ML20041B291
| ML20041B291 | |
| Person / Time | |
|---|---|
| Site: | Midland |
| Issue date: | 02/12/1982 |
| From: | Jackie Cook CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, 14681, 81-07-#2, 81-7, 81-7-#2, NUDOCS 8202230497 | |
| Download: ML20041B291 (4) | |
Text
_. _ _ _ _ _ _ _ _ _ _ _ _ _ _ - _ _ _. _ _ _ _ _. _ _ _ _ _.. _ _ _ _ _ _.,
Consumers power James W Cook OhfOf Vice President - Projects, Engineering and Construction General officos: 1945 West Parnali Road, Jackson, MI 49201 e (517) 788-0453 February 12, 1982 81-07 #2 Mr J G Keppler, Regional Administrator US Nuclear Regulatory Commission Region III 799 Roosevelt Road Glen Ellyn, IL 60137 4
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MIDLAND PROJECT -
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DOCKET HOS 50-329 AND 50-330 3
EXCESSIVE VOLTAGE DROP DUE g
FEB 22 7982b'd T
t D N 6Jvr g TO LONG CONTROL CABLES FILE:
0.4.9 56, E,7 SERIAL:
1h681 hfM-
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Reference:
J W Cook letter to J G Keppler, Same Sabject,
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'M \\ p dated October 2, 1982 The referenced letter was an interim 50.55(e) report concerning excessive voltage drop due to long control cables. This letter is the final 50.55(e) report on this subject.
l provides a description of the condition and the actions which have been taken to correct the deficiency.
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WRB/lr : Bechtel MCAR 53, Final Report, " Excessive AC Motor Starter Control Voltage Drop," dated January 25, 1982 CC:
Document Control Desk, NRC Washington, DC (1)
RJCook, NRC Resident Inspector Midland Nuclear Plent (1) b e20223o497 a20212 FEB I 7 1982
/ f PDR ADOCK 05000329 S
c.
Serial 1h681 2
81-07 #2 CC: CBechhoefer, ASLB Panel RSDecker, ASLB Panel FPCowan, ASLB Panel
.JHarbour, ASLB Panel AS&L Appeal Panel IG1 Cherry, Esq MSinclair BStamiris CBStephens, USNRC WDPaton, Esq, USNBC FJKelley, Esq, Attorney General SHFreeman, Esq, Asst Attorney General WHMarshall GJMerritt, Esq, TNK&J
05668"7
' Serial lh681 81-07 #2
Subject:
MCAR 53 (issued 9/14/81) 6559 Excessive AC Motor Starter Control Voltage Drop Final Report Date:
January 25, 1982 Project:
Consumers Power Company Midland Plant Units 1 and 2 Bechtel Job 7220
References:
A)
Bechtel TP0 Problem Alert, AC Motor Starter Control Circuit Undervoltage 7220-E-80-5, 12/17/80 B)
CPCo Safety Concern and Reportability Evaluation No. 13, 3/25/81 C)
Midland Electrical Calculation QPE-17(Q)
Rev 0, Motor Starter Control Circuit Sizing, 9/2/81 Introduction This report provides final status of Bechtel action pursuant to MCAR 53.
Description of Deficiency As a result of Reference A and B an investigation was conducted to determine whe ef fect on motor starter coil pickup at minimum motor control center (MCC) buss voltage with the existing Midland plant control circuit design.
The voltages across the coils of entor starters during energization have been calculated assuming minimum utilization voltage on the MCC bus (Reference C).
The results indicate, for certain control circuits, a voltage potentially below the limits for proper operation of the MCC starter coils as specified by the equipment supplier. The line voltage drop is a direct result of coil inrush currents passing through long control circuits.
Probable Cause The deficiency is a result of a lack of a design requirement to establish maximum control circuit lengths for given loads, and conductor and starter size.
L56682 Attachment Page 2 056559 Corrective Action 1)
A finalized list of control circuits which potentially could experience excessive voltage drop has been generated. Each Class 1E circuit affected has been evaluated and the design changes for implementing the planned corrective action have been completed.
The design changes consisted of one or more of the following:
a)
Installation of higher volt-ampere rated control power trans-former.
b)
Revised control cable routing, achieving shortened lengths.
c)
Installation of an interposing relay in the control circuit.
2)
As corrective action to preclude reoccurrence, a calculation has been issued for the purpose of identifying maximum allowable-control circuit lengths for specific starter sizes. This cal-culation is used as a referenced design requirement for control circuit design and cable routing.
3)
In addition, a Safety Analysis Report (SAR) change notice has been issued stating that control circuit lengths are evaluated to prevent excessive voltage drop.
Safety Implications Based upon a review of actual circuit design and Feference C it was found that some of the motor starters for Class 1E equipment may have failed to pick up under anticipated plant conditions. The net result could have been the failure of Class 1E equipment of redundant safety groups to perform its intended function.
Based on the possible safety implication, this discrepancy has been reported in accordance with the Code of Federal Regulations, Part 50.55(e).
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Submitted by:
N B.T. Kononetz y
Electrical Grou Supervisor Approved by:
mb%
E.M. Hughes\\
Ann Arb Proje
- eer, Concurrence by:
K.D.
ey Engineering /Mana M.A. Dietrich PQAE