RHR - 1.0

Question 1

What are the 7 functions of RHR? Which are primary and which are secondary functions?

Answer 1

1. LPCI - Primary
2. TORUS(SUPPRESSION POOL) COOLING - Primary
3. TORUS(SUPPRESSION POOL)/DRYWELL SPRAY - Primary
4. SHUTDOWN COOLING - Primary
5. FUEL POOL COOLING ASSIST - Secondary
6. ALTERNATE INJECTION - Secondary
7. CONTAINMENT FLOODING - Secondary

Question 2

Describe the purpose of the LPCI mode of operation and its automatic initiation signals.

Answer 2

System functions in conjunction with the other ECCS to restore and maintain reactor coolant inventory following a LOCA.

Initiation - Level 1(-129”) or 1.68# with the injection valve not opening until <450#

Question 3

Which RHR loops have the capacity to perform which modes in the RHR system?

Answer 3

LPCI - All 4
Suppression Pool(Torus) Cooling, Drywell spray and Torus Spray - A and B
Shutdown Cooling - A and B
Fuel Pool Cooling - A and B
Alternate Injection - B

Question 4

Describe the SUPPRESSION(TORUS) COOLING mode of operations purpose and its automatic initiation signals.

Answer 4

Heat must be removed from the suppression pool to ensure its ability to perform pressure suppression and to maintain containment integrity.

Manually initiated from 10C650A

Question 5

What can be used to maintain the ECCS keep fill if the jockey pump is unavailable?

Answer 5

Condensate fill and transfer

Question 6

on a loss of power what will happen to all of the valve/pumps that were overridden and closed/stopped?

Answer 6

the logic resets on a loss of power and all pumps and valves will reposition as though they were just initiated. This will require you to manually over ride everything that was previously overridden.

Question 7

What is the immediate action for a significant loss of fuel pool inventory?

Answer 7

1. Evacuate the refuel floor
2. return irradiated fuel assembly to the vessel or pool
3. lower any bundle in the fuel prep machine to the full down position

Question 8

What is the RHR Injection valve open permissive setpoint?

Answer 8

450 psig

Question 9

What is the RHR Injection shutoff discharge pressure?

Answer 9

366psig

Question 10

What is the RHR Injection flowrate?

Answer 10

10,000gpm

Question 11

What causes the RHR pumps to trip?

Answer 11

No suction path.

Question 12

What is important about the HX Bypass?

Answer 12

F048 will not respond to a shut signal for 3 minutes after initiation.

Question 13

What does a LOP do to F017?

Answer 13

LOP kills the Auto Open override to the F017’s.

Question 14

What are the different start sequences?

Answer 14

-LOCA w/ offsite power: A + B start at T=0; C + D start at T=5
- LOCA w/o offsite: All 4 start at T=0

Initiates LPCI mode when pumps start.

Question 15

What are the DW spray requirements?

Answer 15

To open F016 and F021 simultaneously (Open permissive):
- LPCI signal present.
- High DW pressure
- F017 shut.

Question 16

Describe operation of the RHR pump minimum flow valve TD’s.

Answer 16

1. Minimum Flow Valve Open [normally open] < 1,250 GPM (AND Pump brkr Closed AND 10 sec. T.D.)
2. Minimum Flow Valve Close > 1,270 GPM (AND 4 sec. T.D.)

Full explanation:
The minimum flow valve is normally open when the RHR System is in standby. The valve will automatically close when the pump is running for >4 seconds AND RHR pump flow exceeds 1270 GPM. If system flow lowers below 1250 GPM for ten seconds or more (with the pump breaker closed) the minimum flow valve will open.

Question 17

Describe the ADS pump running permissive signal.

Answer 17

ADS - RHR pump discharge pressure (greater than or equal to 125 psig) is utilized for verification of an available water source as a permissive for ADS Automatic blow down.

This permissive is required only for automatic initiation of ADS and is not required to manually initiate ADS.

Question 18

What channels of ADS are associated with which channels of RHR?

Answer 18

1. RHR pumps A and C input to ADS logic D, only one of the two pumps need be running as an initiation permissive.
2. RHR pumps B and D input to ADS logic B, only one of the two pumps need to be running as an initiation permissive.

Question 19

If an RHR pump is stopped via the the manual stop pushbutton will the pump autostart if a signal is received? Under what conditions will it autostart again?

Answer 19

Depressing STOP will override a pump auto start signal and trip the pump.

The override is lost if the associated 4.16KV bus power is lost. Thus, if the plant suffers a LOCA, and the auto-start override is enabled, the override would be lost during a subsequent LOP. When the EDG restores power to the bus, the pump will automatically start.

Question 20

What are the F008 & F009 interlocks? (SDC in service setpoints)

Answer 20

• Auto isolate at 12.5” or Rx Press ≥82#.
• Rx pressure must be <82# to open.

