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Flashcards in Safety Injection System Deck (50)

What is the purpose of the Safety Injection System?

  1. Inject borated water into PCS to keep the core covered.
  2. Inject borated water into Primary Coolant System to raise shutdown margin.
  3. Remove core heat for extended period of time by keeping core covered via Recirculation and Once-Through-Cooling out the break.
  4. Provide flushing flow via simultaneous Hot/Cold Leg injection.
  5. Remove heat from PCS during normal Shutdown Cooling operations.
  6. Transfer refueling water


What is the operational design of SIS?

Originally designed to prevent fuel and cladding damage that could interfere with adequate emergency core cooling, and to limit the cladding-water reaction to less than 1% following DBA LOCA.

Also functions to provide rapid injection of large quantities of borated water for added shutdown capability during rapid cooldown of the primary system from a main steam line break.



When is the design basis of the SIS met?

Design bases met:

3 of 4 SITs

1-HPSI Pump

1-LPSI Pump

1 D/G

and 25% spillage of SI flow assumed to go out the break to the Containment.


What are minimum tank levels assosicated with SIRW?

DWO-1  in MODE 1, 2, or 3 requires;

  • T-58 volume greater than or equal to 275,970 gallons (92%).

LCO 3.5.4 in Modes 1,2 and 3 requires;

  • 250,000 gallons is based on two factors:       
    • At least 20 minutes of full flow from one train of ESF pumps prior to reaching a low level switch over to the containment sump
    • The containment sump water volume must be sufficient to support continued ESF pump operation after the switch over to recirculation occurs. 

Twenty minutes is the point at which approximately 75% of the design flow of one HPSI pump is capable of meeting or exceeding the decay heat boil off rate

Minimum in MODE 4 is 200,000 gallons (67%)


What is the SIRW boron concentration limit?

LCO 3.5.4

  • Max - 2500 ppm
  • Min - 1720 ppm

Maximum is based on time before the requirement to establish simultaneous hot and cold leg injection due to boron precipitation in the upper core region.

Minimum is based on the reactor remaining subcritical in the cold condition following mixing of the SIRWT, Safety Injection Tanks, and PCS water volumes


What are the SIRW temperature limits?

Maximum - 100°F

Minimum - 40°F

Preferred band is 85-90°F. 

Maximum is based on exceeding 100°F resulting in higher containment pressure due to reduced containment spray cooling capacity.

Minimum temperature limit of 40ºF was selected to maintain a small margin above freezing.


What are the SIRWT outlet valves?

CV-3031, CV-3057 (SIRWT Outlet Valves)


  • CV-3031 supplies west engineered safeguards
  • CV-3057 supplies east engineered safeguards

Motive Forece

  • High Pressure air with Instrument Air backup. Fail As Is


  • C-03 - Keylock Handswitch (HS)
  • C-33 - Handswitch
  • OPEN & CLOSED indication on both C-03 and C‑33. 
  • Normal position is Electrically Locked OPEN (ELO)


What are the SIRWT recirculation valves?

CV-3027, CV-3056


  • HPSI and LPSI  recirculation lines. Pumps are at shutoff head on SIS until PCS pressure falls below pump discharge pressure. 

Motive Force

  • HP Air with backup from N2 station 3A
    • N2 supplies 24 hours of operation
    • Valves fail as is


  • C-03: Hand switch (A) AND keylock switch (B). 
  • Normal position for HS-A is OPEN / HS - B is ELO
  • RAS signal and the 3027A HS in the closed position will close valve. 
  • 3027A HS in close and “B” keyswitch in close will close the valve.



What are the containment sump outlet valves?

CV-3030, CV-3029 (Containment Sump Outlet Valves)

  • CV-3030 supplies west engineering safeguards
  • CV-3029 supplies east engineering safeguards

Motive Force

  • HP Air with Instrument Air backup.  Fail as is on loss of air.


  • C-03 - keylock HS
  • C-33 - handswitch
  • OPEN & CLOSED indication on both C-03 and C-33. 
  • Normal position is Electrically Locked CLOSED (ELC)

Sump outlet valves begin openning before SIRWT outlet valves close during RAS.


What are the HPSI pumps?

Seven stage horizontal centrifugal pump.

Minimum flow 25 gpm

Design Flow: 300 gpm at 1,084 psia

P-66A - D Bus

P-66B - C Bus


What are the HPSI subcooling valves?

