Q82 — PZR Level Channel Fails High / TS 3.3.1.1 [EDITED]
028 PZR Level Control Malfunction-AA2.12 (3.5)
Given:
• Unit 2 is at 100% Reactor Power
• PZR pressure is 2235 and stable
• 21 Backup Heaters are in MANUAL and ON
• 2LT-459 (Channel I PZR Level) is the controlling PZR Level channel
At time 15:00:00
• 2LT-459 Fails high
Which ONE of the following completes the statements below?
At 15:00:30, 22 Backup Heaters are _(1)_.
In accordance LCO 3.3.1.1 (REACTOR TRIP SYSTEM INSTRUMENTATION), 2LT-459 must be placed in the tripped condition within a MAXIMUM of _(2)_ hour(s).
• Unit 2 is at 100% Reactor Power
• PZR pressure is 2235 and stable
• 21 Backup Heaters are in MANUAL and ON
• 2LT-459 (Channel I PZR Level) is the controlling PZR Level channel
At time 15:00:00
• 2LT-459 Fails high
Which ONE of the following completes the statements below?
At 15:00:30, 22 Backup Heaters are _(1)_.
In accordance LCO 3.3.1.1 (REACTOR TRIP SYSTEM INSTRUMENTATION), 2LT-459 must be placed in the tripped condition within a MAXIMUM of _(2)_ hour(s).
A. _(1)_ energized _(2)_ 1
B. _(1)_ energized _(2)_ 72
C. _(1)_ de-energized _(2)_ 1
D. _(1)_ de-energized _(2)_ 72
▶ Show Answer & Explanation
✓ B. Correct. For Part 1 since the controlling LT has failed high, 22 Backup heaters will automatically energize since there is a +5% PZR level deviation (LACTUAL - LREF). For Part 2 and in accordance LCO 3.3.1.1 (REACTOR TRIP SYSTEM INSTRUMENTATION), 2LT-459 must be placed in the tripped condition within a MAXIMUM of 72 hours.
✗ A. Part 1 is correct. For Part 2, the candidate could incorrectly conclude that LCO 3.3.1.1 (REACTOR TRIP SYSTEM INSTRUMENTATION) requires 2LT-459 must be placed in the tripped condition within a MAXIMUM of 1 hour.
✗ C. For Part 1, PZR B/U Heaters have an automatic function to energize when PZR pressure is less than 2210 psig. Since PZR pressure is > 2210 psig when LT-459 fails high, the candidate could incorrectly conclude that the 22 Backup heaters are OFF. For Part 2, the candidate could incorrectly conclude that LCO 3.3.1.1 requires 2LT-459 must be placed in the tripped condition within a MAXIMUM of 1 hour.
✗ D. For Part 1, PZR B/U Heaters have an automatic function to energize when PZR pressure is less than 2210 psig. Since PZR pressure is > 2210 psig when LT-459 fails high, the candidate could incorrectly conclude that the 22 Backup heaters are OFF. Part 2 is correct.
Ref: LCO 3.3.1.1, NOS05PZRP&L-10 (PRESSURIZER PRESSURE AND LEVEL CONTROL) | LO: 10. Given a situation dealing with Pressurizer Pressure and Level Control System operability, examine the situation and apply the appropriate Technical Specification action. | Source: New | Cognitive: Higher
Connections
- Related systems: Pressurizer Level & Press Control
- Related tech specs: TS 3/4.3 — Instrumentation
- Related exam: 2018 NRC Written Exam