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Exams > 2023 Q52 — Phase A / CA330 Instrument Air to Containment

2023 Q52 — Phase A / CA330 Instrument Air to Containment

⚠️ DRAFT
Q52 — Phase A / CA330 Instrument Air to Containment T2G1 078 A3.05 (3.3)
Given:
• Salem Unit 2 experienced a Safety Injection
• The crew enters 2-EOP-TRIP-1, Reactor Trip or Safety Injection
• Phase A signal failed to actuate on BOTH trains

Which of the following completes the statement concerning instrument air to containment?

1. 21 and 22 CA330s, Instrument Air Containment Isolation, valves are currently in the (1) position.
2. MINIMUM requirement per 2-EOP-TRIP-1 for isolating instrument air to containment requires (2) CA330(s) to be closed.
A. (1) closed (2) both
B. (1) closed (2) ONLY one
C. (1) open (2) ONLY one
D. (1) open (2) both
▶ Show Answer & Explanation
✓ D. Correct. CA330s are closed by a Phase A isolation signal. Although SI actuated, with both trains of Phase A not actuated, then the 21 and 22 CA330s will remain open. Both 21 and 22 CA330s are required to be closed to fully isolate air to containment. 21 CA330s supplies 2A control air header and 22CA330s supplies 2B control air header to containment. Each instrument air supply line to containment is isolated by its respective CA330 and a check valve. It is for this reason that both CA330s need to be closed to ensure a failure of one of the two components will still isolate a pathway from containment. Backup air receivers inside containment ensure that the PZR PORVs have sufficient air to allow the PZR PORV to stroke during steps in the EOP Network (Inadvertent SI, SGTR, etc.)
✗ A. Incorrect. Part 1 is incorrect. Plausible because the operator may believe that the CA330s close on an SI signal. Incorrect in that each CA330s will close on a Phase A signal only. Part 2 is correct. Plausible because the operator may believe that the CA330s are in series and need both to close.
✗ B. Incorrect. Part 1 is incorrect. Plausible because the operator may believe that the CA330s close on an SI signal. Incorrect in that each CA330s will close on a Phase A signal only. Part 2 is incorrect. Plausible because the operator may believe that the CA330s are in series and only need one of the two to isolate containment as a minimum.
✗ C. Incorrect. Part 1 is correct. Part 2 is incorrect. Plausible because the operator may believe that the CA330s are in series and only need one of the two to isolate containment as a minimum.
Ref: NOS05CONAIR-13 | Source: Modified Bank — Farley 2019 NRC RO14 | Cognitive: Fundamental/Memory
K/A: 078 A3.05 — Ability to monitor automatic features of the Instrument Air System, including: Isolation of instrument air to containment

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