SI (Safety Injection) Flashcards
The HPSI cold leg injection orifice is used during simultaneous hot and cold leg injection to:
A. help balance SI flow to the hot and cold leg injection headers by being sized to allow approximately 50% flow.
B. provide instrumentation to measure flow to the hot and cold leg injection headers.
C. provide minimum recirculation flow for the HPSI pumps to prevent overheating.
D. prevent exceeding runout condition in the HPSI pumps to prevent pump cavitation.
Answer: A
Which one of the following is true concerning the 1A safety injection tank? The safety injection tank can inject water into:
A. Loop 1A only.
B. Loop’s 1A and 2A.
C. Loop’s 1A and 1B.
D. Loop’s 1A, 1B, 2A and 2B.
Answer: A
Which one of the following describes why the safety injection tanks are considered a passive system? (Assume the plant is at 100% power.)
A. Outlet valves automatically open on an actuation signal.
B. Tanks require minimal maintenance.
C. Injection from the tanks involves single manual action.
D. They require no electrical power to perform their function.
Answer: D
Which of the following parameter values would exceed the allowable ECCS design criteria per 10CFR50.46 ?
A. 2% sump water Iodine 131 concentration.
B. 2150°F peak clad temperature.
C. 20% through wall clad degradation due to oxidation.
D. .75% hydrogen generation due to the zirc water reaction.
Answer: C
Which one of the following will automatically occur when a recirculation actuation signal (RAS) is received?
A. Containment spray header isolation valve will open.
B. Refueling water tank outlet valve will close.
C. Low Pressure Safety Injection pumps will stop.
D. High Pressure Safety Injection pump discharge valve will close.
Answer: C
Which of the following statements correctly identifies when a HPSI pump is to be used for Emergency Boration per 40AO-9ZZ01, “Emergency Boration”?
A. Anytime RCS pressure is less than HPSI shutoff head.
B. Anytime a SIAS/CIAS occurs.
C. Only if Charging pumps are unavailable.
D. Only if Reactor Coolant System Tcold is less than 350 degrees F.
Answer: C
Which one of the following describes the signal that would have been generated when the reactor coolant system pressure lowers to 1800 psia?
A. Safety injection actuation signal
B. Main steam isolation signal
C. Recirculation actuation signal
D. Containment spray actuation signal
Answer: A
Which one of the following describes the signal that will be generated when the pressurizer reaches 1837 psia?
A. Main Steam Isolation Signal (MSIS)
B. Safety Injection Actuation Signal (SIAS)
C. Recirculation Actuation Signal (RAS)
D. Containment Spray Actuation Signal (CSAS)
Answer: B
Which of the following describes why the safety injection tanks do not dump their contents into the reactor coolant system during normal operation?
A. RCS pressure is less than SIT pressure and the force (D/P) upon the RCS check valves keep them closed.
B. The safety injection tanks are normally isolated until a SIAS signal is generated.
C. The safety injection tank injection valves are normally closed with their power supply breakers open.
D. RCS pressure is greater than SIT pressure and the force (D/P) upon the SIT check valves keep them closed.
Answer: D
Which one of the following is an important reason to locate and stop a leak in the safety injection piping outside of containment during a large LOCA?
A. Reduces the amount of fixed contamination that will remain in the containment after repair of the leak.
B. Prevent safety injection pump runout during the injection phase following a LOCA.
C. A LOCA outside of containment could result in inadequate containment sump inventory to allow recirculation.
D. Prevent short circuit of the auxiliary building electrical systems with resultant possibility of electric shock.
Answer: C
When filling a safety injection tank (NOP/NOT), which of the following is one possible consequence of stopping the HPSI pump and not closing the SIT fill/drain valve?
A. The SIT will flow into the RCS.
B. The SIT will flow into the RWT.
C. The RWT will flow into the SIT.
D. The RCS will flow into the SIT.
Answer: B
Shutdown cooling is used to cool the Reactor Coolant System from a maximum of _____ to the temperature required for refueling.
A. 350°F
B. 250°F.
C. 410°F
D. 500°F
Answer: A
A large break LOCA has occurred on Unit 2. Containment pressure is presently 13 psig. RWT level has dropped to approximately 6%. Which one of the following would you expect to occur based on this?
A. Safety injection suction valves from the RWT close.
B. Both HPSI pumps trip.
C. Containment spray valves close.
D. All safety injection pump recirculation valves close.
Answer: D
Which one of the following is a reason for Containment Spray flow following a LOCA?
A. To prevent the containment sump pH from exceeding 7.0.
B. To minimize the containment sump oxygen levels.
C. To reduce containment pressure during a loss of coolant accident (LOCA).
D. To minimize the possibility of corrosion cracking of metallic components inside containment.
Answer: C
Pressurizer pressure is 1250 psia. Pressurizer level is 45%. HPSI injection is 330 gpm/cold leg (acceptable flow). Reactor coolant system is 28°F subcooled. Reactor vessel level monitoring system indicates 100% in plenum and upper head. No reactor coolant pumps are running. Containment temperature and pressure are 195°F and 11 psig, respectively. SIAS, CIAS, MSIS, and CSAS have actuated. A cooldown is in progress using steam generators, both WR levels are 50%. WHICH ONE of the following identifies the action the Control Room Supervisor is to direct concerning high pressure safety injection use?
