Q87 — EOP-TRIP-4 Loss of PZR Level / SI Actuation
T2G1 006 A2.12 (4.5)
Given:
• A Loss of Offsite Power has occurred on Salem Unit 2
• The crew is performing actions in 2-EOP-TRIP-4, Natural Circulation Cooldown
• 21 Charging Pump is running
• RCS cooldown to establish required subcooling is in progress
• Low PZR Pressure SI signal is BLOCKED
• RCS temperature is 537 degrees F
Then:
• RCS pressure is 1183 psig and lowering
• 2CV55, Charging Flow Control Valve, is fully open
• 2CV71, Seal Injection Backpressure Valve, is fully open
• Pressurizer level is 10% and lowering
Which of the following describes the correct action(s) for these conditions per 2-EOP-TRIP-4?
• A Loss of Offsite Power has occurred on Salem Unit 2
• The crew is performing actions in 2-EOP-TRIP-4, Natural Circulation Cooldown
• 21 Charging Pump is running
• RCS cooldown to establish required subcooling is in progress
• Low PZR Pressure SI signal is BLOCKED
• RCS temperature is 537 degrees F
Then:
• RCS pressure is 1183 psig and lowering
• 2CV55, Charging Flow Control Valve, is fully open
• 2CV71, Seal Injection Backpressure Valve, is fully open
• Pressurizer level is 10% and lowering
Which of the following describes the correct action(s) for these conditions per 2-EOP-TRIP-4?
A. Stop the RCS cooldown and wait until PZR level and subcooling are restored.
B. Align the Charging Pump suction to the RWST, open the BIT isolation valves, and transition to 2-EOP-LOCA-1, Loss of Reactor or Secondary Coolant.
C. Operate Pressurizer heaters as necessary to maintain saturated conditions in the pressurizer per 2-EOP-TRIP-4.
D. Actuate Safety Injection and return to 2-EOP-TRIP-1, Reactor Trip or Safety Injection.
▶ Show Answer & Explanation
✓ D. Correct. Per the foldout page (CAS) of 2-EOP-TRIP-4, if subcooling is 0 degrees F or PZR level can NOT be maintained greater than 4%, then Actuate SI and go to 2-EOP-TRIP-1. In this case subcooling is greater than 0 degrees F, but PZR level is lowering and cannot be maintained based on the 2CV55 and 2CV71 fully open. Letdown is isolated.
✗ A. Plausible because operator may believe that the reason for the PZR level lowering is due to excessive cooldown of the RCS.
✗ B. Plausible because this is similar to CAS step 6.1 in EOP-TRIP-4. Incorrect in that TRIP-4 does not direct entry into EOP-LOCA-1.
✗ C. Plausible because this is similar to CAS step 3 in EOP-TRIP-4. Incorrect in that PZR heaters will not energize with level less than 17%.
Ref: 2-EOP-TRIP-4 (R41) | LO: NOS05TRP004-08, Obj 4 — Determine the basis for each step, caution, note or continuous action step relative to a NATURAL CIRCULATION COOLDOWN | Source: Bank - DC Cook 2008 NRC SRO86 | Cognitive: Comprehension/Analysis
Connections
- Related systems: Pressurizer & PRT, ECCS, CVCS
- Related procedures: EOP-TRIP-4 — Natural Circulation, EOP-TRIP-1
- Related exam: 2023 NRC Written Exam