Q1 — Reactor Trip Status Panel
000007EK2.03 (3.5)
Given:
• Unit 2 is at 60% Power.
The following sequence of events occurs:
• A Main Turbine trip occurs.
• OHA F-36, TURB TRIP & P-9, is illuminated.
• One of the Turbine Stop Valve Closed indicating lights on 2RP4 is flashing.
The flashing light on 2RP4 indicates that …
• Unit 2 is at 60% Power.
The following sequence of events occurs:
• A Main Turbine trip occurs.
• OHA F-36, TURB TRIP & P-9, is illuminated.
• One of the Turbine Stop Valve Closed indicating lights on 2RP4 is flashing.
The flashing light on 2RP4 indicates that …
A. the valve has left its open seat, but has NOT fully closed.
B. SSPS Train "A" and SSPS Train "B" disagree as to the position of the valve.
C. EHC fluid pressure to the valve operator remains above 45 psig.
D. the solenoid-operated dump valve in the EHC fluid supply line has NOT de-energized.
▶ Show Answer & Explanation
✓ B. Correct. As stated in the Reactor Protection System lesson plan; "if information sent by Trains A and B differ, the control board status lamps will flash."
✗ A. Incorrect. Plausible because the candidate may believe that the indicator lights start to flash as the valves stroke closed and then are fully lit only once they are full closed. Incorrect, because the indicating lights fully lit for turbine stop valves indicate both trains see the valve at ≤ 85% open, if information sent by Trains A and B differ, the control board status lamps will flash.
✗ C. Incorrect. Plausible because the candidate may believe that Auto Stop Oil > 45 psig (as 45 psig is the Tech Spec value) is maintaining the "interface valve" closed and therefore preventing the stop valve from fully closing. However, the pressure is set to ≤ 50 psig and OHA-36 confirms that a turbine trip above P-9 has occurred.
✗ D. Incorrect. Plausible because the candidate may believe that the 2RP4 indicator lights will flash when a turbine trip demand signal has been sent, but if the EHC fluid is still being maintained to the stop valves, then the indicating lights won't fully light. Incorrect because there are redundant trip solenoids, the 20-ET, 20-AST-1, and 20-AST-2. Also incorrect, because the OHA F-36 is a demand for a reactor trip, but confirms that a turbine trip above P-9 has taken place. It confirms that either 4/4 Turbine Stop Valves are ≤ 85% open or 2/3 Auto Stop Oil Pressures ≤ 50 psig.
Ref: NOS05RXPROT-12, 2-EOP-TRIP-1 | LO: Objective 18 | Source: Bank – Salem Vision Database, modification made to stem only | Cognitive: Comprehension
Connections
- Related systems: RPS/SSPS, Main Turbine
- Related exam: 2020 NRC Written Exam