GB2132814A

GB2132814A - Container arrangement

Info

Publication number: GB2132814A
Application number: GB08333584A
Authority: GB
Inventors: Gunter Hohlein; Wilhelm Hempelmann; Joseph Boschert
Original assignee: Kernforschungszentrum Karlsruhe GmbH
Current assignee: Forschungszentrum Karlsruhe GmbH
Priority date: 1980-12-06
Filing date: 1983-12-16
Publication date: 1984-07-11
Also published as: GB2091477B; GB2132814B; GB2091477A; FR2495817B1; GB8333584D0; FR2495817A1

Abstract

Packed radioactive waste (1) is stored or transported in the innermost steel containers (2) of a plurality of containers e.g. (5) and (2) made of concrete and steel and/or lead. The containers are placed one inside the other, are each sealed with at least one cover (3) (6) and the container (2) is fixed in place by a filler extending to the upper end of the outer concrete container before its closure (6) is positioned. The surface covered by (3) is surrounded by an annular wall which is the upper part of a cup-shaped lining container having a cylindrical base portion of the same or greater wall thickness than container (2). The lining fits into the cup formed in its outer container and has container (2) positioned in its cup so that an annular gap occurs between the lining and the container (2) which gap can be filled by sealant from the open upper end. <IMAGE>

Description

1 GB 2 132 814 A. 1

SPECIFICATION

Container arrangement The present invention relates to a container system 70 chiefly, but not essentially, intended for storing and transporting at least one chill mould filled with radioactive waste fused in glass.

One such known system comprises a plurality of containers made of concrete and steel and/or lead, the containers being inserted one inside another and each container being sealed by means of covers. The inner container is made of steel and which contains the chill mould is disposed in a cup-shaped concrete shielding container and is secured therein by utilis ing a sealing filler which extends to the charging opening provided at the upper end of the concrete container.

Such storage containers are chiefly used for radioactive wastes which have little or low activity.

However, radioactive fission product solutions, which have a relatively high activity and which are produced during the reprocessing operations are also fused into specific types of glass. This glass is located in a mould which is similar to a chill mould and, after being filled, the mould is sealed by shrink-fit welding. These wastes are highly radioac tive and have a specific activity of up to 104 Ci/1.

Plants for manufacturing these chill moulds have only existed hitherto as prototypes and experimental plants. Because of the high radiation of these containers, they must be manipulated in hot cells.

Parts of these wastes, particularly if they include relatively fresh fission products, give off consider able amounts of heat. However, there are also fission product solutions which have lost their radioactivity, and the development of heat therefrom is of the order of 10 to 20 watts per chill mould. To the best of our knowledge, no solution has yet been found for storing such chill moulds.

There have, however, already been several prop osals for solving this problem. One such proposal is to store the chill moulds in a salt mine. Other proposals include storing the chill moulds in con crete blocks which are provided with bore-holes and 110 are ventilated, or storing the chill moulds in shielded or screened chambers which are simultaneously ventilated and cooled.

The technical feasibility of such known solutions has, however, only been tested experimentally. The 115 main disadvantage of such solutions is that the wastes have to be located in a transport container and, after transportation, transferred from the transport container to the storage place. One single exception to this is a proposal to provide shielded storage in conjunction with a vitrifying plant. In the method of working in a hot glazing cell, it is, however, to be expected that the chill moulds will be considerably contaminated in the hot cells. In order to be able to ensure satisfactory transport and safe storage, the chill moulds would need to be decontaminated extremely carefully by remote control.

The present invention seeks, to provide a container having improved shielding and heat dispersion particularly when used to accommodate chill 130 moulds containing materials transmitting large amounts of heat, such container nevertheless providing a stable covering for the glass chill mould.

According to the present invention, there is provided a container arrangement for storing and transporting at least one chill mould filled with radioactive wastes fused into glass, comprising a plurality of containers made of concrete and steel and/or lead, the containers being located one inside another and each container being sealed by at least one cover member whereby the innermost container is made of steel and, in user contains the chill mould, the inner container being disposed in a substantially cup-shaped concrete shielding container and being secured therein by a suitable sealing filler, the filler extending to the charging opening provided at the upper end of the concrete container prior to such opening being closed by the cover member, wherein the inner steel container is sealed by a cover member, the surface thereof sealed by the cover being surrounded, a second cup-shaped wall open at its upper end, the second wall having a cylindrical base portion of the same or greater wall thickness than that of the container, the container being removably insertable into the interior space defined by the second wall so that an annular gap, open at its upper end, is defined between the container wall and the second cup-shaped wall.

