ML20100Q371

Revises Commitment Date for Completion of Unit 1 Distribution Circuit Mods to Same Commitment Date as Unit 2 Distribution Circuit Mods & Clarifies List of 120 Volt Ac Distribution Circuits W/Voltage Concerns

ML20100Q371
Person / Time
Site:	LaSalle
Issue date:	02/27/1996
From:	Querio R COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9603110613
Download: ML20100Q371 (8)

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• f Commonwealth IMiv>n Company j.I

• l2Salle Gencrating Station 2601 North 21st Road

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• Marseilles IL 613-i19757

j. Tel HI43574,761 j '

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~i February 27,1996 i

j United States Nuclear Regulatory Commission

! Attention: DocumentControlDesk j Washington, D.C. 20555 4

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Subject:

LaSalle County Station, Units 1 and 2 j Supplemental Response to Electrical Distribution System 1

Functional inspection (EDSFI) Reports 50373/91019 and 50

. 374/91019 l Deviation 373/91019-05D and 374/9101H5D on Degraded

{ Voltage Setpoint Methodology i Deviation 373/91019-05D and 374/9101906 on 4160 Volt l

< Degraded Voltage >

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Request for Schedule Extension NRC Docicet Nos. 50-373 and 50-374 i

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References:

1. T. J. Kovach letter to USNRC dated January 16,1992, l transmitting response to NRC Inspection Reports 50 373/91019 and 50 374/91019 regarding the Electncal Distribution System Functional inspection (EDSFI) EDSFl report.

2. T. J. Kovach letter to USNRC dated April 30,1992, transmitting supplemental response to the subject unresolved item. j i

3. T. O. Martin (USNRC) letter to LO. DelGeorge dated March 12,1993, transmitt'ng  ; inspection Report Nos. 50-373/93002 and 50 374/93002.

4. M. B. Depuydt (CECO) letter dated June 22,1993, to T.E.

Murley (USNRC) transmitting supplemental response to the subject unresolved item.

5. G. G. Bones (Comed) letter dated January 27,1994, to T.E. Murley (USNRC) transmitting supplemental response 110049 to the subject unrosoived item.

9603110613 960227 PDR ADOCK 05000373 G PDR j / ]l A Unicom Company j

• 1 In reference 5 LaSalle County Station provided a '::44:=> and status of the degraded voltage modsfications that were required to resolve the subject EDSFl Unresolved item. In this letter LaSalle County Station also committed to complete the 120 VAC distribution circuit modifications on each unit prior to startup following the respective seventh refueling outage and to complete the remaining 480 VAC equ'pment modifications on each unit during the respective sixth refueling outage.

In addition, LaSalle County Station committed in reference 1 to complete tne corrective actions required to resolve the deviation on the degraded voltage setpoint methodology per the same schedule as the degraded voltage moddications. As indicated in our original response, the " permanent" degraded voltage setpoint con not be implemented until the degraded voltage "hardwars" modifications are implemented.

The purpose of this letteris to:

1. Revise the commitment date for completion of the Unit 1 distnbution circuit modifications to the same commitment date as the Unit 2 distribution circuit modifications, and clarify the list of 120 VAC distnbution circuits with voltage concems.

2. Provide a status of the degraded voltage modifications for the 480 VAC equipment.

3. Revise each unit's commitment date for completing the degraded voltage setpoint change to the first refueling outage following the approval of the Technical Specification amendment for revising the trip setpoint and allowable value.

The statur of the degraded voltage design changes and the justification for the schedule changes are provided in the following attachments:

1. Attachment A summarizes the scope of work, status, and schedule of the 120 VAC distribution circuit modifications. In summary, the modifications for both Units 1 and 2 are scheduled to be completed during or prior to the Unit 2 seventh refueling outage.

2. Attachment B provides the status of the 480 VAC equipment modifications. In the previous correspondence (ref. 5) LaSalle County Station reported that all degraded voltage modifications required for the motor control circuits and 480 VAC equipment had been completed except for two (2) 480 VAC equipment changes. As noted in this attachment, the remaining modsfications were completed on schedule.

