Q36 — PZR Pressure Channel Fails Low
010000A3.02 (3.6)
Given:
• Unit 2 is in MODE 3.
• Pressurizer (PZR) Pressure is 2235 psig.
• RCS Temperature is 547 °F.
• PZR Pressure Channel I (2PT-455) is selected for Control.
• PZR Pressure Channel II (2PT-456) is selected for Alarm.
If PZR Pressure Channel I fails LOW and with NO operator action, PZR pressure will rise until ______.
• Unit 2 is in MODE 3.
• Pressurizer (PZR) Pressure is 2235 psig.
• RCS Temperature is 547 °F.
• PZR Pressure Channel I (2PT-455) is selected for Control.
• PZR Pressure Channel II (2PT-456) is selected for Alarm.
If PZR Pressure Channel I fails LOW and with NO operator action, PZR pressure will rise until ______.
A. PZR PORV 2PR1 opens.
B. BOTH PZR PORVs, 2PR1 and 2PR2 open.
C. BOTH PZR Spray Valves, 2PS1 and 2PS3 open.
D. PZR PORV 2PR2 opens.
▶ Show Answer & Explanation
✓ D. Correct. Channel I failing low will block the AUTO operation of 2PR1. Additionally, 2PR2 is controlled by channels II & IV and therefore will operate as pressure rises to the open setpoint.
✗ A. Plausible because the candidate may believe that Channels II & IV control 2PR1 and therefore it will open. Incorrect as Channel I failing low will block the AUTO operation of 2PR1.
✗ B. Plausible because the candidate may believe that only a single channel is required to cause a PORV to open and therefore both would open. Incorrect as Channel I failing low will block the AUTO operation of 2PR1.
✗ C. Plausible because the PZR Spray valves open in automatic prior to the PORV open setpoint and therefore would control pressure. Incorrect as the pressurizer spray valves will only function in AUTO via the controlling channel and it is failed low.
Ref: NOS05PZRP&L-10, Pressurizer Pressure and Level Control | LO: N/A | Source: Bank — Salem Vision Database | Cognitive: Comprehension
Connections
- Related systems: Pressurizer Level & Press Control, Pressurizer & PRT
- Related exam: 2020 NRC Written Exam