels of up to 99% power throughout the inspection perio No violations or deviations were identifie . Unit 1 High Steam Generator Level Resulting in Turbine / Reactor Trip Event of February 24, 198 On February 24, 1988, at approximately 10:12 AM CST, the unit I reactor tripped from approximately 49% power. Approximately fifteen minutes before the trip, all four steam generator level deviation alarms and all four feed flow / steam flow mismatch annunciators had come in for no apparent reason. At the time, the licensee was also conducting a turbine poppet valve test on the IB steam driven feedwater pump. The 1A motor driven feedwater pump was in automatic mode and was used to compensate for the feedwater flow variances due to the IB pump test. The unit I reactor operator then requested an "A" work request to investigate the reason for the annunciators. An "A" work request requires top mainten-ance priority and must be started as soon as possible. Approximately six minutes before the trip, the turbine poppet valve test was completed on the 18 feedwater pump and the turbine was unlatched, leaving the 1A feedwater pump as the sole operating source of feedwater. The eight l annunciators previously identified did not clear. At approximately 10:12 Afi, the reactor tripped from 49% powe ,

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Review of available steam generator level, feedwater flow and steam flow strip chart traces indicated that the trip occurred due to a high level in steam generator "C." High steam generator level in any steam generator causes the operating feedwater pumps and the main turbine to trip. With the reactor at greater than 10% power, a turbine trip causes a reactor tri At this time, it is not clear what caused the high level in steam generator "C". The licensee had neither determined the root cause nor completed the post trip investigation at the time of the exit ,

I for this report. Completion of the licensee's evaluation of the February 24, 1988, trip and associated corrective actions will be tracked as an unresolved item (295/88005-02; 304/88006-02). ,

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No violations or deviations were identifie . _ _ _ _ _ _ . _ . .

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5. Operational Safety Verification and Engineered Safety Features System ~

Walkdown (71707, 71709, 71710 and 71881)

The inspectors observed control room operations, reviewed applicable logs and conducted discussions with control room operators from January 15 through February 24, 1988. During these discussions and observations, the inspectors noted that operators were alert, cognizant of plant conditions, attentive to changes in those conditions, and took prompt action when appropriate. The inspectors verified the operability of selected emergency systems, reviewed tagout records and verified proper return to service of affected components. Tours of the auxiliary and turbine buildings were conducted to observe plant equipment conditions, including potential fire hazards, fluid leaks, and excessive vibration The inspectors by observation and direct interview verified that selected physical security activities were being implemented in accordance with the station security pla The inspectors observed plant housekeeping / cleanliness conditions and verified implementation of radiation protection controls. The inspectors noted that general plant conditions have significantly improved as a result of the licensee's painting and labelling programs. From January 15, 1988 to February 24, 1988, the inspectors walked down the accessible portions of the safety injection, AC electrical distribution, auxiliary feedwater, and portions of the service water systems to verify operability. The inspectors also observed portions of the radioactive waste system controls associated with radwaste shipment These reviews and observations w'r .iucted to verify that facility operaticns were in confonnance i m requirements established under Technical Specifications,10 CFR, w administrative procedure No violations or deviations were identifie . Monthly Surveillance Observation (61726)

The inspector observed and reviewed portions of the following test activities to ascertain whether testing was performed in accordance with adequate procedures, whether test instrumentation was calibrated, whether limiting conditions for operation were met, whether removal and restoration of the affected components were accomplished, whether test results conformed with technical specifications and procedure requirements and were reviewed by personnel other than the individual directing the test, and whether any deficiencies identified during the testing were properly reviewed and resolved by appropriate management personnel:

PT-7A Starting procedure for Auxiliary Feedwater Pump Lube Oil Pump PT-11 Diesel Generator Loading Test IB PT-0, App. X Auxiliary Building Operator Checklist, Third Shif TSSP 87-29 Poppet Lift Data on IB Feedwater Low Pressure Steam Governor PT-0, App. N Radiation Monitor Check

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The inspector also witnessed portions of the following test activities:

IN-44-E Power Range Nuclear Instrument Electronics PT-7 Auxiliary Feedwater System Checks and Tests TSS-15.6.10.C Personnel Hatch Local Leak Rate Tests TSSP 87-29 Poppet Lift Data on 18 Feedwater low Pressure Steam Governor PT-9 Service Water Valve Operability Checks During performance of IN-44-E, the inspector noted that a procedure anomaly in the form of an erroneous instrument setpoint was discovered by the instrument technician. The technician correctly ceased work, exited the surveillance procedure and requested that his foreman rectify the anomaly prior to resumption of test activity. The inspector was informed that steps to preclude the recurrence of such anomalies would be taken and that a temporary procedure change, followed by a permanent procedure change would be writte No violations or deviations were identifie . Monthly Maintenance Observation (62703)

