Q65 — Condensate Pump Trip Response
056 A2.04 (2.6)
Given:
• Unit 2 is at 75% Power.
• Power was reduced 2 days ago when 21 Condensate Pump tripped.
• 21 Condensate Pump remains out of service.
• Condensate Polisher is in service with full flow.
Subsequently, 22 Condensate Pump trips.
Which ONE of the following completes both statements?
1. Based on the above condition, which plant parameter is expected to be impacted FIRST?
2. In accordance with S2.OP-AB.CN-0001, Main Feedwater/Condensate System Abnormality, what is the NEXT required action to mitigate this event?
• Unit 2 is at 75% Power.
• Power was reduced 2 days ago when 21 Condensate Pump tripped.
• 21 Condensate Pump remains out of service.
• Condensate Polisher is in service with full flow.
Subsequently, 22 Condensate Pump trips.
Which ONE of the following completes both statements?
1. Based on the above condition, which plant parameter is expected to be impacted FIRST?
2. In accordance with S2.OP-AB.CN-0001, Main Feedwater/Condensate System Abnormality, what is the NEXT required action to mitigate this event?
A. Lowering SG NR levels. Initiate a rapid load reduction at 15%/min to a maximum power level not to exceed 30%.
B. Lowering SG NR levels. Open 21-23 CN108s Polisher Bypass Valves.
C. Lowering SGFP suction pressure. Initiate a rapid load reduction at 15%/min to a maximum power level not to exceed 30%.
D. Lowering SGFP suction pressure. Open 21-23 CN108s Polisher Bypass Valves.
▶ Show Answer & Explanation
✓ D. Correct. At 75% power and with only one condensate pump running, the first operational impact will be seen by rapidly lowering SGFP suction pressure. The SGFPs speed will increase in an attempt to increase flow and the BF19s will throttle open more to increase feedwater flow. Subsequently, SG NR levels will start to lower based on reduction of condensate flow, until the 21-23 CN108s are opened, and if necessary, the 2CN47 bypass is opened. The CN108s and CN47 do not open automatically on a condensate pump trip. Opening the CN108s first will bypass the condensate polishers and help restore SGFP suction pressure to prevent the loss of the feedpumps.
✗ A. Incorrect. First part is incorrect. Second part is incorrect. Plausible because the SG levels will be impacted but SGFP suction pressure will be the first parameter to see the effect. Part 2 is plausible because the procedure will direct a load reduction to 30% power, however the applicant may believe that reducing load is the priority to stabilize the plant and that 15%/min ramp is reasonable since it is used for a SGFP trip runback which is not the rate specified in the procedure of a maximum of 5%/min. Restoring SGFP suction pressure is the priority to prevent loss of the SGFPs.
✗ B. Incorrect. First part is incorrect. Second part is correct. Plausible because the operator may believe that SG levels will be impacted first. SGFP suction pressure will be the first indication seen by the operators and has the priority to open the CN108s to bypass the polishers and restore SGFP suction pressure to avoid losing the feedpumps.
✗ C. Incorrect. First part is correct. Second part is incorrect. Part 2 is plausible because the procedure will direct a load reduction to 30% power, however the applicant may believe that reducing load is the priority to stabilize the plant and that 15%/min ramp is reasonable since it is used for a SGFP trip runback which is not the rate specified in the procedure of a maximum of 5%/min. Restoring SGFP suction pressure is the priority to prevent loss of the SGFPs.
Ref: S2.OP-AB.CN-0001 (R31) | LO: NOS05ABCN01-07, Obj 2 — Describe, in general terms, the actions taken in AB.CN-0001 and the bases for the actions in accordance with the technical bases document | Source: Bank — Salem 2011 NRC RO53 | Cognitive: Comprehension/Analysis
Connections
- Related systems: Feed & Condensate, Steam Generator & Blowdown
- Related abnormals: AB.CN-0001 — Condensate System Abnormality
- Related exam: 2022 NRC Written Exam