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Exams > 2023 Q51 — SW122 Loss of Air / RHR Cooldown Rate

2023 Q51 — SW122 Loss of Air / RHR Cooldown Rate

⚠️ DRAFT
Q51 — SW122 Loss of Air / RHR Cooldown Rate T2G1 076 K3.05 (3.6)
Given:
• Salem Unit 2 is in MODE 4
• 21 RHR Pump is in service providing shutdown cooling through 21 RHR HX
• RCS pressure is 300 psig
• 21RH18, RHR HX Flow Cont. Valve, and 2RH20, RHR HX Bypass Valve, are being throttled to maintain a RCS cooldown rate of 5°F per hour

Then:
• Instrument air supply line to the actuator of 21SW122, SW Inlet Control Valve, to CCW HX, severs

Assuming NO operator action, which of the following completes both statements?

1. RCS cooldown rate will (1).
2. The 21SW122 (2) be manually operated.
A. (1) rise (2) can NOT
B. (1) rise (2) can
C. (1) lower (2) can
D. (1) lower (2) can NOT
▶ Show Answer & Explanation
✓ B. Correct. 21SW122 fails open on loss of air (fails closed on loss of 125VDC power). When the 21SW122 opens, SW flow will rise through the CCW HX causing CCW temperature to lower and therefore the outlet temperature of 21 RHR HX to lower raising the cooldown rate. Per S2.OP-AB.CA-0001, the 21/22SW122 can be manually operated.
✗ A. Incorrect. Plausible because the operator may incorrectly recall if this valve can be manually operated from the field since not all AOVs can be manually operated in the field.
✗ C. Incorrect. Plausible because the question is asking about the cooldown rate and the operator may confuse the concept that a lower temperature means a higher cooldown rate.
✗ D. Incorrect. Plausible because the question is asking about the cooldown rate and the operator may confuse the concept that a lower temperature means a higher cooldown rate.
Ref: NOS05SW0NUC-13, S2.OP-AB.CA-0001 (R22) | Source: New | Cognitive: Comprehension/Analysis
K/A: 076 K3.05 — Knowledge of the effect that a loss or malfunction of the Service Water System will have on the following systems or system parameters: RHRS

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