Patent Number: 
Section: description

Referring now to the figures of the drawing in detail and first, particularly, to FIG. 1 thereof, there is seen a nuclear reactor fuel assembly 3 in an elongated storage container 2. The square outline of the nuclear reactor fuel assembly 3 is suggested by dashed lines. The nuclear reactor fuel assembly 3 has fuel rods 4 and guide tubes 5. The fuel rods 4 are filled with spent nuclear fuel, such as UO2 and/or U/PuO2, which contains radionuclides. The nuclear fuel is located in each case on a cladding tube of the fuel rods 4 which for instance comprises a zirconium alloy sealed with a plug of zirconium alloy on each of the two ends of the tube. These zirconium allow plugs are welded in gas-tight fashion to the cladding tube. The guide tubes 5 served to guide control rods and are open on at least one end. They do not contain any radionuclides. The storage container 2 is filled with a bulk fill 6 of zeolite granulate. The bulk fill 6 need not be compacted, and the spaces around the fuel rods 4 and hence necessarily the guide tubes 5 of the nuclear reactor fuel assembly 3 are also filled with it. The container 2 comprises steel and is welded in gas-tight fashion to a steel plate on both ends. Referring now to FIG. 2, the container 2 that contains the nuclear reactor fuel assembly 3 with the spent fuel rods is inserted into a bore, located for instance in a salt dome of an ultimate storage site. Also located in this bore on the outside of the container 2 is a further bulk fill 7, once again a zeolite granulate. The container 2 is completely embedded in the bulk fill 7. Activated charcoal can also be admixed with the bulk fills 6 and 7 of zeolite in FIGS. 1 and 2. With regard to zeolites, reference is had to Ullmanns xe2x80x9cEnzyklopxc3xa4die der Technischen Chemiexe2x80x9d [Ullmann""s Encyclopedia of Industrial Chemistry], vol. 24, pp. 575-578, 1983, and Ullmanns xe2x80x9cEnzyklopxc3xa4die der Technischen Chemiexe2x80x9d, vol. 17, pp. 9-17, 1979. Zeolite type A, preferably of at least one of the substances in the group comprising MgA, CaA and SrA, is especially suitable for the bulk fills 6 and 7. Type A zeolite of this kind can also be doped with silver, rendering it especially suitable at trapping radioactive iodine that might possibly escape from a leak in the cladding tube of a fuel rod 4 but is then already trapped in front of the wall of the container 2, whose retention action is accordingly still further increased by the zeolite of the bulk fill 6 in the container 2. Chabazite and mordenite are also well-suited as zeolite bulk fills. For example, zeolites with the tradename xe2x80x9cZeolon Molecular Sievesxe2x80x9d of the 400 Series, 500 Series, 700 Series and 900 Series, which bind via an ion exchange of Cs and Sr, are especially highly suitable. Particles of at least one of the substances in the group comprising metal grit, MnO2, Al2O3, MgO, SuO2, ZrO2 and silicate, which are admixed with at least one of the bulk fills 6 and 7, increase the thermal conductivity of these bulk fills 6 and 7 in order to dissipate the afterheat of the fuel rods 4. Referring now to FIG. 3, the container 2 is formed from a suitable steel with steel walls 2a and steel plates 2b closing off the ends. The steel plates 2b are tightly welded to the steel walls 2a at weld seams 2c.