IR 05000220/1993019

Insp Rept 50-220/93-19 on 930823-27.No Violations Noted. Major Areas Inspected:Electrical Distribution Sys

ML20058Q388
Person / Time
Site:	Nine Mile Point
Issue date:	10/18/1993
From:	Kay L, Ruland W NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
To:
Shared Package
ML20058Q355	List: IR 05000220/1993019 ML20058Q352
References
50-220-93-19, NUDOCS 9310260167
Download: ML20058Q388 (9)

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U.S. NUCLEAR REGULATORY COMMISSION

REGION I

REPORT N /93-19 DOCKET N ;

LICENSE N DPR-63 LICENSEE: Niagra Mohawk Power Corporation FACILITY NAME: Nine Mile Point Station, Unit 1 INSPECTION DATES: August 23-27,1993 l

INSPECTOR: -

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-Leanne M. Kay, Reactor Engineer '~~ Dale Electrical Section, EB, DRS

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APPROVED BY: ,. , // w _

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Wiiliain H. Muiand", Chief Date'

Electrical Section, EB, DRS l

I 9310260167 931019 PDR ADOCK 05000220L 0 PDR

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~ Area Insoccted: This was an announced inspection to review the licensee's corrective actions of six previously identified electrical distribution system functional inspection (EDSFI)

findings and process for addressing Information Notices and Generic letters related to electrical issue Ecs. uhs: No violations or deviations were identified. Of the six open unresolved items reviewed for Unit 1, three unresolved items were closed and the remaining four items were updated. These items are discussed in Section < - _)

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DETAILS y

• ' 1.0L PURPOSE-p The purpose of.this inspection'was to review and verify the licensee's corrective actions for f previously identified NRC findings including Electrical Distribution System Functional

$ . Inspection (EDSFI) open items and the licensee's process for addressing Generic Letters and

- Information Notices; In addition, a clarificationivas made regarding the closure of a f '-

> previous'EDSFI unresolved item.

o 2.0 , FOLLOWUP OF PREVIOUSLY IDENTIFIED FINDINGS

- 2.11 (Open) Violation (50-220/91-80-01) for failure to test EDGs adequately The EDSFI team identified that the licensee had not adequately tested the emergency diesel

- generators (EDGs) to determine the capabilities of both the generator and excitor under rated load conditions. The team's review found that the monthly surveillance test needed further clarification to envelope accident load conditions and continuous nameplate rating of the machine. The licensee committed to perform a special test during the first forced outage

following March 31,1992, to verify the EDGs capabilities at rated load and power facto . Periodic testing of EDGs under rated load is required to demonstrate the functional capability of the generator and its excitation system as required by Technical Specification ,

- The licensee reviewed the EDG monthly surveillance (N1-ST-M4) loading requirements for ~

testing.the diesel at design basis load and power factor. Based on this review, the licensee ]

concluded that the monthly test was in accordance with the values presented in the. Technical

- Specifications. In addition, the licensee completed special test N1-STP-31, Revision 0,

" Diesel Generator 102 and 103 Load Testing," to ' confirm generator capability per the design {

basis. This test was' conducted on February 25,1993, and demonstrated the EDGs capability {

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. to supply a minimum of 1550 KVAR and 2612 KW for approximately sixty minutes as

- expected under a design basis event. These values were determined to bound the requirements presented in the licensee's steady state loading calculation number 4.16 q l KVAC-DG-E In a letter dated April 13, 1992, the licensee disagreed with this violation and presented their

justification for Technical Specification compliance. The licensee stated that documentation contained in the Technical Specification bases file provided justification that the emphasis of j the monthly surveillance test was on the engine and that no requirements for testing the generator on a monthly basis were given. The licensee stated the testing performed was adequate for ensuring that the diesel generators will perform their intended safety functio This violation remains open pending completion of the current review by the NRC. Based l C

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on this review, determination.'will be made by the NRC to retract or re-affirm this violation L at a later date.