Preferably, the second wall, togetherwith its base is cast orfused directly into the substantially cupshaped concrete shielding container.

Desirably, the annular gap is filled with a sealing filler which extends to the charging opening formed in the upper end of the container, a crossbar member being fused or cast into the sealing filler in the region of the charging opening of the concrete container, the crossbar member being additionally anchored in the concrete container and having a carrying eyelet mounted thereon, the eyelet project- ing beyond the upper end of the container.

Advantageously, the sealing filler comprsies a material of high thermal conductivity and is a bearing metal formed from an alloy of copper or tin.

The invention will be further desribed, by way of example, with reference to the accompanying drawings, in which:- Figure 1 is a schematic longitudinal section through an embodiment of a container arrangement which is not in accordance with the present invention but which assists in the understanding of the present invention, Figure 2 shows a schematic longitudinal section through an embodiment of a container in accordance with the present invention and Figure 3 is a cross-sectional view taken through the container shown in Figure 2.

In Figure 1 there are shown chill moulds 1 which contain radiactive fission product solutions fused in glass. The moulds are hermetically sealed and may be contaminated to some extent on their surface. In orderto reduce the contamination level of the chill moulds they are first inserted into an inner container 2 made of steel or speroidal graphite iron, by remote control. The insertion may be effected by remote control through a double cover arrangement so that 2 GB 2 132 814 A 2 the container is only slightly contaminated external ly. The container 2 is then sealed by a cover 3 provided with a seal 4, the seal 4 being protected, to a large extent from the radiation from the chill moulds 1 by the cover 3.

The container 2, which need only be roughly machined and therefore can be easily manufactured, is then inserted into a cup-shaped concrete shielding container 5 made either of conventional concrete or of barium concrete. After insertion into the container, the chill mould 1 is shielded bythe steel or iron inner container 2 and by the concrete container 5, so that the amount of radioactivity measurable at the outer wall of the container 5 is considerably reduced relative to that of the mould 1. The concrete container 5 is then sealed in a relatively simpie manner by means of a crossbar 6 which simultaneously serves as a means for suspending the container. The crossbar 6 also prevents the steel container from failing out of the concrete container. If, for example, the container is overturned. The intermediate space 8 between the steel and concrete containers 2 and 5 is filled with a suitable sealing compound.

The crossbar 6 is fixedly connected to the concrete container 5 by means of tension rods 7 which are anchored in the concrete container 5 and is also fused directly into the sealing compound located in the upper region 9 of the container 5 above the steel container 2. Accordingly, the crossbar is located in the region of the opening of the concrete container 5 through which the container 2 is inserted. A carrying eyelet 10 is provided on the upper surface of the crossbar 6 which projects above the sealing material in the upper portion 9 and beyond the upper edge of the concrete container 5.

If the chill moulds 1 have a low heat transmission, the sealing material or intermediate layer 8 may be in the form of a type of mortar. If, however, the chill moulds 1 have a relatively high heat transmission, the sealing material or intermediate layer may be made from a type of bearing metal. The advantage of bearing metals which are usually alloys from copper or tin is that they have a high thermal conductivity. By using such materials, heat producted by the moulds 1 can be conducted away from the concrete container 5 and can be conducted to the upper surface of the container 5 by the metallic layer 8. The arrangement thus produced forms a tight and permanent covering for the glass chill moulds 1. The container arrangement can be stored in shielded chambers without separate ventilation being necessary. Any slight buildup of pressure in the chill mould 1 can easily be absorbed by the walls of the steel container 2.

If it is intended to store the moulds 1 for a relatively long period in simple, above-ground buildings and if it is necessary to further reduce the radiation so that the radioactivity of the container can be monitored at any time, the inner container 5 containing the chill moulds 1 may be inserted into a second concrete container 11, the thickness or shielding strength of which may be varied in dependence upon the radiation emitted by the inner container 5. The outer concrete container 11 thus only fulfils a shielding function. The container 11 may, therefore be provided with air supply conduit 12. a suitable air gap 13 is left between the inner container 5 and the outer container 11. The outer container 11 is sealed at its upper and lower ends by a concrete cover 14 and a concrete base 17 respectively. However, the lateral surface thereof may have ventilation slots 15 formed therein. These ventilation slots 15 have angled portions 18, so that the shielding action of the container 11 is unaffected by the presence of the slots 15.

