instrument and control failure analysis

Question 1

What will happen if LT-112 fails low?

What will happen if LT-112 fails hi?

Answer 1

low

• auto makeup starts
• actual level will rise
• LCV-112a will mod open (from LT-114)
• if makeup > letdown, VCT overfill (relief valve)

hi

• makeup not start
• LCV-112a will trip open
• actual level lowers
• RWST swap will not happen (2/2 logic low)
• CCP loose suction

Question 2

What happens if LT-114 fails Hi?

What happens if LT-114 fails Lo?

Answer 2

Hi

• LCV-112a will modulate open
• actual level will lower
• @ 14% makeup will actuate
• makeup > letdown
• level will cycle between 14-24%

Lo

• alarm on low level

Question 3

How is SCMM (subcooling margin monitor) calculate subcooling?

Answer 3

• hottest CET
• RCS T_hot
• RCS Press (PT-405, 403)
• calculates subcooling based on hottest temp and lowest pressure