ML17199V022
| ML17199V022 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 08/31/1981 |
| From: | COMMONWEALTH EDISON CO. |
| To: | |
| References | |
| DOA-6900-1, NUDOCS 8804010209 | |
| Download: ML17199V022 (3) | |
Text
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DC ELECTRICAL SYSTEMS' FAILURE A.
SYMPTOMS
- 1.
DC Bus Feed Air Circuit Breaker tripped.*
DOA 6900-1 Revision 2 August 1 981,
- 2.
Battery charger experiences circuit failure or trips.
- 3.
Battery ground is detected.
- 4.
Inability to operate DC powered equipment.
- 5.
Loss of indicating lights to DC powered equipment.
- 6.
DC Annunciator Power Failure Alarms on Panel 902(3)-5.
- 7.
Loss of Source Range Monitor (SRM) and Intermediate Range Monitor (IRM) channels.
- 8.
Loss of DC to the Off-Gas Monitor, the Radwaste Dis-charge Monitor, the Stack Gas Monitor and the Process Radiation Monitor [12E2487, 88 and 89 (12E3487, 88 and 89)].
B.
AUTOMATIC ACTIONS Loss of 125vDC could cause a turbine *trip and a possible reactor scram.
C~
IMMEDIATE OPERATOR ACTIONS Dispatch an Equipment Operator to the affected battery, bus or DC equipment.
D.
SUBSEQUENT OPERATOR ACTIONS
- 1.
Isolate the failed equipment as necessary.
- 2.
If there is a need to locate a ground refer to:
250 Volt Ground Detection Unit 2, DOP 6900-4, 250 Volt Ground Detection Unit 3, DOP 6900-5, 125 Volt Ground Detection Unit 2, DOP 6900-6 or 125 Volt Ground Detection Unit 3, DOP 6900-7 *
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DOA 6900-1 Revision 2
- 3.
CHECK that the electrical feeds. to the appropriate battery chargers are CLOSED.
Electrical feeds are as follows:
24/48v Charger 2(3)A Instrument Bus 24/48v Charger 2(3)B Instrument Bus 125v Charger 2(3)
MCC 29-2(39-2) 125v Charger 2(3)A MCC 28-2(38-2) 250v Charger 2 ( 3)
MCC 28-2(38-2) 250v Charger 2/3 MCC 29-2 or 39-2
- 4.
If the battery charger in service fails, shift to the appropriate alternate charger.
- 5.
In the event of a battery failure, isolate the battery and use the appropriate battery charger to supply the DC loads.
- 6.
If disconnect links can be shifted to supply the bus from an alternate feed, consider shifting the disconnect links.
- 7.
Refer to Section 3.9 of the Technical Specifications.
E.
DISCUSSION
~;
Much of the equii:rnent supplied by the DC Systems is safety-related or reliability-related equipmen~.
The Reactor Building 250vDC Buses supply power to the High Pressure Coolant Injection (HPCI) Valves and the auxiliary equipment.
The Turbine Building 250vDC Buses supply such essential equipment as the Turbine Emergency Bearing Oil Pumps, the Generator Emergency Hydrogen Sea 1 Oil Pump, the Essential Service M.G. DC Drive Motor, the Fire Pump Dis-charge Valve and the Recirculation M.G. Coast Down Lube Qi 1 Pump.
The 125vDC System supplies control power to all 4Kv breakers in the plant.
4Kv breakers would fa i1 11as i s 11 and would have to be operated manually.
Since the Emergency Core Cooling System (ECCS) logic is 125vDC and energized to function, all ECC Systems would be disabled.
ECC Systems would not start
. automatically and could not be started manually from the Con-trol Room.
The Automatic Depressurization System logic is also 125vDC and therefore would not function to control the reactor pressure.
The Diesel Generators would not start auto-matically.nor could they be started manually by the Operator.
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2 of 3 APPROVED AUG24 '81 0.0.S.R.
DOA 6900-1 Revision 2 The 24/48vOC System supplies the IRM channels, the SRM channels,
.the Stack Gas Monitor, the Radwaste Discharge Monitor, the Off-Gas Monitor, the Process Radiation Monitors and an alternate for the Off-Gas Radiation Monitor.
F.
REFERENCES
- 1.
GEK Manual 786, Chapter 10 Electrical Systems.
- 2.
Section 3.9 of the Technical Specifications.
- 3.
Electrical blueprints.
- a.
12E2321(12E3321}, 250vDC Motor Control Center.
- b.
12E2322(12E3322}, 125vDC Distribution.
- c.
12E2324(12E3324}, 48/24vOC Distribution for Neutron Monitoring.
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