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Systems > CRD Hydraulic > Flashcards

CRD Hydraulic Flashcards

1
Q

What is the purpose of CRD Hydraulics?

A

Provides the motive force for positioning the CRD’s under all conditions (including SCRAM)

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2
Q

What are the 4 headers for the CRD System?

A

Charging Water Header, Drive Water Header, Cooling Water Header, Exhaust Water Header

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3
Q

What is the suction source for the CRD System?

A

Hotwell Reject

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4
Q

What is the flow path from source to FCV? & how many of each components

A

Hotwell Reject, suction filter (2; 1 in service), pump (2; 1 in service); Drive filter (2; 1 in service); Flow Element; FCV

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5
Q

How many suction filters are there and how many are normally in service?

A

2 total, 1 in service

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6
Q

Which suction filter can the “A” CRD pump take suction from?

A

Either, there is a crossing line between such that either suction filter can lead to either CRD pump

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7
Q

Where are the suction filters?

A

TB 495

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8
Q

Where are the CRD Pumps and how many are there?

A

TB 495, 2

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9
Q

What is the purpose of the CRD Crosstie, and where is it?

A

Allows for opposite unit CRD operation in EMERGENCY situation. Off mezz TB 549 (by freight elevator)

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10
Q

Where in line does the CRD Unit cross tie branch?

A

After Pumps, before Drive Water FIlters

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11
Q

Where are the drive water filters?

A

After Pumps, located RB 517

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12
Q

Where in line does the Recirc Pump Seal Purge take suction?

A

Downstream of Drivewater Filter, upstream of Flow element

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13
Q

What are the alternate flow paths for the CRD system (other than associated with CRDs)?

A

Head Spray, Recirc Seal Purge, Unit Cross Tie, RWVLIS

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14
Q

What is the flow to Recirc Seal Purge

A

2gpm (indicated at Corner Room Mezz)

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15
Q

What is RWVLIS Support from CRD?

A

Provides 0.5gph/line (4) into level sensing reference leg to flush noncondensibles

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16
Q

When does CRD Support Headspray?

A

During Shutdown and Hydro

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17
Q

What is the normal system flow rate?

A

~60gpm

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18
Q

What is the normal suction rate from hotwell reject?

A

~110gpm

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19
Q

How many minflow lines are there?

A

Two, 1 back to CST 1 back to hotwell reject

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20
Q

What flow rate is accounted for in minflow lines?

A

30gpm in one, 20 gpm in another

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21
Q

What are the power supplies for the CRD pumps?

A

Bus 23(33) (Div I) and 24(34) (Div II)

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22
Q

What provides cooling for the CRD Pumps?

A

TBCCW cools the oil cooler and thrust bearing; backup from service water

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23
Q

What initiating action transfers TBCCW cooling to SW for CRD pumps?

A

Manual swap only

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24
Q

How many drive filters are normally in service?

A

1

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25
Q

Can the Drive Water Filter provide MCR alarm?

A

Yes. DP of 20psid. can crush the cartridge if too high.

usually caused by backflow for cleaning

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26
Q

After a Scram what is the charging header flow rate?
What component limits the flow, and why?
What is the position of the FCV? Why?

A

179gpm at 0psig reactor pressure.
Restricting Orifice, to prevent pump runout.
Closed, because Flow Element senses full flow and tries to correct through FCV, but the charging line still sees full flow and unaffect by FCV.

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27
Q

How many Flow Control Valves are present and how are they configured?

A

2, one in operation, one in standby

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28
Q

How does the FCV fail?

A

Fail Closed on loss of Instrument Air.

May fail open or closed on loss of signal

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29
Q

Normal flow setpoint through FCV?

A

~60gpm

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30
Q

What pressure does the PCV try to maintain?

A

260psid; too high can cause double notching

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31
Q

What is the number for the CRD PCV?

A

8 valve

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32
Q

What is the impact on the drive water and cooling water pressure by closing the PCV?

A

Raise drive water pressure will lower the cooling water pressure.

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33
Q

What is the required (TS) pressure for the drive accumulators?

A

940psig

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34
Q

Which valves open to drive rods in (normally)?

A

121 and 123 valves (odd)

35
Q

Which valves open to drive rods out?

A

120 and 122 (Evens go out)

36
Q

What is normal pressure for the cooling water line?

A

18 - 37psid

37
Q

What is alarm setpoint for CRD mechanism?

A

250F

38
Q

What is the affect of high temperatures?

A

degradation to drive seals

39
Q

What is the purpose of the stabilizing valves?

A

Provides system flow stability when insterting and withdrawing CRD

40
Q

What is the stab valve flow during insertion?

A

4gpm

41
Q

What is the stab valve flow for withdrawal?

A

2gpm

42
Q

What is the power source for the Stabilizing valves?

A

RMCS

43
Q

What is the purpose of the Scram Discharge Volume?

A

Receives and contains all water exhausted during scram

44
Q

Where does the SDV drain to?

A

Scram instrument volume

45
Q

Where does the SIV drain to?

