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Condensate System (CD) Flashcards

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0
Q

The three condensate pumps are capable of providing what capacity of flow?

A

50%

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1
Q

What is the purpose of the condensate system?

A

Provides condensate to the FW system (FW pump NPSH)

Heat sink for the exhaust steam from turb gen, fwpts, and turbine bypass steam

Provides required deaeration of the condensate

Minimize air leakage into the steam thermal cycle

Provides the first four stages of FW heating
Provides makeup, cooling and seal water to various secondary components.

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2
Q

Where do the condensate pumps take suction from?

A

The condenser hotwells via two headers.

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3
Q

Where do the condensate pumps discharge to?

A

To a common header which can flow to, or bypass the demineralizers.

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4
Q

Where in the condensate system flow path is the chemical addition system located?

A

Downstream of the demineralizers.

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5
Q

What side of the LP FW heaters (shell and tube heat exchanger) does condensate flow?

A

Condensate flows through the tubes while extraction steam is on the shell side causing the heating.

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6
Q

After exiting the three trains (a, b, c) of parallel LP FW heaters where does the water discharge?

A

Discharge is to a common header and is directed to the main FW pump auctions.

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7
Q

Where does the condensate pump A recirc flow discharge?

A

Hotwell 2C

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8
Q

Where does condensate pump B recirc flow discharge?

A

Either 1C or 2C.

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9
Q

What governs the B pump recirc flow?

A

The position of the pumps suction valves.

If one of the suction valves is closed the associated mini flow valve for that hotwell half is also closed.

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10
Q

Where does condensate pump C recirc flow discharge?

A

Hotwell section 1C.

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11
Q

What happens when the condensate pump recirc lines experience low flow?

A

A low flow alarm alerts the operator.

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12
Q

Where is makeup water for the hotwell drawn from?

A

The condensate storage tank by vacuum drag.

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13
Q

How is excessive condensate inventory handled?

A

Inventory is controlled through the hotwell level control drawoff valve by allowing CD pump discharge to reject water back to the CST.

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14
Q

Where is the drawoff valve located in the condensate flow path?

A

It is piped in downstream of the polishing demineralizers.

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15
Q

Where can the condensate flow be directed?

A

CST, main turbine exhaust hood spray, BD heat exchanger, CD crosstie header.

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16
Q

What is the purpose of long path recirc flow?

A

Used for the condensate and FW system start up recirculation, warm up and clean up.

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17
Q

Describe the flow path of recirc flow.

A 
Main condenser
CD pumps
CD demineralizers 
LP FW heaters
Bypasses main FW pumps
To HP FW heaters
Back to the condenser
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18
Q

What cools the CD pump motor lube oil coolers?

A

Turbine cooling

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19
Q

How does the DW system interact with the condensate system?

A

Can be used to supply the condensate service header as a backup via MOV 275.

Also used to fill the CD pump min-flow recirc lines via a portable hose prior to starting the first pump.

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20
Q

Where do the condensate pumps receive power from?

A

NBN-S01&02

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21
Q

What is the purpose of the condensate storage tank?

A

Provides normal makeup for the hotwells and receives excess condensate when hotwell is high.

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22
Q

Where does the FW pump turbine exhaust go?

A

The condenser

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23
Q

What portions of the FW pump turbine drain to the condenser?

