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Exams > 2019 Q59 — Loss of 2A 125 VDC Bus EDG Impact

2019 Q59 — Loss of 2A 125 VDC Bus EDG Impact

⚠️ DRAFT
Q59 — Loss of 2A 125 VDC Bus EDG Impact APE: 058 Loss of DC Power-AA2.03 (3.5)
Given:
• Unit 2 is at 100% Reactor Power

At time 16:00
• OHA B-2, "2A 125 VDC CNTRL BUS VOLT LO" actuates
• 2A Vital 125 VDC Bus voltage is reading 0 VDC on 2RP9

Considering ONLY the following equipment malfunctions below:
1. #1 SGFP Emergency Oil Pump loses power
2. Main Turbine Emergency Oil Pump loses power
3. 2A EDG is NOT available for start

Which ONE of the following completes the statements below?

With a confirmed 2A Vital 125 VDC Bus voltage of 0 VDC, Unit 2 will experience equipment malfunction(s) ___
A. 2 ONLY
B. 3 ONLY
C. 1 and 2 ONLY
D. 2 and 3 ONLY
▶ Show Answer & Explanation
✓ B. Correct. When OHA B-2, "2A 125 VDC CNTRL BUS VOLT LO" actuates, the only affected malfunction is that 2A EDG is not available for start.
✗ A. Incorrect but plausible. All of the equipment malfunctions can be caused by a loss of a portion of the DC Power System (250 VDC, 125 VDC or 28 VDC). Consequently, all of the distractors are plausible.
✗ C. Incorrect but plausible. All of the equipment malfunctions can be caused by a loss of a portion of the DC Power System (250 VDC, 125 VDC or 28 VDC). Consequently, all of the distractors are plausible.
✗ D. Incorrect but plausible. All of the equipment malfunctions can be caused by a loss of a portion of the DC Power System (250 VDC, 125 VDC or 28 VDC). Consequently, all of the distractors are plausible.
Ref: S2.OP-AR.ZZ-0002, Alarm B-2 | LO: NOS05DCELEC-09 (DC ELECTRICAL SYSTEMS) | Source: New | Cognitive: Higher

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