AOP-13 LOSS OF PREFERRED AC BUS EY-20

Question 1

What are the entry conditions for AOP-13, Loss of Y-20?

Answer 1

EK-0545, “PREFERRED AC BUS NO 2 TROUBLE”

AND

Channel ‘B’ RPS Trip Ladder Logic Lights Illuminated

Question 2

Besides entry conditions, what are some indicators of a loss of Y20?

Answer 2

• Lowering Main Feedwater Pump suction pressure
• Maximum Charging and Letdown Isolated (if Channel ‘B’ PLCS selected)
• Auxiliary Feed Pump P-8C trips (if operating)

Question 3

What are the reactor trip criteria of AOP-13, Loss of Y-20?

Answer 3

CV-0710, Feed Pump P-1B Recirculation Valve, fails open with Reactor power greater
than 80%

Question 4

What are the Automatic Actions of AOP-13, Loss of Y-20?

Answer 4

Main Feedwater control for E-50B, ‘B’ S/G, transfers to EY-40, Preferred AC
Bus No 4.

Question 5

What are the immediate actions of AOP-13, Loss of Y-20?

Answer 5

none

Question 6

If the reactor is less than 15% power, why don’t you isolate CV-0710, Feed Pump P-1B
Recirculation?

Answer 6

Not necessary below 80% power.

Would cause deadheading of the pump.