Steam dumps

Question 1

Effect of losing ANY unit specific 125VDC bus:

Answer 1

Steam dumps will not open due to loss of power to at least one control solenoid.

Question 2

Effect of loss of offsite power:

Answer 2

Loss of off site power, steam dumps will not open due to C-9.

Question 3

If ‘A’ RTB fails to open on reactor trip:

Answer 3

Steam dumps control on Plant trip controller @557F if armed by load rejection (10% in 2 minutes).

Question 4

If ‘B’ RTB fails to open on reactor trip:

Answer 4

Controls on load rejection controller @560F (3F error)

Question 5

When does each steam dump open based on demand signal?

Answer 5

0-25% A, E, J
25-50% B, F, K
50-75% C, G, L
75-100% D, H, M

Question 6

C-7 Loss of load setpoint, coincidence and function

Answer 6

10% decrease w/i 120 seconds on 2/3 coincidence (PT505, 506 and EH Pimp).
Arms steam dumps in Tave mode after load rejection.

Question 7

C-9 Condenser available setpoint, coincidence and function

Answer 7

Condenser pressure >23” vacuum and CW brkr closed.
Condenser available for steam dumps.

Question 8

P-12 Low-Low Tave setpoint, coincidence and function

Answer 8

<550F, 2/4, Blocks steam dumps. If 3/4 Tave exceeded 550F, the bypass interlock must be reactivated when 2/4 Tave lower to <550F.

Question 9

What happens when the A-train reactor trip breaker auxiliary contacts open?

Answer 9

Arms steam dumps in Tave mode after plant trip.

Question 10

The input to the ‘A’ solenoid is ___ and it receives power from DC bus ____.

Answer 10

P-12 ‘A’ Train
DC 113

Question 11

The input to the ‘B’ solenoid is ___ and it receives power from DC bus ____.

Answer 11

P-12 ‘B’ train
DC114

Question 12

The input to the ‘C’ solenoid is ___ and it receives power from DC bus ____.

Answer 12

Tave/Tref/no load Tave
DC113

Question 13

The input to the ‘D’ solenoid is ___ and it receives power from DC bus ____.

Answer 13

‘Steam press’ position
Load rejection C-7
A-train RTB/BYB open
-and- C-9
DC113

Question 14

There are _____ bypass interlock trn switch(es). The function of the off/reset position is____, the function of the on position is_____, and the function of the bypass position is_____.

Answer 14

2, train A and B
Off/reset blocks air to steam dump by de-energizing the A and B solenoids; also resets Lo-2 Tavg interlock being bypassed.
On- Steam dumps operate normally.
Bypass- Permits operation <550F using the 3 cooldown dumps, spring return to ‘on’.

Question 15

Purposes of steam dump system: (5)

Answer 15

1. Provide an artificial steam load
2. Remove 40% load without actuation of SG safeties after a reactor trip, and bring plant to equilibrium.
3. Control steam pressure at no-load conditions.
4. Used when transient exceeds rod control design of >10% step change.
5. Provide manual cooldown of plant.

Question 16

Function of A and B solenoids:

Answer 16

Prevents excessive cooldown
De-energizes to block air from passing; block auto clear >550F

Question 17

Function of C solenoid:
Normally ____ to pass air to D solenoid.
______ positioner on large error signals.
When_____ full IA changes stroke to ____ seconds.
Hi-1 bypasses groups ______
Hi-2 bypasses groups_______

Answer 17

Normally de-energized to pass air to D solenoid.
Bypasses positioner on large error signals.
When bypassed, full IA changes stroke to 3 seconds.
Hi-1 bypasses groups 1 and 2
Hi-2 bypasses groups 3 and 4

Question 18

Function of D solenoid:

Answer 18

Normally de-energized; energizes to ARM passing air to B solenoid.

Question 19

If the mode select switch is in STM PRESS, compares ____ to _____.

Answer 19

Validated 2nd highest steam pressure to desired steam pressure.

Question 20

Steam dump armed light will be caused by: (3 items)

Answer 20

C-9 -and any of the following-

‘Steam press’ position
Load rejection C-7
A-train RTB/BYB open

Question 21

Group 1 ____
Group 2 _____
Group 3 _____
Group 4 _____

Answer 21

1-A, E, J
2-B, F, K
3-C, G, L
4-D, H, M

Question 22

Steam dump valves are ___ to open and ____ to close.

Answer 22

Air
Spring

Question 23

_____Hi fast opens group __and ___ valves when on the load reject controller.

Answer 23

8.2F(7.4F) Hi fast opens group 1 and 2 valves

Question 24

_____ HiHi Fast opens group _ and _ valves when on the load reject controller.

Answer 24

13.4F(11.8F) HiHi Fast opens group 3 and 4 valves

Question 25

_____Hi fast opens group __and ___ valves when on the plant trip controller.

Answer 25

15F
groups 1 and 2 valves

Question 26

_____HiHi fast opens group __and ___ valves when on the plant trip controller.

Answer 26

30F
Groups 3 and 4

Question 27

Load reject controller controls at ____ above Tave and the plant trip controller controls at _____above Tave.

Answer 27

3F
0F

Question 28

The steam dump actuated light means that ______ and the steam dump armed light means that_____.

Answer 28

Any of the trip open temperature bistables has reached or exceeded its setpoint.

One of the arming circuits has armed the steam dumps.

Question 29

The reset position of the mode select switch _______.

Answer 29

Resets the C-7

Question 30

Normally steam dumps have a ___ second stroke time and will fast open in ____ seconds.

Answer 30

20
3

Question 31

Group __ valves are the cooldown valves and can cool the RCS to <_____.

Answer 31

1 (A, E, J)
<550F

Question 32

Load reject controller range from 0-100% demand is ____ and plant trip controller range from 0-100% demand is ______.
Load reject helpful hint:
Hint add 5.2 for hi 5.2 more for hi hi
Add4.4 for hi and 4.4 more for hi hi

Answer 32

10.4F (8.8F) (Accounts for the 3F at 0%)

30F

Question 33

PK-507 (steam pressure controller) normally set at ______ and output is ___% demand for each ___ psi error.

Answer 33

1092#
1% demand for each 1 psi error

Question 34

When is the Load Reject controller in service?

Answer 34

Steam Dumps in Tave Mode w/RTB or BYB closed

Question 35

If a single Bypass/Interlock switch is placed in OFF, how many steam dump valves will NOT be able to open?

Answer 35

12 (No valves can open)

Question 36

Loss of Instrument Bus 111:

Answer 36

Steam Dumps will not arm on a Load Reject (C-7)