Q27 — EOP-LOCA-2 RCS Depressurization
W E03 EA1.1 (4.0)
Given:
• Salem Unit 2 is performing 2-EOP-LOCA-2, Post LOCA Cooldown and Depressurization.
• ALL ECCS Pumps are running.
• 21 Charging Pump was stopped at step 13, Charging Pump Reduction.
• The crew is at step 14, SI Pump Reduction.
• Conditions are met for stopping one Safety Injection (SI) Pump.
In accordance with 2-EOP-LOCA-2, which ONE of the following identifies the SI Pump that should be stopped and the reason for the selection?
• Salem Unit 2 is performing 2-EOP-LOCA-2, Post LOCA Cooldown and Depressurization.
• ALL ECCS Pumps are running.
• 21 Charging Pump was stopped at step 13, Charging Pump Reduction.
• The crew is at step 14, SI Pump Reduction.
• Conditions are met for stopping one Safety Injection (SI) Pump.
In accordance with 2-EOP-LOCA-2, which ONE of the following identifies the SI Pump that should be stopped and the reason for the selection?
A. 21 SI Pump to reduce the load on the bus for starting additional loads later.
B. 22 SI Pump to reduce the load on the bus for starting additional loads later.
C. 22 SI Pump to ensure ECCS injection flow if any single vital bus failure occurs.
D. 21 SI Pump to ensure ECCS injection flow if any single vital bus failure occurs.
▶ Show Answer & Explanation
✓ C. Correct. IAW 2-EOP-LOCA-2 Note on step N13-2, "The centrifugal charging pumps and SI pumps should be stopped on alternate ECCS trains when possible". Since 21 Charging pump (B bus) was stopped and that leaves 22 Charging pump running on C bus. 21 SI pump is supplied from A bus and 22 SI pump supplied from C bus, the operator should stop 22 SI pump (C bus) to ensure ECCS flow if a loss of a vital bus occurs (21 CV pump B bus and 21 SI pump A bus).
✗ A. Incorrect. First part is incorrect. 21 SI pump is supplied from A bus. If C bus is lost, then both 22 Charging and 22 SI pump will be lost and resulting in a complete or significant loss of ECCS flow. Second part is incorrect. Credible distractor if the operator believes that stopping the SI pump is to reduce load on the bus. Reducing load on the bus is not the reason for stopping an SI pump on an alternate bus.
✗ B. Incorrect. First part is correct. Second part is incorrect. Reducing load on the bus is not the reason for stopping an SI pump on an alternate bus.
✗ D. Incorrect. 21 SI pump is supplied from A bus. If C bus is lost, then both 22 Charging and 22 SI pump will be lost and resulting in a complete or significant loss of ECCS flow.
Ref: 2-EOP-LOCA-2, Rev 40 | LO: NOS05LOCA02-06, Objective 1 | Source: Bank – Salem 2011 NRC RO23 | Cognitive: Comprehension/Analysis
Connections
- Related systems: ECCS, CVCS, 4KV
- Related EOPs: EOP-LOCA-2 — Post LOCA Cooldown and Depressurization
- Related exam: 2022 NRC Written Exam