LOT 202.09 Steam Dumps

Question 1

• LOT 202.09 Steam Dumps*
• • *

What causes the #3 solenoid to energize?

Answer 1

• T_avg Mode:*
• *C-9**
• Condenser Vacuum > 22” Hg AND CW breaker Shut [1/4]*

AND

• *C-7 OR C-8**
• C-7: 10% load reduction OR 5%/min*
• C-8: EH pressure 1245.8 psig [2/3] OR TVs closed [2/4]*
• Pressure Mode:*
• *C-9**
• Condenser Vacuum > 22” Hg AND CW breaker Shut [1/4]*

AND
Steam Header Pressure > Setpoint

If C-7 energizes #3 solenoid, must reset on CP007 to de-energize #3 solenoid.

Question 2

• LOT 202.09 Steam Dumps*
• • *

What is the stroke time of the steam dumps?

Answer 2

• Trip Open:*
• *3 seconds**
• Trip Closed:*
• *5 seconds**
• Modulate:*
• *20 seconds**

Question 3

• LOT 202.09 Steam Dumps*
• • *

Where do the steam dumps discharge steam?

Answer 3

Condensers

• Each bank consists of 3 steam dumps
• ^{1 dump}/_condenser

Question 4

• LOT 202.09 Steam Dumps*
• • *

What causes the #1 and #2 solenoids to de-energize?

Answer 4

P-12: T_avg < 563 ˚F [2/4]

Two redundant channels. One for each solenoid.

Can bypass P-12 for Bank #1 Steam Dumps by placing switches on CP007 to Bypass Interlock. (Spring returns to ON)

• Must take switch to OFF/RESET to secure C/D feature.

Question 5

• LOT 202.09 Steam Dumps*
• • *

What causes the #4 solenoid to energize?

Answer 5

Turbine Trip (C-8):

• *High 1: T_avg - T_ref > 13 ˚F**
• Trips open steam dump banks 1 and 2*
• *High 2: T_avg - T_ref > 26 ˚F**
• Trips open steam dump banks 3 and 4*

No Deadband

Load Rejection (C-7):

• *High 1: T_avg - T_ref > 7.41 ˚F**
• Trips open steam dump banks 1 and 2*
• *High 2: T_avg - T_ref > 11.81 ˚F**
• Trips open steam dump banks 3 and 4*

Setpoint changes based on chart

• *3 ˚F deadband at 592 ˚F T_avg**
• Allows Rods a chance to fix deviation*

Active in T_avg MODE only.

• Note:*
• T_avg driven off Auctioneered High T_avg
• T_ref driven of PT-505

Question 6

• LOT 202.09 Steam Dumps*
• • *

How does the operator determine the correct setpoint for the Header Pressure Controller (PK-0557) on CP007?

Answer 6

^{Desired Pressure}/_{Span of PI-557}*10

^{1185 psig}/_{1400 psig} *10 = 8.46 turns

Question 7

• LOT 202.09 Steam Dumps*
• • *

What is the steam dump capacity?

Answer 7

40%
12 steam dumps (^3.33%/_{Steam Dump})

Controls pressure/temperature following a 50% load reject (10% is covered by rods)

Question 8

• LOT 202.09 Steam Dumps*
• • *

When is steam pressure mode used?

Answer 8

Startup (< 15% power)

Shutdown

Cooldown

Question 9

• LOT 202.09 Steam Dumps*
• • *

How do the steam dumps and steam dump drain valves respond to a loss of power or air?

Answer 9

• Steam Dumps:*
• *Fail Shut**
• Steam Dump Drains:*
• *Fail Open**

Question 10

• LOT 202.09 Steam Dumps*
• • *

What does the Imp Selector switch do on CP007?

Answer 10

• Defeat PT-505:*
• *PT-506 used for C-5 interlock**
• Defeat PT-506:*
• *Nothing**

C-5: Turbine Impulse pressure < 15% [1/1]

• Stops AUTO outward rod motion.