On RAS, Containment Spray Pumps ARE the suction source for HPSI

CV-3070, P-66B Subcooling

CV-3071, P-66A Subcooling

Motive Force

  • Instrument Air with N2 backup from station 3B.
  • N2 provides 120 hours of operation
  • Fails closed on loss of air


  • C-03 - Key Switch
  • C-33 - Handswitch
  • OPEN & CLOSED indication on both C-03 and C-33
  • RAS - automatic
  • CV-3070, P-66B Subcooling opens on P-66B running and CV-3030 open
  • CV-3071, P-66A Subcooling opens on P-66A running and RAS signal

Restrictions on Spray Pumps due to Suction Head concerns when providing subcooling - runout conditions possible.


What are the HPSI train supply valves?

CV-3059, HPSI P-66B to TRN 1

CV-3036, P-66A to TRN 2

Motive Forece

  • HP Air. Fail open on loss of air.


  • C-03 - Key Switch
  • C-33 - Handswitch
  • OPEN & CLOSED indication on both C-03 and C-33.
  • Electrically Locked OPEN (ELO)


What are the HPSI cross tie valves?

CV-3018, P-66B to Train 1 Cross-Tie

CV-3037, P-66A to Train 2 Cross-tie

Motive Force

  • HP air (CV-3018 has SCBA bottle backup - 72hour operation)
  • Fail Closed on loss of air


  • C-03 - Key Switch
  • C-33 - Handswitch
  • OPEN & CLOSED indication on both C-03 and C-33.
  • Electrically Locked CLOSED (ELC)


What are HPSI HL and CL injection valves, including the function of hot leg injection?

MO-3080, HPSI Train 2 Cold Leg Injection - MCC-24

MO-3081, HPSI Train 1 Cold Leg Injection - MCC-21

MO-3082, HPSI Train 1 Hot Leg Injection - MCC-22

MO-3083, HPSI Train 2 Hot Leg Injection - MCC-23

  • Cold Leg Injection flow is split between a restricting orifice and an injection vavle (50% to each). In order to open a Hot Leg Injection valve, the cold leg injection vavle must first be closed. Prevent runout on HPSI pump.
  • With HLI, flow is split between orifice to cold leg and valve to hot leg.
  • Keyswitches/HS at C-03, HS at C-33. Light Indication at both.


What are the HPSI Train 1 (Left) Injection Valves?

HPSI Train 1 (P-66B) Loop Injection Valves

  • MO-3007, MO-3009 to Loop 1A and 1B Respectively
  • MO-3011, MO-3013: to Loop 2A and 2B Respectively

C-03 or C-33 Controls

  • Can be throttled
    • MO-3007 - MCC-1
    • MO-3009 - MCC-1
    • MO-3011 - MCC-1
    • MO-3013 - MCC-1


What are the HPSI Train 2 Injection Valves?

HPSI Train 2 (P-66A) Loop Injection Valves

  • MO-3068, MO-3066: to Loop 1A and 1B Respectively
  • MO-3064, MO-3062 to Loop 2A and 2B Respectively

C-03 or C-33 Controls

Can be throttled

  • MO-3007 - MCC-2
  • MO-3009 - MCC-2
  • MO-3011 - MCC-2
  • MO-3013 - MCC-2


Describe the LPSI Pumps?

Single Stage Horizonal Centrifugal Pumps

P-67A - D-Bus

P-67B - C-Bus

  • Minimum Flow 170 gpm
  • Maximum Flow 3000 gpm at 152 psia


What are the LPSI suction valves?

MO-3189, MO-3190: LPSI suction for SIRWT or CNTMT Sump

MO-3198, MO-3199: LPSI suction from SDC

C-03 Controls

  • MO-3189, MO-3190: LPSI suction for SIRWT or CNTMT Sump ELO
  • MO-3198, MO-3199: LPSI suction from SDC ELC


What is the SDC bypass valve?

CV-3006, SDC HX Bypass Valve

Motive Force

  • Instrument Air and fails open on loss of air


  • Keylock HS-0306A on C-02
    • Normally in “OPEN” Provides Full LPSI flow to Injection
    • Must be in “AUTO” to use FIC-0306
  • keylock HS-0306B on C-33
  • KS in “ON”, HIC in “AUTO”, this allows control of CV-3006 from the Control Room

SV powered by Y-01

Loss of Y-01 results in valve going open


What are the LPSI injection valves?

  • MO-3008 - MCC1; Loop 1A injection
  • MO-3010 - MCC-1; Loop 1B injection
  • MO-3012 - MCC-2; Loop 2A injection
  • MO-3014 - MCC-2; Loop 2B injection

CS on C-03 or C-33


Describe the safety injection tanks.

