Steam Dumps (RQ-C-4742)

Question 1

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

Answer 1

• Auctioneered High Tavg

Question 2

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

Answer 2

• Group 1 only

Question 3

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

Answer 3

• Groups I and II

Question 4

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

Answer 4

• Groups I, II, and III

Question 5

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

Answer 5

• Auctioneered High Tavg - Tno-load

Question 6

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

Answer 6

• Auctioneered High Tavg - Tref

Question 7

*** 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.

Answer 7

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

Question 8

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

Answer 8

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

Question 9

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

Answer 9

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

Question 10

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

Answer 10

• 5°F