Q19 — Dropped Rod Step Counter Reset
APE03AK3.04 (3.8)
Given:
• Unit 2 reactor power was reduced to 74% Power.
• A dropped Control Bank D Group 1 rod is being recovered in accordance with S2.OP-AB.ROD-0002, Dropped Rod.
Shortly before the crew starts withdrawing the dropped rod, S2.OP-AB.ROD-0002 directs the crew to reset the control bank D group 1 step counter to zero.
Why does the affected group step counter need to be reset to zero?
• Unit 2 reactor power was reduced to 74% Power.
• A dropped Control Bank D Group 1 rod is being recovered in accordance with S2.OP-AB.ROD-0002, Dropped Rod.
Shortly before the crew starts withdrawing the dropped rod, S2.OP-AB.ROD-0002 directs the crew to reset the control bank D group 1 step counter to zero.
Why does the affected group step counter need to be reset to zero?
A. This prevents OHA E-8 RIL LO and E-16 RIL LO-LO alarms from coming in during rod recovery.
B. This prevents a OHA E-40 ROD BANK URGENT FAILURE alarm from coming in during rod recovery.
C. This ensures that the step counter matches actual rod position and the rod is withdrawn to the proper height.
D. This ensures that the P/A converter will send the proper rod height data to the RIL circuitry.
▶ Show Answer & Explanation
✓ C. Correct. The group step counter is reset to zero IAW AB.ROD-2 to ensure that the step counter matches actual rod position and that the recovered dropped rod position is at the proper height before the event.
✗ A. Since this is a control bank group 1 rod, the P/A converter will be reset to zero IAW AB.ROD-2. After the P/A converter is reset to zero, OHAs E-8 RIL LO and E-16 RIL LO-LO will annunciate.
✗ B. OHA E-40 will annunciate following rod withdrawal due to a Power Cabinet Regulation failure for the affected bank with the lift coil disconnect switches in OFF position.
✗ D. Control bank D group 1 rods will need the P/A converter reset to zero IAW AB.ROD-2 which is performed locally at the RPI-2 cabinet. The group step counter does not input into the P/A converter. Input to the P/A converter is from the Group 1 Data Logging card. Resetting the P/A converter ensures bank overlap is maintained.
Ref: S2.OP-AB.ROD-0002(Q), Dropped Rod and Bases | LO: N/A | Source: Modified Bank - Salem Vision Database | Cognitive: Fundamental
Connections
- Related systems: Control Rod Drive
- Related procedures: AB.ROD-0002 — Dropped Rod, S2.OP-AR.ZZ-0005 — Overhead Annunciators Window E
- Related exam: 2020 NRC Written Exam