Explosive pipe cutting by shaped charges in an annular configuration

For the decommissioning of nuclear power stations it is necessary to develop dismantling techniques to minimize the dose of radioactivity for the personnel. Concerning the primary cooling system the separation of contaminated steel pipes is solved up to now only unsatisfactorily by usual cutting techniques like sawing or thermal cutting if there is impeded access to the tubing by narrow constructions. An explosive pipe cutting technique was developed to separate thick walled tubes. The simplicity of the arrangement and its easy applicability are the advantages of this dismantling method. The developed sleeve charge is assembled from linear modules surrounding the tube wall as a polygon. When initiated the projectiles formed from the metallic liner of the charge hit the tube wall simultaneously and pipes up to 610 mm diameter and 36 mm wall thickness were cut. Such pipes comply with the fresh steam pipe of a recent German boiling water reactor. The impulse load to the tube wall outside the cutting region is far below the value which would lead to destructions at the remaining pipe system. Strong confinement of the charge reduces the blastwave pressure and the damage boundary value of 1 bar is exceeded only within a distance of 3 m to the center of the tube. To avoid fragment damage it is necessary to apply a heavy protective construction. Using such a construction the developed sleeve charge technique was tested when cutting a section of the cooling system of a hot steam reactor