Designed to injected at a PCS pressure of approximately 250 psia

LCO 3.5.1 Levels

  • Max 66%
  • Min 14%

Normal Level 40/45%

Design Pressure 250 psig

  • Normal 210/215 psig
  • Minimum N2 cover pressure >= 200 psig
  • Ensure flows utilized in safety analysis

Boron Max: 2500ppm

Boron Min: 1720 ppm


What are the SIT outlet valves?

MO-3041 – A SIT Outlet; MCC 21

MO-3045 – B SIT Outlet; MCC 23

MO-3049 – C SIT Outlet; MCC 22

MO-3052 – D SIT Outlet; MCC 24


  • OPEN, CLOSED, and MOTOR OVERLOAD (Blue light) indications on C-03


What are the SIT drain and fill valves?

SIT Drain and Fill Valves

  • CV-3039 - A SIT
  • CV-3043 - B SIT
  • CV-3004 - C SIT
  • CV-3003 - D SIT

Motive Force

  • Instrument Air. Fail Closed

HICs on C-03. 

  • Manuall thumbwheel to Open and Close the valve. 
  • Indication of signal to valve is 0% (full closed) to 100% (full open).


What are the SIT Pressure Control Valves?

SIT Pressure Control Valves

  • CV-3042
  • CV-3046
  • CV-3047
  • CV-3038


  • Operated from PICs on C-03.  PICs are normally in manual and CLOSED. Manual and Auto positions on PIC setpoint can be adjusted on a scale of 0 to 2500 psig 
  • OPEN and CLOSED position indication available for CVs just below PIC.


  • Used primarily to fill SITs. 
  • May also be used to lower pressure in SIT injection line due to PCS check valve leakage at lower PCS pressures.  CV is opened and inventory is drained to PSDT via CV-3069


Where are SIT drained?

Primary system drain tank via CV-3069.

C-03 Open/Closed switch and indication


Where do SIT get vented?

Vent gas collection header via

CV-3067, CV-3065, CV-3063, CV-3051 (SIT Vent Valve)

C-03 Open/Closed switch and indication


What are the SIT N2 supplies?

CV-3040, CV-3044, CV-3048, CV-3050 (SIT N2 Supply)



Where do the SIT relieve to?

RV-3113, RV-3128, RV-3143, RV-3158 (SIT Relief Valve)

Relieves on SIT pressure of 250 ± 7 psig

Relieves to Containment Atmosphere


Where does the SIT drain and fill line releive to?

Quench Tank

Sized to pass 200 gpm with a maximum backpressure of 110 psig in Q.T.

Relieves on drain line pressure of 500 psig


What is the design pressure on LPSI piping?

500 psig


What is the HPSI piping design pressure?

1600 psig

Redundant header added later has a design pressure of 2485 psig.  This difference is because of the system cross connection of the redundant header and the CVCS. 

  • Used to test SIT check valves


What initiates SI?

Two out of four Pressurizer low-low pressure signals (1605 psia)

Two out of four containment high pressure signals

Manual initiation


How does SIS logic handle power vs loss of offsite power?

SIAS (with Offsite Power available)

  • SIS relays actuate and "Seal In"
  • SIS-X relays actuate and after 5 seconds drops out.  Allows changing position of certain SIS components, i.e., ECCS injection MOVs can be throttled & pumps stopped for SI Throttling.

SIAS coincident with Loss of Offsite Power

  • SIS relays actuate and "Seal In"
  • SIS-X relays are blocked to allow the DBA sequencers to start components (prevents overloading EDG).  Following EDG start and load shed, DBA sequencer picks up and loads equipment on to EDG.


What are the SIS left and right channel logic power supplies?

Left Channel

  • Y-20

Right Channel

  • Y-30


What is SIS Block?

Used during "Controlled" Plant Cooldown to prevent receiving SIAS

Blocks only SIAS on Pressurizer Pressure Lo-Lo (1605 psia)

  • CHP and Manual still available

Logic Requirements to Block

  • 3 out of 4 Pressurizer Pressure Low relays 1687 (nominal) psia.  Indicated by EK-1369 "SAFETY INJECTION BLOCK PERMIT."
  • "SIAS NORMAL / BLOCK" PB3-1 and PB3-2: Turn and hold in "BLOCK" until SIS Block Annunciators alarm. Must do both channels before 1605 psia.


When and how do you disable SI?

MODE 4, 5 or 6 only

On C-13

  • Left Channel, place HS-SISL (Key #358) in DISABLE position.
  • Right Channel, place HS-SISR (Key #367) in DISABLE position.

