ML20031F302
| ML20031F302 | |
| Person / Time | |
|---|---|
| Site: | Midland |
| Issue date: | 10/02/1981 |
| From: | Bailey K, Jackie Cook, Curtis L, Kononetz B CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, 14372, NUDOCS 8110190510 | |
| Download: ML20031F302 (5) | |
Text
A%6A6Mj O Power Consumers
^ ~ " "
ompany Vice ITesident - Projects, lingineering and Constrsection General offices: 1945 West Parnell Road, Jackson, Mi 49201 e (517) 788 0453 October 2,1981 Mr J G Keppler, Regional Director 03 Office of Inspection & Enforcenent S
{[
US Nuclear Regulatory Commission Region III II L
799 Boosevelt Road O.
OCTI 619813 clen Ellyn, IL 60137 7,
,dl s
p.
m=* mane MIDLAND FROJIET -
p DOCKET NOS 50-329 AND 50-330 EXCESSIVE VOLTAGE DROP DUE
/Q p
TO LONG CONTROL CABLES FILE 0.h.9.56, E-7 SERIAL 1h372 This letter is an interim 50.55(e) report concerning excessive voltage drop due to long control cables. This condition was reported September 11, 1981 to Mr C Jones of US HEC Region III. provides a descripticn of the condition and the status of the planned corrective actions.
Another report, either interim or final, vill be sent on or before February 12, 1982.
WEB /Jn Attachment (1) Bechtel ?* CAR 53, Interim Report 1, " Excessive AC Motor Starter Control Voltage Drop."
CC Director, Office of Inspection & Enforcement phN Att Mr Victor Stello, US NRC (15)
Director, Office of Management Information & Program Control, US NRC (1) l P J Cook, US NRC Resident Inspector Midland Nuclear Plant (1) 0110190510 811002 PDR ADOCK 05000329 g 199 sS PDR MCT
4 a
Serial 14372 2
i i
CC CBechhoefer, ASLB Panel RSDecker, ASLB Panel FICowan, ASLB Panel AS&L Appeal Panel
?GiCherry, Esq
!Cinclair BStamiris t
CRStephens, US NRC WDPaton, Esq, US IEC FJKelly, Esq, Attorney General i
SHFreenan, Esq, Asst Attorney General WHMarshall GJMerritt, Esq, THK&J Great Lt.kea QA Managers l
I i
l S
l i
l i
l l
i t
i l-l l
l, 1
l -.--.,.---.:.~..-.-.-....--.
s o
o S
043475 Sabject:
MCAR 53 (issued 9/14/81) 04350a-Excessive AC Motor Starter Control Voltage Drop Interim Report 1 Date:
i i
t Project:
Consumers Power Company Midland Plant Units 1 and 2 l
Bechtel Job 7220
References:
A)
Bechtel TP0 Problem Alert, AC Motor Startec Control Circuit Undervoltage 7220-E-80-5, 12/17/80 B)
CPCo Safety Concern and Reportability Evaluation No. 13, 3/25f81 C)
Midland Electrical Calculation QPE-17(Q)
Rev 0, Motor Starter Control Circuit Sizing, 9/2/81 Introduction This report provides interim status and the course of corrective action required purr.Jant to MCAR 53.
Description of Potential Deficiency As a result of Reference A and B an investigation was conducted to determine the effect on motor starter coil pickup at minimum motor control center (MCC) buss voltage with the existing Midland plant control circuit design.
The voltagem across the coils of motor starters during energization have been calculated assuming minimum utilization voltage on the MCC buss (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.
i
O O
043475 043505 Page 2 Corrective Action 1)
A preliminary list of control circuits which potentially could experience excessive voltage drop has been generated and is currently undergoing final review. Each circuit affected will be individually evaluated to determine the appropriate corrective action based on actual circuit length, transformer loading, and Reference C.
The corrective action will consist of one or more of the following:
a)
Install higher volt-ampere rated control power transformer.
b)
Revise control cable routing to achieve shorter lengths.
c)
Increase control cable size.
d)
Install interposing relay in control circuit.
e)
Perform testing to verify control circuit adequacy.
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 calculation will be used as a referenced design requirement for control circuit design and cable routing. In addition, a Safety Analysis Report (SAR) change notice will be issued to state that control circuit lengths are evaluated to prevent excessive voltage drop.
Safety Implications Based upon a review of actual circuit design and Reference C it was found that some of the motor starters for Class 1E equipment may fail to pick up under anticipated plant conditions. The net result could be the failure of Class IE equipment of redundant safety groups to perform its intended function.
Forecast Date on Corrective Action 1)
A final list of control circuits with excessive voltage drop and the corrective action for each is scheduled to be completed by December 31, 1981.
o o
043505 043475
- ch=*"t Page 3 2)
The electrical calculation for motor starter control circuit sizing was issued on September 2, 1981.
3)
A SAR change notice will be issued by October 2, 1981.
Submitted by:
).P.TKononetz
([i Electrical Group Supervisor Approved by:
t c,/
.H.
Curtis Project g
r Concurrence by:
)
Ar K.D Bailey Engineering /Ma r
l l
_ _ _ _ _ - _ _ _