3. Attachment C contains the justification for revising the schedule of the degraded voltage setpoint change as indicated above. The schedule requires revision because the final change to the degraded voltage trip setting at the

- 4160 voit level requires further analysis of the final plant configuration with the planned modifications, and a Technical Specification change is required prior to implementation. Although the degraded voltage setpoint will not be

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i implemented in a timeframe commensurate with the original commitment, modifications to plant equipment to ensure adequate voltage to safety equipment under degraded voltage conditions will be completed by the end of the Unit 2 seventh refuehng outage. In addition, the final degraded voltage setpoint has been prehminary determined to be approximately the sann value as the current compensatory setpoint for the degraded voltage relays.

Please direct any questions you may have concoming this matter to this office. i Respectfully, ex R. E. Querio Site Vice President LaSalle County Station Enclosure cc: H. J. Miller, NRC Region til Administrator P. G. Brochman, NRC Senior Resident inspector- LaSalle C. Matthews, IDNS Resident inspector - LaSalle F. Niziolek, IDNS Senior Reactor Analyst INPO - Records Center D. L Farrar, Nuclear Regulatory Services Manager i

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. ATTACHMENT A Supplemental Response To inspection Report 5 4 373/91019;50 374/91019 Unresolved item 373/9101906; 374/9101906

. 120 VAC Distribution Circuit Modifications Description of Modifications The corrective actions that have been initiated for the 120 VAC distribution circuits with inadequate voltage at the degraded voltage setpoint consist of one or more of the following plant changes:

1. Tap changes of the === Maw 480120/208V distribution transformers to increase the voltage on the secondary side.

2. Increase in the size of the power supply cable to decrease the voltage drop between the bus and load.

3. Addition of voltage regulatmg transformers to the circuits. .

The 120 VAC distribution circuits which require modification are identified below:

Unit 1:

1. MCC 135X-1, ekt #5 - Post Accident Primary Containment Momtoring

2. MCC 135X-3, ekt #15 - Leak Detection

3. MCC 136X-1, ekt #5 - Post Accident Primary Containment Monitoring

4. MCC 136X-1, ekt #19 - SBGT Flow Control Damper 1VG002

5. MCC 136X-1, ekt #36 - Control Room HVAC

6. MCC 136X-2, ekt #5 - Process Radiation l I

7. MCC 136X-2, ekt #17 - Switchgear Heat Removal

8. MCC 136X-2, ckt #25 - Nuclear Boiler Process instrumentation

9. MCC 136X-2, ckt #29 - Post Accident Containment Monitoring *

10. MCC 136X-2, ckt #30 - Post Accident Containment Monitoring *

11. MCC 136X-3, ekt #7 - Leak Detecten Unit 2:

1. MCC 235X-1, ckt #5 - Post Accident Containment Mon;teiing*

2. MCC 235X-2, ckt #18 - Containment Monitonng

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l ATTACHMENT A Supplemental Response To inspection Report 50-373/91019;50-374/91019 Unresolved item 373/9101906; 374/91019-06 120 VAC Distribution Circuit Modifications

3. MCC 235X-3, ckt #15- Leak Detection l l

4. MCC 236X-1, ckt #5 - Post Accident Primary Containment Monitoring i

5. MCC 236X-1, ekt #13 - SBGT Flow Control Damper 2VG002 j

6. MCC 236X-1, ekt #36 - Control Room HVAC l

MCC 236X-2, ckt #9 - Post Accident Containment Monitonng*

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8. MCC 236X-2, ckt #32 - Containment Monitoring l

0. MCC 236X-3, ekt #19 - Leak Detection The four circusts marked with an asterisk, ", were added since the previous correcpondence (ref. 5). These circuits were not included in reference 5 because the original analysis determined that the malfunction of the components with insufficient voltage in these circuits would only result in the loss of an alarm or monitoring function; components which perform a safety related function were calculated to have adequate terminal voltages. While this analysis is still accurate, it was determined that the alarm or monitoring function performed by these circuits is required by Reg. Guide 1.97.

In addition, one circuit - MCC 235Y-1, ckt. #16, RH Service Water Cubicle Vent Dampers - was removed because a detailed review concluded that the components in this circuit fail safe. Therefore, the components in this circuit are not required to operate following the Design Basis Accident (DBA).

The 120 VAC distnbution circuits listed above were determined to have adequate voltage to perform their safety-related function following an accident under the compensatory measures taken by the station in response to the degraded voltage issue. These compensatory measures are described in detailin reference 1.

