Q29 — CVCS VCT Level Transmitter Fails High / Auto Swapover
004 K3.13 (3.8)
Given:
• Salem Unit 2 is at 100% power
• 21 Charging Pump is in service
• 2LT-112, VCT level, transmitter fails HIGH
Which of the following describes the operational impact to the CVCS system and the effect on the running charging pump, if any (assume no operator action taken)?
• Salem Unit 2 is at 100% power
• 21 Charging Pump is in service
• 2LT-112, VCT level, transmitter fails HIGH
Which of the following describes the operational impact to the CVCS system and the effect on the running charging pump, if any (assume no operator action taken)?
A. No automatic make-up, VCT level lowers, automatic swapover to RWST occurs.
B. No automatic make-up, VCT level lowers, no automatic swapover to RWST, charging pump damage.
C. Automatic make-up maintains VCT level.
D. Automatic make-up initiates but cannot maintain VCT level.
▶ Show Answer & Explanation
✓ B. Correct. LT-112 fails high, causing CV35 high level divert valve to open, which drains the VCT. Automatic make-up will not actuate because only LT-112 actuates automatic make-up, and it is failed high. Automatic swapover to RWST requires 2/2 VCT levels low-low (LT-112 AND LT-114); with LT-112 failed high, the 2/2 coincidence is not met. The charging pump loses suction as VCT empties and runs dry, resulting in pump damage.
✗ A. Incorrect. VCT level does lower and auto make-up will not actuate, but automatic swapover to RWST requires 2/2 VCT levels low-low (both LT-112 AND LT-114). With LT-112 failed high, the coincidence logic is not satisfied and no auto swapover occurs.
✗ C. Incorrect. Only LT-112 actuates automatic make-up. Since LT-112 is failed high, the controller sees a high VCT level and will not initiate make-up. VCT level will lower uncontrolled.
✗ D. Incorrect. Automatic make-up does not initiate at all. Only LT-112 actuates the auto make-up function, and it is failed high, so the controller sees no need for make-up.
Ref: NOS05CVCS00-18 | Source: New | Cognitive: Comprehension/Analysis
Connections
- Related systems: CVCS, ECCS
- Related exam: 2023 NRC Written Exam