[ED] - Extraction Steam and Drains

Question 1

[ED]

[ED] purpose?

Extraction Steam & Drains

Answer 1

Preheats CD and FW prior to feedwater entering the S/Gs to increase plant efficiency

Question 2

[ED]

What provides steam to #4 LP feedwater heater during startup?

Extraction Steam & Drains

Answer 2

[AS]

Question 3

[ED]

What water system makes-up to the bottom of the ED blowdown stack?

Extraction Steam & Drains

Answer 3

[DS] Domestic Water

Question 4

[ED]

What is the purpose of the ED blowdown stack?

Extraction Steam & Drains

Answer 4

-collection point for steam traps, HP heater relief valves and miscellaneous [AS] header drains

Aux Steam

Question 5

[ED]

When is [DS] added to [ED] blowdown stack?
What occurs if [DS] is OOS?

(Domestic Water)

Extraction Steam & Drains

Answer 5

If temp of water >150F

Steam will come out of the blowdown stack and north Condenser sump

Question 6

[ED]

GA-N2 & ED?

Extraction Steam & Drains

Answer 6

Supplies Nitrogen blanketing of FW Heater Shells & HDTs during long term shutdown operations

Feedwater
Heater Drain Tanks

Question 7

[ED]

[IA] & [ED]?

2

Extraction Steam & Drains

Answer 7

[MT] control system uses [IA] in Turbine Critical and Non-Critical Relay Dump Valves (provide a signal to control BTVs)

For use all [ED] AOVs

Main Turbine
Bleeder Trip Valves
Instrument Air
Air Operated Valves
Extraction Steam & Drains

Question 8

[ED]

How are BTV’s affected by a loss of [IA]?

Extraction Steam & Drains
Bleeder Trip Valves

Answer 8

go partially closed (Lose open permissives)

remain open due to [ED] flow

Bleeder Trip Valves
Extraction Steam

Question 9

Where are the Heater Drain Pumps powered from?

Extraction Steam & Drains

Answer 9

‘A’ from NBN-S02

‘B’ from NBN-S01

Question 10

[ED]

Where does seal water for each Heater Drain Pump come from?

Extraction Steam & Drains

Answer 10

Condensate Header
(375-500 psig)

Question 11

[ED]

What positions the Heater Drain Pump mini-flow valves? When will it close? What controls the position of the heater drain pump discharge valve?

Extraction Steam & Drains

Answer 11

Heater Drain Pumps flow transmitter

as the unit comes up in power and more extraction drain flow is available

heater drain tank normal level control valve

Question 12

[ED]

What signals stop the Heater Drain Pumps?

3

Extraction Steam & Drains

Answer 12

HDT lo-lo level alarm

Heater Drain Pump low flow after a time delay

Electrical protection signal

Question 13

[ED]

Where are Heater Drain Pumps located?
What allows one heater drain pump operation?

Extraction Steam & Drains

Answer 13

TB 100’ (West of Main Feed Pumps)

Open suction
and vent cross-tie between HDTs

Heater Drain Tanks

Question 14

[ED]

Why doesn’t #5 FW Heater have a level control system?

Extraction Steam & Drains

Answer 14

No drain cooler region

Drains directly to the HDT

Heater Drain Tank

Question 15

[ED]

Which LP FW heaters have four inlets?
How many do the others have?

Extraction Steam & Drains

Answer 15

1 & 2

3 & 4 have 1 inlet each

Question 16

Which feedwater heater has an input from S/G blowdown system?

Extraction Steam & Drains

Answer 16

3

Question 17

[ED]

What is the purpose of the BTVs? Which feedwater heaters have BTVs?

Extraction Steam & Drains
Bleeder Trip Valves

Answer 17

Prevent [MT] reverse steam flow (overspeed) on Turbine Trip

3-7

Main Turbine

Question 18

[ED]

What on the BTVs assists disc opening with min differential steam pressure?

Extraction Steam & Drains
Bleeder Trip Valves

Answer 18

Balance Arm device

Question 19

What happens the Bleeder Trip Valve test valve actuates?

Extraction Steam & Drains

Answer 19

air pressure across the operator piston is equalized to allow partial closing of valve disc by spring force

Question 20

Why are there 2 BTVs on #4 FW heater extraction line?

Extraction Steam & Drains
Feedwater

Answer 20

there is enough energy in #4 by itself to cause an overspeed trip

Question 21

[ED]

Which level control valves are reverse acting in [ED]?

Extraction Steam & Drains

Answer 21

All high level CVs and #1 LP heater normal level CVs

Low Pressure
Control Valves

Question 22

At what air signals are the reverse acting valves full open and full closed in the ED system?