A. HPSI flow may be throttled until HPSI flow is the same as break flow.
B. Continue maximum injection flow until subcooling is at least 24°F.
C. HPSI flow may be throttled to restore pressurizer level 10 to 70%.
D. Continue maximum injection flow until subcooling is at least 44°F.
Answer: D
A loss of coolant accident (LOCA) has occurred. Several seconds after the trip, a lockout of PBA-S03 occurs. RCS pressure is observed to be 550 psia and lowering. Based on these conditions, the expected safety injection would be increasing HPSI flow…
A. to reactor coolant loops 2A and 2B.
B. to all reactor coolant cold legs.
C. and LPSI flow to all reactor coolant cold legs.
D. and LPSI flow to reactor coolant loops 2A and 2B.
Answer: B
A LOCA has occurred on Unit 1. Approximately one minute after the Train B Essential Chiller started, a fault locks out PBB-S04. RCS pressure is 750 psig and lowering. Based on this, the expected safety injection would be:
A. increasing HPSI flow into reactor coolant loops 1A and 1B only.
B. increasing LPSI and HPSI flow into all reactor coolant loops.
C. increasing HPSI flow into all reactor coolant loops.
D. increasing LPSI and HPSI flow into reactor coolant loops 1A and 1B only.
Answer: C
During an ESD, why should safety injection be throttled as soon as the throttle criteria is met?
A. Minimizes the possibility of pressurized thermal shock.
B. Prevents excessive cooldown.
C. Minimizes erosion damage to the injection valves.
D. Minimizes the time SI pumps are running on mini-flow.
Answer: A
Reactor coolant system pressure is 30 psig. A large break, design basis Loss Of Coolant Accident occurred 90 minutes ago. All safety injection systems have been operated as designed. Which one of the following is the suction source for the containment spray pump (assume the operators have performed the required actions)?
A. Spent fuel pool and Recirculation Sump
B. Refueling water tank ONLY
C. Recirculation sump and RWT
D. Recirculation sump ONLY
Answer: D
Reactor Tripped SIAS CIAS MSIS All equipment is operating as required The Operator places the control switch for SIB-P02 (HPSI Pump) into the START position and then to the STOP position. What effect, if any, will this manipulation have on further pump operation? HPSI pump "B" has been placed into SIAS override ....
A. and stopped, it will now respond to any automatic actuation signals.
B. but will continue to run, unless taken to stop a second time.
C. and stopped, all further starts and stops will have to be done manually.
D. and stopped, it can only be restarted after the SIAS has been reset.
Answer: C
Following a Loss of Coolant Accident (LOCA), RCS pressure is at 450 psia and dropping. The expected safety injection indications would be:
A. constant HPSI and LPSI flow.
B. increasing HPSI flow with no LPSI flow.
C. increasing HPSI and LPSI flow.
D. constant HPSI flow with no LPSI flow.
Answer: B
A large break LOCA has occurred. Refueling Water Tank (RWT) level is 10% and lowering. SIAS/CIAS/CSAS/MSIS have actuated. No other ESF actuations have occurred. Which ONE of the following actions should the operators take in regards to Recirculation Actuation Signal (RAS)?
A. Manually initiate RAS from Board 5 on trend.
B. Wait until the RWT reaches the RAS actuation setpoint and verify that RAS automatically actuates.
C. Manually initiate RAS from the Aux Relay Cabinets on trend.
D. Trip both Low Pressure Safety Injection Pumps and close all SI pump recirc valves, then manually initiate RAS from B05.
Answer: B
The bases for the minimum required volume of the RWT ensures that at the time of RAS initiation the water level in the containment sump will be enough to provide NPSH for the ESF pumps and the decay heat boil-off rate is less than …
A. the minimum design flow of two HPSI pumps and two LPSI pumps.
B. the minimum design flow of two HPSI pumps.
C. the minimum design flow of one HPSI pump and one LPSI pump.
D. 75% of the minimum design flow of one HPSI pump.
Answer: D
Reactor power is steady at 99%. Safety Injection Tank (SIT) “1B” indicates the following: 1. Level is 60% narrow range (NR). 2. Boric acid concentration is 2400 ppm. 3. Nitrogen cover pressure is 580 psig. 4. Nitrogen vent valve is closed and de-energized. Which ONE of the following SIT “1B” parameters must be corrected prior to declaring SIT “1B” operable?
A. SIT nitrogen pressure must be > 600 psig.
B. SIT level must be > 70% NR.
C. SIT nitrogen vent valves must be energized.
D. Boric acid concentration must be > 4000 ppm.
Answer: A