Station maintenance activities on safety related systems and components listed below were observed or reviewed to ascertain whether they were conducted in accordance with approved procedures, regulatory guides industry codes or standards and in conformance with Technical Specification The following items were considered during this review: the limiting conditions for operation were met while components or systems were removed from service; approvals were obtained prior to initiating the work; activities were accomplished using approved procedures and were inspected as applicable; activities were accomplished by qualified ,

personnel; parts and materials used were properly certified; radiological controls were implemented; and fire prevention controls were implemente Work requests were reviewed to determine the status of outstanding jobs ;

and to assure that priority is assigned to safety related equipment  :

maintenance which may affect system performanc l The inspector reviewed the licensee's administrative procedure ZAP 3-51-1, "Origination and Routing of Work Requests," and noted the following:

The inspector noted that the revision date on the work request

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form included in the ZAP as an example was 12/83; however, the '

forms currently in use are dated 01/8 Section A.9 of the ZAP refers to "approved lists" for verification whether or not a given job is safety related, but does not specify who is authorized to approve the lists of who maintains such lists. The term "approved list" appears to be a nebulous ter i

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Section A.20 of the ZAP states that determination of whether a given job is "regulatory related" must be made; however, no guidance on how to determine such is give Section A.23.a of the ZAP refers to the July 1984, Safe Shutdown Capability Reassessment and Proposal Modifications Submittal, which has been superseded by Revision 1 dated July 1987. The licensee stated that the ZAP would be updated to reflect the correct revision of the subject referenc Section A.33 of the ZAP states that determination of whether the work request requires "reliability related controls" must be made; however, no guidance on how to make such a determination is give The following maintenance activities on the following components were observed or reviewed:

Work Request T i tle Z 66619 Unit 2 BIT Recire Heat Tracing Z 66628 Unit 1 BAT Recirc Heat Tracing Z 66807 2B Containment Spray pump Discharge Valve Z 67253A 1A Rod Drive MG Set Z 65378 Overhaul of 2A Service Water Pump Z 66759 Safety Injection Pump Suction Isolation Valve Repair 2MOV SI 8923A Z 66962 Install Clampatron (Controlatron) Flowmeter on Unit 2 BIT Recirc Line Z 66579 Repair of 2 MOV-SW0100 2 66249 Repair Leak on 1 MOV-SW0009 l

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Z 67269 Repair Breaker Control Transformer for #2 PP Air Compressor Z 67401 Repair Breaker Control Transformer for #2 PP Air Compressor Regarding the installation of a Controlatron flowmeter on the unit 2 boron injection tank (BIT) recirculation line as described in work request number Z 66962, the inspector noted that the calibration records for the subject instrument stated that calibration was only required prior to taking flow readings as requested by the technical staff. The inspector also noted that the calibration sheet was not signed by the individual performing the calibration. The licensee stated that actual flow readings were not being used to quantify BIT recirculation flow, but only to indicate whether recirculation flow was established, and that the Controlatron was only a temporary installation pending the repair of the normal instrument used to monitor BIT recirculation flow. The inspector noted that the facility Technical Specifications did not define a required BIT recirculation flowrate and that the technical manual for the flowmeter stated that only gross changes in fluid viscosity would affect flowmeter accurac .

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0Y Regarding the work performed ender 'rork (equest I (/269, members of the electrical meintenar.ce department rebufit, bench tested and installed the brs.aler control traG1former for the #2 penstratiin pressurization (PP)

air compressw which had overhLte6. ihe rotation and amperage for the

1. 2 PP air compressor were vertTied to be witGin norGal operating limits, and the breakce ud compressor were then turned over to operation Shortly after the air compressor was retutned to service, the breaker cabinet in the motor control ceGter overheated again. A second work request, Z 67401, was written. Additional investigation by electrical niintenancc reveald that a scienoid on the solenoid coil had developed an intermittent short which caused the breaker to overheat and smok The licensee stated that this was due to the fact that the solenoid was only energized when the compressor was not running, and that the solenoid was not part of the normal component checkout procedures. The licensee also stated that in the past, only the components in the MCC and associated breakers were tested prior to return to service. The inspector noted that as plant components age, degraded breakers and their associated circuits may go undetected with the inspection and testing used. The licensee stated that in order to identify such problems in the future, they would revise their check out and troubleshooting methods to include the portions of the control circuit from the motor control centers to the affected componen All electrical maintenance personnel except those on vacation method or on within twoextended week medical leave were retrained on the new check out Following completion of maintenance on 2MOV S1 8923A, and the 2A service water pump, the inspectors verified that these systems had been returned to service properl No violations or deviations were identifie .

