Q50 — EDG Starting Air Receiver Capability
064000K6.07 (2.7)
Given:
• The Unit 2 is at 100% Power.
• 2A Emergency Diesel Generator (EDG) Starting Air Receiver 21A is isolated and cleared tagged for maintenance.
• A Loss of Off-Site Power has just occurred.
Complete the following statement regarding the 2A Emergency Diesel Generator (EDG) starting air system capability and response.
Following an SEC start signal, the 2A EDG __(1)__ start and achieve rated speed of 900 RPM in ≤ 13 seconds. The 21B starting air receiver is aligned to supply __(2)__ air start motors.
• The Unit 2 is at 100% Power.
• 2A Emergency Diesel Generator (EDG) Starting Air Receiver 21A is isolated and cleared tagged for maintenance.
• A Loss of Off-Site Power has just occurred.
Complete the following statement regarding the 2A Emergency Diesel Generator (EDG) starting air system capability and response.
Following an SEC start signal, the 2A EDG __(1)__ start and achieve rated speed of 900 RPM in ≤ 13 seconds. The 21B starting air receiver is aligned to supply __(2)__ air start motors.
A. (1) will
(2) four
(2) four
B. (1) will NOT
(2) two
(2) two
C. (1) will
(2) two
(2) two
D. (1) will NOT
(2) four
(2) four
▶ Show Answer & Explanation
✓ C. Correct. Each air receiver supplies two air start motors (one train). Two air start motors will start the diesel in < 10 seconds.
✗ A. Incorrect. Plausible because the first part is correct. Each receiver is capable of 3 cold starts and only two motors are required to start the diesel in < 10 seconds. The second part is plausible because the candidate may believe that each air receiver is lined up to supply all four air start motors. Incorrect as each receiver only supplies two air start motors.
✗ B. Incorrect. Plausible because the candidate may believe that only two air start motors are not capable of starting the diesel in ≤ 13 seconds. Incorrect, because just one air start motor can enable the diesel to reach full speed within 14 seconds. The second part is correct.
✗ D. Incorrect. Plausible because the candidate may believe that one air receiver is not capable of starting the diesel in ≤ 13 seconds. The second part is plausible because the candidate may believe that each air receiver is lined up to supply all four air start motors. Incorrect as each receiver only supplies two air start motors.
Ref: NOS05EDG000-12, Emergency Diesel Generators | LO: ELOs 14 | Source: New | Cognitive: Fundamental
Connections
- Related systems: EDGs
- Related exam: 2020 NRC Written Exam