Primary systems

Question 1

The Pressurizer Pressure control system is designed to provide satisfactory operations without a Reactor trip during what load transients?

Answer 1

-Loading or unloading at 5% of full power per minute
-Step load change of +/- 10% with automatic rod control
-Step load reduction of 95% of full power with automatic rod control and steam dump operation.

Question 2

Which Selected Pressurizer Pressure channel blocks PZR PORV (NC-32B & NC-36B) at 2177 psig.

Answer 2

Selected Pressurizer Pressure - 1

Question 3

What is total core bypass flow? Where Does it go?

Answer 3

7.5%
-Head Cooling 4%
-Control Rod and Instrument Thimble 2%
-Nozzle flow 1%
-Baffle flow .5%

Question 4

How many NR T-Hot thermowells? Why?

Answer 4

3 per loop
Located in Hot Leg (laminar flow)

Question 5

How many NR T-Cold thermowells? Why?

Answer 5

1 per loop
Located at the discharge of the NCP (turbulent flow)

Question 6

How is flow provided through the PZR?

Answer 6

By D/P across the core and the spray line suctions

Question 7

PZR Purpose

Answer 7

Provide a point in the NCS where liquid and vapor is maintained saturated to provide pressure control and accommodate positive and negative surges caused by load transients
**Overpressure control

Question 8

How many PZR PORVs?

Answer 8

3
NC-32B, 34A and 36B
Air operated
Each with an associated block valve

Question 9

How many PZR Safeties and their setpoint?

Answer 9

3
NC-1,2 and 3
set at 2485#

Question 10

PZR PORV Power Supplies

Answer 10

NC-34A EPA
NC-32B EDF
NC-36B EDF

Question 11

How is Loop Flow Sensed?

Answer 11

-3 d/p transmitter connected across the elbow of the crossover piping
-Share a common penetration on outside elbow (HP side)
-Each transmitter has its own penetration on the inside elbow (LP side)
-Flow increase = d/p increase
-System design flow = 101,000gpm per NCP

Question 12

What is Hot Zero Power Specs (Both Units)?

Answer 12

Pressure - 2235#
PZR Temp - 653F
Loop Th - 557F
Loop Tc - 557F
Tavg - 557F

Question 13

What is Hot Full Power Specs (Unit 1)?

Answer 13

Pressure - 2235#
PZR Temp - 653F
Loop Th - 615.9F
Loop Tc - 554.3F
Tavg - 585.1F

Question 14

What is Hot Full Power Specs (Unit 2)?

Answer 14

Pressure - 2235#
PZR Temp - 653F
Loop Th - 616.7F
Loop Tc - 558.3F
Tavg - 587.5F

Question 15

What is PZR Insurge?

Answer 15

-PZR Temp > NCS Temp
-Charging increased or loops heat up then cold water will surge into PZR
-Could lead to severe stratification of the lower head
-Potential for high stress when hot metal is cooled rapidly
-Counteracted by outsurge (use of heaters and spray)

Question 16

Why is there a .5gpm bypass flow around spray line?

Answer 16

Reduce thermal stress on spray piping and nozzle

Question 17

What temperature differential between PZR and spray fluid shall spray flow not be used?

Answer 17

> 320F

Question 18

What is PZR Outsurge?

Answer 18

-Occurs when NCS coolant temps lower
-Steam volume expands causing pressure to start to lower
-Flashing of water to steam limits the pressure drop

Question 19

How is NC-34A PORV Operated? What is its setpoints?

Answer 19

-Operated automatically by PZR pressure Master
-Lifts 100# above pressure setpoint and recloses at 80# above setpoint
-Manual Operation on MCB and ASP-A
-Auto controls blocked when transferred to ASP

Question 20

NC-32B and NC-36B Setpoints

Answer 20

-Lift at 2335# and reclose at 2327#
-Manual operation from MCB and ASP-B
-Auto controls blocked when transferred to ASP

Question 21

At what pressure are all PORVs Blocked?

Answer 21

2177#
**Manual control still available

Question 22

How do you isolate a PORV using its block valve?

Answer 22

Place the block valve switch into the close position
**Interlocked that only first valve placed in “close” will close (Remaining valves must be placed in “override: to close)

Question 23

When is LTOP used? Why?

Answer 23

<300F (and “Low Press” selected)
Brittle Fracture

Question 24

What PORVS are used during LTOP and what are setpoints?

Answer 24

NC-34A and 32B
400#

Question 25

PORV response with loss of VI

Answer 25

-NC-32B and 34A can use N2 from CLA B and A respectively **CLA N2 automatically aligned when LTOP selected -NC-36B will not function without VI (No N2 Backup)

Question 26

What is reduced inventory level?

Answer 26

Less than 16% with fuel in the core

Question 27

What is Mid-Loop Level?

Answer 27

at or below 7.25% NC Level **2 specified incore thermocouples required to be functional **2 redundant and independent level indications must be operating below 16% WR NC Level **One Hot leg shall be maintained with no nozzle dam for venting **One NI pump must be available before establishing an NC vent path **One Gravity flow path must be available