Q1 — Reactor Trip Breakers / SSPS Train Failure
EPE07 EK2.02 (2.6)
Given:
• Unit 2 is at 100% Reactor Power.
• Reactor Trip Breaker testing is in progress.
• Reactor Trip Breakers (RTB) 'A' and 'B' are closed.
• Operators have just closed Reactor Trip Bypass Breaker (BYB) 'A'.
Subsequently the following occurs:
• A valid Reactor Trip demand signal is actuated.
• SSPS Train A actuates as designed.
• SSPS Train B fails to actuate.
Which ONE of the following describes how the RTB 'B' and BYB 'A' will respond?
• Unit 2 is at 100% Reactor Power.
• Reactor Trip Breaker testing is in progress.
• Reactor Trip Breakers (RTB) 'A' and 'B' are closed.
• Operators have just closed Reactor Trip Bypass Breaker (BYB) 'A'.
Subsequently the following occurs:
• A valid Reactor Trip demand signal is actuated.
• SSPS Train A actuates as designed.
• SSPS Train B fails to actuate.
Which ONE of the following describes how the RTB 'B' and BYB 'A' will respond?
A. RTB 'B': OPEN; BYB 'A': OPEN
B. RTB 'B': CLOSED; BYB 'A': OPEN
C. RTB 'B': CLOSED; BYB 'A': CLOSED
D. RTB 'B': OPEN; BYB 'A': CLOSED
▶ Show Answer & Explanation
✓ C. Correct. SSPS Train A will deenergize the UV coils for RTB 'A' and BYB 'B' and only energize the shunt coil for RTB 'A'. SSPS Train B will deenergize the UV coils for RTB 'B' and BYB 'A' and only energize the shunt coil for RTB 'B'. The shunt coils on the RTBs and BYBs will also energize from; 1) Manual SI from either train, 2) either Pistol Grip switches, or 3) RTB 'A' or RTB 'B' PB bezels on CC2 (trips the associated train RTBs only).
✗ A. Incorrect. The RTB 'B' and BYB 'A' will not open with a failure of SSPS Train B to actuate. Plausible because the operator may believe that either SSPS Train will open all of the RTBs.
✗ B. Incorrect. BYB 'A' will not open with a failure of SSPS Train B. Plausible because the operator may believe that SSPS Train A will open BYB A.
✗ D. Incorrect. RTB 'B' will not open with a failure of SSPS Train B.
Ref: Logic drawing 221051, simplified ESF-2 | LO: NOS05RXPROT, Obj 7 — Describe the function of SSPS components and how their normal and abnormal operation affects the Reactor Protection System: Reactor Trip Breaker and Bypass Breakers | Source: Bank — Beaver Valley 2018 NRC RO36 | Cognitive: Comprehension/Analysis
Connections
- Related systems: RPS/SSPS
- Related exam: 2022 NRC Written Exam