The present invention relates to a closed vessel arrangement (1) comprising a closed vessel (2) for safe destruction of a rocket motor (3) containing a solid propellant (4) by burning the rocket motor (3) inside the closed vessel (2), which closed vessel (2), is adjustable in size to a rocket motor (3). The invention is characterized in that the closed vessel (2) comprises two communicating chambers (7, 8) coaxially arranged to each other, one outer chamber (8) and one inner chamber (7), which chambers (7, 8) are divided into a plurality of connectable sections (13), which sections (13) are connectable in various numbers for adjusting the size of the vessel (2) to rocket motors (3) of various sizes.