The method of disposal of radioactive waste in rock masses with heterogeneous geological structure

 

(57) Abstract:

The invention relates to the disposal of solid radioactive waste in the ground. The method includes drilling a borehole in a rock mass, creating a perimeter wells in areas of shallow permeable formations annular cavities, placing in the borehole containers with solid radioactive waste, filling the free volume of the borehole backfill material and sealing her mouth. The invention provides improved reliability localization of radionuclides disposed RAO and durability of their burial. 1 C.p. f-crystals, 1 Il.

The inventive method relates to the field of environmental protection, and more specifically to the field of disposal of radioactive waste (RW) in the ground. Most effectively the inventive method can be implemented at the disposal of solid and solidified radioactive waste in rock masses with heterogeneous geological structure (representing alternating layers of waterproof and permeable rocks).

There is a method of disposal of radioactive waste [1], including drilling in rock array well depth 610 - 3500 meters, the casing of the well by pumping cement the raw less than the diameter of the borehole, between the cylinders and the borehole wall is formed an annular gap.

The disadvantages of this method are: the impossibility of implementation of the method in the rocks with heterogeneous geological structure, due to nepredusmotritelnost create reliable waterproofing protective barrier between the cylinders with raw and the borehole wall; economiccost, due to the need for safe disposal of radioactive wastes in a similar fashion, create wells of great depth.

There is a method of disposal of containers with radioactive waste [2], including the creation of the breed array of vertical shaft, placement in the mine containers with waste and filling the space between the walls of the mine and containers with raw bentonite.

The disadvantage of this method is that it is impossible to implement the method in the rocks with heterogeneous geological structure, due to the danger of destruction of the underground groundwater protective bentonite barrier.

The closest to the technical nature of the claimed method is a method of disposal of radioactive waste in rock masses with heterogeneous geological structure [3], including the drilling of nicemy layers), zone containing salt water (water-permeable layer), and areas containing petroleum hydrocarbons (waterproof layer) to a depth that provides the location of the bottom of the borehole in the zone containing hydrocarbons, installation in a metal well casing to the bottom, creating in the bottom of the metal casing of the concrete tube, the upper level which is located above the upper level of the zone containing hydrocarbons, in the zone of occurrence of stable geological formations, the entire volume of the metal casing on concrete tube mixed with cement (cemented) RAO to a level below the lower level zones, containing salt water, creating over cemented RAO cement tube, the upper level which is located above the upper level of the zone containing salt water in the zone of occurrence of layers stable geological formations, the entire volume of the metal casing above the cement plug, but below the level of the wellhead, in the zone of occurrence of the formation of a stable geological formations, mixed with cement RAO, and sealing the wellhead.

Features of the known method is that RAO (solid imennogo solution, which eventually seizes in the cement stone, placed in a metal casing pipe installed in the well, below the level of the bottom of the water basin. A metal pipe in a known way in addition to tools that strengthen the walls of the borehole, functions both as a protective (waterproofing) barrier for cemented RAO, T. K. direct contact with water or moisture during storage of the last invalid. Concrete and cement plugs are used to isolate areas for cemented RAO from salt water and petroleum hydrocarbons.

The disadvantages of this method are:

the uncertainty in the localization of radionuclides disposed of radioactive waste and the fragility of their burial, due to:

- use as a protective barrier for radioactive waste metal casing in contact with moisture reservoirs stable geological formations and zone containing highly corrosive salt water [5];

- use as a tombstone object cemented RAO without protective shells, because the cement matrix does not provide reliable waterproof protection of radionuclides RAO from water [6], in case of violation of the increasing the reliability of radionuclide localization, buried radioactive waste and durability of their burial.

These advantages are achieved by the inventive method includes drilling in rock masses with heterogeneous Geology, wells, creating a perimeter wells in the combined layers, each of which consists of a water-permeable layer and the adjacent top and bottom parts of the waterproof layers, the annular cavity length S and height around the perimeter of the hole equal to HCCwhere HCC- the height of the combined layer permeable layer and the adjacent top and bottom parts of the waterproof layers, placing in the borehole below the level of her mouth, but above the level of the bottom of containers with radioactive waste, filling the free volume of the well and the annular cavity to the level of her mouth backfill material and sealing the wellhead, and the height of each of the parts of the waterproof layers L, adjacent the top and bottom to the water-permeable layer is not less than 0.05 HCCand the length of the annular cavity S is not less than 0.2 DSLEwhere DSLEthe diameter of the hole, the bottom of the well is placed outside the boundaries of the occurrence of combined words which leads to the formation of a protective barrier in the well, moreover, these protective barriers are effective in cases where they are in turn surrounded by a waterproof layers, because in contact with groundwater, there is a real danger of their destruction.

