Q79 — Loss of Air / TDAFW Pump Overpower
APE 65 G2.4.31 (4.1)
Given:
• Unit 2 is at 100% Power.
• 2MS132, 23 AFP TURBINE STEAM INLET VALVE, air supply line ruptures.
Based on the above failure, which ONE of the following completes the statement concerning the status of the Turbine Driven Auxiliary Feed Pump and the actions the crew take to mitigate this event?
1. The Turbine-Driven Auxiliary Feed Pump is _(1)_.
2. The crew will _(2)_.
• Unit 2 is at 100% Power.
• 2MS132, 23 AFP TURBINE STEAM INLET VALVE, air supply line ruptures.
Based on the above failure, which ONE of the following completes the statement concerning the status of the Turbine Driven Auxiliary Feed Pump and the actions the crew take to mitigate this event?
1. The Turbine-Driven Auxiliary Feed Pump is _(1)_.
2. The crew will _(2)_.
A. 1. shutdown
2. ONLY enter TS 3.7.1.2, for INOPERABLE AFW Pump because 23 AFW Pump will not respond to any start signals, and repair the airline within 72 hours.
2. ONLY enter TS 3.7.1.2, for INOPERABLE AFW Pump because 23 AFW Pump will not respond to any start signals, and repair the airline within 72 hours.
B. 1. shutdown
2. continue power operations because the TDAFW remains operable due to availability of the opposite train steam supply.
2. continue power operations because the TDAFW remains operable due to availability of the opposite train steam supply.
C. 1. running
2. implement S2.OP-AB.CA-0001, Loss of Control Air, Attachment 12, Local Control of SG Pressure and Level, to locally shutdown 23 AFW Pump.
2. implement S2.OP-AB.CA-0001, Loss of Control Air, Attachment 12, Local Control of SG Pressure and Level, to locally shutdown 23 AFW Pump.
D. 1. running
2. reduce turbine load using S2.OP-IO.ZZ-0004, Power Operation, until the reactor thermal overpower condition has cleared
2. reduce turbine load using S2.OP-IO.ZZ-0004, Power Operation, until the reactor thermal overpower condition has cleared
▶ Show Answer & Explanation
✓ D. Correct. IAW S2.OP-AB.CA-0001, Attachment 2, on loss of instrument air the 2MS132 fails open which results in 23 AFW pump running. This will result in cold AFW entering the SGs causing reactor power to rise and exceed the reactor power limit of 3459 MWt (reactor overpower condition). The CRS should direct the crew to reduce turbine load to lower reactor power below the administrative limit using S2.OP-IO.ZZ-0004, Power Operation. Note: S2.OP-AB.LOAD-0001 is used only if turbine load rate is ≥ 5%/min which in this case the crew should not require reducing turbine load at this rate.
✗ A. Incorrect. Part 1 is incorrect. Plausible if the applicant incorrectly determines that the MS132 fails closed instead of open on loss of air. Part 2 is incorrect. Plausible because this is the correct action (not the only action) for an Inoperable AFW pump, however, the overpower condition must also be addressed first and can be mitigated by performing a load reduction.
✗ B. Incorrect. Part 1 is incorrect. Plausible if the applicant incorrectly determines that the MS132 fails closed instead of open on loss of air. Part 2 is incorrect. Plausible because the applicant may confuse how the MS132 impacts the steam supply to the TDAFW pump. Steam is supplied from #1 and #3 SGs thru the MS45s. The applicant may believe that the MS132 failure impacts one of the steam supplies and that the other steam supply remains available.
✗ C. Incorrect. Part 1 is correct. 2MS132 fails open on loss of air. Part 2 is incorrect. Plausible because S2.OP-AB.CA-0001 can be used for a loss of control air, however, this procedure does not provide direction to shutdown 23 AFW pump and only directs local control of 23 AFW pump governor and AF21s.
Ref: S2.OP-AB.CA-0001 (R22), S2.OP-AB.CN-0001 (R31), S2.OP-IO.ZZ-004 (R87) | LO: NOS05ABCA01-08, Objective 2 | Source: Bank - Beaver Valley U1 2016 SRO89 | Cognitive: Comprehension/Analysis
Connections
- Related systems: AFW, Control Air
- Related exam: 2022 NRC Written Exam