The ventilation slots 15 which, as shown, are stepped form dividing lines between individual, annular concrete modules or elements 16 from which the container 11 is formed. These modules 16 are stacked vertically on one another and are centred on one another by the angled portions 18 or are otherwise prevented from being displaced. The thickness and depth of the modules 18 may be varied as desired. It is, however, advantageous if they are all of a uniform size because this simplifies the manufacture thereof. The concrete cover 14 is then placed upon the elements and the base of the container is sealed by the concrete base member 17.

the modules or elements 16, the base 17 and the cover 14 are fixedly interconnected by means of anchoring rods 19 which are inserted axially through the elements or modules and which are fixedly connected to the base 17 and the cover 14 by means of screws 20.

The inner container 5 is thus located in an outer container 11 which is simple to produce and which, in adition to providing a shielding effect, also acts as an additional safeguard during, for example, trans- portation of radioactive material. The heat produced in the inner container 5 is removed from the container system by natural air uptake and heating of the inner container is therefore eliminated or at least substantially reduced. Conventional inner con- tainers may therefore be used which are inserted into outer containers 11 the dimensions of these latter being selected in ependence upon the degree of shielding required. The inner containers 5 may be removed from the outer containers 11 at any time, and the outer contamers 11 may be re-used. Accordingly, the inner containers 5 can be produced economically in a conventional manner. The outer containers 11 may be manufactured from a relatively inexpensive material and may be adapted to the particular shielding requirements appropriate to the situation.

In Figures 2 and 3, there is shown a container in accordance with the present invention, which container could be used as the inner portion of the container arrangement shown in Figure 1.

In this embodiment the inner steel container 2 around the chill mould 1 is itself surrounded by a second steel wall 21, the intermediate space 8 as in the embodiment shown in Figure 1 being filled with a suitable sealing filler. However, in this embodiment, the space 8 is located between the external wall of the container 2 and the internal surface of the second wall 11 instead of between the wall of the container 2 and the wall of the container 5.

In the region of the cover 3 for the steel container d i 3 GB 2 132 814 A 3 2, the second steel wall 21 has a shoulder portion 22, thereby widening the upper end portion 23 of the chamber defined within the second wall 11 for receiving the sealing filler. The entire inner container 5 2 is therefore surrounded by the second steel wall 11, the second wall 21 being spaced at a uniform distance from the container 2 so as to define an annular gap 8 between the wall 21 and the container 2. If desired, but not shown, the second steel wall 21 may have the same wall thickness as the container. The second wall is fused directly into the concrete container 5 and is fixed therein by means of ribs 24. The wall is sealed at its lower end by a base 15 and thus effectively forms a steel cup which is placed directly in the concrete container 5. The steel container 2 and the chill mould 1 are then inserted into the concrete container 5. The container therefore includes a double-walled internal steel shell, the gap 8 between the walls of which may be filled with any suitable filler, such as a bearing metal to the level of the upper seal 9. Such a container system may then be inserted, if desired, into an outer concrete container 11 of the type shown in Figure 1.

Claims

1. A container arrangement for storing and transporting at least one chill mould filled with radioactive wastes fused into glass, comprising a plurality of containers made of concrete and steel and/or lead, the containers being located one inside another and each container being sealed by at least one cover member whereby the innermost container is made of steel and, in use, contains the chill mould, the inner container being disposed in a substantially cup-shaped concrete shielding container and being secured therein by a suitable sealing filler, the filler extending to the charging opening provided at the upper end of the concrete container prior to such opening being closed by the cover member, wherein the inner steel container is sealed by a cover member, the surface thereof sealed by the cover being surrounded, a second cup-shaped wall open at its upper end, the second wall having a cylindrical base portion of the same or greaterwall thickness than that of the container, the container being removably insertable into the interior space defined by the second wall so that an annular gap, open at its upper end, is defined between the container wall and the second cup-shaped wall.

2. A container arrangement as claimed in claim 1 wherein the second wall, together with its base, is castor fused directly into the substantially cupshaped concrete shielding container.

3. A container arrangement as claimed in claim 1 or 2, wherein the annular gap is filled with a sealing filler which extends to the charging opening formed in the upper end of the container, a crossbar member being fused or cast into the sealing filler in the region of the charging opening of the concrete container, the crossbar member being additionally anchored in the concrete container and having a carrying eyelet mounted thereon, the eyelet projecting beyond the upper end of the container.

4. A container arrangement as claimed in claim 3, wherein the sealing filler comprises a material of high thermal conductivity and is a bearing metal formed from an alloy of copper ortin.

5. A container arrangement constructed and 7 /0 arranged to operate substantially as herein before described with reference to and as illustrated in Figures 2 and 3 of the accompanying drawings.

Printed for Her Majesty's Stationery Office, by Croydon Printing Company Limited, Croydon, Surrey, 1984. Published by The Patent Office, 25 Southampton Buildings, London, WC2A lAY, from which copies may be obtained.