Extraction Steam & Drains

Answer 22

Full open with 3#

Full closed with 15#

(Direct acting is the complete opposite)

Question 23

What happens upon a hi-hi signal in a HP feedwater heaters?

Extraction Steam & Drains

Answer 23

Isolates extraction steam

Closes the normal level control valve of the preceding heater

Opens the affected heater’s motor operated extraction steam line drain valve

In addition, for the HP heaters, the 1st and 2nd stage reheater drain tank vents isolate from the affected heater and vent to the main condenser

Question 24

What happens upon a hi-hi signal in a LP feedwater heaters?

Extraction Steam & Drains

Answer 24

Isolated entire LP heater train by closing the heater train isolation valves

Isolated extraction steam to #3 and #4 heaters

Opens the extraction line solenoid operated drain valves for #3 and #4 heaters

Question 25

Below what power level may there be insufficient D/P between the heater shells to allow for proper operation of the normal level control valves in the ED system? ## Footnote Extraction Steam & Drains

Answer 25

20% | high level control valves operate to keep alarms clear until power level is sufficiently raised

Question 26

When is the first heater drain pump started? ## Footnote Extraction Steam & Drains

Answer 26

25% power

Question 27

When is the second heater drain pump started? ## Footnote Extraction Steam & Drains

Answer 27

Between 30 and 40%

Question 28

During a plant shutdown, when are the Heater Drain Pumps secured? ## Footnote Extraction Steam & Drains

Answer 28

First one at 40%, second one at 25%

Question 29

How is the ED system affected by a loss of IA? ## Footnote Extraction Steam & Drains

Answer 29

Heater Drain Pump discharge valve fails closed, recirc valve fails open, putting the pump on recirc Heater Drain Tank, MSR Drain Tank, 1st and 2nd Stage Reheater Drain tank, and Feedwater heater High Level Dump valves will all fail open and the Normal Level Control Valves fail closed (Except #1 heater) Heater Drain pump will eventually trip on low flow or Heater Drain tank lo lo level signals The main steam supply to the 2nd stage reheater will isolate and the 1st and 2nd stage Reheater Drain Tanks and Tube Bundles will vent to the condenser instead of their associated Feedwater heaters

Question 30

What is the purpose of the HDTs (heater drain tanks)? ## Footnote Extraction Steam & Drains

Answer 30

ultimate collection point for most of the normal drains within the ED system provides suction for the heater drain pumps tank level regulated flow to the Main feed pumps receives mini flow line from heater drain pump

Question 31

Where are the heater drain tanks located? ## Footnote Extraction Steam & Drains

Answer 31

120' turbine building, above the heater drain pumps

Question 32

Concerning the ED system, where do the MSR 1st stage reheater drain tanks flow to? 2nd stage reheater drain tanks? ## Footnote Extraction Steam & Drains

Answer 32

#6 FW heaters, then to the heater drain tank #7 FW heaters, then cascades to the #6 FW heaters, then to the heater drain tank

Question 33

How many stages are the heater drain pumps? ## Footnote Extraction Steam & Drains

Answer 33

5

Question 34

What is the purpose of the Feedwater heaters? ## Footnote Extraction Steam & Drains

Answer 34

aid in improving the secondary system efficiency

Question 35

Concerning the High pressure feedwater heaters, what are the flow paths for the extraction steam and feedwater flow? ## Footnote Extraction Steam & Drains

Answer 35

extraction steam from HP turbine comes in through the top, condenses and is drained from the bottom feedwater flows in through the bottom, passes through the U-tubes and exits through the top

Question 36

Concerning the HP feedwater heaters, what are the differences between the #6/7 heaters and the #5 heaters? ## Footnote Extraction Steam & Drains

Answer 36

#6/7 have condensing and subcooling zones, has level control system, #7 drains to the #6 heater, #6 drains to the HDT #5 does not have a drain cooler region, no level control, drains straight to the HDT

Question 37

What is the purpose of the vents on the various tanks, heat exchangers and pumps in the ED system? ## Footnote Extraction Steam & Drains

Answer 37

to remove non-condensable gases and direct them to the condenser for removal

Question 38

What is the motive force of extraction steam while traveling from the turbine to the feedwater heaters? ## Footnote Extraction Steam & Drains

Answer 38

the differential pressure between the turbine stages and the feedwater heater shells

Question 39

Which feedwater heaters have the supplying extraction lines cross-connected and what does the cross connect allow for? ## Footnote Extraction Steam & Drains

Answer 39

3a, b, c 4a, b, c 6a, b 7a, b allows unit operation without all high and low pressure feedwater heaters in service

