The Compton-Dry Cask Imaging Scanner is a system that verifies and documents the presence of spent nuclear fuel rods in dry-cask storage and determines their isotopic composition without moving or opening the cask.

A dry storage cask has multiple spent fuel assembly storage positions within it. The γ-ray signal observed through a dry storage cask lid above a stored spent fuel assembly will show specific fission product activity peaks in the observed γ-ray energy spectrum. The γ-ray signal above empty fuel assembly positions within the storage cask will show a smooth energy continuum of scattered γ-rays. The presence of fission product γ-ray energy peaks can be used to verify the presence of a spent fuel assembly in the observed dry cask assembly storage position.