Q41 — Rod Position After Downpower
G2.1.43 (4.1)
REFERENCES PROVIDED
Given:
• Unit 2 is at 100% Reactor Power and stable
• Core Burnup is 8000 EFPH
• RCS Boron Concentration is 900 ppm
• Control Bank D is at 228 steps
At time 10:00:00
• The crew is planning to reduce Reactor Power to 80% to support unplanned maintenance activities
• As part of the down power, the crew will change core reactivity by (-) 216 pcm by raising RCS Boron Concentration
Which ONE of the following completes the statements below?
Using the given references and disregarding any core reactivity change due to Xenon, Control Bank D will be at approximately _____ steps after the down power and RCS Boron Concentration change are completed.
Given:
• Unit 2 is at 100% Reactor Power and stable
• Core Burnup is 8000 EFPH
• RCS Boron Concentration is 900 ppm
• Control Bank D is at 228 steps
At time 10:00:00
• The crew is planning to reduce Reactor Power to 80% to support unplanned maintenance activities
• As part of the down power, the crew will change core reactivity by (-) 216 pcm by raising RCS Boron Concentration
Which ONE of the following completes the statements below?
Using the given references and disregarding any core reactivity change due to Xenon, Control Bank D will be at approximately _____ steps after the down power and RCS Boron Concentration change are completed.
A. 186
B. 175
C. 166
D. 150
▶ Show Answer & Explanation
✓ A. Correct. IAW S2-RE-RA.ZZ-0016 (Figure 17A or Table 2-1), for the given Core Burnup and RCS Boron Concentration, lowering power from 100% to 80% will add (+) 396 pcm of reactivity to the core. Since the crew will change core reactivity by (-) 216 pcm by raising RCS Boron Concentration, Control Bank D will need to make up for the remaining (-) 180 pcm by inserting from 228 steps. Using the Integral Rod Worth from IAW S2-RE-RA.ZZ-0016 Figure 2C, Control Bank D will be at approximately 186 steps after the down power and RCS Boron Concentration change are completed.
✗ B. Incorrect but plausible. Determining the correct answer requires multiple calculations and reading of multiple curves / tables. Consequently, there are several incorrect steps the candidate could perform to incorrectly determine Control Bank D final position. Since the distractors are all possible positions of Control Bank D, all of the distractors are plausible.
✗ C. Incorrect but plausible. Determining the correct answer requires multiple calculations and reading of multiple curves / tables. Consequently, there are several incorrect steps the candidate could perform to incorrectly determine Control Bank D final position. Since the distractors are all possible positions of Control Bank D, all of the distractors are plausible.
✗ D. Incorrect but plausible. Determining the correct answer requires multiple calculations and reading of multiple curves / tables. Consequently, there are several incorrect steps the candidate could perform to incorrectly determine Control Bank D final position. Since the distractors are all possible positions of Control Bank D, all of the distractors are plausible.
Ref: S2-RE-RA.ZZ-0016 (Curve Book - Salem Unit 2 Cycle 23) | LO: NOS05RODS00-12 (Rod Control and Position Indication Systems) | Source: New | Cognitive: Higher
Connections
- Related systems: Control Rod Drive
- Related procedures: S2-RE-RA.ZZ-0016 — Curve Book (Salem Unit 2 Cycle 23)
- Related exam: 2018 NRC Written Exam