Q24 — Core Cooling Red Path Validation
EPE74G2.1.19 (3.9)
Given:
• Unit 2 has experienced a LOCA.
• The crew is implementing the Critical Function Status Trees.
• The RO has identified that the SPDS Overview Screen indicates a Red Path for Core Cooling.
• RCS Subcooling is < 0 °F.
• No RCPs are running.
Which ONE of the following RCS Parameters would validate a Core Cooling Red Path?
• Unit 2 has experienced a LOCA.
• The crew is implementing the Critical Function Status Trees.
• The RO has identified that the SPDS Overview Screen indicates a Red Path for Core Cooling.
• RCS Subcooling is < 0 °F.
• No RCPs are running.
Which ONE of the following RCS Parameters would validate a Core Cooling Red Path?
A. Three (3) hottest CETs reading 751 °F – 755 °F, with RVLIS Upper Range reading 38 %.
B. Five (5) hottest CETs reading 701 °F – 705 °F, with RVLIS Full Range reading 39 %.
C. Three (3) hottest CETs reading 1200 °F, with RVLIS Upper Range reading 44 %.
D. Five (5) hottest CETs reading 750 °F – 800 °F with RVLIS Full Range reading 43 %.
▶ Show Answer & Explanation
✓ B. Correct. Five CETs are > 700°F and RVLIS Full Range is reading ≤ 39%.
✗ A. Plausible because the first part is correct, five CETs are > 700°F. The candidate may believe that CETs need to be > 750°F as well. The second part is plausible as RVLIS Full Range reading ≤ 39% would be correct, however it says “Upper Range”. Incorrect, because the bases states that “the Upper Range is not applicable for use in accessing core cooling status since it only provides indication from the hot leg piping connection to the top of the reactor vessel.”
✗ C. Plausible because the candidate may believe that for inadequate core cooling, only three (3) CETs need to be ≥ 1200°F. Incorrect because five (5) CETs need to be > 1200°F. Also plausible because, although the stem says RCPs are out of service, the candidate may remember that ≤ 44% RVLIS Dynamic Range results in a Purple Path of degraded core cooling being met. Upper Range is also incorrect, see choice “A” discussion.
✗ D. Plausible because the first part is correct, five CETs are > 700°F. The candidate may believe that CETs need to be ≥ 750°F as well. The second part is plausible because Full Range Level is correct and the value of 43% is below the existing dynamic level of 44%. Incorrect because RVLIS Full Range Level needs to be ≤ 39% for a Red Path. This would be a Purple Path.
Ref: 2-EOP-CFST-1, Critical Safety Function Status Trees and Bases. 2-EOP-FRCC-1, Response to Inadequate Core Cooling and Bases. | LO: N/A | Source: New | Cognitive: Fundamental
Connections
- Related systems: RVLIS, ECCS
- Related EOPs: EOP-FRCC-1 — Response to Inadequate Core Cooling, EOP-CFST-1 — Critical Safety Function Status Trees
- Related exam: 2020 NRC Written Exam