Q53 — RCP Shaft Shear Delta-T and SG Shrink
APE: 015/017 RCP Malfunctions-AK1.04 (2.9)
Given:
• Unit 1 is at 25% Reactor Power and rising due to a plant startup
At time 17:00:00
• 13 RCP shaft shears
Which ONE of the following completes the statements below?
13 RCS Loop ΔT will _(1)_ and 13 SG NR Level will INITIALLY _(2)_.
• Unit 1 is at 25% Reactor Power and rising due to a plant startup
At time 17:00:00
• 13 RCP shaft shears
Which ONE of the following completes the statements below?
13 RCS Loop ΔT will _(1)_ and 13 SG NR Level will INITIALLY _(2)_.
| (1) | (2) |
A. (1) lower (2) shrink
B. (1) lower (2) swell
C. (1) rise (2) shrink
D. (1) rise (2) swell
▶ Show Answer & Explanation
✓ A. Correct. When 13 RCP shaft shears, Loop 13 RCS flow will go to minimum and 13 SG steam flow will lower significantly. This will cause 13 RCS Loop ΔT to lower and 13 SG NR level will initially shrink.
✗ B. Incorrect but plausible. Part 1 is correct. For Part 2, the candidate could not understand the shrink/swell concept and incorrectly conclude that 13 SG will initially swell.
✗ C. Incorrect but plausible. For Part 1, the candidate could misunderstand the thermodynamic processes in play with unbalanced flow in an RCS loop and incorrectly determine that 13 RCS Loop ΔT will rise. Part 2 is correct.
✗ D. Incorrect but plausible. For Part 1, the candidate could misunderstand the thermodynamic processes in play with unbalanced flow in an RCS loop and incorrectly determine that 13 RCS Loop ΔT will rise. For Part 2, the candidate could not understand the shrink/swell concept and incorrectly conclude that 13 SG will initially swell.
Ref: NOS05RCPUMP-13, NOS05STMGEN-14 | LO: NOS05RCPUMP-13 (REACTOR COOLANT PUMP), NOS05STMGEN-14 | Source: New | Cognitive: Higher
Connections
- Related systems: RCPs, Steam Generator & Blowdown, RCS
- Related exam: 2019 NRC Written Exam