The following information was provided by the licensee via phone:
Per the licensees Technical Specifications (TS) 6.1.3.a, "The minimum staffing when the reactor is not secured shall be: . A reactor operator or the senior reactor operator on duty in the control room.
On May 7, 2024, following the reactor shutdown, there was an indication that one control rod was not fully inserted. Both the reactor operator and reactor engineer left the control room to investigate and discovered that one control rod was not fully inserted. The reactor operator leaving the control room violated the minimum control room staffing requirements of TS 6.1.3.a.
On May 8, 2024, the licensee determined that the cause for the control rod not being fully inserted was a dislodged plastic buffer at the bottom of the control rod barrel.
The NRC Project Manager has been notified.