Q17 — Loss of Emergency Recirculation Mitigation Strategies
WE11EK1.2 (3.6)
Given:
• Unit 2 has experienced a design bases Large Break LOCA coincident with a Loss of Off-Site Power.
• 2B Emergency Diesel Generator tripped.
• 21 RHR Pump tripped.
• The CRS has transitioned to 2-EOP-LOCA-5, Loss of Emergency Recirculation.
In accordance with 2-EOP-LOCA-5, which of the following mitigation strategies are applicable based on CURRENT plant conditions and will NEED to be implemented?
1. Run All CFCUs in High Speed.
2. Minimize SI Flow to minimum for adequate decay heat removal.
3. Depressurize the RCS to minimize RCS subcooling.
4. Make up to the RWST.
• Unit 2 has experienced a design bases Large Break LOCA coincident with a Loss of Off-Site Power.
• 2B Emergency Diesel Generator tripped.
• 21 RHR Pump tripped.
• The CRS has transitioned to 2-EOP-LOCA-5, Loss of Emergency Recirculation.
In accordance with 2-EOP-LOCA-5, which of the following mitigation strategies are applicable based on CURRENT plant conditions and will NEED to be implemented?
1. Run All CFCUs in High Speed.
2. Minimize SI Flow to minimum for adequate decay heat removal.
3. Depressurize the RCS to minimize RCS subcooling.
4. Make up to the RWST.
A. 1, 2, 3, and 4 Only.
B. 2, 3, and 4 Only.
C. 1 and 4 Only.
D. 2 and 4 Only.
▶ Show Answer & Explanation
✓ D. Correct. Because of the failure of 2B EDG to start, 22 & 24 CFCUs were not available and a DBA LOCA has already resulted in the RCS being completely depressurized and RCS Subcooling would not exist.
✗ A. Plausible because they are all actions / mitigation strategies provided in 2-EOP-LOCA-5, Loss of Emergency Recirculation. Incorrect because of the failure of 2B EDG to start, 22 & 24 CFCUs were not available and a DBA LOCA has already resulted in the RCS being completely depressurized and RCS Subcooling would not exist.
✗ B. Plausible because they are all actions / mitigation strategies provided in 2-EOP-LOCA-5, Loss of Emergency Recirculation. Incorrect because a DBA LOCA has already resulted in the RCS being completely depressurized and RCS Subcooling would not exist.
✗ C. Plausible because they are all actions / mitigation strategies provided in 2-EOP-LOCA-5, Loss of Emergency Recirculation. Incorrect because of the failure of 2B EDG to start, 22 & 24 CFCUs were not available.
Ref: 2EOP-LOCA-5, Loss of Emergency Recirculation and Bases | LO: N/A | Source: New | Cognitive: Comprehension
Connections
- Related systems: ECCS, RCS, CFCUs, EDGs, RHR
- Related EOPs: EOP-LOCA-5 — Loss of Emergency Coolant Recirculation
- Related exam: 2020 NRC Written Exam