By filling the plugging material of the annular cavities protective barrier in areas of shallow permeable formations will have a ring-shaped thickening, which protects it from groundwater. Depending on the possible shape of the annular cavity ring-shaped thickening of the protective barrier may have a vertical section of triangle, traicionado or rectangular shape, and a ring-shaped thickening of the rectangular are the most effective.

If the height L of each of the parts of the waterproof layers adjacent the top and bottom to the permeable layer will be less than 0.05 HCCmay occur leakage of groundwater along the surface of the annular thickening to the parts of the protective barrier, located in the zones of occurrence of waterproof layers, with the consequence may be the risk of fracture.

If the length of the annular cavities S will be less than 0.2 DSLEin volumes calceolaria grouting material, may occur the formation of pores and cracks, due to uncontrolled infiltration of backfill material into the permeable layers between the particles of his breed. In this case, will not provide reliable protection of containers with radioactive waste from groundwater.

If the length of the annular cavities S will be equal to not less than 0.2 DSLEthe formation of pores and cracks will occur only in the part of the annular thickenings, which is in direct contact with groundwater. In this case, the protective barrier will be isolated from groundwater, adjacent and without pores and cracks, a part of the annular thickenings that will provide reliable isolation of containers with waste from groundwater.

If the location of the bottom of the well within the combined layer, would be insulated from ground water containers with waste in the bottom of the well.

As the plugging material can be used hydraulic binding materials based on cement or blast furnace slag without any special additives.

The inventive method is illustrated in the drawing, which shows a section of the well (in the variant with two annular floor is stranstvo which are filled with grouting material.

The inventive method implemented as follows:

In a rock mass 1 with heterogeneous geological structure and consisting of alternating waterproof layers 2 and permeable layers 3, drill hole diameter DSLEto a depth that provides the location of the bottom of the well outside the bounds of occurrence of the combined layers in the zone of occurrence of the waterproof layer 2.

Perimeter wells in the combined layer thickness of HCC, each of which consists of a water-permeable layer 3 and the adjacent top and bottom parts of the waterproof layers 4 of a thickness of L = 0,05 HCCcreate an annular cavity triangle and trapeznogo section with height around the perimeter of the hole equal to HCCand the length of S = 0,2 DSLE(the most stringent conditions). In the well below the level of her mouth 5, but above the level of the bottom 6 place the containers with radioactive waste 7. In free volume of the well and the annular cavity to the level of her mouth 5 download backfill material forming a protective barrier 8 and the annular thickenings 9 protective barrier 8, after the hardening of cement material are sealing the mouth 5 by pouring tar, bitumen or similar is determined, as the height of the permeable layer /0,9.

The test results of the proposed method, it was found that RAO have more reliable waterproofing than in the method prototype that provides improved reliability localization of radionuclides disposed RAO and durability of their burial.

1. The method of disposal of radioactive waste in rock masses with heterogeneous geological structure, comprising drilling a borehole in a rock mass consisting of waterproof and water-permeable layers, to a depth of, for placement of the bottom of the borehole in the zone of occurrence of waterproof layer, placing well above its bottom and below its mouth radioactive waste, surrounded by a protective barrier, sealing the wellhead, wherein the radioactive waste is placed in containers that are placed in the well with the formation in it of free volume, perimeter wells in the combined layers of the rock mass, consisting of a water-permeable layer and the adjacent top and bottom parts waterproof seams, creating an annular cavity with a height around the perimeter of the hole equal to HCCwhere HCC- height to the permeable layer, is not less than 0.05 HCCthe length of the annular cavity is not less than 0.2 DSLEwhere DSLEthe diameter of the hole, create a protective barrier by filling the free volume of the well and the annular cavities backfill material after placing in the borehole containers with radioactive waste as backfill material used hydraulic binder based cement or blast furnace slag, and the bottom of the well is placed outside of occurrence of the combined layers.

2. The method according to p. 1, characterized in that the annular cavity have a vertical section of a rectangular shape.

 

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