Through-Wall Inspection of Nuclear Facilities Using GPR Imaging

Inspection of nuclear facilities poses a number of technical challenges in the terms of inaccessible areas. To carry out facility inspections tasks there is a need to develop inspection technologies, particularly developing portable through-the-wall imaging systems. The ability to employ GPR sensing technology for “seeing” through walls and mapping out the pipes and plumbing through walls, floors and grounds, might be of great benefit to the inspector. While GPR has advantages in terms of wall penetration, resolution, and small sensor form factor and convenience of use, conventional GPR systems available as COTS are quite cumbersome for inspection tasks, and the resulting 2D image is often hard to interpret. In this study we leverage the capability that was recently developed at LLNL for the detection and characterization underground facilities that has resulted in high-resolution 3D images using multi-static radar sensors. The objective is to make available the advanced scene reconstruction algorithms and methods in the framework of a handheld GPR sensor to accelerate the pace and also to improve the accuracy of the inspection tasks. Declared blueprints could be automatically compared with the 3D radar images to discover undeclared or clandestine metal pipes or storage tanks during inspections. Obstructions such as concrete walls or walls with metal shielding, in decommissioned nuclear plants, can make the task of discovering the interior plumbing quite difficult for inspectors. The interior plumbing of a fission plant can be quite complex and the verification of interior pipe structure can be difficult to discern. However with 3D imaging targets inside walls and grounds, the correlation of the radar returns with the arbitrary 3D surface of the walls and floors and objects in the surrounding can be addressed.