Q5 — PZR Pressure Channel Fails High / OT Delta-T Effect
APE 27 AA2.11 (4.0)
Given:
• Salem Unit 2 is at 100% power
• PZR Pressure controlling channel fails HIGH
Based on the conditions above, the (1) reactor trip setpoint on the unaffected RCS loops will (2).
• Salem Unit 2 is at 100% power
• PZR Pressure controlling channel fails HIGH
Based on the conditions above, the (1) reactor trip setpoint on the unaffected RCS loops will (2).
A. (1) OT Delta-T (2) lower
B. (1) OT Delta-T (2) rise
C. (1) OP Delta-T (2) rise
D. (1) OP Delta-T (2) lower
▶ Show Answer & Explanation
✓ A. Correct. The failed PZR pressure controlling channel will result in PZR pressure lowering. The lowering PZR pressure is one input into OT Delta-T to determine its trip setpoint. As RCS pressure lowers, the OT Delta-T setpoint will lower. With no operator action, the PZR pressure will continue to rapidly lower until the OT Delta-T reactor trip setpoint is reached first (per S2.OP-AB.PZR-0001 bases section for Attachment 1). Note: OP Delta-T does NOT have a pressure input.
✗ B. Incorrect. While OT Delta-T is the correct trip function (it does have a pressure input), the setpoint would lower, not rise. As PZR pressure lowers due to the controlling channel failing high, the OT Delta-T setpoint decreases.
✗ C. Incorrect. OP Delta-T does NOT have a pressure input. Changes in PZR pressure do not affect the OP Delta-T trip setpoint.
✗ D. Incorrect. OP Delta-T does NOT have a pressure input. Changes in PZR pressure do not affect the OP Delta-T trip setpoint.
Ref: S2.OP-AB.PZR-0001 (R20) | LO: NOS05ABPZR1-05, Obj 2 | Source: Bank - Salem | Cognitive: Comprehension/Analysis
Connections
- Related systems: Pressurizer & PRT, RPS/SSPS
- Related procedures: AB.PZR-0001 — Pressurizer Pressure Control Malfunction
- Related exam: 2023 NRC Written Exam