Q6 — Shutdown LOCA
000025AA2.04 (3.3)
Given:
• 21 RHR Pump is in service aligned for Shutdown Cooling.
• RCS Temperature is 325 °F.
• RCS Pressure is 300 psig and lowering.
• PZR Level is 10% and lowering rapidly.
• Containment Pressure is 0.1 psig.
• 2R41D, Plant Vent, radiation monitor is rising.
Which ONE of the following identifies the required procedure and action to mitigate this event?
• 21 RHR Pump is in service aligned for Shutdown Cooling.
• RCS Temperature is 325 °F.
• RCS Pressure is 300 psig and lowering.
• PZR Level is 10% and lowering rapidly.
• Containment Pressure is 0.1 psig.
• 2R41D, Plant Vent, radiation monitor is rising.
Which ONE of the following identifies the required procedure and action to mitigate this event?
A. Enter S2.OP-AB.RHR-0001, Loss of RHR, Isolate letdown and Start Safety Injection and Charging Pumps as required to Control Pressurizer Level between 5% and 50%.
B. Enter S2.OP-AB.RC-0001, Reactor Coolant System Leak, Isolate Letdown and Start one Charging or Safety Injection Pump to maintain Pressurizer Level between 11% and 50%.
C. Enter S2.OP-AB.LOCA-0001, Shutdown LOCA, Stop the operating RHR Pump aligned for Shutdown Cooling and Close 2RH1 and 2RH2 (RHR Common Suction).
D. Enter S2.OP-AB.RC-0001, Reactor Coolant System Leak, Stop the operating RHR Pump aligned for Shutdown Cooling and close 21SJ49 (RHR Discharge to Cold Legs).
▶ Show Answer & Explanation
✓ C. Correct. The entry conditions for AB.LOCA-0001 are any uncontrolled reduction in Pressurizer Level in Mode 4. The first step of the procedure is to initiate Attachment 1, Continuous Action Summary and the CAS states if Pressurizer Level is <11%, then stop the operating RHR Pump aligned for Shutdown Cooling and Close 2RH1 and 2RH2.
✗ A. Plausible because the candidate may believe that AB.RHR-0001 is the appropriate procedure for an RCS leak outside of containment effecting RHR shutdown cooling. It is also plausible that isolating letdown sources will stop the leak and charging/safety injection will restore RCS inventory. Both of these are actions taken in AB.RHR-0001 for a loss of inventory in Modes 5 or 6 affecting RHR. Incorrect because AB.RHR-0001 will direct you per a CAS to AB.LOCA-0001 if in Mode 4.
✗ B. Plausible because AB.RC-0001 can be appropriately entered for any indication of an RCS leak, but incorrect because Unit is in Mode 4 and the procedure will direct you to AB.LOCA-0001. It is also plausible that isolating letdown sources will stop the leak and charging/safety injection will restore RCS inventory. Both of these are actions taken in AB.RC-0001.
✗ D. Plausible because AB.RC-0001 can be appropriately entered for any indication of an RCS leak, but incorrect because Unit is in Mode 4 and the procedure will direct you to AB.LOCA-0001. Plausible because the candidate may believe that the loss of inventory is related to an intersystem LOCA on the discharge loops for 21 RHR Pump, isolating 21RH49 could stop that leakage. The action is taken in AB.RC-0001 after isolating RHR suction valves in Modes 1-3.
Ref: S2.OP-AB.LOCA-0001, Shutdown LOCA | LO: N/A | Source: New | Cognitive: Comprehension
Connections
- Related systems: RHR
- Related procedures: AB.LOCA-0001 — Shutdown LOCA, AB.RHR-0001 — Loss of RHR, AB.RC-0001 — Reactor Coolant System Leak
- Related exam: 2020 NRC Written Exam