Main Steam

Question 1

How many Atmospheric Dump Valves are available for Heat Removal if PKC loses power?

Answer 1

2 ADV’s

The Permissive circuits are powered from PKA, PKB,
PKC or PKD. Each power supply supplies two
switches, impacting two ADVs.

Question 2

How many Atmospheric Dump Valves are available for Heat Removal if PNB loses power?

Answer 2

2 ADV’s

Loss of PNA or PNB – two ADVs failed closed

Question 3

How many Atmospheric Dump Valves are available for Heat Removal if PNC loses power?

Answer 3

4

Atmospheric Dump Valves (SG1 178/184, SG2 179/185)

MCR Controllers powered from PNA/PNB (120Vac)

Loss of PNA or PNB – two ADVs failed closed

Question 4

What are the setpoints for the Main Steam Safety Valves?

Answer 4

Main Steam Safety Valves
5 per steam line (setpoint A/L 1%, A/F 3% per Tech Spec bases)
o 1st – 1250 psig
o 2nd – 1290 psig
o 3-5th – 1315 psig

Question 5

What powers MSIVs (SG1 – 170/180, SG2 – 171/181)?

How do the MSIV’s fail on loss of power?

Answer 5

Power supplies (125Vdc):
* Normal: directly from the battery (PKA or PKB).
* Back-up: from the bus (PKA or PKB).

Selected by closing breakers on the PK bus.

• Loss of power: fails closed.

Question 6

Does the MSIV/FWIV “Exercise” test switch fast close or slow close?

Answer 6

Exercise/Test switches (MSIVs/FWIVs)
* Exercise: valve will slow close using hydraulic pump discharge. At 90%, limit switch causes it to slow open.

Question 7

What does the MSIV/FWIV “ACC CH TEST” switch do?

Answer 7

ACC CH TEST: actuator system is lined up to discharge the associated accumulator to the hydraulic reservoir so that the accumulator N2 pre-charge pressure can be checked without causing valve movement.

Question 8

How far open do you have to open the ADV controller to come off the seat?

Answer 8

30% controller output required to start opening the ADV (overcomes bonnet pressure)

Question 9

What does 0% NR correlate to on WR for Steam Generator Level?

Answer 9

60% WR
(Top of U-tubes (~24% NR))

Question 10

MSIVs (SG1 – 170/180, SG2 – 171/181)
* Loss of power
* Loss of IA only
* Loss of IA and air reservoir

Answer 10

• Loss of power: fails closed.
• Loss of IA only: does not change position, remains capable of Fast Closing with air reservoir.
• Loss of IA and air reservoir: fails as is, cannot fast close

Question 11

Downcomer Isolation Valves (SG1 130/172, SG2 135/175)

• Loss of power (PK):
• Loss of all pneumatic pressure (air, N2, & accumulator):

Answer 11

• Loss of power (PK): fail OPEN (allows AFN to feed SGs)
• Loss of all pneumatic pressure (air, N2, & accumulator): fail closed

Question 12

What is the pneumatic force for Downcomer Isolation Valves (SG1 130/172, SG2 135/175)?

Answer 12

Pneumatically-operated by N2
sized for 8 hours of backup