Licensee Event Report (LER) Followup (92700)

l Through direct observations, discussions with licensee personnel, and review of records, the following event report was reviewed to determine that reportability requirements were fulfilled, imediate corrective action was accomplished, and corrective action to prevent recurrence had been accomplished in accordance with Technical Specifications. The LER listed below is considered closed:

UNIT 1 LER N DESCRIPTION i

87013 Containment Hatch Inner Door Opened with Outer Door Inoperable due to Component Failure Regarding LER 295/87013, this event was reviewed in inspection report 50-295/87013 unresolved item and corrective actions for this item are being tracked by 295/87016-0 No violations or deviations were identifie _

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ls Trainino (41400)

During the inspection period, the inspectors reviewed abnormal events

.and unusual occurrences which may have resulted, in part, from training deficiencies. Selected events and activities were evaluated to determine whether the classroom, simulator, or on-the-job training received before the event was sufficient to have either prevented the occurrence or to have mitigated its effects by recognition and proper operator actio Personnel qualifications were also evaluated. In addition, the inspectors determined whether lessons learned from the events were ,

incorporated into the training progra During review of approved and issued procedure revisions, the inspector noted that the task of obtaining vibration data for several safety related pumps hdd been reassigned to "B" me Previous test procedures i assigned vibrations data collection to "A" men who typically receive more specialized and in-depth training commensurate with their responsibilities. Members of the licensee's training staff stated that they were unaware of the change in task assignments and that "B" men had not yet been trained on how to obtain vibration reading Discussions with members of the Operations Department revealed that although the procedure revisions assigning vibration data collection to "B" men had .

been received, shift engineers had been requiring "A" men to actually

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obtain the data. The training department verified that all "A" men had ;

received on the job training on how to obtain vibration data and proceeded to develop a lesson plan for the "B" me :

Four training sessions were attended by the resident inspector staff, ,

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No violations or deviations were identifie . Cold Weather Preparations (71714)

The inspectors perfcrmed systems walkdowns and reviewed associated documentation associated with the performance of TSGP-43, "Cold Weather i Preparation Program." This surveillance procedure was initiated by the licensee in October, 1987, and completed in November, 1987. On

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January 15, 1988, DVR 22-1-88-001 was authored by the facility. The subject DVR concerns a frozen steam generator pressure transmitter ;

located in the 10 steam generator safety valve hous Review of the completed TSGP revealed that all cold weather preparations, ,

including those for the 10 steam generator safety valve house had been '

completed during November, 1987. Discussions with members of the licensee's staff revealed that upon the return of warmer weather during December,1987, the 10 safety valve house dampers were blocked open due to excessively high temperatures in that space. Upon return of cold weather, the dampers were left open and TSGP-43 was not re-performe This resulted in the frozen pressure transmitter described abov The

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inspectors noted on January 22, 1988, that the dampers were still open despite the fact that the ambient temperature of the environment was subzero. The inspectors noted that there is no formal guidance or direction defining when or if TSGP-43 should be performed following a warm weather cold weather cycle which occurs after initial completion of the TSGP. The licensee stated that determination of whether guidance or instructions addressing this matter would be made following an evaluation by the appropriate technical staff group. Completion of the licensee's evaluation will be~ tracked as an open item (295/88005-03; 304/88006-03).

No violations or deviations were identifie . IE Bulletin 84-02; "Failures of General Electric Type HFA Relays in Use in Class lE Safety Systems (92703)

With regards to IE Bulletin (IEB) 84-02, the licensee stated that the subject relays use nylon or Lexan as the coil spool material. When these relays are energized for long periods of time (e.g... normally energized)

the coil spool material may crack resulting in increased coil temperature and eventual relay failur The licensee has replaced all of the normally energized relays subject to this IE Bulleti Due to problems experienced in obtaining replacement relays, the normally de-energized relays of the type addressed in the IEB have not yet been replaced. Since the replacement relays are now on-site, the normally de-energized relays that are scheduled for replacement will be replaced during the next unit 1 and 2 outage scheduled to begin in March and October, 1988, respectively. This bulletin was closed in inspection report 50-295/87035; 50-304/8703 ;

