Q17 — Loss of Emergency Recirc / Upper Head Voiding
W E11 EK1.07 (3.7)
Given:
• LOCA, all RCPs stopped
• Loss of emergency recirc
• Crew in EOP-LOCA-5
• RCS depressurization in progress
Is upper head voiding expected and what should be monitored?
• LOCA, all RCPs stopped
• Loss of emergency recirc
• Crew in EOP-LOCA-5
• RCS depressurization in progress
Is upper head voiding expected and what should be monitored?
A. Voiding IS expected, monitor CETs
B. Voiding IS expected, monitor PZR level
C. Voiding is NOT expected, monitor PZR level
D. Voiding is NOT expected, monitor CETs
▶ Show Answer & Explanation
✓ B. Correct. Per EOP-LOCA-5 step 23, during RCS depressurization upper head voiding CAN be expected. Hotter liquid in upper head flashes to steam, displaces water into PZR causing rapidly rising PZR level. Monitor PZR level to stop depressurization before going solid.
✗ A. CETs may increase but EOP-LOCA-5 specifically directs monitoring PZR level for this condition, not CETs.
✗ C. Upper head voiding IS expected during RCS depressurization with no RCPs running. The monitoring parameter (PZR level) is correct but the voiding expectation is wrong.
✗ D. Upper head voiding IS expected during RCS depressurization with no RCPs running.
Ref: 2-EOP-LOCA-5 (R43) | LO: NOS05LOCA05-06, Obj 6 | Source: New | Cognitive: Comprehension/Analysis
Connections
- Related systems: RCS, ECCS
- Related procedures: EOP-LOCA-5 — Loss of Emergency Coolant Recirculation
- Related exam: 2023 NRC Written Exam