[en] The Molten Salt Reactor Experiment (MSRE) at Oak Ridge National Laboratory has been shut down since December 1969, at which time the molten salt mixture of LiF-BeF₂-ZrF₄-²³³UF₄ (64.5-30.3-5.0-0.13 mol%) was transferred to fuel salt drain tanks for storage. In the late 1980s, increased radiation in one of the gas lines from the drain tank was attributed to ²³³UF₆. In 1994 two gas samples were withdraw (from a gas line in the Vent House connecting to the drain tanks) and analyzed. Surprisingly, 350 mm Hg of F₂, 70 mm Hg of UF₆, and smaller amounts of other gases were found in both of the samples. To remote this gas from above the drain tanks and all of the associated piping, the reactive gas removal system (RGRS) was designed. This report details the laboratory testing of the RGRS, using natural uranium, prior to its implementation at the MSRE facility. The testing was performed to ensure that the equipment functioned properly and was sufficient to perform the task while minimizing exposure to personnel. In addition, the laboratory work provided the research and development effort necessary to maximize the performance of the system. Throughout this work technicians and staff who were to be involved in RGRS operation at the MSRE site worked directly with the research staff in completing the laboratory testing phase. Consequently, at the end of the laboratory work, the personnel who were to be involved in the actual operations had acquired all of the training and experience necessary to continue with the process of reactive gas removal