Brings in Annunciators: EK-21, "SIS Initiation and Sequence Loading CKT #1 Disable" and EK-22, "SIS Initiation and Sequence Loading CKT #2 Disable"

SIS will still ocurr on CHP. To deveat: Pull 

  • Left Channel (FUZ/S41-1)
  • Right Channel (FUZ/S42-1)


How can a SIAS Block be reset?

Automatically 2/4 Pressurizer Pressure Low relays > 1690 psia

Automatically on CHP (i.e. SIS will occur on CHP)

Manually initiate SIAS (i.e. SIS will occur manually)


What is the function of the SIAS Reset pushbutton?

Driven by in use EOP (unless actuation was spurious).  Need to block SI if less that 1605psia and then depress reset pushbuttons to break the seal in.  This allow the components actuated by the SIS relays to be manipulated (SISX relay actuated components can be manipulated after the 5 second period has ended.)


How is SIAS testing accomplished?

QO-1 is one method.

Test switches on C-13 panel

Tests with standby power and Test without standby power using TS SS-L or R and depressing and holding TS-PB-L or R.


Opening of:

  • 152-102, P-40A Dilution Pump.
  • 152-302, Safeguards bus feed to E Bus.
  • 152-303, Startup transformer feed to E Bus.
  • 52-7701, Station Power transformer #77 feed to Bus 77.
  • 52-7804, Tie Breaker between Buses 77 and 78.
  • MO-2169, Boric Acid Gravity Feed.
  • MO-2170, Boric Acid Gravity Feed.
  • Opening of MO-2140, Boric Acid Pumped Feed

.Closing of:

  • Closing of CV-1359, Non-Critical Service Water Isolation.
  • Closing of MO-2087, Volume Control Tank Outlet Isolation


With offsite power, Left Channel SIS does what?

With offsite power avaialbe:

  • P-7B SW Pump ON
  • P-52A CCW Pump ON
  • P-52C CCW Pump ON
  • P-67B LPSI Pump ON
  • P-66B HPSI Pump ON
  • P-55C Charging Pump ON
  • P-56B Boric Acid Pump ON
  • V-4A VHX-4 Fan ON
  • CV-0938 SDC Hxs Inlet OPEN
  • MO-3010 LPSI Loop 1B OPEN
  • MO-3008 LPSI Loop 1A OPEN
  • MO-2169 Gravity Feed From T-53A OPEN
  • MO-2170 Gravity Feed From T-53B OPEN
  • MO-3009 HPSI Train 1 Loop 1B OPEN
  • MO-3011 HPSI Train 1 Loop 2A OPEN
  • MO-3007 HPSI Train 1 Loop 1A OPEN
  • MO-3013 HPSI Train 1 Loop 2B OPEN
  • P-54B Containment Spray Pump STBY White light lit
  • P-54C Containment Spray Pump STBY White light lit
  • V-4B VHX-4 Fan OFF
  • CV-1103 Containment Sump Drain CLOSED
  • CV-3085 HPSI Hot Leg Letdown to PSDT CLOSED
  • CV-2130 P-56A Recirc CLOSED
  • MO-2087 Charging Pump Suction from VCT CLOSED
  • CV-2155 Makeup Stop Valve CLOSED


What makes a SI Tank operable?

<66% and >14% level
<2500 ppm and >1720 ppm Boron
>200# Pressure
Drain and Fill Valves closed
Vent Valve closed


With Offsite power, Right Channel SIAS does what?

  • P-7A SW Pump ON
  • P-7C SW Pump ON
  • P-52B CCW Pump ON
  • P-67A LPSI Pump ON
  • P-66A HPSI Pump ON
  • P-54A Containment Spray Pump STBY White light lit
  • P-55B Charging Pump ON
  • P-55A Charging Pump ON
  • P-56A Boric Acid Pump ON
  • MO-2140 Pumped Feed From P-56A&B OPEN
  • MO-3012 LPSI Loop 2A OPEN
  • MO-3014 LPSI Loop 2B OPEN
  • MO-3066 HPSI Train 2 Loop 1B OPEN
  • MO-3064 HPSI Train 2 Loop 2A OPEN
  • MO-3068 HPSI Train 2 Loop 1A OPEN
  • MO-3062 HPSI Train 2 Loop 2B OPEN
  • CV-0861 VHX-1 SW Outlet OPEN
  • CV-0864 VHX-2 SW Outlet OPEN
  • CV-0873 VHX-3 SW Outlet OPEN
  • CV-0937 SDC Hxs Inlet OPEN
  • V-1A VHX-1 Fan ON
  • V-2A VHX-2 Fan ON
  • V-3A VHX-3 Fan ON
  • V-1B VHX-1 Fan OFF
  • V-2B VHX-2 Fan OFF
  • V-3B VHX-3 Fan OFF
  • CV-2136 P-56B Recirc CLOSED
  • CV-1104 Containment Sump Drain CLOSED
  • CV-3084 HPSI Hot Leg Letdown to PSDT CLOSED


What components are repositioned by both left and right channel SIAS?