Question 21

What happens when LPCI is actuated?

Answer 21

a. The RHR pumps START (dependent upon power availability as previously discussed)

b. The following valves receive CLOSE signals:
1) Test Return Valves HV F010A,B; F024A,B
2) Suppression Pool Spray Valves HV F027A,B

c. The following valves receive OPEN signals:
1) RHR HX Bypass Valves HV F048A,B (for 3 min)
2) LPCI Injection Valves HV F017A-D (when reactor pressure lowers to less than 450 psig).

d. When the initiation signal is sealed-in, the white “A(B,C,D) INIT AND SEALED-IN” indication will be illuminated. Logic RESET PB is located adjacent to the indication on 10C650.

Question 22

What are F017 Interlocks?

Answer 22

• Opens at 450#
• F017 must be shut to open F016, F021, F024, or F027.

Question 23

What is required for F006 to be open permissive?

Answer 23

The following must be shut:
- F004
- F024
- F027

Question 24

What are the bases for the different modes of RHR?

Answer 24

1. LPCI - Restore and maintain RWL following a LOCA (ECCS function).
2. TORUS Cooling - Remove energy from the TORUS to maintain pressure suppression function.
3. TORUS/DW Spray - Remove energy from primary containment to maintain pressure suppression function.
4. SDC - Removes decay and sensible heat from nuclear boiler.
5. FPC Assist - Alternate means to remove decay heat.

Question 25

When do the RHR pumps auto start?

Answer 25

1. The RHR pumps will auto start in the LPCI mode of operation on 2 initiation signals: a) Hi Drywell Pressure: 1.68 psig b) Low Reactor Level: -129”

Question 26

What are the LCPI Injection Valves (F017A-D) ratings?

Answer 26

The LPCI injection valves (F017A, B, C, D) will NOT open without a valid initiation signal as sensed by it’s channels logic and a low Rx pressure condition of <450 psig: a) The shutoff head of RHR pump is 366 psig. b) Rated flow is 10,000 gpm at 171 psig

Question 27

What are the RHR flow paths?

Answer 27

1. The C & D pumps can only take suction from the torus. 2. The A and B pumps can be aligned for shutdown cooling or fuel pool cooling. a. In order to align RHR for fuel pool cooling, the suction valve trip interlocks must be overridden using switch S66A(B) on C617(8) in the lower control equipment room. b. In general, to establish a suction path, either the torus suction valve (F004) must be open or the shutdown cooling flow path must be established (F008, F009, F006, must all be open for A and B pumps, otherwise they trip [unless FPC mode byp switch in BYP]).

Question 28

Describe the operation of the RHR pump start interlock.

Answer 28

Depressing the RHR pump STOP will o/r a pump auto start signal and trip the pump. This o/r is lost if the associated 4.16kv bus power is lost. Thus if the plant suffers a LOCA and the auto-start o/r is enabled, the o/r would be lost during a subsequent LOP. When the EDG restores power to the bus, the pump will start.

Question 29

What are the F004 valve interlock?

Answer 29

The torus suction valves (F004A or B) are interlocked such that they CANNOT be opened unless the RHR pump shutdown cooling suction valve (F006A or B) are full closed and vice versa. (Prevents draining the Rx vessel to the torus.) a) F004 does not ever automatically reposition

Question 30

What are the F006 interlocks?

Answer 30

2. In order to open the SD cooling suction valve (F006), the following must be full closed (All communications to the torus): a) F004 – RHR pump torus suction b) F024 – Pump test return to the torus c) F027 – Torus spray isolation (This interlock is not reciprocated by F027)

Question 31

What is the interlock for valves F008/009?

Answer 31

In order to open RHR S/D cooling isolation valves (F008/9) reactor pressure must be <82 psig regardless of where these valves are controlled from.

Question 32

The following valves will CLOSE in response to ANY of the conditions listed which exist concurrently in Ch A & B of NS4 or Ch A (inboard) Manual isolation:

Answer 32

1. HV-F009* Shutdown Cooling Inboard Suction [A channel AC valve] a. Low RPV Level 3 (+12.5”) (Needs 2 transmitters) b. High Rx Pressure (82 psig (rising) (SINGLE coincidence – existing in Channel A or B) 2. HV-F079A/B RHR Sample Inboard Isolation, HV-F049 RHR Discharge to Radwaste Inboard Isolation a. Low RPV Level 3 (+12.5”) b. High Drywell Pressure (1.68#)

Question 33

The following valves will CLOSE in response to ANY of the conditions listed which exist concurrently in Ch C & D of NS4 or Ch D (outboard) MANUAL isolation:

Answer 33

1) HV-F015A* & B* shutdown cooling return valves; HV-F008* [D channel AC vavle] shutdown cooling outboard suction. a. Low RPV LEVEL 3 (+12.5”)(needs 2 transmitters) b. High Rx Press. (82 psig (rising)) (single coincidence - existing in Channel C or D) 2) HV-F080A,B RHR sample outboard isolation; HV-F040, RHR discharge to Radwaste outboard isolation. a. Low RPV LEVEL 3 (+12.5”) b. High Drywell pressure (1.68#) *However, if valve control is at the RSP/Local the valves will not reclose if Rx pressure rises above 82 psig.

