Q40 — Containment Spray Pump Sequencing / SEC Not Reset
026 K2.01 (3.9)
Given:
• Salem Unit 2 experienced a LOCA
• Containment pressure is 10 psig and slowly rising
• ALL available safeguards equipment have started with the exception that 2B SEC failed to actuate
• SECs have NOT been RESET
Based on the conditions above, which of the following completes the statement?
(1) containment spray pump(s) is/are still available from a Class 1E vital power source and (2) automatically start when containment pressure exceeds the containment pressure HI-HI setpoint.
• Salem Unit 2 experienced a LOCA
• Containment pressure is 10 psig and slowly rising
• ALL available safeguards equipment have started with the exception that 2B SEC failed to actuate
• SECs have NOT been RESET
Based on the conditions above, which of the following completes the statement?
(1) containment spray pump(s) is/are still available from a Class 1E vital power source and (2) automatically start when containment pressure exceeds the containment pressure HI-HI setpoint.
A. Only one CS pump available; WILL auto-start on Hi-Hi containment pressure.
B. Only one CS pump available; will NOT auto-start on Hi-Hi containment pressure.
C. BOTH CS pumps available; WILL auto-start on Hi-Hi containment pressure.
D. BOTH CS pumps available; will NOT auto-start on Hi-Hi containment pressure.
▶ Show Answer & Explanation
✓ C. Correct. Both CS pumps are powered from A and C 4KV vital buses. The 2B SEC failure does not affect CS pumps since neither is powered from the B bus. A and C SECs actuated in Mode 1. With the sequence complete and SECs NOT reset, the CS pump start contact is re-closed — CS pumps WILL auto-start when the Hi-Hi containment pressure signal is received.
✗ A. Incorrect. Both CS pumps are available, not just one. 21 CS pump is on the A bus (A SEC) and 22 CS pump is on the C bus (C SEC). The failed B SEC does not power either CS pump.
✗ B. Incorrect. Both CS pumps are available (not just one), and they will auto-start. With SECs not reset, the CS start contact remains active for auto-start on Hi-Hi containment pressure.
✗ D. Incorrect. Both CS pumps being available is correct, but they WILL auto-start. Since SECs have NOT been reset, the CS pump start contact remains re-closed after the initial sequence, allowing auto-start on Hi-Hi containment pressure.
Ref: NOS05SEC000-09 | Source: New | Cognitive: Comprehension/Analysis
Connections
- Related systems: Containment Spray, 500KV, RPS/SSPS
- Related exam: 2023 NRC Written Exam