A

RBEDT

46
Q

Where are the SIV’s

A

SDC Pump room, TIP room

47
Q

What is the position of the SDV vent and drain valves normally? on a scram?

A

Normally Open, close on a scram (air to open, spring to close valves)

48
Q

How are the SDV vent and drain valves controlled?

A

Each vent and drain valve held open by IA through solenoid operated pilot valves powerd from instrument bus. Piplot valves normally de-energized allowing IA to keep valves open.

49
Q

How many level switches are installed on SIV?

A

6

50
Q

What are the level switches for each of the SIVs?

A

U2 - 4 thermal, 2 DP; U3 - all 4 DP

51
Q

What are the SIV Level Alarms and signals?

A

1) 10 gallons - VOLUME NOT DRAINED
2) 25 for U2 (19 for U3) - Rod Block - SDV High Level
3) RPS Trip Signals

52
Q

What are the SIV Thermal Switches powered by?

A

A&B RPS

53
Q

What are the SIV Level Switches powered by?

A

24/48 vDC 2A & 2B

54
Q

TS CRD Hydraulic - What is required for the SDV/SIV to be operable?

A

Vents and Drains must be able to be opened and closed.

55
Q

Power Source for Scram Pilot Valves?

A

117 - RPS A, 118 - RPS B

56
Q

What causes CRD Pump Trips?

A

Suction Filter Pressure
Overcurrent
Undervoltage

57
Q

What are the 19A/B valves and what do they do?

A

Backup Scram Valves - provide means to isolate air and bleed air from scram valves following scram signal. minimize effect of malfunctioning scram pilot valve.

58
Q

Power for the backup scram valves (19A/B)

A

19A - 125vdc 2A-1; 19B - 125vdc 2B-1

59
Q

What are the Scram Dump Valves and waht do they do?

A

20A/B valves - 3 way solenoid valve to bleed air off air header feeding SDV and drains following scram signal.

60
Q

Position of Scram Dupm Valves (20A/B) Normally? Scram?

A

Normally Energized - De-energized on scram

61
Q

What happens if Scram dump valves fail to de-energize on a Scram?

A

SIV vents and drains remain open, allowing high rad, post accident Rx water to be released into secondary containment via RBEDT.

62
Q

Power source for Scram Dump Valves 20A/B?

A

20A - RPS Bus A; 20B - RPS Bus B

63
Q

What is ARI?

A

Alternate Rod Insertion - 6 three way solenoid actuate valves block air supply and/or vent scram air header, causing all 177 scram inlet/outlet valves to open and SDV/SIV vents and drains to close.

64
Q

What is condition of Recirc Pumps following manual ATWS initiation?

A

Running - Manual initiation does not trip recirc pumps

65
Q

What are the power sources to the ARI valves?

A

Div I - 125vdc 2A-2; DIv II - 125vdc 2B-2 (through RR control power)

66
Q

ATWS Initiation Signals?

A

Rx Pressure High (1250psig)
Rx Low Water Level (-59inces)
Manual

67
Q

What is the power source for the CRD directional valves?

A

Instrument Bus

68
Q

What is the normal CRD speed?

A

3in/second

69
Q

Which is larger: underpiston or overpiston area?

A

Underpiston

70
Q

What is the Scram water flow path?

A

Charging Water from accumulator sent to underpiston area through 126 valve and overpiston area exhausted out 127 valve to SDV.

71
Q

Which must open first: Scram inlet or scram outlet valve?

A

Scram outlet to allow for a water exhaust pathway.

72
Q

What is signal received during a scram- how will it display in the CR??

A

When both scram valves open, a red rod scram signal on full core display illuminates.

73
Q

What are the accumulator alarms?

A

High Water (1.5 inches on nitrogen side) ; low pressure <980psig

74
Q

What will cause a rod drift in?

A

Leaking inlet/outlet valves

High cooling flow/pressure

75
Q

What is the trip setpoint for CRD Pump Suction Pressure? alarm?

A

18inHg vacuum; 13 inHg alarm

76
Q

What happens with two or more accumulator alarms?

A

Rod Block

77
Q

Purpose of RMCS?

A

Provides signal to HCUs to control directional valves for normal rod control.

78
Q

What happens to CRD system on loss of 125vdc bus?

A

Depending on bus lost, one or more backup scram valves or ARI may not energize to operate; YOU ONLY NEED ONE backup SCRAM or ARI valve to depressurize the air header.

79
Q

If The CRD Hydraulic FCV fails open during shutdown, what will hapen?

A

RPV level will rise

80
Q

What happens to FCV with a leak upstream of Flow element?

A

FCV goes open

81
Q

What happens to FCV with leak downstream of Flow element?

A

FCV goes closed.

82
Q

What is the impact of the SDV being full?

A

Potential for hydraulic lock or overpressure during scram

83
Q

If the drive seals are worn, will you need higher, lower, or the same amount of pressure to move the rod?

A

Higher due to leakby.

Systems (97 decks)

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