Steam Dumps Flashcards by Kenneth Anderson

On a turbine trip/load rejection what are the steam dump controls based on

Auctioneered High Tavg

How well did you know this?

Not at all

Perfectly

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

Group 1 only

How well did you know this?

Not at all

Perfectly

Where are the arm/block solenoids powered from?

VDCD (Train “A”)

- VDAB (Train “B”)

How well did you know this?

Not at all

Perfectly

How do the arm/block solenoids fail?

Fail to Vent (Blocks Steam Dumps)

How well did you know this?

Not at all

Perfectly

What are CRID 1 steam dump loads?

Turbine Trip Controller
Load Rejection Controller
MPC-253 (T-Ref)
UPC-101 (bypass steam header)

How well did you know this?

Not at all

Perfectly

What are CRID 2 steam dump loads?

Steam Pressure Controller
MPC-254
Tref Computer

How well did you know this?

Not at all

Perfectly

What are CRID 3 steam dump loads?

No CRID 3 loads are associated with steam dumps

How well did you know this?

Not at all

Perfectly

What are CRID 4 steam dump loads?

Arm/Block Solenoid Relays

- Auctioneered High Tavg computer

How well did you know this?

Not at all

Perfectly

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

Arming signal (Load Rej)

- 10% Step Load Change or 5% / min on MPC-254.
Allows operation of Group 1 and 2 Valves

How well did you know this?

Not at all

Perfectly

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

Arming Signal (Load Rej)

- 30% Step Load Change on MPC-254.
Allows operation of Group 3 Valves

How well did you know this?

Not at all

Perfectly

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

Arming Signal (Turb Trip)
4/4 Main Turbine Stop Valves Closed
OR
2/3 Oil Pressure switches below 800#

How well did you know this?

Not at all

Perfectly

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

Blocking Signal
1 Circulating Water pp breaker closed.
CRID 2 energized.
Pressure switches on 3/3 Condensers ≥ 20.6 inHg

How well did you know this?

Not at all

Perfectly

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

Blocking Signal
2/4 Tave < 541°F - Status Light ON
(P-12 Active (Status Light ON) Steam Dumps are Blocked in All Modes until placed in “Bypass Interlock“)

(3/4 Tave > 541°F - Status Light OFF)

How well did you know this?

Not at all

Perfectly

What does the bypass interlock for P12 allow?

allows group I steam dumps to operate when P12 met

Bypass seals in until reset or P-12 block clears

How well did you know this?

Not at all

Perfectly

Which ctrl switch will reset C7A and C7B conditionals and how are they reset?

Mode Ctrl Switch and must be taken to off/reset

How well did you know this?

Not at all

Perfectly

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

Groups I and II

How well did you know this?

Not at all

Perfectly

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

Groups I, II, and III

How well did you know this?

Not at all

Perfectly

What is the design capacity of the steam dumps? **

Plant design accepts a step load reduction of 50% from full power by using the 40% from Non-Safety Related Steam Dump system and 10% from Rods

How well did you know this?

Not at all

Perfectly

What is the purpose of the steam dumps?

Reduce RCS transients following substantial turbine load reductions by dumping steam to the condensers.
Remove decay and sensible heat stored in the RCS following a reactor & turbine trip without actuating SG safety valves.
Control RCS temperature when the turbine is at low load, or during startup, cooldown, and when maintaining mode 3.

How well did you know this?

Not at all

Perfectly

What is high Auctioneered Tavg?

The highest Tavg of all 4 rcs loops

What signals does the turbine trip ctrlr use to open steam dumps?

Auctioneered High Tavg - Tno-load

What signals does the load rejection ctrlr use to open steam dumps?

Auctioneered High Tavg - Tref

What signal gives you Tref?

MPC-253 (First Stage Impulse #)

When will group I open with the Turbine Trip Ctrlr?

0°F to 10°F ΔT - Modulates open
0%-33% Demand
If > 10°F ΔT -Trips Open

When will group II open with the Turbine Trip Ctrlr?

- 10°F to 20°F ΔT - Modulates Open - 33%-67% Demand - If > 20°F ΔT - Trips Open

When will group I open with the Load Reject Ctrlr?

- 5°F to 9°F ΔT - Modulates open - 0%-33% Demand - If > 9°F ΔT - Trips Open

When will group II open with the Load Reject Ctrlr?

- 9°F to 13°F ΔT - Modulates open - 33%-67% Demand - If > 13°F ΔT - Trips Open

When will group III open with the Load Reject Ctrlr?

- 13°F to 17°F ΔT - Modulates open - 67%-100% Demand - If > 17°F ΔT - Trips Open

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

- Rods are good for a 10% load rejection

What are the two modes of the steam pressure controller?

- Auto (setpoint is 1005#) | - Manual

Which mode only allows modulating of steam dumps?

- Steam Pressure Mode | No trip functions

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

- 40% Load

How do the Trip Open Solenoids fail?

- Fail to Modulate

What is the Power Supply for the trip open solenoids?

- VDAB

*** 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 and group 2 modulating. 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. armed and dumping steam to the condenser with group 1 trip open solenoid bistables energized and group 2 modulating.

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

- Will have no affect

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

- Will have no affect because it has no arming signal

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

- Will have no affect because it has no demand signal

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

- If you previously bypassed your P12 signal, it will re-enable P12 - De-energizes arm/block solenoids

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

- 10°F Group I - 20°F Group II (Direct 20# air to the trip/open valves)

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

- 9°F Group I - 13°F Group II - 17°F Group III (Direct 20# air to the trip/open valves)

If CRID 1, 2 and 4 are lost, can steam dumps still operate?

No, steam dumps remain closed

Whats the fastest cooldown rate allowed with steam dumps?

- 100°F per hour

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

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

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

- Any open steam dump valves will close

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

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

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

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

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

- 5°F

While in Tavg mode if MPC-254 fails low, what will the happen to the steam dumps

- Since no actual temperature deviation is present, no air signal will be developed to open the steam dumps even though C7A and C7B are present