No violations or deviations were identifie . IE Information Notice 87-04, "Diesel Generator Fails Test Because of Degraded Fuel" (92701)

The information notice (IEN) identifies predicted problems pertaining to long term storage of fuel for emergency diesel generator (EDG) fouling of a screen in the "Y" strainer between the day tank and the EDG. This would result in failure of the EDG to complete a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> endurance test due to fuel starvation. The IEN stated that high concentration of particulates resulting from oxidation and biological contaminants caused l the clogging of the straine '

In response to the subject IEN, the licensee stated that all fuel filters and strainers are cleaned annually, the fuel storage tanks are drained and cleaned once every five years and the storage tanks are sampled quarterly from the bottom of the tank. The station has biocide on hand for treatment of contaminated fue This IEN is considered close No violations or deviations were identifie l l

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1 IE Information Notice 87-08, "Degraded Motor Leads in Limitorque DC Motor Operators (92701)

The subject IEN addresses the degradation of Nomex-Kapton insulated leads. Motors fitted with said leads. are H.K. Porter (now Peerless-Winsmith) which were manufactured between December 1984 and December 1985. The insulation degradation could cause short circuit failure of the motor The licensee's response to the IEN stated that Zion station does not use any DC Limitorque motor operators on safety-related valves. The licensee also stated that motor lead insulation was Nomex with epoxy impregnated braided fiberglass. The testing of motors fitted with this insulation is documented in Qualification report B-0009. The licensee stated that test procedures for motor operated valve routine surveillances and maintenance requires that motor leads be visually inspected for signs of degradatio This IEN is considered close No violations or deviations were identifie . IE Information Notice 87-47, "Transportation of Radiography Devices" (92701)

The IE notice 87-47 updates previously issued IEN 81-02, which was sent to all licensees on January 23, 198 d The licensee stated that since Zion station does not possess a license to manufacture, distribute and/or operate radiographic exposure devices and/or source changers, this IEN does not apply to Zion station, and is therefore, considered close No violations or deviations were identifie '

1 IE Information Notice 87-34, "Single Failures in Auxiliary Feedwater Systems (92701)

This item addresses potential single failures of auxiliary feedwater pumps due to protective pump trip circuit,y that is common to both motor driven auxiliary feedwater pumps and could prevent both pumps from starting automatically in the event of either a low-low steam generator level or loss of main feedwater. Such a loss would cause partial or complete loss of capability to supply auxiliary feedwater which is disallowed by the design basi ,

Review of Zion auxiliary feedwater system description and associated drawings revealed that each of the two subsystens is powered from separate diesel generators and is physically separated into two distinct ESF trains with their controlling instrumentation and controls from the redundant ESF buses. Zion FSAR chapter 6.7-1 also states that the loss of one bus would not cause the loss of all auxiliary feedwater supply as each pump and their associated valves are powered from different essential buses. This IEN is considered close . - - . - . -

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No violations or deviations were identifie . IE Information Notice 87-24, "Operational Experience involving Losses of .

Electrical Inverters" (92702) i This information notice concerns failure of components in inverter cabinets caused by high temperatures in the cabinets. Three potential failure mechanisms are identified: (1) high ambient temperature or high humidity within the inverter enclosure, or a combination of the first two, (2) the physical arrangement involving the electrical interconnecting circuitry of the inverter components, and (3) voltage spikes and/or perturbations which affect the solid state devices in the inverter circuitry resulting in blown fuses and subsequent component failures. Also, secondary voltage perturbations caused by lightning strikes or switching surges can have an adverse affect on inverter operation ,

l Zion FSAR 9.1.0.1.3.11, indicates that the maximum temperature limit for l the inverters is 105 degrees Fahrenheit and that nonnal ventilation j should keep the ambient temperature range in the inverter room to 75 .

degrees plus or minus 10 degrees as stated in Zion FSAR 9.10.1. l

The inverter technical manual specifies that the normal ambient temperature range should be between 0 and 40 degrees Centigrade or 32 to 104 degrees Fahrenheit. The auxiliary electric room (AER) temperatures ;

