Main Feed And FWPT

Question 0

How much flow can one heater train bypass line pass?

Answer 0

25%. You can still get 75% flow through one train of HPFHs.

Question 1

What is the purpose of feedwater system (FW)?

Answer 1

Provide feed water to the steam generators at the required pressure, temp, and flow rate

Provide the final 3 stages of feed heating in two parallel heater trains

Question 2

What are the steam supplies to the FWPT and when are they supplying?

Answer 2

Aux steam - for uncoupled overspeed testing only
Main steam- when MT is insufficient (low powers)
MT - normal source from D MSR

Question 3

What are the pressures of the condensate coming into the feed pump and feed leaving the feed pump?

Answer 3

350 psig going in and 1200 psig leaving the feed pump

Question 4

How much feed flow can one feed pump handle?

Answer 4

65%, but we are limited to 62% on a down power

Question 5

What pressure is seal water supplied to the MFP casing at?

Answer 5

150 psig

Question 6

What differential pressure is maintained across the MFP seals?

Answer 6

15 psid

Question 7

What has to be true in order for the HP stop valve on the FWPT to be opened?

Answer 7

The control valve must be closed.

Question 8

How can you tell if the HP control valve is closed prior to stop valve testing?

Answer 8

A local green indicating light will tell you that the control valve is closed.

Question 9

Which two FWPT steam valves are controlled by the same hydraulic operating cylinder?

Answer 9

The high pressure control valve and the low pressure control valve.
The LP opens first and if it isn’t supplying enough steam to get the turbine to the desired speed, the HP control valve will open.

Question 10

Why does the LP stop valve only close half way when testing it?

Answer 10

Because the LP control valve is always open, so if it went full closed, you could not get it back open without shutting down the pump.

Question 11

Why does the LP control valve on the FWPT close when the turbine is tripped?

Answer 11

Because when the turbine trip is reset, the stop valves go full open. This could be an uncontrolled start if the control valve wasn’t closed.
It also acts as a second line of defense to shut off all steam flow and prevent turbine damage.

Question 12

How many stages are in a FWPT?

Answer 12

6 stages

Question 13

Where are the FWPT drain valves controlled from?

Answer 13

The control room.
Lead drain lines drain upstream of the stop valve to prevent slugs of water to the turbine.
Normally closed, but bypasses with orifice plates to remove water are placed in service.

Question 14

What interlocks must be met to start the FWP turning gear?

Answer 14

Oil pressure must be sufficient on the feed pump and the feed pump turbine.

Question 15

What happens on a FWPT trip?

Answer 15

HP and LP stop & control valves close; FWP mini flow valves close

Question 16

What are the FWPT trips?

Answer 16

Turbine oil pressure low
Pump oil pressure low
Exhaust vacuum low
Low suction pressure
High discharge pressure
Active or inactive thrust bearing wear high
Low control oil pressure

Question 17

What does the trip exerciser do?

Answer 17

Allows for overspeed trip testing without causing a turbine trip.

Question 18

What controls the position of the LP control valve poppets?

Answer 18

The operating cylinder is controlled by the speed governor that gets a signal from the FWCS or from the potentiometer in the control room

Question 19

At what point during startup is a main feed water pump started?

Answer 19

Prior to exceeding 3% RX power. That’s the capacity of 1 AFP
A second pump is started at 50% RX power

Question 20

What happens on a loss of one feed water pump?

Answer 20

A RX power cutback actuates.

If both pumps trip then the RX would trip

Question 21

What happens to the MFP mini flow valve on a turbine trip?

Answer 21

Closes to prevent free wheeling of the pump due to CD system flow through the mini flow to the condenser

Question 22

When are the mini flow valves open on the MFP?

Answer 22

Fully open when the pump discharge valve is shut and provide a % of the flow up to about 30% load is achieved.

Question 23

How does the turbine trip control oil affect the mini flow valve?

Answer 23

They are interlocked so that the mini flow goes closed and remains closed if pressure is < 75 psig.
This is accomplished by having 2 3 way solenoid valves. One vents air off the bottom of the valve actuator and the other supplies air to the top of the actuator.

Question 24

How does the mini flow fail on a loss of air? 120VAC? 125vDC?

Answer 24

Air- open
120vac - loss of power to controller, output goes to 0 => fails open
NOTE: if the FWP trips or was already tripped, the valve will close due to the solenoids energizing
125vDC - during normal ops, no affect. If the FWP had tripped, loss of power to the solenoids would fail the valve open