GB2186419A

GB2186419A - Radioactive waste disposal

Info

Publication number: GB2186419A
Application number: GB08618901A
Authority: GB
Inventors: William Robert Burton
Original assignee: NUCLEAR TECHNOLOGY
Current assignee: NUCLEAR TECHNOLOGY
Priority date: 1985-08-05
Filing date: 1986-08-01
Publication date: 1987-08-12
Also published as: GB8618901D0; GB8519644D0

Abstract

Radioactive waste is buried at a land site e.g. a trench and voids between disposed items are filled with particulate material e.g. sand. At least some of the items may be containers which themselves may contain items the voids between which are filled with particulate material. The containers may be vibrated whilst being filled with sand and the sand may be vibrated using an air pulsed hose during filling of voids between items in the trench. The sand may include material to hold leach nuclides and assist in nuclide immobilisation.

Description

SPECIFICATION Radioactive waste disposal This invention relates to the land burial of radioactive waste.

A long term problem arising with the land burial of radioactive waste is that of "slumping". This arises by the degradation of containers holding the waste which may allowthe content of the containersto re- orientate itself into the voidage within and between containers. Any cap on the burial site may thereby be caused to change its position with two possible results: thefirst is the creation of a water mass (such as a pond) above the burial site and the second is stressing of the cap such that its imperviousness may be lost, such as by cracking.

It is already appreciated that voidage within and between containers can be reduced by injecting cement. This can be expensive.

According to one aspect the invention provides a method of land burial of radioactive waste in which voids between disposed items are filled with particulate material. The particulate material may be subject to vibration during filling ofthevoids.

From another aspect the invention provides a land site of buried radioactive waste in which voids between disposed items are filled with particulate material.

At least some of the items may be containers. At least some of the items may be in containers.

The containers contain ing items may be vibrated whilst voids therein are filled with particulate material.

The particulate material may comprise material for holding nuclides released by leaching.

The particulate material may include material to assistin nuclideimmobilisation.

Examples of the invention will now be described.

In one general form land burial of radioactive waste is conducted with the use of a granular or powdered material (such as sand) filling containers holding the waste or the voids in disposed items, such as glove boxes. Additionally, and preferably or alter natively, the voids between the containers can be similarly filled.

Thefilling material mayhaveaddedtoitsubstances (such as illite) which can pickup and hold hazardousnuclides (such as caesium)which could be released from waste by leaching if water enters the burial site. Additives could also be used to adjust the chemistry (such as pH) to assist in nuclide immobilisation, such as calcium carbonate.

The filling material may be encouraged to enter all voids by vibration. Existing burial sites still having access can bye treated to introduce a granular or powdered filling in the voids between containers. Typic allythefillingwould beencouragedtoenterthe voids by using an air pulsed tube such as used for assisting the settling of newly-poured concrete.

Thus the invention avoids, on the one hand, any need for compaction of the waste (other than that which may be required in the context of overall volume limitations orcan be easily effected) and, on the other hand, the employment of costly materials.

In one way of carrying the invention into effect, solid low level radioactive waste material (such as steel or concrete parts from a dismantled nuclear power station, discarded handling tools, rubber gloves, glove boxes) is placed in cylindrical drums and, before sealing the drums, the latter are placed on a vibrating platform below a hopper filled with sand. The drums are vibrated as sand from the hopper isfedtothe drums. When the drums arefull they are sealed and taken to a burial site such as one similar to that disclosed in patent specification GB 2148,585 A. Alternatively a simple trench could provide a burial site.

When the drums are in position in cells or other section on the burial site, the cells or the interstices between containers and/or large items such as glove boxes are filled with sand and vibrations applied to the sand filling. The cells are then closed and iater the burial site is capped.

Wherethedrumsarefilledwith continuous solids (such as sludg es) these solids can fill the drums without sig nificant voidage. There is then only a need tofill the voids between the drums with the sand.

Sand, or otherfiller material, could be introduced as a slurry. The liquid part of the slurry could then be removed when the sand has settled and re-used to form a further slurry, thus confining the liquid part, which itself may become active, to a closed cycle.

The containers may be self-draining,forexample provided with drain holes covered by a layer of easily draining granular material.

The repository could with advantage be located so that the base ofthe repository is above the level of the local ground water table and the repository would with advantage be provided with drain means for removing liquid and inhibiting ground water from gaining access to the waste. Water gaining access can then drain away and the particulate material facilitates this.

1. A method of land burial of radioactive waste in which voids between disposed items are fi I led with particulate material.

2. A method as claimed in claim 1, in which at least some of the items are containers.

3. A method as claimed in claim 1 in which at least some of the items are in containers.

4. A method as claimed in claim 3 in which the containers containing items are vibrated whilstvoids therein are filled with particulate material.

