Flashcards in DC Distribution Deck (33):
List the battery capacity of the following battery systems:
1. 125/250VDC Station (each division)
2. 24/48VDC Station (each division)
3. 125VDC Caswell Beach Station
1. 1200AH (150A for 8 hours)
2. 600AH (75A for 8 hours)
3. 200AH (20A for 10 hours)
Describe what battery voltage indication on the RTGB is monitoring under various conditions.
1. Charger Output Voltage: Charger has AC input.
2. Battery Bus Voltage: Loss of charger AC input (loss of charger), but charger output breaker shut.
3. Zero Volts: Charger has no AC input and output breaker is open.
State the nominal voltage range for Battery Charger Output.
Which battery chargers have an alternate AC power source?
B-Bus chargers have an ASSD power supply for U1 (1XB) and U2 (2XD).
State the battery charger output undervoltage alarm.
State the Float Charge voltage setpoint.
State the Equalize Charge voltage setpoint.
List the power supplies to the U1 battery chargers.
1A-1: 1CA (E5 - Div 1)
1A-2: 1CA (E5 - Div 1)
1B-1: 1CB (E6 - Div 2) / 1XB (E6 - Div 2)
1B-2: 1CB (E6 - Div 2) / 1XB (E6 - Div 2)
List the power supplies to the U2 battery chargers
2A-1: 2CA (E7 - Div 1)
2A-2: 2CA (E7 - Div 1)
2B-1: 2CB (E8 - Div 2) / 2XD (E8 - Div 2)
2B-2: 2CB (E8 - Div 2) / 2XD (E8 - Div 2)
250 VDC Major Loads
HPCI MOV's (1XDA/2XDA)
RCIC MOV's (1XDB/2XDB)
Outboard Containment MOV's
DC Oil Pumps
125 VDC Major Loads
4160 VAC / 480 VAC Breaker Control
EDG Start/Stop/Run Controls
ECCS System Initiation Logic / Annunciators
RPC / ECCS Trip Cabinets
ESS Logic Cabinets
Switchyard Control Power
With a loss of the associated battery charger, what is the minimum battery voltage? What action(s) should be taken when this voltage is reached and why?
Open battery breakers to prevent cell reversal (damage).
State whether the 125/250 VDC subsystem is grounded or not and the basis for this design feature.
Ungrounded - The system can sustain one solid ground fault and still meet all requirements for continued safe operation.
Describe the basic operation of the 125/250 VDC subsystem ground detector.
Utilizes current detection devices that monitor for current flow from either the P or N bus to ground. No current flow means no ground. Current flow results from degradation of electrical insulation in the system.
The ground detector automatically switches connection to the P and N buses every 15 seconds. When connected to the P bus, it is monitoring for grounds on the N bus and vice versa.
At what magnitude of grounds on 125/250 VDC subsystem will a control room annunciator be received?
When mA current corresponding to an insulation resistance of 25 kohm or less. This annunciator is also received on loss of power to the ground detector.
How is the grounded bus determined?
mA reading of the N and P buses compared. If P > N, the N bus is grounded. If N > P, the P bus is grounded. If the mA readings are approximately equal, the ground is on the PN bus.
Describe when Action Level 0 is reached and monitoring/actions for ground correction.
Ground resistance is greater than or equal to 25 kOhms. No action required if ground detector alarms are operable. If not operable, take ground readings once per shift.
Describe when Action Level 1 is reached and monitoring/actions for ground correction.
Ground resistance is between 15 kOhms and 25 kOhms. At ground levels <25 kOhms, situations could develop that might hold in a normally energized relay (0AI-115, 5.2.3).
Commence ground isolation and take ground readings once per shift.
Priority 3 Ground Hunting: Ground hunt 8hrs / day, 5 days / week. If not corrected within 14 days, enter Action Level 2.
Describe when Action Level 2 is reached and monitoring/actions for ground correction.
Ground resistance is less than or equal to 15 kOhms. At ground levels <15 kOhms, sufficient currents develop which could result in holding in a normally energized relay, dropping a normally energized relay or picking up a de-energized relay (0AI-115, 5.2.4)
Take ground readings twice per shift.
Priority 2 Ground Hunting: Ground hunt 24hrs / day, 7 days/week.
State the purposes of the battery room ventilation system.
Remove Hydrogen gas generated during charging operations (primarily an Equalize charge) and to control room temperature/cleanliness.
State the minimum battery room temperature for battery design requirements.
Describe the method of temperature control for battery rooms.
Inlet and outlet vortex dampers are maintained in a minimum position until temperature reaches 72F. This minimum position ensures enough airflow for Hydrogen control.
Temperature above 72F causes vortex dampers to move from minimum.
For decreasing temperatures, first stage strip heaters in the supply air duct energize at 67F. A second stage energizes at 66F.
State the power supplies to the battery room fans.
Powered by same division 480 VAC.
1A - 1CA
1B - 1CB
2A - 2CA
2B - 2CB
State the sources of Control Power to the EDG's.
EDG #1: 1A/2A
EDG #2: 1B/2B
EDG #3: 2A/1A
EDG #4: 2B/1B
Describe the effect on EDG's from a Loss of DC.
Loss of an EDG's associated control power supply removes start/stop/run capability of that EDG. If the EDG is running, it will trip. If not running, it will not be able to start. Alternate control power supply must be manually selected at the EDG excitation cabinet.
State LCO 3.8.4 "DC Sources - Operating" and its Applicability.
The following DC electrical power subsystems shall be OPERABLE:
a. Unit 2 Division I and Division II DC electrical power subsystems; and
b. Unit 1 Division I and Division II DC electrical power subsystems.
Applicable in MODES 1, 2, and 3.
State LCO 3.8.5 "DC Sources - Shutdown" and its Applicability.
One Unit 2 DC electrical power subsystem shall be OPERABLE.
Applicable in MODES 4 and 5, during movement of irradiated fuel assemblies in the secondary containment.
Note: LCO 3.0.3 is not applicable.
List REQUIRED ACTIONS and COMPLETION TIMES when LCO 3.8.5 "DC Sources - Shutdown" is not met.
CONDITION A: One required DC electrical power subsystem inoperable.
A.1 - Declare affected required feature(s) inoperable (Immediately)
A.2.1 - Suspend CORE ALTERATIONS (Immediately)
A.2.2 - Suspend movement of irradiated fuel assemblies in the secondary containment (Immediately)
A.2.3 - Initiate action to suspend operations with a potential for draining the reactor vessel (Immediately)
A.2.4 - Initiate action to restore required DC electrical power subsystems to OPERABLE status (Immediately)
State LCO 3.8.6 "Battery Cell Parameters" and its Applicability.
Battery cell parameters for the Unit 2 Division I and II batteries and the Unit 1 Division I and II batteries shall be within the limits of Table 3.8.6-1.
Battery cell average electrolyte temperature for the Unit 2 Division I and II batteries and the Unit 1 Division I and II batteries shall be within the required limits.
APPLICABILITY: When associated DC electrical power subsystems are required to be OPERABLE.
Define "DC Electrical Power Subsystem" per TS B3.8.4/B3.8.5.
Each Unit Division: Two 125VDC batteries, two battery chargers, and corresponding control equipment and interconnecting cabling supplying power to the associated bus.
State the battery voltage requirement to meet LCO 3.8.4.
Battery terminal voltage must be greater than or equal to 130 VDC while on a float charge, and must be verified at a FREQUENCY of 7 days.
State the required battery electrolyte temperature IAW LCO 3.8.6 "Battery Cell Parameters" Surveillance Requirements.
Average electrolyte temperature of representative cells is greater than or equal to 60F.