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Exams > 2019 Q85 — Natural Circulation RVLIS Cooldown Rate

2019 Q85 — Natural Circulation RVLIS Cooldown Rate

⛔ OUTDATED
Q85 — Natural Circulation RVLIS Cooldown Rate [OUTDATED] WE10 Nat Circ with Steam Void - G2.4.46 (4.2)
Given:
• The crew is performing 2-EOP-TRIP-4 (NATURAL CIRCULATION COOLDOWN)
• Wide Range Loop 22 T HOT has failed low

At time 12:00
• OHA B-11 "2B VTL INSTR BUS INVRT FAIL" actuates
• ALL Channel II indications are lost
• The crew enters S2.OP-AB.115-0002 (LOSS OF 2B 115V VITAL INSTRUMENT BUS)

At time 12:30
• The crew has just completed the RCS Stabilization Steps of 2-EOP-TRIP-4 and is now preparing to Cooldown and Depressurize the RCS
• ALL Channel II indications are still lost

In accordance with 2-EOP-TRIP-4, which ONE of the following completes the statement below?

The crew will transition to _(1)_ if the required RCS Cooldown Rate is greater than a MINIMUM of _(2)_ °F / Hour.

NOTE:
• 2-EOP-TRIP-5 (NATURAL CIRCULATION RAPID COOLDOWN WITH RVLIS)
• 2-EOP-TRIP-6 (NATURAL CIRCULATION RAPID COOLDOWN WITHOUT RVLIS)
A. (1) 2-EOP-TRIP-6 (2) 25
B. (1) 2-EOP-TRIP-6 (2) 50
C. (1) 2-EOP-TRIP-5 (2) 25
D. (1) 2-EOP-TRIP-5 (2) 50
▶ Show Answer & Explanation
✓ C. Correct. IAW 2-EOP-TRIP-4, if RVLIS is available then the crew will transition to 2-EOP-TRIP-5 (NATURAL CIRCULATION RAPID COOLDOWN WITH RVLIS) if the required RCS Cooldown Rate is greater than a MINIMUM of 25 °F / Hour. Loop 22 THOT provides input to Train A of RVLIS. 2B Vital Instrument Bus provides the power for RVLIS Train A Microprocessor Panel. Consequently, ONLY Train A of RVLIS is inoperable at 12:30. Train B of RVLIS not affected.
✗ A. Incorrect but plausible. For Part 1, the candidate could correctly identify that Train A of RVLIS is inoperable when 2B Vital Instrument Bus de-energized. The candidate could then incorrectly conclude that Train B of RVLIS becomes invalid with Wide Range Loop 22 THOT has failed low. The candidate would then incorrectly conclude that both trains of RVLIS are inoperable and performance of 2-EOP-TRIP-6 (NATURAL CIRCULATION RAPID COOLDOWN WITHOUT RVLIS) is warranted. Part 2 is correct.
✗ B. Incorrect but plausible. For Part 1, the candidate could correctly identify that Train A of RVLIS is inoperable when 2B Vital Instrument Bus de-energized. The candidate could then incorrectly conclude that Train B of RVLIS becomes invalid with Wide Range Loop 22 THOT has failed low. The candidate would then incorrectly conclude that both trains of RVLIS are inoperable and performance of 2-EOP-TRIP-6 (NATURAL CIRCULATION RAPID COOLDOWN WITHOUT RVLIS) is warranted. For Part 2, other EOPs and SOPs have maximum cooldown rates of 50 °F. Consequently, the candidate could incorrectly conclude transition to 2-EOP-TRIP-5 or 2-EOP-TRIP-6 is warranted when the required RCS Cooldown Rate is greater than a MINIMUM of 50 °F / Hour.
✗ D. Incorrect but plausible. Part 1 is correct. For Part 2, other EOPs and SOPs have maximum cooldown rates of 50 °F. Consequently, the candidate could incorrectly conclude transition to 2-EOP-TRIP-5 or 2-EOP-TRIP-6 is warranted when the required RCS Cooldown Rate is greater than a MINIMUM of 50 °F / Hour.
Ref: 2-EOP-TRIP-4 (NATURAL CIRCULATION COOLDOWN), S2.OP-AB.115-0002 (LOSS OF 2B 115V VITAL INSTRUMENT BUS) | LO: NOS05TRP004-06 — Describe the mitigation strategy for any NATURAL CIRCULATION COOLDOWN | Source: New | Cognitive: Higher

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