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' 2.2~ . (Closed) Unresolved item (50-220/91-80-04) regarding EDG auto start circuits !

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l The EDSFI team reviewed the functionality of control circuits under voltage fluctuations L' initiated during emergency diesel generator (EDG) loading. This review identified possible voltage fluctuations exceeding the manufacturers' operation ranges of timers and relays.

1 Based upon these fluctuations, the proper operation of relays and timers could not be guaranteed. A preliminary analysis performed by the licensee concluded that the delays caused by the large voltage fluctuations during automatic motor starts are short and the timing sequence was within the design basis. The licensee committed to confirm this l i

- conclusion by final analysis and tes !

The inspector reviewed the results of Special Test Procedure N1-STP-23, Revision 0, " Core Spray, Containment Spray, and ADS Load Sequence Circuit Test." This test was conducted !

in March 1993, to. verify the pickup and dropout voltages of relays and timers associated i with initiation circuits that load on the EDG. Determination for proper pickup and dropout ;

voltages also considered worst-case voltages expected under degraded voltage condition Assumptions used were determined to be conservative and included a delay in timer pickup i during the first load block for consideration of motor start overlap and EDG overloa Results of this test and analysis by engineering confirmed that the design requirements for the ;

timers and relays were met and sufficient margin existed. These test results were used to )

ensure the. proper operation of equipment required during EDG loadin The inspector reviewed test results which demonstrated that all devices picked up below manufacturer's minimum device operating voltage and dropout voltages were low enough to preclude inadvertent dropout during motor-starting transients. Based upon satisfactory completion of the special test and review of the test results, this item is close .3 (Closed) Unresolved Item (50-220/91-80-05) regarding the fast bus transfer scheme During this inspection, the inspector noted that unresolved item number 50-220/91-80-05 was inaccurately titled as unresolved item number 50-220/91-80-12 in Inspection Report 50-220/93-15. Inspection report 93-15 closed unresolved item number 50-220/91-80-05 based on the adequate corrective actions completed by the licensee as described in

' Paragraph 3.3. The inaccurately titled unresolved item, number 50-220/91-80-12, pertaining to hydrogen concentration concerns in the battery room was found to be closed in an earlier NRC Inspection Report, 50-220/92-19, dated November 13, 199 .4 (Open) Unresolved Item (50-220/91-80-06) regarding cable ampacity analysis The EDSFI team identified that the licensee had no formal calculations for demonstrating adequate cable ampacity in 600 volt cables. The licensee stated that this will be addressed in their design basis reconstitution program. However, the team was concerned that fire L retardant material, "Flameastic," had been applied to a number of cables without considering a

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~ , 5 ampacity derating. The licensee established an action plan to complete a derating study of

"Flameastic" coated cables and implement corrective actions, if required, by the end of 199 . In _ addition, the licensee committed to analyze additional sample cable trays in the turbine

and reactor buildings by March 199 A follow-up inspection (50-220/92-19) included a review of this analysis performed by the licensee and revealed no concerns. The inspector noted that a significant number of cables in the sampled trays had sufficient ampacity margin During this inspection, the inspector found that the licensee had completed their analysis of

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all plant power cables. This analysis included comparison of full load currents to maximum ampacity derate values presented in the published Insulated Conductors Engineering Association (ICEA) tables. The individual cables were evaluated by comparison of their expected loading requirements to the calculated effects of ambient temperature, tray fill, and

"Flameastic" coating on rated ampacity. The results of this evaluation demonstrated that all safety-related cables were well below their calculated ampacity derated value The inspector noted that the licensee had expanded the scope of this evaluation to include all nonsafety-related cables throughout the plant. In addition, the licensee has loaded all plant cabling information into a cable and raceway management software program to determine more accurately the cable ampacities due to actual cable my till conditions and ambient temperature effects. This ampacity study utilizes the Stolpe methodology for a :? ore conservative determination of cable ampacities. This item remains open pending the final analysis of the ampacity study using the Stolpe methodology and subsequent NRC revie ' (Open) Unresolved Item (50-220/91-80-07) involving protection and coordination g

