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Exams > 2019 Q78 — Loss of RHR in Mode 4 / Shutdown LOCA

2019 Q78 — Loss of RHR in Mode 4 / Shutdown LOCA

⚠️ DRAFT
Q78 (SRO) — Loss of RHR in Mode 4 / Shutdown LOCA APE: 025 Loss of RHRS-G2.1.27 (3.8)
Given:
• Unit 2 is in MODE 4
• 21 RHR Loop is in service
• PZR Level is 10% and stable

At time 17:00
• The crew enters S2.OP-AB.RHR-0001 (Loss Of RHR) due to a malfunction of 21RH18 (RHR HX FLOW CONT VALVE)

At time 17:05 (5 minutes later)
• PZR level is 9% and lowering
• 2R11A (Containment Particulate Monitor) reading is rising

In accordance with S2.OP-AB.RHR-0001, which ONE of the following completes the statement below?

At 17:05, the crew will _(1)_.
A. IMMEDIATELY GO TO S2.OP-AB.LOCA-0001 (Shutdown LOCA)
B. PERFORM S2.OP-AB.RHR-0001 Attachment 9 (Steam Generator Reflux Cooling)
C. IMMEDIATELY GO TO S2.OP-AB.RHR-0002 (Loss of RHR at Reduced Inventory)
D. CONTINUE in the main body of S2.OP-AB.RHR-0001 (Loss Of RHR)
▶ Show Answer & Explanation
✓ A. Correct. IAW S2.OP-AB.RHR-0001 (Loss Of RHR) CAS, going to S2.OP-AB.LOCA-0001 (Shutdown LOCA) is correct since the Unit is in MODE 4 when the RCS Inventory was lost.
✗ B. Performing S2.OP-AB.RHR-0001 Attachment 9 (Steam Generator Reflux Cooling) would have been correct if at any time a complete loss of all vital buses occurs, NOT as a result of a Beyond-Design-Basis-External-Event (IAW S2.OP-AB.RHR-0001 CAS).
✗ C. Going to S2.OP-AB.RHR-0002 (Loss of RHR at Reduced Inventory) would have been correct if RCS had been aligned for operation <101 ft. elevation (S2.OP-AB.RHR-0001 Steps 3.3 and 3.4).
✗ D. "START Safety Injection and Charging Pumps as required and CONTROL Pressurizer level between 5% and 50% while maintaining RHR System in service" would have been correct if the Unit was in MODE 5 or 6.
Ref: S2.OP-AB.RHR-0001 (Loss Of RHR) | LO: NOS05ABRHR1-05 | Source: Modified Bank (ILOT 16-01 NRC SRO Q12) | Cognitive: Higher

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