Container for long-lived low to high level radioactive waste

Abstract

A container for radioactive waste including an outer Steel wall, an inner Steel wall, a layer of lead located between the two steel walls, a steel base, a steel cover, a volume of quartz sand located inside the container, at least one internal receptacle/cassette/box that is coated/surrounded/covered at least partially by the volume of quartz sand; and radioactive waste located inside the receptacle, where the internal container may be made of steel and may contain low level radioactive waste, and alternatively, the receptacle(s) may be made of ceramic material and may contain high level radioactive waste, and in one preferred embodiment, the container has an internal rack into which the internal receptacles are placed.

Claims

1. A container for radioactive waste comprising: a steel outer wall; a steel inner wall; a layer of lead between the two steel walls; a steel bottom; a steel lid; a volume of quartz sand inside the container at least one inner vessel coated at least partially with quartz sand, the quartz sand disposed between the steel inner wall and a vessel wall; radioactive waste inside the vessel; and wherein the steel outer wall comprises a pressure relief valve configured to evacuate gases from the layer of lead contained between the two steel walls.

2. A container according to claim 1, wherein the quartz sand layer between the vessel and the steel inner wall has a thickness of at least 2 cm.

3. A container according to claim 1, wherein the inner vessel is made of stainless steel.

4. A container according to claim 3, wherein the inner vessel contains low-level radioactive waste.

5. A Container according to claim 1, wherein the inner vessel is ceramic.

6. A container according to claim 5, wherein the inner vessel contains highly radioactive waste.

7. A container according to claim 1, wherein the cover comprises a steel outer wall, a steel inner wall and a lead layer between the two steel walls.

8. A container according to claim 1, wherein the bottom comprises a steel outer wall, a steel inner wall and a lead layer between the two steel walls.

9. A container according to claim 1, wherein the inner vessel comprises a removable cap.

10. A container according to claim 1, further comprising an inner rack comprising one or more compartments, the vessel or vessels arranged in the said inner rack.

11. A container according to claim 10, wherein the inner rack comprises one or more doors giving access to the compartment(s).

12. A container according to claim 10, wherein the inner rack comprises one or more centering means and/or one or more gripping means.

13. A container according to claim 10, wherein the inner rack has one or more holes.

14. A container according to claim 1, wherein the steel is stainless steel.

15. A container according to claim 1, further comprising a plastic layer coating the radioactive waste in the at least one inner vessel.

16. A container according to claim 1, further comprising a rubber outer casing covering the outer wall.

17. A container according to claim 14, wherein the steel is type 316L steel.

18. A container according to claim 1, further comprising an inner rack positioned inside the container and including a plurality of openings configured to receive the volume of quartz sand from the space between steel inner wall and the vessel wall and into the plurality of openings.

19. A container according to claim 18, wherein the vessel or vessels are arranged within the inner rack such that the volume of quartz sand covers the vessel or vessels and is configured to pass through one or more mounts or trays attached to the inner rack and surround the vessel or vessels.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Other peculiarities and characteristics of the disclosure will become apparent from the detailed description of some advantageous modes of realization presented below, by way of illustration, with reference to the accompanying drawings. These show:

(2) FIG. 1: is a sectional view of a container according to the disclosure and in a first mode of realization;

(3) FIG. 2: is a sectional view of a container according to the disclosure and in a second mode of realization;

DETAILED DESCRIPTION

(4) FIG. 1 illustrates a container 10 for radioactive waste according to a first mode of realization of the disclosure. The container 10 for radioactive waste comprises a steel outer wall 12, a steel inner wall 14, a lead layer 16 contained between the two steel walls 12 and 14, a steel bottom 18, a steel lid 20, a volume 22 of quartz sand located inside the container and at least one inner vessel/cassette/inner box 24.sub.1 and 24.sub.2 coated encircled covered at least partially covered by the volume of quartz sand 22 (represented by crosses in the image). The radioactive waste 26 is located inside the vessel 24.

(5) Internal wall 14, bottom 18 and lid 20 of the container 10 mean that once assembled, the inner wall, bottom 18 and lid 20 of the container form an inner envelope of waste insulation 26. This inner envelope defines an interior space in which the vessels 24.sub.1 and 24.sub.2 are housed with the waste 26 and quartz sand 22.

(6) The steel bottom 18 is a wall receiving the vessel and the outer and inner walls 12 and 14, which extend from the bottom 18 to the lid 20, around the vessel 24.sub.1 and 24.sub.2. The bottom forms a circular outline, it can alternatively form an oval, square or any polygonal shape. The outer and inner peripheral walls and the lid may be of corresponding or different shape.

(7) The inner and outer walls 12 and 14 may be made, for example, by welding two steel sheets preliminarily rounded. The inner and outer walls 12 and 14 are welded at their lower edge on the steel bottom 18. Molten lead or lead alloy is then preliminarily poured between the inner and outer walls to form the lead layer 16. In case of fusion, the lead layer 16 does not spread inside the container. Moreover, the bottom 18 may be flat or include particular shapes, for example for the positioning of the vessel/s 24.sub.1 and 24.sub.2.

(8) The outer wall is of circular section with an outer diameter between 500 mm and 1000 mm. The container is, from a height between the bottom and the lid, between 800 mm and 1500 mm.

(9) The inner and outer walls 12 and 14 are of a thickness of between 3 mm and 10 mm and the lead layer 16 has a thickness of between 25 mm and 50 mm.

