Residual Heat Removal

Question 1

What are the Safety Related functions of RHR?

Answer 1

• Transfer heat from the RCS to the CCW system via the RHR HX’s. (Forced cooldown)
• Used as a part of ECCS.
• Used as a part of CTS.
• Provides RCS LTOP during shutdown conditions. (450# relief)

Question 2

What are the RHR pump auto starts?

Answer 2

• SI (Train Specific)
• Load shed with SI (Train Specific)

Question 3

What are the RHR pump trips?

Answer 3

• Load shed
• RWST Lo-Lo (9.6%) with respective suction valve open (IMO-310/320)
• Overcurrent
• Overload

Question 4

What are the requirements to open IMO-128/ICM-129? (RCS Loop 2 Hot Leg to RHR Suction)

Answer 4

To open these valves, RCS # must be < 410#
- NPS-122 -> IMO-128
- NPS-121 -> ICM-129

Question 5

What is the setpoint for SV-103 (RHR Suction relief valve) and what is its purpose?

Answer 5

• 450# at 900gpm
• Provides LTOP and RHR suction overpressure protection

Question 6

What is the setpoint for IMO-312/322? (RHR pump recirc valves)

Answer 6

Open and Close:
- Unit 1: 820gpm and 1335gpm
- Unit 2: 900gpm and 1500gpm

Question 7

What are the fail positions for the air operated valves in the RHR system?

Answer 7

• IRV-311 (RHR HX Bypass Flow Control Vlv) -> Fail Open
• IRV-310/320 (RHR HX Outlet Recirc Line Shutoff) -> Fail Open
• IRV-300 (RHR HX to CVCS Demin Shutoff) -> Fail Closed

Question 8

What is ICM-305/306?

Answer 8

Recirc Sump to RHR/CTS Pump Suction Valves

Question 9

What is IMO-340/350?

Answer 9

East/West RHR HX to CCP/SI Pump Suction Valves.

Question 10

What is IMO-330/331?

Answer 10

East/West RHR Spray Supply Valves

Question 11

What is IMO-310/320?

Answer 11

East/West RHR Pump Suction Valves

Question 12

What is IMO-215/225?

Answer 12

RWST to East/West CTS Pump Suction Valves

Question 13

What is IMO-262 and -263?

Answer 13

CCP to SI Pump Suction X-Connect Valves

Question 14

What are the interlocks to open ICM-305/306?

Answer 14

• IMO-310/320 Closed
• IMO-215/225 Closed

Question 15

What are the interlocks to open IMO-340/350?

Answer 15

• ICM-305/306 Open
• IMO-262 OR 263 Closed

Question 16

What are the interlocks to open IMO-330/331?

Answer 16

• ICM-305/306 Open

Question 17

What are the interlocks to open IMO-310/320?

Answer 17

• ICM-305/306 Closed
• IMO-340/350 Closed
• IMO-330/331 Closed

Question 18

What prevents dead heading an RHR pump (weak pump) during the injection phase following a LOCA?

Answer 18

Check valves between the tee for the RHR pump recirc valve and the tee for RHR spray and IRV-310/320.

Question 19

What level is Reduced Inventory?

Answer 19

618’ 1.5”

Question 20

What level is Mid Loop?

Answer 20

614’

Question 21

What does Hot Leg Recirc do for the RCS?

Answer 21

Prevents boron precipitation is the RX Vessel.

Question 22

When can RHR be placed in service following a RX Shutdown?

Answer 22

• RCS# less than or equal to 400#
• RCS Temp < 350F

Question 23

What are the time restrictions for transferring to Hot Leg Recirc and why?

Answer 23

• Minimum: 5.5 Hours, to avoid core uncovery due to high decay heat.
• Maximum: 7.5 Hours, to prevent boron precipitation in the RX vessel head.

Question 24

Why must RHR Loop Injection Valves be closed prior to aligning RHR Spray?

Answer 24

Prevent RHR pump run-out.

Question 25

How many RHR pumps can be ran at Reduced Inventory and why?

Answer 25

• One
• Prevents air entrapment due to vortexing at the suction.

Question 26

Upon SI, what does the CCW outlet of the RHR HX throttle to? (CMO-419/429)

Answer 26

3000-3500 gpm

Question 27

What is the purpose of Hot Sleeve Fans?

Answer 27

Cools concrete around containment penetrations to prevent dryout.

Question 28

What is the LCO requirement for RCS Loops in MODE 4? (LCO 3.4.6)

Answer 28

Two loops consisting of any combination of RCS loops and RHR loops shall be OPERABLE, and one loop shall be in operation.

Question 29

What 1 hour or less actions are required if one required tech spec loop is INOPERABLE while in MODE 4?

Answer 29

• Initiate action to restore a second loop IMMEDIATELY.

Question 30

What 1 hour or less actions are required if two required tech spec loops are inoperable OR the required loop is not in operation?

Answer 30

• Suspend ops that would cause introduction of coolant < required boron concentration IMMEDIATELY
  AND
• Initiate action to restore one loop to OPERABLE status and operation IMMEDIATELY

Question 31

What is the LCO requirement for RCS Loops in MODE 5, Loops Filled? (LCO 3.4.7)

Answer 31

One RHR loop shall be OPERABLE and in operation, and either:
- One additional RHR loop shall be operable
OR
- SGWL of 2 S/G’s shall be above the lower tap of the wide range instrumentation by greater than or equal to 420 inches.

Question 32

What is the LCO requirement for RCS Loops in MODE 5, Loops NOT Filled? (LCO 3.4.8)

Answer 32

Two RHR loops shall be OPERABLE and one RHR loop shall be in service.