AP1000 – Under-Vessel Stair Lock

Application: Vogtle Units 3 & 4 The Under-Vessel Stair Lock is a Health Physics Engineered Barrier designed to restrict access to the AP1000 under-vessel area. The locking system provides both physical deterrence and visual control to improve radiological boundary integrity during outage or maintenance conditions. Key Features Access Control: Prevents unauthorized entry into under-vessel areas during radiological or maintenance work Robust Mounting: Requires installation using (8) 3/8" diameter mounting holes (field-drilled) for secure, semi-permanent attachment Locking Arm: Integrated locking mechanism enables LOTO (Lock-Out-Tag-Out) for enhanced compliance and safety High Visibility: Contrasting materials and integrated hardware increase awareness and help reinforce safe behaviors Construction & Materials Frame & Grating: Durable steel construction with welded grid floor insert Custom Fit: Tailored to integrate with existing stairwell structure at Vogtle Uni