(10) The steel bottom 18 and the steel lid may be of a thickness equal to more than twice, for example three times the value of the thickness of the inner and outer walls 12 and 14.

(11) The container 10 comprises a circular ring 19 for fixing the steel lid 20 and attached to the upper end of the outer and inner walls 12 and 14. The fixing ring 19 comprises holes for receiving bolts for fixing the lid passing through corresponding holes on the steel cover 20.

(12) Quartz sand means silica sand with traces of different elements such as Al, Li, B, Fe, Mg, Ca, Ti, Rb, Na, OH. Quartz sand has the property of vitrifying after melting then hardening. Quartz sand with a low melting point will be chosen. The volume of glass thus formed can also block some of the radioactive radiation (for example with a premix of the quartz sand with a radiation absorbing material).

(13) The outer wall 12 comprises a pressure relief valve 40. In addition to evacuation of gases emitted in case the lead layer 16 melts.

(14) The container 10 further comprises racking means 50 or rack/display comprising one or more superimposed compartments 52i and 52.sub.2 receiving the two vessels 24i and 24.sub.2. The compartments each include a door (not shown) allowing easy access to the interior of the compartments.

(15) The inner rack 50 comprises a bottom wall 53 in contact with the bottom 18 of the container 10, an upper wall 54, a cylindrical wall 56 extending between the lower and upper walls 53 and 54, and an intermediate wall 58 forming a bearing between the lower and upper walls 52 and 54.

(16) The first vessel 24i is positioned on the bottom wall 52 of the inner rack 50. The second vessel 24.sub.2 is deposited on the intermediate wall 58. The side wall 56 comprises several holes or orifices 60.

(17) The inner rack 50 is positioned inside the container before the quartz sand. The holes 60 in the side wall 56 of the inner rack 50 allow for the transfer of quartz sand into compartments 52i and 52i in order to surround and call vessels 24i and 24.sub.2. Depending on the arrangement of the holes in the inner rack 50, the sand may also cover the vessels 24i and 24.sub.2. It is noted that the sand could also, preliminarily, be deposited under the vessel 24.sub.1. Alternatively, the inner rack 50 may comprise vertical/horizontal/diagonal mounts, and trays connected to the mounts; the quartz sand can thus surround/coat the vessels by passing through the mounts and trays.

(18) The inner rack 50 is made of stainless steel. The inner rack 50 comprises a second upper wall 54′ and a lead plate 70 positioned between the two upper walls 54 and 54′.

(19) The inner vessels 24.sub.1 and 24.sub.2 include a removable cap 28.sub.1 and 28.sub.2 as well as means for securing/flanging/clipping/screwing 30.sub.1 and 30.sub.2 from the removable cap to the vessel 24.sub.1 and 24.sub.2.

(20) The inner vessels 24.sub.1 and 24.sub.2 comprise centering means and/or one or more means for gripping/hooking/affixing eyelets (not shown), for example on the lid 20.

(21) In this first mode of realization, the container 10 comprises two ceramic inner vessels 24.sub.1 and 24.sub.2, preferably made of ACA 997 type ceramic, more preferably of special ceramic ACS 99,8LS 172. The vessel 24.sub.1 and 24.sub.2 with its cap 28i and 28.sub.2 has a height of between 250 mm and 300 mm. The vessel 24.sub.1 and 24.sub.2 has a capacity of between 10 L and 20 L and withstands temperatures up to 1400° C.

(22) The waste 26 placed in the vessel 24.sub.1 and 24.sub.2 is highly radioactive. In particular, this mode of realization is intended for the storage of long-lived medium-to-high level radioactive waste, and in particular the non-recoverable final waste containing fission products and minor actinides, nuclear fuel ash.

(23) What's more, the container 10 comprises an outer rubber/plastic/silicone envelope 80 covering the outer wall 12. The outer rubber envelope 80 is partially shown on the image at the lower zone of the container 10. The outer rubber envelope 80 is made by dipping the container 10 into a liquefied rubber bath. The outer envelope 80 will prevent degradation of the container by water.

(24) FIG. 2 illustrates a second mode of realization of the container 10 seen in relation with FIG. 1. They will have in common the characteristics described in connection with FIG. 1's first mode of realization. FIG. 2's reference numbers are used in FIG. 1 for the corresponding elements, these numbers being however increased by 100 for the second mode of realization illustrated in FIG. 2. Specific reference numbers are used for a specific element, these numbers being between 100 and 200.

(25) In this second mode of realization, the container comprises a single inner vessel 124. The inner vessel 124 is placed in a single compartment 152 of the inner rack 150. The inner vessel 124 is made of stainless steel. The inner vessel 124 with its cap 128 has a height of between 500 mm and 1000 mm. The inner vessel 124 has a capacity of between 50 L and 350 L.

(26) The waste 126 located in the inner vessel 124 is faintly radioactive. For example, the waste constitutes metal structures of fuel elements, resulting from the operation of the reactor, used gloves, protective suits, irradiated tools, shells, connectors, radioactive mining residues that may pose problems of chemical toxicity if uranium is present with other otherwise toxic products such as lead, arsenic, mercury etc., the radioactive waste of the medical sector and whose half-life is less than 100 days.

(27) In the mode of realization of the disclosure presented here, the container 100 also comprises a plastic layer 190, preferably a low density polymer, covering the radioactive waste in the inner container 124. The plastic can be liquefied beforehand and mixed with a load and/or come from several low/high density polymers.