ML20059L159
| ML20059L159 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 01/27/1994 |
| From: | Benes G COMMONWEALTH EDISON CO. |
| To: | Murley T Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 9402030249 | |
| Download: ML20059L159 (5) | |
Text
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/ Dowoors Grove.14nos 60516 January 27,1994 Dr. Thomas E. Murley, Director Office of Nuclear Iteactor llegulation U.S. Nuclear llegulatory Commission Washington, D.C. 20555 Attn: Document Control Desk
Subject:
LaSalle County Station, Units 1 and 2 Supplemental Itesponse to EDSFI Unresolved Item 373/91019 06 and 374/91019-06 for 4160 Volt Degraded Voltage Nltlkn:keLNos. 59-alaanulE0aB lteferences:
(1)
T.J. Kovach letter to USNRC dated January 16,1992, transmitting response to EDSFI report.
(2)
T.J. Kovach letter to USNItC dated April 30,1992, transmitting supplemental response to the subject unresolved it em.
(3)
T.O. Martin (USNItC) letter to L.O. DelGeorge dated March 12,1993, transmitting 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) transmitGng supplemental response to the subject unresolved item.
Dear Dr. Murley:
In Reference 4 we provided a description of the modifications that were implemented for resolving the ESF Division 3 motor contrtd circuits with inadequate contactor voltages. We also indicated that we would provide another supplemental response after the end of the Unit 2 fifth refueling outage to identify the corrective actions for the 120 VAC distribution circuits with voltage concerns.
Attachment A identifies the 120 VAC distribution circuits with voltage concerns and the proposed corrective actions. The status of the degraded voltage modifications fbr the motor control circuits and 480 VAC equipment are summarized in Attachments B and C fbr your information.
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4 To the best of my knowledge and belief, the ' statements contained above are '
true and correct.- In some respect these statements are not based on my personal-
[
knowledge, but obtained information furnished by other Commonwealth Edison employees, contractor employees, and consultants. Such information has been i
reviewed in accordance with company practice, and I believe it to be reliable.
Please direct any questions you may have concerning this submittal to this i
office.
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Sincerely,
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Gary G. Benes Nuclear Licensing' Administrator Attachments l
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cc:
J. B. Martin, Regional Administrator - RIII D. L. Ilills, Senior Resident Inspector - LSCS A. T. Gody, Jr., Project Manager, NRR Office of Nuclear Facility Safety - IDNS
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l ATTACHMENT A
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Supplemental Response To Inspection Report l
50-373/91019; 50-374/91019 j
Unresolved Item 373/91019-06; 374/91019 d 120 VAC Distribution Circuit Modifications 1
i The voltage calculations for the 120 VAC distribution circuits have been completed, and-2i these calculations indicate that all of these circuits have adequate voltages to perform '
their safety-related function following an accident under the compensatory measures j
taken by tho station in response to the degraded voltage issue. These compensatory measures are described in detail in Reference 1.. However, the following 120 VAC) distribution circuits were determined to have inadequate voltage at the-degraded.
M voltage setpoint of 3814V:
Unit 1:
1.
MCC 135X-1, ekt #5 - Post Accident Primary Containment Monitoring 2.
MCC 135X-3, ekt #15 - Leak Detection 1
3.
MCC 136X-1, ekt #5 - Post Accident Primary Containment Monitoring.
J 4.
MCC 136X-1, ekt #19 - SBGT Flow Control Damper IVG002 Ji 5.
MCC 136X-1, ekt #36 - Control Room HVAC i
6.
MCC 136X-2, ekt #5 - Process Radiation.
t 7.
MCC 136X-2, ekt #17 - Switchgear Heat Removal 8.
MCC 136X-2, ekt #25 - Nuclear Boiler Process Instrumentation -
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MCC 136X-3, ckt #7 - Leak Detection i
Unit 2:
i 1.
MCC 235X-2, ekt #18 - Containment Monitoring 2.
MCC 235X-3, ekt #15 - Leak Detection 3.
MCC 235Y-1, ekt #16 - RHR Service Water Cubicle Vent Dampers 4.
MCC 236X-1, ekt #5 - Post Accident Primary Containment Monitoring 5.
MCC 236X-1, ekt #13 - SBGT Flow Control Damper 2VG002 6.
MCC 236X-1, ekt #36 - Control Room HVAC 7.
MCC 236X-2, ekt #32 - Containment Monitoring 8.
