[en] To minimize the radioactivity in the primary water of nuclear reactors and prevent local corrosion on reactor fuel rods, inspection techniques are required to detect any fuel materials deposited on the fuel rod surfaces during manufacture. This report provides the description and operational features of a large 4π geometry alpha detector capable of inspecting fuel rods up to 10 feet long and 1 inch in diameter. The system allows the inspection of fuel rods with a minimum of delays for loading and unloading the detector. The sensitivity is sufficient to detect minute amounts of fuel materials remaining on the fuel rod after manufacturing and testing operations down to the level of the natural radioactivity of the Zircaloy cladding material