Q41 — CFCU High/Low Speed SW Flow
022 A4.04 (3.1)
Given:
• Unit 2 is at 100% Power.
• The crew is performing surveillance testing on 21 CFCU in accordance with S2.OP-ST.CBV-0003, Containment Systems – Cooling System.
Which ONE of the following describes how the CFCU will respond when the operator shifts from HIGH to LOW speed operation?
The 21SW223, CFCU Outlet Flow Control Valve, will __(1)__ and the service water flow through the CFCU will __(2)__ as compared to the flow when operating at HIGH speed.
• Unit 2 is at 100% Power.
• The crew is performing surveillance testing on 21 CFCU in accordance with S2.OP-ST.CBV-0003, Containment Systems – Cooling System.
Which ONE of the following describes how the CFCU will respond when the operator shifts from HIGH to LOW speed operation?
The 21SW223, CFCU Outlet Flow Control Valve, will __(1)__ and the service water flow through the CFCU will __(2)__ as compared to the flow when operating at HIGH speed.
A. 1) throttle or modulate
2) be higher
2) be higher
B. 1) throttle or modulate
2) remain the same
2) remain the same
C. 1) open to a fixed position
2) be higher
2) be higher
D. 1) open to a fixed position
2) remain the same
2) remain the same
▶ Show Answer & Explanation
✓ D. Correct. The CFCUs employ a fixed resistance flow scheme, with two orifices on the inlet of each CFCU and two orifices on the outlet of each CFCU; these orifices, along with a mechanical stop on the open travel of the SW223 valves, ensure that the SW flow is greater than that required by Tech Specs for the minimum flow to the CFCU for Containment Cooling requirements in an accident condition and that SW flow to all safety related equipment can be met. The SW223 valves are closed when the CFCU is O/S and open to the mechanical stop when the CFCU is in service; the mechanical stops are set at approximately 50% travel. Based on the operation of the SW223, service water flow will remain the same in High and Low speed operation.
✗ A. Incorrect. First part is incorrect. SW223 has a mechanical stop set to approximately 50% travel. Second part is incorrect. Plausible if the operator believes that service water flow will increase during accident (Low Speed) conditions.
✗ B. Incorrect. First part is incorrect. SW223 has a mechanical stop set to approximately 50% travel. Second part is correct.
✗ C. Incorrect. First part is correct. Second part is incorrect. Plausible if the operator believes that service water flow will increase during accident (Low Speed) conditions.
Ref: NOS05SW0NUC | LO: NOS05SW0NUC-15, Obj 4 — Describe the function of the following components and how their normal and abnormal operation affects the Service Water – Nuclear Header System: Containment Fan Coil Units and SW58, SW72, and SW223 | Source: Modified — Salem 2014 NRC RO46 | Cognitive: Fundamental/Memory
Connections
- Related systems: CFCUs, Service Water
- Related procedures: S2.OP-ST.CBV-0003 — Containment Cooling Systems Surveillance
- Related exam: 2022 NRC Written Exam