  • CV-0944 Evaporator CCW Supply CLOSED
  • CV-0977B Evaporator CCW Return CLOSED
  • CV-1359 Non-critical SW Isolation CLOSED
  • CV-0869 VHX-4 SW Inlet CLOSED
  • CV-3042 T-82A Pressure Control MANUAL CLOSED
  • CV-3046 T-82B Pressure Control MANUAL CLOSED
  • CV-3047 T-82C Pressure Control MANUAL CLOSED
  • CV-3038 T-82D Pressure Control MANUAL CLOSED
  • CV-3069 SI Tank Drain to PSDT CLOSED
  • CV-0944A SFP Hx Supply CLOSED
  • CV-0913 ESS Pumps Cooling Supply OPEN
  • CV-0950 ESS Pumps Cooling Return OPEN
  • CV-0867 VHX-4 SW Outlet OPEN



What is RAS?

Recirculation Actuation Signal (RAS)

SIRWT level of 2% (24")

  • (> 21 inches and , < 27 inches above tank bottom)
  • Upper Limit is based on sufficient water in the containment sump to support pump suction and sufficient borated water is injected to ensure the reactor remains shut down in the recirculation.
  • Lower Limit is based on switchover occuring before the SIRWT empties to prevent damage to the ECCS pumps and a loss of core cooling capability.


  • 3 position switch "RESET - NORMAL - TEST"
  • Reset SIRWL-CS and SIRWR-CS located on panel C-13


What is power supply for left channel RAS and actuated equipment?


  • Open Sump Suction CV-3030
  • Opens SW from CCW Hx CV-0826 (Hard stop)
  • Open CCW Hx “A” SW outlet CV-0823 (Hard Stop)
  • Open CCW to CCW Hx CV-0946 (Normally open)
  • Close SIRW tank suction CV-3031
  • Close CCW TCV’s CV-0821 and CV-0822
  • Close signal SIRW tank recirc valve CV-3027 (requires HS-3027A in close)
  • Trip LPSI pump P-67B


What is power supply for Right channel RAS and actuated equipment?


  • Open sump suction CV-3029
  • Close SIRW Tank suction CV-3057
  • Close signal to SIRW Tank recirc CV-3056
  • Close CCW TCV’s CV-0821 and CV-0822
  • Open SW from CCW Hx CV-0823 (Hard Stop)
  • Open CCW Hx “B” SW Outlet CV-0826 (Hard Stop).
  • Open CCW to CCW Hx CV-0945 (Normally Open).
  • Open CV-3071 (Requires HPSI Pump P-66A running)
  • Close Cont Spray valve CV-3001 after 30 seconds if cont sump CV-3030 does not open.
  • Trip LPSI pump P-67A


SIRWT Indications are?

Level and Temperature located on panel C-13

  • Left Channel – LIA-0332A and TIA‑0328
  • Right Channel – LIA-0331 and TIA-0332

Recirc flow FI-0404 located on panel C-03


  • LIA-0332B


HPSI LPSI indications are?


Left Channel

  • PIA-0377 – LOOP 1 PRESS
  • FI-0308A – LOOP 1A HPSI FLOW
  • FI-0307A – LOOP 1A LPSI FLOW
  • FI-0310A – LOOP 1B HPSI FLOW
  • FI-0309A – LOOP 1B LPSI FLOW

Right Channel

  • FI-0312A – LOOP 2A HPSI FLOW
  • FI-0311A – LOOP 2A LPSI FLOW
  • FI-0314A – LOOP 2B LPSI FLOW
  • FI-0313A – LOOP 2B HPSI FLOW


Why and how is LPSI pump trip on SIRW level low (RAS) defeated?

For SDC operations via 

C-03 next to associated LPSI Pump

  • Two position keylock switch: DEFEAT / ENABLE


SIT indications are?


Wide or Narrow range selector - should be in narrow rand at all times, unless I&C requests otherwise.

  • A SIT – LIA-0365 & PIA-0363
  • B SIT - LIA-0368 & PIA-0367
  • C SIT – LIA-0371 & PIA-0372
  • D SIT – LIA-0369 & PIA-0379

HI/Lo Level Alarm - 48%: Low Level - 32%

HI Alarm - 62%

Lo Alarm - 18%

LCO 3.5.1

High 66%; Low 14%