Question 34

Describe the operation of the F007.

Answer 34

The RHR min flow valves (F007's) are normally open (ALL LOW PRESSURE ECCS PUMP MIN FLOW VALVES ARE NORMALLY OPEN. HPCI/RCIC HIGH PRESSURE MIN FLOW VALVES ARE NORMALLY CLOSED) and will automatically close once RHR pump flow exceeds 1270 gpm with a 4 second time delay. If system flow decreases below 1250 gpm for > 10 sec* with the pump breaker closed the valve will reopen. a) *If the min flow valve is closed when the RHR pump is stopped, the valve will remain closed and will have to be positioned by the operator. The min flow valve is normally closed and breaker tagged open during outages.

Question 35

What are the F048 valve operations?

Answer 35

The RHR heat exchanger bypass valves (F048) receive an open signal upon receipt of a LPCI initiation signal. This initiation signal is sealed in for 3 minutes. Control of F048B from the RSP or control of F048A from it's MCC bypasses the 3 minute interlock and removes all automatic operation of these valves.

Question 36

Describe the F024 and F010 valve operations.

Answer 36

The RHR loop test return valves (F024's & F010's) will auto close in response to an automatic or manually initiated LPCI injection signal. In addition, F024 cannot be opened unless the associated F006 valve is full closed, and vice versa (prevent draining the reactor to the torus). The F024 can be reopened by using the Auto Close Override provided the initiation signal is in and F017 is shut. F024 does nothing on LOP

Question 37

Describe the F027 valve ops.

Answer 37

The RHR torus spray isolation valves (F027's) will automatically close in response to a LPCI initiation. It can be reopened by using the Auto Close Override. In addition, F027 must be full closed to allow the opening of F006 (However, F027 does not reciprocate this interlock). a) The following must be satisfied in order to open using the AUTO CLOSE OVERRIDE: 1. Initiation Signal Present [1.68 COUNTS] 2. DW Pressure > 1.68# 3. F017 Closed

Question 38

Describe the F017 valve ops.

Answer 38

The LPCI injection valves (F017's) will auto open in response to an initiation signal if the following conditions exist: a) LPCI initiation signal present in proper channel. b) Power available on proper RHR pump bus (no UV). c) Rx pressure is < 450 psig.(sensed by Lo D/P across F041 LPCI check valve) Additionally, the auto open signal can be overridden if the AUTO OPEN OVERRIDE P.B. is depressed. The injection valve must be full closed with a LPCI initiation signal present in order to open F027, F024, or F016/F021.

Question 39

What are the F016 and F021 interlocks?

Answer 39

The containment spray valves (F016 & 21) cannot be opened simultaneously unless all conditions are present to allow for a containment spray. The following must be met in order to spray the drywell/torus: a) A valid LPCI initiation signal is present. b) High drywell pressure > 1.68 psig. c) LPCI injection valve (F017's) full closed. (Auto Open Ovrd)

Question 40

What happens to F048 during TORUS cooling mode?

Answer 40

During SP cooling, the HX bypass valve is closed. If another LOCA signal comes in while you are in this lineup (without resetting the first), the valve remains closed. If all operator actions are complete per zz-001, F017 is overridden closed and will not open on receipt of new LPCI signal.

Question 41

What happens to the Suction Path Trip during shutdown cooling mode?

Answer 41

While in SDC, the Suction Path Trip for the RHR pump is bypassed. This is done in SO.BC-2 immediately AFTER the pump start, so, it can be assumed that if you are in SDC mode, the pump suction trip no longer exists. Additionally, the interlock is removed just BEFORE removing the pump from service. a) This override is taken away RIGHT BEFORE the pump is secured b) The switch is called FPC MODE SUCT VLV CLOSURE TRIP OVERRIDE

Question 42

What is done to NSSSS during Cold Shutdown to refueling?

Answer 42

In IO.ZZ-5 (Cold Shutdown to Refueling) the NS4 isolations to F008/9/15a/b are defeated immediately after the head is removed (just before flood-up) and are restored immediately before the head is installed in IO.ZZ-1 (Refueling to CSD).

Question 43

What are the DC power supplies and associated loads?

Answer 43

DC Power 1A(C)D417 A(C) Logic Power Supply / pump & MOV breaker ctrl power 1B(D)D417 B(D) Logic Power Supply / pump & MOV breaker ctrl power