Q88 — Loss of Control Air PZR Level
078 G2.2.44 (4.4) SRO
Given:
• Unit 1 is at 100% Power.
• 11 Charging Pump is in service.
• A Loss of All Control Air has occurred.
• The crew enters S1.OP-AB.CA-0001, Loss of Control Air.
• The CRS directs manually tripping the reactor and entering 1-EOP-TRIP-1, Reactor Trip or Safety Injection.
• Operators are locally controlling AFW valves to maintain post trip SG Narrow Range levels.
Which ONE of the following completes both statements?
1. What will be the subsequent impact on PZR level?
2. What is the preferred course of action?
• Unit 1 is at 100% Power.
• 11 Charging Pump is in service.
• A Loss of All Control Air has occurred.
• The crew enters S1.OP-AB.CA-0001, Loss of Control Air.
• The CRS directs manually tripping the reactor and entering 1-EOP-TRIP-1, Reactor Trip or Safety Injection.
• Operators are locally controlling AFW valves to maintain post trip SG Narrow Range levels.
Which ONE of the following completes both statements?
1. What will be the subsequent impact on PZR level?
2. What is the preferred course of action?
A. 1) PZR level will rise
2) Locally control charging flow by adjusting the 1CV54, CENT CHG PUMP FLOW CONT VLV.
2) Locally control charging flow by adjusting the 1CV54, CENT CHG PUMP FLOW CONT VLV.
B. 1) PZR level will rise
2) Transfer to 13 Charging Pump and locally control the speed changer.
2) Transfer to 13 Charging Pump and locally control the speed changer.
C. 1) PZR level will lower
2) Transfer to 13 Charging Pump and locally control the speed changer.
2) Transfer to 13 Charging Pump and locally control the speed changer.
D. 1) PZR level will lower
2) Locally control charging flow by adjusting the 1CV54, CENT CHG PUMP FLOW CONT VLV.
2) Locally control charging flow by adjusting the 1CV54, CENT CHG PUMP FLOW CONT VLV.
▶ Show Answer & Explanation
✓ A & B. Both Correct. Question 88 was determined to have two correct answers based on post-examination comments.
A: Part 1 is correct. On loss of all control air, with letdown isolated, the 1CV55 failed open, and the 1CV71 failed closed, the operating centrifugal charging pump will result in higher flow and pressure to the RCP seals. This will result in higher flow into the RCS and thus raise PZR level faster. Part 2 is correct. S1.OP-AB.CA-0001 provides guidance in both the Selected Continuous Action Summary (CAS) Items and Attachment 1 Continuous Action Summary sections to maintain Pressurizer level by locally adjusting the 1CV54, CENT CHG PUMP FLOW CONT VLV, to control charging flow.
B: Part 1 is correct per above. Part 2 is correct. Per S1.OP-AB.CA-0001, Attachment 8, CRS Decisions, it is recommended to operate 13 PDP since its speed controller is failed at the low speed stop that will minimize RCP seal flow, allowing reducing charging flow and extending time for PZR level to reach the limit of 90%.
A: Part 1 is correct. On loss of all control air, with letdown isolated, the 1CV55 failed open, and the 1CV71 failed closed, the operating centrifugal charging pump will result in higher flow and pressure to the RCP seals. This will result in higher flow into the RCS and thus raise PZR level faster. Part 2 is correct. S1.OP-AB.CA-0001 provides guidance in both the Selected Continuous Action Summary (CAS) Items and Attachment 1 Continuous Action Summary sections to maintain Pressurizer level by locally adjusting the 1CV54, CENT CHG PUMP FLOW CONT VLV, to control charging flow.
B: Part 1 is correct per above. Part 2 is correct. Per S1.OP-AB.CA-0001, Attachment 8, CRS Decisions, it is recommended to operate 13 PDP since its speed controller is failed at the low speed stop that will minimize RCP seal flow, allowing reducing charging flow and extending time for PZR level to reach the limit of 90%.
✗ C. Incorrect. Part 1 is incorrect. Plausible because the SRO may not correctly assess the impact of the components on a loss of air and incorrectly determine that PZR level will lower. The SRO may determine that both the 1CV55 and 1CV71 fail closed, resulting in the centrifugal charging pumps in recirculation back to the VCT and no flow to the RCP seals. Part 2 is correct.
✗ D. Incorrect. Part 1 and Part 2 are incorrect. Part 1 is plausible because the SRO may not correctly assess the impact of the components on a loss of air and incorrectly determine that PZR level will lower. Part 2 is plausible because the centrifugal charging and adjusting the 1CV54 can be used to supply charging flow.
Ref: S1.OP-AB.CA-0001 (R25) | LO: NOS05ABCA01-08, Objective 3 | Source: New | Cognitive: Comprehension/Analysis
Connections
- Related systems: Control Air, CVCS, RCPs, Pressurizer & PRT
- Related procedures: AB.CA-0001 — Loss of Control Air
- Related EOPs: EOP-TRIP-1 — Reactor Trip or Safety Injection
- Related exam: 2022 NRC Written Exam