A

Various drains from the casing

HP and LP stop valve above and below seat drains

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24
Where is the FW pump mini-flow and seal leak-off routed to?
The condenser
25
What do the condensate and heater drain pumps provide suction for?
Main feed pumps
26
What is the source of steam for the FW pump seals?
Directly off the condensate header.
27
Where does the GS system unloading valve dump?
Condenser.
28
Where does the steam packing exhauster drain tank drain to?
Drains to the condenser when there was a vacuum.
29
What valves are air operated and supplied by IA?
``` CD pump mini flow valves Hotwell makeup and drawoff valves Vacuum breaker isolation valves Demineralizer bypass valve CD service header control valve CD cross-tie pressure control valve ```
30
What provides exhaust hood spray to cool the LP turbines during startup?
CD system
31
Where do the LP turbines discharge to?
Main condenser
32
Where is condensate pumped for hotwell cleanup or level control?
The circ water canal
33
What system provides the ability to cross tie the CD systems of all three units for CD system transfers as necessary?
Auxiliary steam system
34
What is the purpose of the sparring steam station?
Heats the condensate in the hotwells during condensate clean up operations.
35
What provides feed water heating to the LP FW heaters during startup and condensate cleanup operations?
Auxiliary steam system.
36
What are the major loads of the condensate service header?
``` CD pump seals Condenser expansion joints Vacuum pump make up Hydrazine and ammonia dilution Heater drain pump cooling jacket Mechanical seal on the heater drain pumps (from CD pumps discharge header) ```
37
What is the purpose of the air removal system?
Removes air and non-condensables from the condenser. Also used as path for rad monitoring of the condenser off gas.
38
What is the purpose of the condensate cross-tie header.
Allows a unit that is supplying steam to another unit to recover the condensate.
39
Describe the main condenser
Multi-pressure, radial flow, single pass, shell and straight tube, reheater type HX.
40
What is the purpose of the dog bone seal?
It is a water sealed, rubber, belt type seal that connects the LP turbine exhaust hood to the condenser shells.
41
What is the purpose of the condenser equalization duct?
Allows pressure between the sections to equalize if an abnormal pressure/temperature differential develops. (30* F deltaT) Located above the A and B shell false bottoms.
42
What protects each condenser section from over pressurization?
Rupture discs, set for 3 psig on the associated LP turbine hood.
43
What is the purpose of the vacuum breaker installed on each condenser section?
Allows for rapid turbine slowing under emergency conditions AND condenser pressure equalization during normal plant shut down.
44
Why are the tube lengths in each progressive condenser longer?
To compensate for the progressively increasing temperature of circ water.
45
Why is it essential to minimize condenser pressure?
In order to maximize turbine efficiency.
46
Where is the air removed from the condensers discharged to?
To atmosphere via the condenser air removale system.
47
Why does the condensate fall to a sump before being drawn into the condensate pumps?
Forms a water seal between the tube bundles and the hotwell. The sump depth allows the condensate to overcome the pressure difference in the A and B shells and the hotwell. The C condenser condensate falls directly from the inner bottom to the hotwell.
48
Describe the sump bottom.
Features perforated plates through which condensate falls to the reheat trays above the hotwell water levels.
49
What heats the reheater trays?
Exhaust steam from the FW pump turbines. The exhaust steam that remains uncondensed after passing through the reheat trays is condensed in the C condenser.
50
What is the purpose of the divider plates in the lower hotwell?
Provides detention time for the condensate which aids in reheating and sampling.
51
What detects circ water leakage between the tubes and tube sheet?
A salinity detection bay near each water box.
52
How is hotwell level normally maintained?
Via two automatic level control systems. One for each hotwell.
53
How is makeup water transported to the hotwell and from where?
The hotwell makeup valve opens and vacuum drags water from the CST to the condenser. Valves automatically close if CST level decreases to approximately 30 feet.
54
What is used to provide make up water to the hotwell if condenser vacuum is degrading?
Manual bypass valves Also used to augment automatic system.
55
Where is the hotwell drawoff automatic level control valve located in the flow path?
On the condensate pump discharge header downstream of the condensate demineralizers. Opens based on the higher of two levels in the higher of the 1C or 2C hotwells.
56
What happens to the hotwell drawoff valve when SG feed water pump suction pressure is low or, any condenser hotwell cation conductivity is high.
The drawoff valve will close. If closed due to high conductivity it cannot be opened from the main control room.
57
