Patent Number: 048633119
Section: description

DETAILED DESCRIPTION A borehole 16 is provided in a salt formation 13. The borehole 16 is tightly lined or covered by superimposed and welded together tubular sections 1 as well as with a correspondingly constructed bottom portion 15 on the bottom of the boreholes, which likewise is welded to the lowermost tubular section 1. Each tubular section 1 consists of steel and is composed of three rings, an outer ring 2, an inner ring 3 and an intermediate ring 4. All three rings, 2, 3, and 4 are securely fixed to each other. The intermediate ring 4 consists of an electrochemically nobler material, than the material (e.g. spherical cast graphite) of the outer ring 2 and the inner ring 3. In the assembly of the total covering of the borehole 16 the tubular section 1 is joined by welding of the intermediate rings 4 with each other via the welding seam 11. In order that the welding can be carried out on the inside, the inner ring for forming a recess 5 has a lower height than the outer and intermediate rings 2 and 4. The recess 5 can have either a rectangular or trapezoidal cross-section. Optionally the recess 5 can contain a surface adapted to the welding apparatus and testing apparatus for guaranteeing the quality of the welding seam 11 respectively a correspondingly shaped recess 14. The outer rings 2 have on the upper and lower edges directly on the intermediate ring 4 in each case a recess 6. In each of the recesses 6 there is applied a support ring 7 having double the height of the depth of the recess of the recess 6. The support ring 7 consists of the same material as the intermediate ring 4 and is welded to the intermediate ring 4. In the assembly of the total covering of the borehole 16 there is applied in each case a support ring 7 in the free recess of the adjacent outer ring. The bottom 8 of the recess 6 in the outer ring 2 thereby sits deeper in the inner ring 3 than the bottom 9 of the recess 5. Altogether there are the following advantages: In producing the welding seam 11 the weld melt is surrounded on all sides by the same material. As a result of this there is guaranteed a homogeneous structure in the welding seam and in the surrounding area and this guarantees a qualitatively trouble-free weld joint. The support ring 7 takes on a static function in regard to the pressure of the rock against the recess 5 and at the same time relieves the welding seam 11. During longterm storage or terminal storage of the terminal storage container or terminal storage package 12 the less noble outer ring 2 can be corroded or in the extreme case completely corroded away. The support ring 7 consisting of a nobler material in such a case supports the hold covered against the geological formation, in cooperation with the intermediate ring 4 protects before there is further corrosion and thus takes on a barrier function for the terminal storage container 12. The total thickness of the tubular section 1 can be chosen so that additionally for the terminal storage container 12 also there can be assumed completely or to a high degree the shielding function against the radioactive rays of the radioactive container material. The same is also true for the static function against the rock pressure so that the terminal storage container 12 can be reduced in size not only in regard to protection against rays but also in regard to stability. The chief static function of the tubular section 1 thereby is assumed by the correspondingly laid out inner ring 3. The covering of the invention thus is preeminently suited to take care of essential container functions so that the numerous terminal storage containers can be laid out tightly, but simply, at low-cost, easily and handled comfortably. As an aid in the assembly of the tubular sections 1, as well as the bottom portion 15 in a bore hole, on one of the recesses 6 of each outer ring 2, there can be inserted a support ring 7 to facilitate interengagement between each layer of rings. In addition, the inner ring 3 may be provided with a recess 10 for cooperation with a manipulating device to facilitate movement of the rings. The entire disclosure of German priority application No. P 3445124.2 is hereby incorporated by reference.