A review performed by the EDSFI team identified miscoordination problems that existed in

- the 4160 Vac, 600 Vac, and 125 Vdc Class IE systems. These miscoordination problems

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included design deficiencies whereby, under fault conditions, protection would not be provided to the overcurrent devices. For example, lack of coordination between the supply breaker to a bus and a feeder breaker connected to the same bus would result in the loss of

'several circuits when a fault occurs in one circuit. The licensee committed to review and

- resolve these deficiencies within all voltage systems and develop an action plan to achieve coordination including plant design changes by December 199 The inspector reviewed Deviation / Event Report (DER) action plans and project reports initiated by the licensee to ensure power service continuity to all circuits except the faulted circuit. Discussions were held with electrical engineers to determine the status of these project reports. These planned actions by the licensee included modifications to decrease the probability of accidents or transients. These modifications included revising settings on existing emergency control (EC) trip devices, installing new EC trip devices, molded-case

' circuit breakers, and cable, and developing new coordination studies for each voltage level.

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. The. inspector determined that the licensee had developed the appropriate analysis in accordance with their committed dates. Engineering staff performed a good _ analysis for determining proper interrupting current ratings for molded-case circuit breakers necessary to

. ensure adequate coordination. Resolution of miscoordination problems is expected to be

• completed by December 31,1993. This item remains open pending completion of licensee corrective actions to correct coordination deficiencies and final review by the NR .6' (Closed) Unresolved Item (50-220/91-80-11) pertaining to heat balance calculations In October of 1991, the EDSFI team identified that heat balance calculations had not been '

established to determine acceptable temperature limits considering seasonal extremes, loss of-nonsafety-related HVAC, and worst-case design basis accident conditions for safety-related areas. The licensee recognized the need for these calculations and committed to establishing a comprehensive HVAC action plan by April 8,199 The licensee identified and completed detailed calculations for the following areas or rooms )

containing safety-related equipment:

- Battery rooms

- Battery board rooms

- EDG rooms-

- EDG switchgear rooms

- Screenhouse

- Reactor building

- Turbine building

- Cable spreading room

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- Outdoors

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- Foam room

- Control and auxiliary control rooms These calculations were performed to determine the expected minimum, maximum, and normal room or area ' temperature assuming normal heating and/or ventilation was los Considerations were also made for significant internal and external heat loads, such as operating motors, which may supply heat to the area or room. Field walkdowns were performed by the licensee of selected equipment to verify components as-installe The licensee has developed a database to determine the design basis temperature limits for each component. From these temperature limits a comparison was made with the

- manufacturer's specified temperature limits for each component. Any nonconforming conditions identified were dispositioned through the licensee's DER system. Approximately thirty DERs were written and have been prioritized according to the greatest temix:rature

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The inspector reviewed resolutions of'he DERs for components with the greatest temperature -l

' y difference. ' These DERs included opecability evaluations based on the application of each !

' component. The inspector noted that disposition of the remaining DERs involved only those .i components with temperature differences or less than four degrees Fahrenheit. The inspector-determined these DERs to be of small safety significance based on component functio ]

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~ Based on the licensee's comprehensive review of components for determining worst-case temperature limits, completion of supporting calculations, and disposition of discrepancies l

through the DER process, this item is close l 2.7. . (Open) Unresolved Item (50-220/91-80-15) regarding degraded bus voltnge j setpoints i

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The EDSFI team performed a review of the adequacy of degraded bus voltage setpoints to j F ,

. ensure sufficient voltage to all safety Class lE equipment and avoid unnecessary separation )

f of safety-related boards from the offsite power supplies. Results of this review necessitated administrative controls by the licensee to control grid power. This issue was unresolved pending the licensee completing an analysis to determine the adequacy of degraded bus voltage setpoints and taking appropriate corrective action j

