Patent Number: 043026800
Section: description

In FIGS. 1 and 2 in each case the left half of the figure shows the shielding cover in the closed condition and the right half of the figure reproduces the shielding cover in the open condition. The cover of the invention can comprise, consist essentially of or consist of the stated parts. DESCRIPTION OF THE PREFERRED EMBODIMENTS The shielding container 1 has an outer transportation cover 2 flanged in any manner on the container 1 to securely include the free radioactivity by means of seals 3 and to protect mechanically against outside influences. Below the transportaion cover 2 there is located the shielding cover 4 for securely sealing the gamma and neutron rays from the irradiated fuel elements against the environment. The shielding cover 4 consists of fixed cover portion 5 and a moveable cover portion 6 which are joined together in such manner that they both twist toward each other as well as also being able to be spreaded. The moveable cover portion 6 has distributed at its periphery claws 7 which fit into corresponding openings 8 of the top of the container 9. They are fastened on the container by twisting according to the principle of the bayonet. The connection between the fixed cover portion 5 and the moveable cover portion 6 of the shielding cover 4 takes place with a screw 10 carried into the moveable cover portion 6 and a pin 11 fitting into the fixed cover portion. By turning in the screw 10 the moveable cover portion 6 is moved away from the fixed cover portion 5 so that a twisting of the moveable cover portion 6 is no longer possible and the seal 12 is so fixed between the fixed cover portion 5 and the container 1 that there is guaranteed the sealing of the container contents against the outer world. To open the shielding cover 4 the spread between the fixed cover portion 5 and the moveable cover portion 6 is decreased through turning the screw 10 outwardly so that by turning of the moveable cover portion around a length of claw both can be raised and the shielding cover 4 can be lifted off. Moreover, screw 10 can be operated either manually or also mechanically by remote control. By further turning out of the screw 10 the moveable cover portion 6 and the fixed cover portions 5 are supported via the pin 11. Thereby the seal 13 tightens the gap 14 between the two cover portions and thus prevents a contamination of this gap. The transportation cover 2 has the function correspondingly to safely seal in the container contents of the transportation container order. It is removed inside the control area for loading and unloading since the shielding cover 4 guarantees a sufficient protection in this area. The transportation cover 2 is secured at the flange of the top 9 of the container with screws (not shown), preferably clamping screws, distributed around the periphery of the transportation cover, through which the necessary compressive strength for tightening the seal 3 can be applied. This seal 3 is so designed that it fulfills the required packing both in the failure of the seal 12 and also in all loads occurring in accidents of design. The function of the cover system of the invention will be further explained in connection with an unloading process employing dry unloading. First the transportation cover 2 is removed in the control area and the transportation container 1 flanged on the container flange under a hot cell lock. The shielding cover 4 then is connected with the hot cell cover and the spread between the two cover portions 5 and 6 of the shielding cover 4 lowered by remote control turning of the screw 10. The moveable cover portion 6 is turned in the opening position and the two cover portions 5 and 6 brought together by further turning of the screw 10 so that the gap 14 is made tight by the seal 13. The shielding cover 4 can now be turned with the hot cell cover in the hot cell without the surface of the shielding cover 4 and the gap 14 being contaminated (double cover system). The cover system of the invention has a number of advantages over the known covers for shielding containers. The dry loading and unloading into or on a hot cell is possible without danger of contamination of the cover system, exactly as the wet loading and unloading in a water vessel. In an accident the transportation cover 2 is not loaded with the weight of the contents of the container and the shielding composition of the shielding cover 4. The dimensioning of the set screw 10 therefore can by itself alone adjust for the sealing after the required initial stress. The seal 3 guaranteeing the tightness of the container system is substantially shielded from gamma and neutron irradiation. The operating temperatures for this sealing system therefore are moderate. The seal 12 protects it in the normal operation extensively from radioactive gases and steam (in wet transport) which largely prevents a premature aging. Besides this sealing system 3 is easily accessible for maintenance and inspection. By constructing the shielding cover 4 as a bayonet closure to open the cover there is only needed a central turning movement which can be carried out readily either by remote control or manually. Because of the division of the shielding cover in two parts it is not necessary to turn the entire cover. The entire disclosure of German priority application No. P 28 30 111.3 is hereby incorporated by reference.