Patent Number: 045284547
Section: description

SPECIFIC DESCRIPTION The transport and storage container for radioactive wastes in accordance with the present invention is composed of cast iron and especially spherulitic or nodular cast iron and is adapted to receive irradiated nuclear elements and similar radioactive materials. Basically it comprises a radiation-shielding vessel 1, the upper end of the wall of which has been made in FIGS. 1 through 3 and which can be of the construction described in the aforementioned copending applications, especially application Ser. No. 966,951, (U.S. Pat. No. 4,278,892) apart from the orientation of the wall bore thereof. The vessel has a closed bottom, not shown, which can be of greater wall thickness, i.e. provided with a thickened portion similar to the thickened portion 6 surrounding the mouth of vessel 1. The mouth of the vessel 1 receives a radiation-shielding or plug-type cover 2 which is of sufficient thickness that escape of radiation through the cover is precluded just as the wall thickness of the vessel and the material from which it is composed or the material which is included therein are selected with respect to the energy of the radioactive emissions from the stored material as to preclude release of radiation. The cover 2 is formed with a plug-type fitting portion 3 and with a flange 4 which are received in a complimentarily-shaped seat 5. At least one additional cover is provided as will be developed below. The wall 1 is formed in the region of the seat 5 and thus the region of the reinforcement bead 6 and within the outline of the shielding cover 2 with the outlet end of a wall bore 7 which can extend to the bottom of the vessel to communicate with the interior thereof (see Ser. No. 966,951--U.S. Pat. No. 4,278,882). While only one such wall bore 7 has been illustrated, it will be understood that a number of such bores can be provided for introducing the radioactive material into the vessel 1, for discharging radioactive material from the vessel, for introducing a control gas, or for monitoring the vessel contents as may be required by law or for safety in the storage or transportion of radioactive material in the vessel. The seat 5 is shown to comprise a wall portion 8 which is complimentary to and sealingly cooperates with the periphery of the cylindrical and/or frustoconical plug portion 3 and is adapted to receive the latter. The bore 7 terminates inwardly of this surface 8 at a shoulder extending perpendicular to the axis of the vessel. A further shoulder 9 receives the flange 4 of the shielding cover 2. The shielding cover 2 is provided with a respective bore 10 for each wall bore 7, the bores 10 serving as connecting bores in which valves or plugs 11 (obturating elements) can be inserted and which can be covered by an additional cover 12. The shielding cover 2 is additionally provided in the region of the seat 5 with control, monitoring or test bores 13 which can receive valves, pressure-monitoring devices, gas analyzers or sample units of any conventional type as represented at 14. These control bores 13 are also covered by the outer cover 12 and lie within the outline thereof. The outer cover 12 itself is received in a recess 15 formed in the open end of the vessel 4 against a shoulder 16. In the embodiment of FIG. 1 the additional cover 12 is formed as a control cover which allows the shielding function of the cover 2 to be monitored. To this end, the cover 12 can define a control compartment 17 with the cover 2 and can be provided with a bore 18 to which a monitoring unit can be attached to communicate with the compartment 17 and determine the leakage of control gas into the latter or the accumulation of radioactive species therein. It is in this form generally that the container, after being loaded, is temporarily stored in or is transported from a nuclear power plant in which the stored radioactive materials were produced. For longer-term storage and more rigorous protection during transportation a further cover 19 can be applied as is shown in FIG. 2. The cover 19 has a plug portion 20 which fits snugly in a recess 21 and a flange 22 which rests upon the upper edge 23 of the vessel 1. While bolts 40, 41, 42 are shown to fix the covers in place in FIGS. 1 through 3, welded lip seals can also be used alone or in combination with bolts (see application Ser. No. 966,951--U.S. Pat. No. 4,278,892 or Ser. No. 243,562, now U.S. Pat. No. 4,450,042. The cover 2 can be provided with seals as described in the last mentioned application and thus forms a first barrier which, by monitoring of compartment 17 through the cover 12, can be controlled to determine the security of the first level of sealing action. Since the cover 19 forms a gap with the cover 12, this gap can constitute a second compartment which is sealed by the cover 19 but which can be monitored. In still another embodiment of the invention shown in FIG. 3, the outer cover can be doubled so that two sealed barriers are provided. In this case, a barrier cover 24 is provided directly above the cover 12 and is welded to the upper end of the vessel 1 in the recess 21 while the outer cover 19a, which can be bolted or welded in place as well with appropriate seals, defines a control cover forming a compartment 25 which can be monitored, e.g. by a sampler 50, in the manner described. As a comparison of FIGS. 2 and 3 will show, the cover arrangements of these two FIGS. can be used interchangeably. The bores 10 can serve to force (pump) radioactive material into the vessels or to evacuate fluid from the vessel after material has been introduced therein, or to receive a sampling lance. The bore 10 of the confronting portion of bore 7 can be provided with O-ring seals 10a which can be omitted when an immersion-type lance is based through the aligned bores 7 and 10. The cover 12 can be formed with a radiation-attenuating material 12a akin to that which may be provided in channels in the wall 1 (see the aforementioned applications) and metal and/or elastomeric O-rings 2a and 2b may be provided as additional seals.