Q41 — ECCS Semi-Automatic Switchover
026000K4.08 (4.1)
Given:
- Unit 2 has experienced a Reactor Trip and Safety Injection due to a Large Break LOCA.
- RWST Level has lowered to less than 15.2 feet on 2/4 RWST Level Channels.
With NO operator action, which choice describes AUTOMATIC actions that will occur based on the above RWST Level?
- Unit 2 has experienced a Reactor Trip and Safety Injection due to a Large Break LOCA.
- RWST Level has lowered to less than 15.2 feet on 2/4 RWST Level Channels.
With NO operator action, which choice describes AUTOMATIC actions that will occur based on the above RWST Level?
A. 21 & 22 SJ44s, RHR Pump Sump Suction Valves OPEN.
B. 21 & 22 SJ113s, SI to Charging Pump Crossover Valves OPEN.
C. 21 & 22 RH4s, RHR Pump Suction Valves CLOSE.
D. 21 & 22 CS36s, RHR Discharge to Containment Spray Header OPEN.
▶ Show Answer & Explanation
✓ B. Correct. Normal 100% Power ECCS Lineup would have both the SJ113 valves "armed" for semi-automatic switchover signal.
✗ A. Incorrect. Plausible because the operator subsequently manually "arms" the SJ44s if sump level is > 62% and the valves will then automatically open.
✗ C. Incorrect. Plausible because the candidate may remember the Unit 1 valve interlock that requires the RH4 to be closed prior to opening the SJ44 and believe that these valves are already "armed".
✗ D. Incorrect. Plausible because the CS36 valve will get manually manipulated depending on the available RHR pump to ensure continued containment spray header flow. These valves are manipulated at LO-LO RWST Level however and also manually.
Ref: NOS05ECCS00-09, Emergency Core Cooling System | LO: ELO 9 | Source: Bank – Salem Vision Database | Cognitive: Fundamental
Connections
- Related systems: ECCS, Containment Spray
- Related exam: 2020 NRC Written Exam