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RO34 - Revised and Upgraded Decks > Steam Dumps > Flashcards

Steam Dumps Flashcards

1
Q

What are the steam dump controls based on?

A

Auctioneered High Tavg

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2
Q

Which group(s) stagger open instead of opening all together?

A

Group 1 only

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3
Q

What is the only CRID that does not power anything for Steam Dumps?

A

CRID 3

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4
Q

What is Conditional C7A and is it an arming or blocking signal?

A

Arming signal (Load Rej)
- Allows operation of Group 1 and 2 Valves
- 10% Step Load Change or 5% / min on MPC-254

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5
Q

What is Conditional C7B and is it an arming or blocking signal?

A

Arming Signal (Load Rej)
- Allows operation all 3 groups of dumps
- 30% Step Load Change on MPC-254

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6
Q

What is Conditional C8 and is it an arming or blocking signal?

A

Arming Signal (Turb Trip)

  • 4/4 Main Turbine Stop Valves Closed
    OR
  • 2/3 Oil Pressure switches below 800psig
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7
Q

What is Conditional C9 and is it an arming or blocking signal?

A

Blocking Signal

  • 1 Circulating Water pp breaker closed.
  • CRID 2 energized.
  • Pressure switches on 3/3 Condensers ≥ 20.6 in Hg
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8
Q

What is Conditional P12 and is it an arming or blocking signal?

A

Blocking Signal

  • 2/4 Tave < 541°F - Status Light ON
  • Steam Dumps are Blocked in All Modes until placed in “Bypass Interlock“
  • (3/4 Tave > 541°F - Status Light OFF)
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9
Q

What does the bypass interlock for P12 allow?

A

allows group I steam dumps to operate when P12 met

Bypass seals in until reset or P-12 block clears

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10
Q

How do you reset C7A and C7B conditionals?

A

Mode Ctrl Switch and must be taken to off/reset

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11
Q

Which steam dump groups are allowed to operate when the turbine trip controller is activated?

A

Groups I and II
(6 vales)

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12
Q

Which steam dump groups are allowed to operate when the load rejection controller is activated?

A

Groups I, II, and III
(9 valves)

Group 3 is only for the 30% C7B

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13
Q

What is the design of the steam dumps?

A
  • Plant design accepts a step load reduction of 50% from full power by using the** 40% from Steam Dump system** and 10% from Rods
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14
Q

What is Tavg?

A

Average of all Thot + Tcold (rcs legs)

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15
Q

What is high Auctioneered Tavg?

A

The highest Tavg of all 4 rcs loops

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16
Q

What inputs do the turbine trip controller use to open steam dumps?

A

Auctioneered High Tavg - Tno-load

Tno-load is 547°F

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17
Q

What inputs do the load rejection controller use to open steam dumps?

A

Auctioneered High Tavg - Tref

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18
Q

What instrument does Tref come from?

A

MPC-253 (First Stage Impulse #)

19
Q

At what Temperature difference will group I open with the Turbine Trip Ctrlr?

A
  • 0°F to 10°F ΔT - Modulates open
  • at 10°F ΔT -Trips Open

This will be 0%-33% Demand on the controller

20
Q

At what Temperature difference will group II open with the Turbine Trip Ctrlr?

A
  • 10°F to 20°F ΔT - Modulates Open
  • at 20°F ΔT - Trips Open

This will be 33%-67% Demand on the controller

21
Q

At what Temperature difference will group I open with the Load Reject Ctrlr?

A
  • 5°F to 9°F ΔT - Modulates open
  • at 9°F ΔT - Trips Open
22
Q

At what Temperature difference will group II open with the Load Reject Ctrlr?

A
  • 9°F to 13°F ΔT - Modulates open
  • at 13°F ΔT - Trips Open
23
Q

At what Temperature difference will group III open with the Load Reject Ctrlr?

A
  • 13°F to 17°F ΔT - Modulates open
  • at 17°F ΔT - Trips Open

This will be 67%-100% Demand on the controller

24
Q

Why do none of the steams dumps open in the first 5°F ΔT on a load rejection?