Question 40

What does the High Pressure turbine provide extraction steam to? ## Footnote Extraction Steam & Drains

Answer 40

3rd stage- 7A/B heaters and first stage reheating steam in the MSRs 5th stage- 6A/B heaters cold reheat- 5A/B heaters

Question 41

Where do the heater drain pumps send their effluent? ## Footnote Extraction Steam & Drains

Answer 41

to the suction of the main feedwater pumps | combines with the condensate just downstream of the feedwater heaters

Question 42

What is the difference in operation between direct acting and reverse acting level control valves in the feedwater heater level control system? ## Footnote Extraction Steam & Drains

Answer 42

direct acting- higher air pressure opens the valve reverse acting- higher air pressure closes the valve

Question 43

Where do the MSR drain tanks vent to? Where does the heater drain pump vent its suction line to? ## Footnote Extraction Steam & Drains

Answer 43

their respective MSR/Hot reheat line respective heater drain tank

Question 44

Where do the first stage reheater drain tanks normally vent to? ## Footnote Extraction Steam & Drains

Answer 44

A and C vent to #6A heater extraction line B and D vent to #6B heater extraction line all four vent back to their respective 1st stage reheater tube bundle outlet for steam scavenging (on high level, vent to the condenser)

Question 45

Where do the 2nd stage reheater drain tanks normally vent to? ## Footnote Extraction Steam & Drains

Answer 45

A and C vent to #7A heater extraction line B and D vent to #7B heater extraction line all four vent back to their respective 2nd stage reheater tube bundle outlet for steam scavenging (on high level, vent to the condenser)

Question 46

Where do the heater drain tanks vent to? ## Footnote Extraction Steam & Drains

Answer 46

to their respective #5 FW heater both tanks also have a vapor cross-connect line to each other

Question 47

Where do the #5, 6 and 7 feedwater heaters vent to? ## Footnote Extraction Steam & Drains

Answer 47

both trains all tie in together to a common header and vent to the condenser

Question 48

How does the ED system interface with the SC (secondary chemical control) system? ## Footnote Extraction Steam & Drains

Answer 48

Blowdown Flash Tank (BFT) vents to both of the Heater Drain Tanks by way of the vapor cross tie line between the HDT’s. The blowdown flow from the Blowdown Flash Tank can be directed to the shell side of the #3 LP Heaters. Cooling water from the blowdown heat exchanger is returned to the discharge of the heater drain pumps, which is then directed to the main feedwater pump suction.

Question 49

How does ED interface with GS? ## Footnote Extraction Steam & Drains

Answer 49

LP turbine 9th stage extraction supplies sealing steam to GS on power ascension

Question 50

In the ED system, what is powered by NH? ## Footnote Extraction Steam & Drains

Answer 50

MOVs, HP heater extraction steam block and drain valves, heater drain pump motor space heaters

Question 51

In the ED system, what is powered by NK? ## Footnote Extraction Steam & Drains

Answer 51

solenoids, controls, indication and alarms for various valves

Question 52

In the ED system, What is powered by NN? ## Footnote Extraction Steam & Drains

Answer 52

LP FW heater steam pressure instrumentation HTR DRN pump discharge/suction D/P, tank level and pump flow instrumentation

Question 53

What cools the HTR DRN pump lube oil coolers? ## Footnote Extraction Steam & Drains

Answer 53

turbine cooling water

Question 54

What maintains water level in the LP feedwater heater drain cooler, or subcooling zone? ## Footnote Extraction Steam & Drains

Answer 54

normal level control valve

Question 55

What is the purpose of having reverse acting normal and high level control valves in the ED system? ## Footnote Extraction Steam & Drains

Answer 55

to ensure that on a loss of IA, the ED system will drain its contents to the main condenser

Question 56

Describe the new level control valves for the LP feedwater heaters. ## Footnote Extraction Steam & Drains

Answer 56

Vee style ball valve, provides beter throttling and seal off flow can be positioned in either fail open or fail closed designation with the same valve mounting configuration, causing less installation errors rotory positioners with rotary actuators with a lever 4 gauges instead of three smaller in size

Question 57

What is the sequence for putting the MSR and 1st/2nd stage drain tanks in service to their normal level control valves? ## Footnote Extraction Steam & Drains

Answer 57

At 10% turbine power, 1st stage and MSR drain tanks go to normal level control valves, leading to the #6 FW heaters (1st stage) and the HTR DRN tank (MSR drain tank) At 20% turbine power, 2nd stage drain tank goes to normal level control valve, leading to #7 FW heaters