MCC 23GX-3, ekt #19 - Leak Detection j
The voltage problems for the above circuits will be resolved by either (1) implementing
. modifications to increase the voltage in these circuits or (2) replacing and/or testing the
.l problem circuit components to reduce the minimum required voltage. These corrective actions are scheduled to be implemented on each unit following the resputive seventh-
.i refueling outage. These refueling outages are currently scheduled for fall,1995, and fall,1996, for units 1 and 2, respectively. Until these corrective actions are completed, the compensatory measures that were taken for the degraded voltage issue will remain in effect.
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1 ATTACHMENT B
' Supplemental Response To Inspection Report 50-373/91019; 50-374/91019 3
Unresolved Item 373/91019-06; 374/91019-06 Slatus of the Mntor Control Circuit Modifications In our pr 'ious responses to the Electrical Distribution System Functional Inspection l
- (EDSFI).. LaSalle County Station, we indicated that the nine motor control circuits j
on each unit had inadequate voltage at the contactor to pickup at the original degraded-1 voltage setpoint of 3814 +/- 76 volts.' The equipment associated with these circuits are i
identified below:
1.
RHR Suction Cooling Inboard Isolation Valve,1(2)E12-F009 l
2.
Control Room HVAC Emergency Make-Up Air Filter Heater, OVC01AA(0VC01AB) 3.
Control Room HVAC Emergency Make-Up Air Filter Fan,0VC03CA(0VC03CB).
4.
Control Room HVAC Return Fan, OVC02CA(0VC02CB) 5.
HPCS Diesel Generator Cooling Water Pump,1(2)E22-C002 6.
HPCS Pump Discharge Valve,1(2)E22-F004 i
7.
HPCS Diesel Generator Room Vent Fan,1(2)VD01C' 8.
HPCS Switchgear Room Exhaust Fan,1(2)VD07C 9.
HPCS Cubicle Cooler Fan,1(2)VY02C D
The first four circuits identified above are associated with ESF Division 2, and remaining circuits are associated with ESF Division 3. No modifications were required 1
for any ESF Division 1 motor control circuits.
The modifications for the ESF Division 2 circuits consisted of adding an interposing-relay between the contactor coil and control circuit. This action significantly reduced _
the conductor length and thus, the voltage drop, between the contactor coil and power
.j supply. The contactors were not replaced for these modifications.
l The modifications for the ESF Division 3 circuits consisted of adding an interposing.
relay between the contactor coil and control circuit and replacing the existing 120 VAC 1
coil in the contactor with a coil rated at 460 VAC +/- 10% Reference 4 provides l
additional details for these modifications.
The motor control circuit modifications for both units were completed prior to startup
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following the Unit 2 fifth refueling outage.
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i Supplemental Response To Inspection Report 50-373/91019; 50-374/91019 Unresolved Item 373/91019-06; 374/91019-06 1
Status of 480 VAC Equipment Modifications I
- j To resolve the voltage concerns fbr the 480 VAC equipment'(motors, heaters, battery; chargers, etc.) with inadequate terminal voltages at the original degraded voltage y
setpoint of 3814 volts except for the motor operated valves (MOV), the followmg
>t corrective actions were taken:
1.
Modifications were initiated to revise the 4160/480V transfbrmer taps for the ESF '
Divisions 1 and 2 unit. substations on both units to boost the secondary voltage by~
l approximately 2.5%. No tap changes are required for the ESF Division 3
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transformers.
' 2.
If the transformer tap change modifications did not increase the starting and/or J
running voltage above the acceptance criteria used in the calculations, either the original equipment vendors were contacted to obtain the actual minimum starting and running voltage requirements or an analysis was performed to' determine tlm l minimum voltage requirement. The low voltage concerns with the motors and L battery chargers were only resolved by obtaining the minimum voltage -
requirements from the vendor; the voltage concerns with the hcaters were resolved..
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j by both methods. 'If no vendor data was available, the acceptance criteria used in 1
the calculations for minimum allowable terminal voltage for motors was'90% of rated fbr running and 85% of rated for starting. ' For battery chargers and heaters 1 3
the minimum allowable terminal voltage was 90% of rated.
q Item 2 has been completed.' The ESF Division 2 transformer tap changes were completed on both units during their last respective refueling outages, and the..
engineering for the ESF Division 1 transfbrmer tap changes was completed in June, 1993. The ESF Division 1 transformer tap changes are scheduled to be implemented' on each unit during their next respective refueling outage.
The modifications that are required to resolve the MOV voltage concerns are being identified and tracked under the GL 89-10 program.
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