[en] This is concerned with a particular type of burst protection in reactor plant, which closely surround pressurised steel vessels or pipelines in the form of concrete jackets. Such jackets usually surround a cylindrical steel body as a coaxial cylinder. This burst protection made of thermally insulating gas concrete has several times the wall thickness of the steel vessel to be protected. It is advantageous to surround it by steel rings, which press closely on the concrete body and prevent flying off of fractured parts in the extreme case. According to the invention the concrete cylinder contains a large type of groove where it touches the steel vessel, which runs longitudinally along the steel surface. This groove or cutout has a rectangular or semicircular crossection, where the centre point of the semicircle lies within the steel vessel. Such a cutout (or 2 oppositely situated cutouts) is (are) positioned, for example, along the longitudinal weld of a steel vessel surrounded by the burst protection device. By the introduction of an ultrasonic or x-ray equipment it makes periodically repeated tests of the welds possible. The crossection of the cutout is kept as small as possible, avoiding sharp edges with notch effects. In operation the strength of the burst protection can be increased by introducing massive shapes, such as rails or by pouring in granulated material such as steel or ceramic balls or similar material into the cutouts. (HP)