Q20 — Misaligned Rod Recovery
APE05 AK2.02 (2.5)
Given:
• Unit 2 is performing a controlled load reduction.
• The following sequence of events occurs:
- OHA E-24, ROD DEV OR SEQ, is LIT.
- The RO reports a group 1 control rod in D bank is at 175 steps.
- The group demand counter is reading 160 steps.
- The crew enters S2.OP-AB.ROD-0001, Immovable/Misaligned Control Rods.
- Control rods are placed in Manual.
- The load reduction is stopped with reactor power at 87%.
Subsequently, the following occurs:
- The misaligned control rod issue has been corrected and is restored to Operations.
- Reactor Engineering approves recovery of the misaligned rod.
In accordance with S2.OP-AB.ROD-0001, which ONE of the following completes the statement?
Prior to recovering the misaligned rod, the operator will place the Lift Coil Disconnect Switches for all rods in the affected bank, except for the misaligned rod, in the _(1)_ position, and then place the Rod Bank Selector Switch to the _(2)_ position.
Note: ON = connected
OFF = disconnected
• Unit 2 is performing a controlled load reduction.
• The following sequence of events occurs:
- OHA E-24, ROD DEV OR SEQ, is LIT.
- The RO reports a group 1 control rod in D bank is at 175 steps.
- The group demand counter is reading 160 steps.
- The crew enters S2.OP-AB.ROD-0001, Immovable/Misaligned Control Rods.
- Control rods are placed in Manual.
- The load reduction is stopped with reactor power at 87%.
Subsequently, the following occurs:
- The misaligned control rod issue has been corrected and is restored to Operations.
- Reactor Engineering approves recovery of the misaligned rod.
In accordance with S2.OP-AB.ROD-0001, which ONE of the following completes the statement?
Prior to recovering the misaligned rod, the operator will place the Lift Coil Disconnect Switches for all rods in the affected bank, except for the misaligned rod, in the _(1)_ position, and then place the Rod Bank Selector Switch to the _(2)_ position.
Note: ON = connected
OFF = disconnected
A. _(1)_ ON
_(2)_ SBD
_(2)_ SBD
B. _(1)_ ON
_(2)_ CBD
_(2)_ CBD
C. _(1)_ OFF
_(2)_ CBD
_(2)_ CBD
D. _(1)_ OFF
_(2)_ SBD
_(2)_ SBD
▶ Show Answer & Explanation
✓ C. Correct. IAW S2.OP-AB.ROD-0001, when recovering a misaligned rod, the lift coils for all the rods in the affected bank are placed in the disconnect or OFF position, with the exception of the misaligned rod which the lift coil needs to remain connected or ON position in order to recover the misaligned rod. Based on the condition of the stem, the misaligned rod is a control rod in D bank. Therefore, in order to insert the misaligned control rod, the operator must place the rod bank selector switch to the CBD position. The CBD position stands for control bank D rods. The SBD position is for selecting rods in shutdown bank D.
✗ A. Incorrect. Plausible because the operator may confuse how the operation of the lift coils work when the switches are placed in ON or OFF position. First part is incorrect. Second part is incorrect. Plausible because the operator may confuse the rod bank selector switch position for shutdown rod versus control rod. See Ans. C for further explanation.
✗ B. Incorrect. Plausible because the operator may confuse how the operation of the lift coils work when the switches are placed in ON or OFF position. First part is incorrect. Second part is correct. See Ans. C for further explanation.
✗ D. Incorrect. First part is correct. Second part is incorrect. Plausible because the operator may confuse the rod bank selector switch position for shutdown rod versus control rod. See Ans. C for further explanation.
Ref: S2.OP-AB.ROD-0001, S2.OP-AR.ZZ-0005 | LO: NOS05ABROD1, Obj 1 — Describe, in general terms, the actions taken in S2.OP-AB.ROD-0001 and the bases for the actions in accordance with the Technical Bases Document | Source: New | Cognitive: Comprehension/Analysis
Connections
- Related systems: RPS/SSPS
- Related procedures: AB.ROD-0001 — Immovable/Misaligned Control Rods
- Related exam: 2022 NRC Written Exam