EW-Essential Cooling Water System Flashcards
What is the purpose of the Essential Cooling Water system?
1 Xfr residual heat from RCS to atmosphere
2 Xfr environment heat from essential chiller to atmosphere via the SP
3 Xfr decay heat from SFP to atmosphere via the SP, when NC unavail.
4 Xfr heat from containment to atmosphere via SP
5 Xfr NC heat norm removed by NC system to atmosphere via SP when NC unavail.
What is the design of the Essential Cooling Water system?
2 independent trains, closed loop, either train can support 100% of the cooling for safe shutdown.
Major components: surge tank, EW pump, Heat loads, EWHX, Chem add tank.
What is the normal flow path of the Essential Cooling Water system?
EW Pump discharges to both Essential chiller and SDCHX->Shell side of the EWHX xfr heat to SP-> back to suction of the pump.
What is the flow path for Esscential Cooling water when it is cross connected to the NC system?
Usually A train to A train via crosstie. This means you must have B train EW operable to remain in tech specs.
What is the difference between ‘A’ train and ‘B’ train Essential Cooling water valves?
‘A’ has motor operatedisolation valves while ‘B’ has manually operated isolation valves.
What powers Essential Cooling Water system pumps, valves, and instrumentation?
PB-powers the pump
PH-powers EW to NC Train ‘A’ crosstie valves
PK-Powers surge tank solenoid valves
PN-Powers system instrumentation
How does the Chemical Waste System (CM) interact with the Essential Cooling Water system?
CM is a backup makeup water supply to the EW system from the Cooling Water Holdup Tank.
Cooling Water HUT in CM receives EW when EW surge tank overpress valves lifts
or out the EW surge tank drain valve.
The EWHX rooms have floor drain to the Cooling Water HUT.
How does the Essential Chilled Water System (EC) interact with the Essential Cooling Water system?
EW removes heat from the Essential Chiller in the EC system.
EC provides chilled water to the EW pump room ACU.
How does the SAfety Equipment Status System (ES) interact with the Essential Cooling Water system?
EW provides output signals to the ES system which monitors & alerts the CR of safety equipment inoperable status and/or safety equipment actuation status.
How does the Oily Waste (OW) system interact with the Essential Cooling Water system?
The EWHX tube side (SP) press relief valve goes to floor drain that is routed to Control Bldg sump. Drains have plugs normally installed. During outage plug removed for draining the SP side of he EWHX to the cntrl bldg sumps.
How does the Nuclear Cooling Water System (NC) interact with the Essential Cooling Water System?
EW can be cross-tie to the NC system to provide backup cooling for NC if NC unavail.
EW can be cross-tie to NC to provide colling to the PC Cooling HX.
Normally in outage. Designed to be done w/i 8 hrs of a loss of NC.
How does the Fuel Pool Cooling and Cleanup System (PC) interact with the Essential Cooling Water System?
EW removes hat from the PC system during LOOP or when norm cooling water from NC is unavail.
During outage EW used to cool one of the PC cooling HX.
How does a Engineered Safety Feature Actuation System (SA) interact with the Essential Cooling Water System?
‘A’ train MOV cross-ties recieve a closed signal upon a SIAS.
EW pumps are started on a SA signal (LOP/Load Shed stops pumps, Load Sequencer starts pumps.)
How does the Safety Injection System (SI) interact with the Essential Cooling Water System?
EW supplies cooling water to the SDCHX to remove RC core decay heat during cooldown and cold shutdown.
Also cools CS during an accident.
How does Radiation Monitoring system (SQ) interact with the Essential Cooling Water System?
SQ provides non-safety related radiation monitoring to the EW system. One radiation monitor by each EW pump to monitor trains for gamma activity.
How does the BOP Analog Instument System (ZJ) Remote Shutdown Panel?
Provide op ofr EW Pump during time when the CR is offline. Panel has ‘B’ train disconnect swiches to separtate the B Remote shutdown panel from the CR.
What is the purpose of the Essential Cooling Water Pumps?
Supply water to the EW system components at the required flow rates.
What is the design of the Essential Cooling Water Pumps?
Horizontal, CP, Single stage, double suction, rated flow 16,650 gpm, powered by Class PB 4.16 kV.
Takes suction from its dedicated surge tank directing flow to their respective EW heat loads. Normally locked open manual valves at suction and discharge for isolation.
What are the automatic features associated with the Essential Cooling Water Pumps?
Pumps will auto-start on:
LOP to PBA/PBB, CSAS, SIAS, CREFAS, CRVIAS, or AFAS 1 & 2.
Pump motors have over-current ground fault protection trips (86 lockout)
EW pump start will start associated EW pump room ACU cooled by Essential Chilled Water (EC).
What is the purpose of the Essential Cooling Water Heat Exchangers?
Transfer heat gained from the EW system loads to the Spray Pond system.
What is the design of the Essential Cooling Water Heat Exchangers?
1 for each train, single pass, shell and tube, SP in tubes and EW in shell. EW outlet temp should be <135*F
What is the danger of a leak in the Essential Cooling Water Heat Exchanger?
Radioactive fluid will escape into the SP system and spread contamination.
What is the purpose of the Essential Cooling Water Surge Tanks?
Accommodate closed loop system expansion and contraction and ensure adequate NPSH for the EW pump.
What is the design of the Essential Cooling Water Surge Tanks?
Upstream of pump suction, 1000 gal, rated to 15 psig, connection for makeup water, overpressure/ underpressure, nitrogen gas addition, and level and pressure indications.
What are the sources of makeup water for the Essential Cooling Water system?
Normal source-Demineralized Water
Primary backup-Condensate Storage and Transfer system
Secondary backup-Cooling Water HUT in Chemical Waste system
Emergency-Fire Protection Header
What maintains the level of the Essential Cooling Water surge tank?
Level is maintained based on the state of the system. Level set point can be changed as needed. On a Lo-Lo 14” signal the makeup valve will auto close so we don’t keep feeding a leak.
What does Nitrogen do in the Essential Cooling Water surge tank?
Prevents oxygen intrusion that could lead to corrosion.
What would cause the ‘A’ train cross-tie valve in the Essential Cooling Water system to close when tied to Nuclear Cooling water?
EW ‘A’ Surge Tank Lo Level 17”
SIAS
What is the purpose of the Essential Cooling Water Chemical Addition Tanks?
Provide a place for the addition of corrosion inhibiting chemicals into the EW system.