Status of Modifications The design drawings for all the 120 VAC distribution circuit modifications have been issued, the design packages for the modifications scheduled to be installed during the l present Unit i refueling outage have been approved, and the voltage regulating transformers have been delivered to the station. The seismic qualification of these transformers has also been completed. However, the environmental qualification of this equipment is incomplete because an essential component failed during the simulated design basis accident test. Additional testing of this component is being performed by the vendor to resolve this problem, and this testing is scheduled to be completed by April,1996.

ATTACHMENT A Supplemental Response To inspection Repod 50 373/91019;50-374/91019 Unresolved item 373/91019-06; 374/91019-06 ,

120 VAC Distribution Circuit Modifications Justification For Schedule Chance i l

The design changes for the circuits of both units are scheduled to be implemented prior to startup following the Unit 2 seventh refueling outage which is currently plarsed for fall,1996.

The commitment date for completing the Unit 2 design changes remains unchanged, but the date for completing the Unit 1 design changes is being revised from the end of the Unit i seventh refuehng outage to the end of the Unit 2 seventh refueling outage.  ;

However, seven (7) of the Unit 1 circuits listed above are scheduled to be modified 1 during the seventh refueling outage on Unit 1. The remaining four design changes (Unit 1 items 1, 3, 5, and 6 above) are currently scheduled to be installed in the period following the refueling outage.

Until these corrective actions are completed, the compensatory measures that were taken for the degraded voltage issue will remain in effect. Thus, extending the schedule for completing the Unit 1 design changes wiu not decrease reliabahty or safety I of the facility.

ATTACHMENTB Supplemental Response To inspection Report 50-373/91019; 50-374/91019 Unresolved item 373/91019-06; 374/91019 06 i Status of 480 VAC Eauloment Modifications l As indicated in reference 5, the degraded voltage concoms for the 480 VAC equipment (motors, heaters, battery chargers, etc.), except for the motor operated valves (MOV),

were resolved by initiating modifications to revise the 4160/480V transformer taps for the ESF Divisions 1 and 2 unit substations on both units to boost the secondary voltage by approximately 2.5% These modifications were compbted wding to the committed schedule (reference 5). No tap changes are required for the ESF Division 3 transformers, and no other design changes are required.

l The modifications that were required to resolve MOV voltage concems have been  !

completed and are identified under the GL 89-10 program. j l

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ATTACHMENT C Supplemental Response To inspection Report 50 373/91019;50-374/91019 Deviation 373/91019-05D and 374/91019-05D Lack of Dearaded Voltaos Setooint Methodoloav Backaround:

During the 1991 LaSalle Electrical Distribution System Functional inspection (EDSFI),

compensatory actions were taken to ensure adequate motor starting and running

voltages, and adequate voltage for the 120 Vac contactors to pick up, during a degraded voltage condition. These compensatory actions included a revised setpoint for the degraded voltage relays.

Summanr Prehminary setpoint calculations which address aN known instrument errors have been completed and indacate that the required lower analytical limit is 3814V. The cahbration setpoint was calculated to be approximately 3875V. These setpoint r=la d% are based on the installation of now, more accurate, undervoltage relays in the degraded voltage circuits in order to decrease the total instrument enor and improve the rehabihty of these circuits. The undervoltage relays on both units have been replaced in accordance with compensatory actions taken for the degraded voltage issue, the degraded voltage relays are currently cabbrated to trip at 3885V. Upon completion of the corrective actions required to close Unresolved item 373/9101906 and 374/91019-06, the setpoint for these relays will be revised as allowed by the setpoint =la daHans.

In reference 1 LaSalle County Station indicated that the schedule for finalizing the setpoint calculations and revising the degraded voltage setpoint is the same schedule that was provided for resolving this Unresolved item. Since the setpoint change can not be implemented until the degraded voltage trip setpoint and allowable value cpecified in the Technical Specifications are revised, LaSalle County Station is revising this commitment in the first refuehng outage following the approval of the Technical Specification amendment for revising the degraded voltage trip setpoint and allowable values. LaSalle County Station will need to update the voltage analysis deperWing on the performance of the voltage regulating transformer during the environmental quahfication testing. LaSalle plans to complete this analysis and submit the Technical Spec #i uon amendment by the end of first quarter 1997.

As indicated above, the final degraded voltage setpoint is not expected to be greater than the existmg cahbration setpoint, and the 120 VAC distnbubon circuit design changes described in Attachment A win be implemented prior to end of the Unit 2 seventh refuehng outage.

UntN these corrective actions are completed, the conpensatory measures win remain in effect, and completion of these schons win allow this Deviation to be closed.

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