Patent Number: 055920276
Section: description

In these two figures, the same references designate the same objects. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The container to be compacted is referenced 1. It has previously been filled with waste 2 and saturated in inert gas 3, and then placed inside the compacting skirt 4 on the anvil 5. Said anvil 5 is a massive part placed on the bottom Jaw of the press to receive the compacting forces. The clearance between said container 1 and said compacting skirt 4 is referenced 6. This limited amount of clearance 6 is saturated with inert gas 3 as soon as the first cracks appear in the structure of the container 1 under the action of the pressure exerted by the piston 7. In FIG. 2, the clearance 6 between the container 1 and the compacting skirt 4 is larger than in FIG. 1. To be absolutely sure that the clearance 6 is saturated with inert gas during compacting, provision is made to fill the clearance 6 with inert gas (G) prior to said compacting. Advantageously, said inert gas G is the same as the gas 3 inside the container 1. Reference 8 designates a gasket and 9 a collecting ring. By using these elements, dispersion of fines in the compacting cell is limited. The invention is also illustrated by the following example. Zircalloy hulls were compacted in accordance with the invention. There must be no water in waste of this type in order to avoid hydrogen being given off. Unfortunately, once dried and a fortiori broken up into small pieces with the presence of fines, said hulls are liable to ignite, even without any particular addition of energy. It is therefore essential to provide blanketing while compacting said dried hulls. The hulls were dried in an appropriate device under an inert gas. They were then loaded (with nitrogen bubbling) into a stainless steel container having a capacity of about 90 liters. The outside diameter of said container was 390 mm, and its height was 800 mm. The thickness of the steel was about 1 mm. The volume of hulls loaded into said container was about 82 liters. The apparent relative density of the nitrogen and hull mixture was about 1 (the relative density of the metal itself is 6.2-6.6). The container loaded in this way was transferred into the compacting cell. In an advantageous manner, a collecting ring was provided therein above the compacting skirt to collect the inert gas escaping through the cracks in the container during compacting. The pressure exerted was about 200 MPa. A compressed compact was obtained having a height of about 150 mm and a relative density of 4.1. Provision is made for transferring and conditioning such a compact into a final storage container.