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Exams > 2023 Q7 — PZR Backup Heater Power Supplies

2023 Q7 — PZR Backup Heater Power Supplies

⚠️ DRAFT
Q7 — PZR Backup Heater Power Supplies W E12 EK2.03 (3.2)
Given:
• Salem Unit 2 is at 100% power
• A reactor trip and Safety Injection occur due to the rapid depressurization of all steam generators.
• 2H and 2E 4KV Group Buses fail to auto transfer and are now de-energized
• The crew is performing actions in 2-EOP-LOSC-2

Which of the following describes the current status of the PZR Backup Heaters?
A. ONLY 21 Backup Group is available, 22 Backup Group can be locally transferred to an emergency backup source.
B. ONLY 22 Backup Group is available, 21 Backup Group can be locally transferred to an emergency backup source.
C. NEITHER 21 or 22 Backup Groups are available, Backup Groups can be locally transferred to an emergency backup source.
D. BOTH 21 and 22 Backup Groups are available, Backup Groups will automatically transfer to an emergency backup source.
▶ Show Answer & Explanation
✓ A. Correct. The preferred or normal power source for the PZR Heater Backup Groups is: Group 1 (21) - 2G and Group 2 (22) - 2E 4KV Group Buses. The PZR Heaters can be manually transferred to the emergency backup source: Group 1 (21) from 2C and Group 2 (22) from 2A 460V vital bus. With 2H and 2E unavailable, only PZR Heater Group 1 (21) remains available from 2G Group Bus. Group 2 (22) is unavailable but can be locally transferred to the emergency backup power. Transfer is manual, not automatic.
✗ B. Incorrect. Group 2 (22) is powered from 2E, which is de-energized. Group 1 (21) is powered from 2G, which is still available. This choice reverses the availability.
✗ C. Incorrect. Group 1 (21) is still available from 2G Group Bus, which has not failed. Only 2H and 2E are de-energized.
✗ D. Incorrect. Group 2 (22) is not available since 2E is de-energized. Additionally, the transfer to emergency backup source is manual (local), not automatic.
Ref: 2-EOP-LOSC-2 (R41) | LO: NOS05PZRPL-12, Obj 5.b | Source: New | Cognitive: Fundamental/Memory

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