The licensee performed calculation "ELMSAC-DEGVOLT-STUDY," Revision 0, to l determine the minimum 4160 Vac emergency bus degraded voltage value. This analytical  ;

limit was determined to be 3702.4 V. Subsequent to this determination, the licensee  !

performed relay setpoint calculation "4.16 KVAC-PB102/103-SLTIYI'/27," Revision 0, to establish the relay setpoint. This relay setpoint was calculated to be 3730V with an operating time of ten second . The inspector reviewed the assumptions, acceptance criteria, and methodology for l determining the setpoints presented in calculation 4.16 KVAC-PB102.102-SETPT/2 l Proper considerations were made for calculating setpoint error including calibration J instrument error, temperature effect including relay repeatability over an established-temperature range, control voltage effects, and maximum dropout value for the undervoltage relay. Based on this calculation the licensee determined the setpoint revisions necessitated a ;

- change to the Technical Specifications. At the time of this inspection the change was l pending the licensee's Site Operations Review Committee (SORC) approval. The licensee !

estimated final approval to be made by October 1993. This item remains open pending completion of the licensee's corrective actions to establish proper relay setpoint .0 IMPLEMENTATION OF INFORMATION NOTICES AND GENERIC LETTERS The inspector performed a review of the licensee's process for addressing Information Notices (IN) and Generic Letters related to electrical issues. The review was made to assess -

[ licensee review of information for applicability to Nine Mile Point and consideration of actions, as appropriate, to avoid similar problems presented in NRC generic communication .

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' Licensee Procedure NIP-ECA-01, Revision 6, " Deviation Event Report," was reviewe ,.

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This procedure sets forth requirements for the management of regulatory correspondence and the assignment'of tasks associated with correspondence that have the potential for affecting the safe and reliable operation'of the plant. Based on review of this procedure, the inspector

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determined that good controls had been established for the tracking of items / issues and individual's responsibilities related to the process were clearly defined. The dispositioning of a selected sample of Information Notices issued within the last 30 months, as listed below, were reviewed for licensee applicability and consideration of necessary actions. This dispositioning is performed by the- Quality Verification Safety Assessment Grou IN 91-29 and Supplement 1: Deficiencies Identified During EDSFIs IN 90-18 Crosby Safety Relief Valves on EDG Air Tanks IN 91-34 EDG Potential Problems

. IN 91-62 ' Diesel Engine Damage Due to Hydraulic Lockup IN 90-51 and Supplement 1: Failures of Voltage Dropping Resistors in Power Supply Circuitry Considerations were found within the licensee's process for correlation of related events occurring both in-house and industry wide. Evaluations performed by the licensee for applicability of degraded or potentially degraded components identified through the IN process were reviewed.'

The inspector verified the ' accuracy of these evaluations and subsequent actions and found no -

discrepancies._ The inspector concluded the licensee adequately addressed the regulatory

' information for the sample reviewed and had established good controls for managing the information provide ' UNRESOLVED ITEMS Unresolved items are matters about which additional information is necessary to determine whether they are acceptable, a deviation, or a violation. Several unresolved items are discussed in detail under Section n 5.0 - EXIT MEETING

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The inspector met with the licensee's personnel denoted in Attachment 1 of this report at the conclusion.of the inspection on August 27,1993. At that time, the scope of the inspection and inspection results were summarized. The licensee acknowledged the inspection findings as' detailed in this report and had no additional comments regarding the result . .,

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9&l ATTACIIMENT 1 PERSONS CONTACTED

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' Niagara Mohawk Corooration  ;

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Fi Constance, I&C Engineering l

_.* D. Greene, Manager, Licensing l

• D. Goodney, Lead Electrical Engineer l

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L. Klosowski, Supervisor, Nuclear Design ;

• ' R. Magnant, Designer, Site Licensing j T. McMahon,- Supervisor, Electrical Design !

• .W. Yaeger, Manager, Unit 1 Engineering l ;

• denotes attendance at exit meeting l

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