Hepenix Nuclear Pool Manipulator Simulator (Prototype)

Spent nuclear fuel is stored underwater. The pool is not decoration: several metres of water absorb radiation while still letting operators see what they are doing, so the fuel can be moved and inspected safely from a platform above the surface. Nothing down there can be touched by hand, which means every operation is carried out by a manipulator, a rigid and precisely controlled arm that reaches into the pool and handles material on the operator's behalf.

That makes the manipulator a safety-critical machine. It must move exactly where commanded, never exceed its permitted envelope, and never collide with the pool structure or the fuel racks. The consequences of a mistake are severe and the hardware is expensive and often radiologically controlled, so operators cannot simply practise on the real system, and engineers cannot casually test new motion logic on it either.

This is where simulation earns its place. A high-fidelity digital model of the manipulator and its pool lets operators build competence, and lets engineers validate motion limits, control response and failure behaviour before anything is attempted on real hardware. The same techniques underpin remote handling in space robotics, deep-sea intervention and any setting where a person directs a machine through an environment they cannot physically enter.

I developed a real-time Unity simulation of a nuclear pool manipulator, replicating a 4-DOF industrial manipulator working in a constrained, highly controlled environment. Each axis (X, Y, Z and Fi) has independent motion control with defined limits, so the manipulator stays mechanically realistic and never leaves its workspace. A custom diagonal wall-following constraint keeps the arm aligned with the pool barrier without clipping through geometry.

The simulator uses a modular architecture with additive scene loading, so pool configurations can be swapped at runtime without restarting. Multiple camera viewpoints give operator-focused and validation views, and a streamlined HMI overlay lets users switch cameras and environments from a simple menu while the simulation keeps running smoothly.