2019 Q11 — Containment Pressure Channel Loss

✓ A. Correct. When Containment Pressure Channel II was removed from service, the logic for Safety Injection and Reactor Trip (on Hi CTMT Pressure) went from 2/3 to 1/2 and the logic for Containment Spray (on Hi CTMT Pressure) went from 2/4 to 2/3. For Part 1, Containment Channels II, III and IV provide the input for the Safety Injection Logic (and Reactor Trip). Additionally, bi-stables for Safety Injection and Reactor Trip are de-energize to actuate. Consequently, when Containment Pressure Channel III loses power at 15:00, Safety Injection will actuate (1/2 logic is met). For Part 2, when Containment Pressure Channel III loses power, Containment Spray will not actuate (2/3 logic is not met).

✗ B. Part 1 is correct. For Part 2 the candidate could incorrectly conclude that based on plant conditions, the logic for Containment Spray is met and Containment Spray has actuated.

✗ C. For Part 1, the candidate could incorrectly conclude that after Containment Pressure II was removed from service that the coincidence for SI went to 2/2. Consequently, the candidate would then incorrectly conclude that SI has not actuated. Part 2 is correct.

✗ D. For Part 1, the candidate could incorrectly conclude that after Containment Pressure II was removed from service that the coincidence for SI went to 2/2. Consequently, the candidate would then incorrectly conclude that SI has not actuated. For Part 2 the candidate could incorrectly conclude that based on plant conditions, the logic for Containment Spray is met and Containment Spray has actuated.

Ref: NOS05ESF000-02 (Introduction to Engineered Safety Features and Design Criteria), DWG 221057 | LO: NOS05ESF000-02 LO 21 — State the setpoints for automatic actuations associated with the Engineered Safety Features | Source: Modified Bank (ILOT 1601 AUDIT RO 16) | Cognitive: Higher