Feedwater Pump & Power Output Metering

[russmashpotatoes]

Hi everybody!

My name is Russ Maschmeyer. I'm a design graduate student at SVA in New York. I'm studying self-regulating systems in a class on cybernetics. I chose a BWR (particularly how it regulates its power output) as my system and I'm in WAY OVER MY HEAD!

if anyone knows, I'm looking for the following information for a diagram I'm drawing:

1. for the feed water pumps I need to know the following:
a. range - what's the maximum gallons per minute? I found one that said 22500gpm. Does that sound accurate?
b. resolution - what are the increments of control? For example, when you turn the pump up "one notch" how many more gpm is it pushing? 5gpm? 100gpm? 5000gpm? Can it vary the gpm by units of 1? 5? 100?
c. frequency - what is it's potential rate of change? For example, in a single second, how many gallons per minute can it increase? 5gpm/s? 100gpm/s? Is it slow or really fast?

2. for the power output metering of the plant:
a. range - what's the range the meter can register? for example, 0MW to 2000MW
b. resolution - if the meter is reading an output of 1400MW how close is it to the "real value"? What's the +/-? Is it really accurate, like 3W? Or is it looser like 5MW? This is sort of like margin of error.
c. frequency - does the meter take a reading every second? every nanosecond? every half hour?

Any help at all would be greatly appreciated. Even if you know generally the answers, they don't have to be dead on, just plausible!

Thanks so much!

[Fermi2]

Hi everybody!

My name is Russ Maschmeyer. I'm a design graduate student at SVA in New York. I'm studying self-regulating systems in a class on cybernetics. I chose a BWR (particularly how it regulates its power output) as my system and I'm in WAY OVER MY HEAD!

if anyone knows, I'm looking for the following information for a diagram I'm drawing:

1. for the feed water pumps I need to know the following:
a. range - what's the maximum gallons per minute? I found one that said 22500gpm. Does that sound accurate?
b. resolution - what are the increments of control? For example, when you turn the pump up "one notch" how many more gpm is it pushing? 5gpm? 100gpm? 5000gpm? Can it vary the gpm by units of 1? 5? 100?
c. frequency - what is it's potential rate of change? For example, in a single second, how many gallons per minute can it increase? 5gpm/s? 100gpm/s? Is it slow or really fast?

2. for the power output metering of the plant:
a. range - what's the range the meter can register? for example, 0MW to 2000MW
b. resolution - if the meter is reading an output of 1400MW how close is it to the "real value"? What's the +/-? Is it really accurate, like 3W? Or is it looser like 5MW? This is sort of like margin of error.
c. frequency - does the meter take a reading every second? every nanosecond? every half hour?

Any help at all would be greatly appreciated. Even if you know generally the answers, they don't have to be dead on, just plausible!

Thanks so much!

1a. Depends on the size of the plant, how many feedpumps it has and the discharge pressure. For a 2 MFP 3400 MW Thermal plant 22,500 GPM is about right, though it will rarely operate there.

1b. Depends on Suction  pressure, discharge pressure, the size of the pipe.

1c: The pump isn't the limiting factor, it's the control system. Digital control systems will ramp the pump up quickly. Analog less quickly. I can tell you on a loss of 1 Feedpump at 100% in a 3430 MW Th BWR it's FAST. Within seconds for Steak Driven pump.

2a: It's not measured that way and it depends on the what power you are at. It's also design dependent. The "meters" are in % power. IIRC in a BWR it's 0-125%. It depends on what the owner wants.

2b: Usually =-.5%

2c: Continuous.

Mike

[HydroDave63]

Within seconds for Steak Driven pump.

That almost sounds like salty sailor jargon for something else entirely 

[russmashpotatoes]

Holy crapola! Thanks so much Broadzilla!

This is perfect! Any idea for 1b? Even a relative idea would be great (you could throw anything out and I'll believe you. So will my class!).

Cheers!
R

[Fermi2]

There is no single answer to 1b. I just told you, thee are too many variables.

[russmashpotatoes]

Oh well, I guess I'll fudge that one somehow. Thanks so much for the help!

[tr]

For a BWR, the feedwater control is (or used to be) a 3 element system.  At full power, the control system generally sets feed flow to match steam flow, with level error serving as a correction factor.

There really isn't a "notch" on the pump controller.  As I recall at Perry, the original manual speed control knob was too coarse, so they changed it to one which took twice as many turns to get to maximum.

I recall the feedpump flow instruments as being 0-25,000 gpm per pump, with major increments of 5000 gpm, minor increments of 1000 gpm.

Total feed flow was something like 37,000 gpm, and the control system could maintain level within about +/- 1 inch, with one inch of level in the reactor representing around 200 gallons.

In the event of a turbine runback to something like 40% power, the feed control system could maintain reactor level within limits (call it a reduction in feed flow from 37,000 gpm to 15,000 gpm in approximately 30 seconds).

This is all based on memory, from a long time ago, for the original analog control system. 

[Fermi2]

That's actually about right. IIRC a feedpump at Fermi could give you up to about 65% power if required.
Normal level was 197 Inches TAF. If a feedpump tripped and level lowered to something like 192 Inches the Recirc Pumps would run back as the remaining feedpump ran up. It all equalized very quickly. Not much loger than 20 seconds. NOTE I said equalized, not stabilized!