I are monitored on a shiftly basis. Should one of the two air conditioners l fail, operator action is to isolate non-essential loads fed by the j ventilation system so that the remaining air conditioning unit is feeding '

just the AER and the technical support center (TSC). Further operator action may involve cpening the AER doors with an air mover unit positioned to further dissipate heat from the room if necessar Zion Unit 2 LER 84-16 dated July 9, 1984 reported a reactor trip which occurred due to an inverter failure. The inverter failure was caused by previous overheating of the regulating transfo.mer due to long term circulating currents. The circulating currents prematurely aged the transformer insulation during the first eight years of operation. There has been previous non-reportable inverter failures. The transformers are scheduled for replacement as soon as parts are availabl The licensee stated that preventative maintenance and surveillance procedures are already in place to prevent similar problems from occurrences in the replacement transformers. Zion Unit 1 LER 84-01 described a similar problem with a reactor trip caused by transformer and capacitor failure. The licensee stated that transformer capacitors will be replaced every 3 years in accordance with the capacitor manufacturer's estimate of capacitor life. The licensee stated that due to the cost and difficulty of obtaining replacement capacitors, it will revise the Unit 1 LER 84-01 to require capacitor replacement frequency to 4.5 years. The revised LER justifying the longer service life will be reviewed when it is issue .

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The licensee indicated that the temperatures measured in the inverter cabinet were within the normal tolerance as compared with similar comparisons made with other vendors. There is no anticipated development of specifications for inverter cabinet internal temperatures. The utility measured the cabinet temperatures on a one time basis in response to the information notice. They also indicated that they did replace the sola transformers based on their failure record and all sola transformers were replaced in both units. The lightning strikes and voltage perturba-tions are mainly protected against by fuses and blocking diodes inside the inverter cabine In conclusion, the inspector visually examined the physical arrangements of the circuitry of the inverter components and found that the physical arrangement is such that the thyristor's (the components carrying the highest current and thus, the largest source of heat) are adequately heat sinked for heat removal and that these components are physically separated i in both the vertical and horizontal planes. Separation is accomplished by both a heat shield and a physical location apart from other components that are sensitive to heat. The technical manual specifies that vertical separation of at least 3 inches should be maintained between inverter cabinets. Zicn inverters are separated by at least 40 inches. The ventilation inside the inverter cabinets flows frem bottom to top with ;

the greatest heat source being located next to the air inlet at the bottom of the cabinet. The licensee has judged the temperature gradient inside the cabinet to be acceptabl With regards to inverter protection from voltage perturbations and i lightning strikes, the licensee installed a lightning protection modificatio No violations or deviations were identifie I 17. IE Information Notice (IEN) 87-42, "Diesel Generator Fuse Contacts" (92702) l This information notice discusses failure of emergency electrical power supplies resulting from misalignment and/or degradation of diesel generator fuse contact Zion station has 4 kv relay and metering equipment cubicles manufactured by ITE/ Brown Bover These cubicles house the potential transformer (PT)

fuse and the PT's. Per drawing 22E-1-4119, the diesel fuse drawer opens up and fuses disconnect with disconnect links and the fuses are horizontal vice vertical. In addition, they don't have the equipment described in the IEN manufactured by Allis-Chalmers. The fuses in the diesel PT drawer are disconnected via disconnect links as opposed to the method described in the information notice. It is concluded that the problems described in the IEN are not applicable to Zion Statio No violations or deviations were identified.

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1 Site Visit By Section Chief On February 17, 1988, a site visit and tour was conducted for Mr. Julian M. Hinds, Chief, Reactor Projects Section 1A. Following the plant tour, Mr. Hinds met with station management and other members of the plant staff. Mr. Hinds noted that the material condition of the plant had improved significantly, but also stated that further improvement was encouraged. Mr. Rieck then presented a summary of the Zion station's goals review for calendar year 1987 and the station goals and priorities for 1988. Mr. Hinds stated that the NRC would continue to monitor the licensee's progres . Open Items Open Items are matters which have been discussed with the licensee which will be reviewed further by the inspector and which involve some action on the part of the NRC or licensee or bot Two Open Items disclosed during this inspection are discussed in paragraphs 2 and 1 . Unresolved Items Unresolved items are matters abuut which more information is required in order to ascertain whether they are acceptable items, violations, or deviations. One Unresolved Item was identified during this inspection and is discussed in paragraph . Exit Interview (30703)

The inspectors met with licensee representatives (denoted in Paragraph 1)

throughout the inspection period and at the conclusion of the inspection on February 24, 1988, to summarize the scope and findings of the inspection activities. The licensee acknowledged the inspectors'

comments. The inspectors also discussed the likely informational content of the inspection report with regard to documents or processes reviewed by the inspectors during the inspection. The licensee did not identify any such documents or processes as proprietar . -. , _ _

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