Steam Dump System

Question 1

Purpose of the Steam Dump system

Answer 1

• After reactor trip this system reduces Tavg to 547F (no-load value) without actuation of the S/G safeties
• Following load rejection, reduces Tavg to within 5F of Tref, then the Rod Control System will take over to reduce Tavg to 1F of Tref in rods are in auto
• When placing the plant in cold shutdown, used to cool down the plant until it can be placed on RHR.

Question 2

Valves are divided into? Each provide how much steam capacity?

Answer 2

• Bank 1 provide a total of 24% (At a 10% Load rejection)
• Bank 2 provide a total of 16% (At a 10% load rejection)
• Bank 4 provide a total of 17% (50% load rejection)

Question 3

Bank 4 is special because?

Answer 3

• Bank 4 is comprised of the S/G PORVs
• Only controlled by steam dump controller with a 50% load rejection.
• The steam dump controller will activate the S/G PORVs only if the turbine is not tripped

Question 4

PORVS are what kind of valve?

Answer 4

• AOVs,
• Normal supply of control gas is from IA
• Backup supply from the Steam dump Nitrogen System

Question 5

Steam Dump Spray line valves off of the condensate system open when?

Answer 5

-Open when we use the steam dump system.