A

Rods are good for a 10% load rejection

25
Q

Which mode only allows modulating of steam dumps?

No ability to trip open

A

Steam Pressure Mode

No trip functions

26
Q

How much turbine load are the steam dumps designed to handle on a load rejection?

A

40% Load

27
Q

A Unit 2 reactor trip occurred from 90% power. The following plant conditions exist:

  • Reactor trip breakers: OPEN
  • Main turbine stop valve (C): OPEN
  • Condenser vacuum: 21.4 in. Hg.
  • RCS Tavg: 561°F
  • Auto Stop Oil Pressure: 400 psig

Assuming all other equipment operated as designed and no operator actions are taken, the Steam Dump system is:

A. armed and dumping steam to the condenser with group 1 trip open solenoid bistables energized.

B. armed and dumping steam to the condenser with groups 1 and 2 trip open solenoid bistables energized.

C. armed but not dumping steam to the condenser because of a blocking signal.

D. not armed and not dumping steam to the condenser.

A

A. armed and dumping steam to the condenser with group 1 trip open solenoid bistables energized.

28
Q

If MPC-253 or MPC-254 Fail High in Tavg mode, what effect will it have on steam dumps?

A

No Effect. There must be a temperature error AND an arming signal

29
Q

If MPC-253 Fails low in Tavg mode, what effect will it have on steam dumps?

A

No Effect. There is a temperature error, but no amring signal.

30
Q

If MPC-254 Fails low in Tavg mode, what effect will it have on steam dumps?

A

No effect. There is an arming signal, but no demand.

31
Q

If you take the ctrl selector switch to off/reset, what will it do?

A

If you previously bypassed your P12 signal, it will re-enable P12

32
Q

What are the trip open signals for Turbine Trip bistables for steam dumps?

A
  • 10°F difference between Tavg and Tnoload for Group I
  • 20°F difference between Tavg and Tnoload for Group II
33
Q

What are the trip open signals for Load Rejection bistables for steam dumps?

A
  • 9°F difference between Tavg and Tref for Group I
  • 13°F difference between Tavg and Tref for Group II
  • 17°F difference between Tavg and Tref for Group III
34
Q

Whats the fastest cooldown rate allowed with steam dumps?

A

100°F per hour

35
Q

If UPC-101 fails high while in steam pressure mode and bypass interlock is NOT bypassed, what will happen to steam dumps?

A

Groups I and II will go full open until P12 is met

36
Q

If UPC-101 fails low while in steam pressure mode, what will happen to steam dumps?

A

Any open steam dump valves will close

37
Q

If Tavg fails high > 20°F ΔT with no turbine trip, what will happen to steam dumps?

A

Nothing will happen, because the C7A and C7B arming signals are not in

38
Q

If Tavg fails high > 20°F ΔT with a turbine trip, what will happen to steam dumps?

A

Groups I and II will go full open and stay full open until P12 is met and then it will cycle at 541°F

39
Q

During the final stages of an RCS heatup, the Steam Dump System is set to automatically control RCS temperature at 541oF.

Which ONE of the following is the correct Steam Dump Pressure Controller setpoint required to
maintain RCS temperature at approximately 541oF Tavg?

Reference STEAM TABLE

A

955#

40
Q

Load Rejection control will maintain temperature within ___ between Auctioneered High Tavg and Tref with no rod motion.

A

5°F

41
Q

Is the steam dump system safety related?

A

NO!!!!

42
Q

If UPC-101 fails high while in steam pressure mode and bypass interlock IS bypassed below P12, what will happen to steam dumps?

A

Group 1 opens until operator action

43
Q

When is the Steam Dump Bypass Turbine Trip C-8 Status LIght lit?

A

Lights when the 1st Control Selector Switch is placed in Bypass Interlock to allow cooldown less than P-12

BOTH selector switches needed for the bypass interlock to work

44
Q

What operator action will block Steam Dump Ops when in Tave modes?

A

Place EITHER Control Selector Switch in “Off”

RO34 - Revised and Upgraded Decks (84 decks)

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