What must be done to open the hotwell drawoff level control valve if high cation conductivity is detected?
The interlock must be bypassed in the local panel by placing the key locked bypass (override) switch to the bypass position.
58
Where does the A CD pump take suction from?
2A, 2B, and 2C hotwells Features one suction valve
59
Where does the C CD pump take suction from?
1A, 1B, and 1C hotwells Features one suction valve
60
Where does the B CD pump take suction from?
Features two suction valves Normally takes suction on both Abnormal lineup takes suction on one or the other. B CD pump will trip if both suction valves are closed...
61
At what dP will the CR receive an alarm for the strainers upstream of the CD pump?
5" H2O
62
What cools and lubricates the CD pumps?
Cooling: TC for upper bearings Lubrication: oil lubricated upper. Grease lower bearings.
63
What is the purpose of the mini flow valves?
Valves are located in a recirculation line that prevents the CD pumps from overheating.
64
Describe the flow path of the mini flow recirc lines...
Runs from the discharge side of the pumps back to there respective hotwell halves.
65
What is the flow set point of the recir mini flow valves?
Maintains 4500 gpm and trips at 3600 gpm after a 45 sec time delay.
66
At what hotwell level will the running condensate pump trip?
30 inches Normal level is 41 inches.
67
Which NBN bus provides power to each CD pump.
A S01 B S01 C S02
68
Describe the purpose of the condensate overboard valves.
The A & C CD pumps have branch lines off of their discharge piping, upstream of the pump discharge valves, that contain motor operated valves to direct the condensate pump discharge to the CW canal. These allow for the feed and bleed of the CD and FW systems to remove rust and contaminants following dry layup. Must be verified non radioactive prior to dumping.
69
What is the condensate service header?
A large discharge header that taps off the condensate pump header and is reduced down to ~90 psig through a pneumatic pressure control valve.
70
How is the condensate service header supplied when no condensate pumps are available?
It is supplied by the DW system through a motor operated isolation valve which is operated from the CR.
71
What is the purpose of the condensate demineralizer inlet, outlet and bypass valves?
All three valves are interlocked. If inlet is open, outlet permissive If both inlet and outlet open, bypass valve modulates flow to maintain a set pressure if dP is less than ~55 psid. Else bypass is wide open.
72
Where is the excess water in the LP FW heaters diverted and how?
The excess water goes to the condenser and the high level control valves control the flow.
73
What's happens if the water level in the LP FW heaters continues to rise until a hi hi level alarm?
The flow to that string of heaters will automatically be isolated by two redundant motor operated isolation valves.
74
What condenser features the level indicators that's decide when make up is needed?
Condense C hotwell.
75
What happens if the hotwell experiences a high level?
Draw off valve LV 75 opens allowing no condensate to flow to the CST.
76
What is the state of the mini flow valves at full power?
They are closed and are set to modulate automatically if CD flow decreases.
77
What happens in the flow path of the cd system when the demineralizers are in full service?
Valves 191 and 199 are open and the bypass valve is in the automatic mode, modulating to maintain a set dP
78
What provides cooling for the S/G blowdown in the blowdown heat exchanger?
Condensate flow is aligned to flow through the BD HX. BD is cooled prior to reaching the IX.
79
What happens to the plant if the condensate system fails?
Feed pumps trip on low suction pressure. After a while the Rx will trip on low SG level. Next main turbine and generator trip. The aux feed system will restore SG level.
80
What happens if only one feed pump trips?
Rx power cutback to 25-75% power.
81
What happens if the main condensers lose vacuum?
SBCS valves won't dump to condenser Main turbine trips followed by both FW pumps. Rx trips on low SG water level. Aux feed will restore SG level.
82
What happens to the CD system on loss of IA or electrical power?
CD pump mini flow valves fail open which could cause a loss of suction to the FW pumps. Hotwell make up and draw off valves fail closed. Hotwell level control will need to be performed manually.
83
What happens to the condensate service header on loss of IA?
The header control valve fails closed but it can be supplied manually from the motor operated DW valve.
84
What happens to the condensate cross-tie pressure control valve on a loss of IA?
The valve fails closed but it is only an issue if the affected unit was sending or receiving condensate through this header.
85
What happens to the vacuum breakers isolation valves on loss of IA?
They fail closed but this has no impact because they are normally closed.
86
What happens to the demineralizer bypass valves on loss of IA?
They fail open which could cause secondary chemistry issues.

Secondary Part Deux (4 decks)

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