Q97 — LCO 3.2.1 AFD Power Reduction
G2.2.39 (4.5)
Given:
• Unit 2 is at 95% Power
At time 15:30
• The CRS has declared LCO 3.2.1 (AXIAL FLUX DIFFERENCE (AFD)) NOT met
In accordance with LCO 3.2.1, which ONE of the following completes the statements below?
The crew is REQUIRED to reduce THERMAL POWER to less than _(1)_ % of RATED THERMAL POWER by 15:45 (15 minutes after LCO 3.2.1 was NOT met).
The LCO 3.2.1 REQUIRED power reduction will ensure _(2)_ limit as specified in the COLR is NOT exceeded.
• Unit 2 is at 95% Power
At time 15:30
• The CRS has declared LCO 3.2.1 (AXIAL FLUX DIFFERENCE (AFD)) NOT met
In accordance with LCO 3.2.1, which ONE of the following completes the statements below?
The crew is REQUIRED to reduce THERMAL POWER to less than _(1)_ % of RATED THERMAL POWER by 15:45 (15 minutes after LCO 3.2.1 was NOT met).
The LCO 3.2.1 REQUIRED power reduction will ensure _(2)_ limit as specified in the COLR is NOT exceeded.
A. (1) 90 (2) FQ(Z) (Heat Flux Hot Channel Factor)
B. (1) 90 (2) FXY(Z) (Radial Peaking Factor)
C. (1) 50 (2) FQ(Z) (Heat Flux Hot Channel Factor)
D. (1) 50 (2) FXY(Z) (Radial Peaking Factor)
▶ Show Answer & Explanation
✓ A. Correct. For Part 1 and IAW LCO 3.2.1, with Reactor Power at 95% power and LCO 3.2.1 NOT met at 15:30, the crew is required to reduce THERMAL POWER to less than 90% of RATED THERMAL POWER by 15:45 (within 15 minutes). For Part 2 and IAW LCO Bases, the LCO 3.2.1 REQUIRED power reduction will ensure FQ(Z) (Heat Flux Hot Channel Factor) limit as specified in the COLR is NOT exceeded.
✗ B. Incorrect but plausible. Part 1 is correct. For Part 2, the LCO Bases for the Power Distribution LCOs (LCO 3.2.x) are designed to protect three different hot channel factors (Heat Flux Hot Channel, Nuclear Enthalpy Rise Hot Channel Factor and Radial Peaking Factor). Consequently, the candidate could incorrectly conclude that LCO 3.2.1 is designed to prevent exceeding the Radial Peaking Factor.
✗ C. Incorrect but plausible. For Part 1 and IAW LCO 3.2.1, once reactor power is between 90%-50%, the crew must then reduce power to less than 50% in the next 30 minutes. Consequently, the candidate could incorrectly conclude that when LCO 3.2.1 was first not met (with RX Power at 95%), the crew is required to reduce THERMAL POWER to less than 50% of RATED THERMAL POWER by 15:45 (within 15 minutes). Part 2 is correct.
✗ D. Incorrect but plausible. For Part 1 and IAW LCO 3.2.1, once reactor power is between 90%-50%, the crew must then reduce power to less than 50% in the next 30 minutes. Consequently, the candidate could incorrectly conclude that when LCO 3.2.1 was first not met (with RX Power at 95%), the crew is required to reduce THERMAL POWER to less than 50% of RATED THERMAL POWER by 15:45 (within 15 minutes). For Part 2, the LCO Bases for the Power Distribution LCOs (LCO 3.2.x) are designed to protect three different hot channel factors (Heat Flux Hot Channel, Nuclear Enthalpy Rise Hot Channel Factor and Radial Peaking Factor). Consequently, the candidate could incorrectly conclude that LCO 3.2.1 is designed to prevent exceeding the Radial Peaking Factor.
Ref: LCO 3.2.1 | LO: NOS05TECHSPEC-12 Obj 14 | Source: New | Cognitive: Lower | SRO Only: Knowledge of TS bases for LCO 3.2.1
Connections
- Related tech specs: TS 3/4.2 — Power Distribution
- Related exam: 2018 NRC Written Exam