DS/DW- Domestic/Demineralized Water Flashcards
What is the purpose of the DW system?
Provides continuous and sufficient supply of demineralized and degasified water to several systems and services
What is the purpose of the DS system?
Supplies potable water within the Power Block for human consumption, eye wash stations, and for other general uses
DW supplies makeup water to which Surge tanks?
Diesel Generator, Essential chilled water, Essential Cooling water, Turbine Cooling Water, Nuclear Cooling water, normal chilled water
What other tanks does DW provide makeup water to?
RMWT, CST, Stator Cooling Coolant Tank
How can DW support CD during a startup?
Can supply water to the Condensate Service Header
Which systems receive seal water from DW? What from DS?
Control building OW sumps and RD
DG sump pumps
How does DS system support ED system?
ED system receives blowdown stack quench water from the DS system
How does DS system support FP system?
FP system receives makeup water from DS
Why is a nitrogen cover gas maintained in the DWST?
To ensure the water remains free of oxygen during storage
What would trip the Demineralized Water Transfer Pumps? What happens when the level is restored?
Low-low level switch provided on the tank, electrical overload
pump auto restarts
What is the status of the Demineralized Water Transfer Pumps under normal operations? What pressure starts the standby DW transfer pump?
One pump (100% capacity) is continuously operating to pressurize the demineralized water supply header with the second pump operated as required by demand as sensed by a low discharge header pressure
96 psig, alarm at 91psig
Where is the control switch for the Demineralized Water Transfer Pumps? Where are the pumps located?
Control Room
south side of the DWST, north yard
How could we get DW if the Transfer Pumps or the Demineralized Water Storage tanks are unavailable?
Can be supplied directly from the Water Reclamation Demineralized Water header via a tank bypass and a valve
What is the purpose of the backflow preventer assembly and what does it consist of?
Designed to prevent any backflow per the Uniform Plumbing Code
Each BPA contains two spring-closed check valves, with a third spring-loaded check valve, which opens to the atmosphere upon a loss of line pressure
Any backflow is vented to atmosphere
Where are the pressure control valves and BPAs located?
North side of 74’ Control Building
What is the storage capacity of the DW storage tanks at each unit and one surge rinse tank at water resources?
125,000 each
1 at each unit and 1 at WR
What system powers the DW transfer pumps, motor space heaters and local instrument panel?
NH
What is the purpose of the demin water booster pumps at WR?
three centrifugal pumps
one of the three is operating continuously to pressurize the common pipeline to the PVGS units, other two in standby
How are the DWST at each unit filled? What is the level band? How is flow monitored?
receives water from water resources supply header and is automatically filled via local level control valve
13’3”-21’5”
flow transmitter in the supply line
Where does the DWST overflow to?
local drain directed to the yard area sump
S-loop in the overflow line to prevent nitrogen leaking through the overflow line with a constant flow from a portion of the recirc header of the transfer pumps to maintain the seal
What alarms are provided by the local instrument panel for the DWST to the control room?
high level, low level, low-low level alarms
Where are the DWSTs located?
north yard next to CST
What is the only place level indication for the DWSTs is provided?
control room
What does NG and NH power in the DS system? What powers the other various water heaters?
Aux. building water heater
QA
Where do the HVAC evaporative coolers receive make up water from?
DS
What system provides cooling water to the instrument air and service air compressors when TC water is unavailable?
DS
What system provides make up to the spray ponds?
DS
Why does each unit have a DS pressure control valve?
to reduce the distribution loop pressure to the constant pressure being applied to various loads
A reduced pressure backflow preventer assembly is installed on each branch line off the Domestic Water loop. What do these consist of and where is backflow vented to?
two spring-closed check-valves, with a third spring-loaded check-valve in between them which opens to the atmosphere upon loss of line pressure
vented to atmosphere
Where are the DS Backflow preventer assemblies and the pressure control valves that are on the DS header into the unit located?
unit DS header enters the unit through the control building basement PCVs and BPAs are on the north side on the 74’ control building
(there are PCVs and BPAs located all around site)