5. A method as claimed in claim 1 or claim 2, in which the particulate material is vibrated during filling of the voids.

6. A method of land burial of radioactive waste as claimed in claim 1 andsubstantiallyashereinbefore described.

7. A land site of buried radioactive waste in which voids between disposed items are filled with particulate material.

8. A site as claimed in claim 7, in which at least some items are containers.

9. Asite as claimed in claim 7 or claim 8, in which

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Radioactive waste disposal This invention relates to the land burial of radioactive waste. A long term problem arising with the land burial of radioactive waste is that of "slumping". This arises by the degradation of containers holding the waste which may allowthe content of the containersto re- orientate itself into the voidage within and between containers. Any cap on the burial site may thereby be caused to change its position with two possible results: thefirst is the creation of a water mass (such as a pond) above the burial site and the second is stressing of the cap such that its imperviousness may be lost, such as by cracking. It is already appreciated that voidage within and between containers can be reduced by injecting cement. This can be expensive. According to one aspect the invention provides a method of land burial of radioactive waste in which voids between disposed items are filled with particulate material. The particulate material may be subject to vibration during filling ofthevoids. From another aspect the invention provides a land site of buried radioactive waste in which voids between disposed items are filled with particulate material. At least some of the items may be containers. At least some of the items may be in containers. The containers contain ing items may be vibrated whilst voids therein are filled with particulate material. The particulate material may comprise material for holding nuclides released by leaching. The particulate material may include material to assistin nuclideimmobilisation. Examples of the invention will now be described. In one general form land burial of radioactive waste is conducted with the use of a granular or powdered material (such as sand) filling containers holding the waste or the voids in disposed items, such as glove boxes. Additionally, and preferably or alter natively, the voids between the containers can be similarly filled. Thefilling material mayhaveaddedtoitsubstances (such as illite) which can pickup and hold hazardousnuclides (such as caesium)which could be released from waste by leaching if water enters the burial site. Additives could also be used to adjust the chemistry (such as pH) to assist in nuclide immobilisation, such as calcium carbonate. The filling material may be encouraged to enter all voids by vibration. Existing burial sites still having access can bye treated to introduce a granular or powdered filling in the voids between containers. Typic allythefillingwould beencouragedtoenterthe voids by using an air pulsed tube such as used for assisting the settling of newly-poured concrete. Thus the invention avoids, on the one hand, any need for compaction of the waste (other than that which may be required in the context of overall volume limitations orcan be easily effected) and, on the other hand, the employment of costly materials. In one way of carrying the invention into effect, solid low level radioactive waste material (such as steel or concrete parts from a dismantled nuclear power station, discarded handling tools, rubber gloves, glove boxes) is placed in cylindrical drums and, before sealing the drums, the latter are placed on a vibrating platform below a hopper filled with sand. The drums are vibrated as sand from the hopper isfedtothe drums. When the drums arefull they are sealed and taken to a burial site such as one similar to that disclosed in patent specification GB 2148,585 A. Alternatively a simple trench could provide a burial site. When the drums are in position in cells or other section on the burial site, the cells or the interstices between containers and/or large items such as glove boxes are filled with sand and vibrations applied to the sand filling. The cells are then closed and iater the burial site is capped. Wherethedrumsarefilledwith continuous solids (such as sludg es) these solids can fill the drums without sig nificant voidage. There is then only a need tofill the voids between the drums with the sand. Sand, or otherfiller material, could be introduced as a slurry. The liquid part of the slurry could then be removed when the sand has settled and re-used to form a further slurry, thus confining the liquid part, which itself may become active, to a closed cycle. The containers may be self-draining,forexample provided with drain holes covered by a layer of easily draining granular material. The repository could with advantage be located so that the base ofthe repository is above the level of the local ground water table and the repository would with advantage be provided with drain means for removing liquid and inhibiting ground water from gaining access to the waste. Water gaining access can then drain away and the particulate material facilitates this. CLAIMS

8. A site as claimed in claim 7, in which at least some items are containers.

9. Asite as claimed in claim 7 or claim 8, in which at least some items are in containers.

10. A land site of buried radioactivewasteas claimed in claim 7 and substantially as hereinbefore described.

11. Amethod orsiteasclaimed inanypreceding claim, in which the particulate material comprises material for holding nuclides released by leaching.

12. A method or site as claimed in any preceding claim, in which the particulate material includes material to assist in nuclide immobilisation.

13. A land burial site for radioactive waste formed using a method as claimed in any of claims 1 to 6 or claim 11 orclaim 12.