DS/DW- Domestic/Demineralized Water

Question 1

What is the purpose of the DW system?

Answer 1

Provides continuous and sufficient supply of demineralized and degasified water to several systems and services

Question 2

What is the purpose of the DS system?

Answer 2

Supplies potable water within the Power Block for human consumption, eye wash stations, and for other general uses

Question 3

DW supplies makeup water to which Surge tanks?

Answer 3

Diesel Generator, Essential chilled water, Essential Cooling water, Turbine Cooling Water, Nuclear Cooling water, normal chilled water

Question 4

What other tanks does DW provide makeup water to?

Answer 4

RMWT, CST, Stator Cooling Coolant Tank

Question 5

How can DW support CD during a startup?

Answer 5

Can supply water to the Condensate Service Header

Question 6

Which systems receive seal water from DW? What from DS?

Answer 6

Control building OW sumps and RD

DG sump pumps

Question 7

How does DS system support ED system?

Answer 7

ED system receives blowdown stack quench water from the DS system

Question 8

How does DS system support FP system?

Answer 8

FP system receives makeup water from DS

Question 9

Why is a nitrogen cover gas maintained in the DWST?

Answer 9

To ensure the water remains free of oxygen during storage

Question 10

What would trip the Demineralized Water Transfer Pumps? What happens when the level is restored?

Answer 10

Low-low level switch provided on the tank, electrical overload

pump auto restarts

Question 11

What is the status of the Demineralized Water Transfer Pumps under normal operations? What pressure starts the standby DW transfer pump?

Answer 11

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

Question 12

Where is the control switch for the Demineralized Water Transfer Pumps? Where are the pumps located?

Answer 12

Control Room

south side of the DWST, north yard

Question 13

How could we get DW if the Transfer Pumps or the Demineralized Water Storage tanks are unavailable?

Answer 13

Can be supplied directly from the Water Reclamation Demineralized Water header via a tank bypass and a valve

Question 14

What is the purpose of the backflow preventer assembly and what does it consist of?

Answer 14

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

Question 15

Where are the pressure control valves and BPAs located?

Answer 15

North side of 74’ Control Building

Question 16

What is the storage capacity of the DW storage tanks at each unit and one surge rinse tank at water resources?

Answer 16

125,000 each

1 at each unit and 1 at WR

Question 17

What system powers the DW transfer pumps, motor space heaters and local instrument panel?

Answer 17

NH

Question 18

What is the purpose of the demin water booster pumps at WR?

Answer 18

three centrifugal pumps

one of the three is operating continuously to pressurize the common pipeline to the PVGS units, other two in standby

Question 19

How are the DWST at each unit filled? What is the level band? How is flow monitored?

Answer 19

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

Question 20

Where does the DWST overflow to?

Answer 20

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

Question 21

What alarms are provided by the local instrument panel for the DWST to the control room?

Answer 21

high level, low level, low-low level alarms

Question 22

Where are the DWSTs located?

Answer 22

north yard next to CST

Question 23

Where is the only place level indication for the DWSTs is provided?

Answer 23

control room

Question 24

What does NG and NH power in the DS system? What system powers the other various water heaters?

Answer 24

Aux. building water heater

QA

Question 25

Where do the HVAC evaporative coolers receive make up water from?

Answer 25

DS

Question 26

What system provides cooling water to the instrument air and service air compressors when TC water is unavailable?

Answer 26

DS

Question 27

What system provides make up to the spray ponds?

Answer 27

DS

Question 28

Why does each unit have a DS pressure control valve?

Answer 28

to reduce the distribution loop pressure to the constant pressure being applied to various loads

Question 29

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?

Answer 29

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

Question 30

Where are the DS Backflow preventer assemblies and the pressure control valves that are on the DS header into the unit located?

Answer 30

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)