DE2754269C2 - Final repository for radioactive waste - Google Patents

Description

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It can be assumed that the ingress of water, if at all, will occur in the area of the groundwater-bearing surface layers takes place in a shaft tube The shaft tube is generally considered to be the most endangered part of the repository respected, as there is an aquifer on the shortest route and the geological bearing formation, e.g. B. rock salt, are penetrated by this (therefore in Future of a manhole construction that is completely watertight as long as possible in this area is the greatest To pay attention). Should a water ingress nevertheless occur, the water would become The deepest of the shaft flow and from there into the horizontally branching bearing floor or bearing stretches pour out. The mountains are heated up locally by the heat produced by the highly radioactive waste The saline solution under hydrostatic pressure could penetrate the bearing bores and become hot Attack waste molds and leach out radioactivity. Because of the high temperatures, it could also too strong convection currents in the vertical Boreholes come. The leachable activity is then quickly distributed due to differences in density Time over the entire horizontal part of the repository. As a result of the higher temperature of the salt solutions In the deepest part of the repository, the radioactive nuclides are also transported vertically into the Manholes of the repository can take place. It is to be feared that it will eventually spread to Level of the water access point and thus in the groundwater. Active countermeasures around Protection of the stored waste from contact with saline solutions is not provided according to the current status and also not conceivable with a cut of the repository in the previous form.

The object of the invention is to cut a repository for to design high, medium or low level radioactive waste in such a way that this waste is prevented from coming into contact with Water can be protected safely, long-term and automatically, with the additional possibility of spreading of water in areas outside of the immediate ingress of water from above ground or to seal off.

The solution to this problem is described in the characterizing features of claim 1.

Advantageous further developments of the invention are listed in the remaining claims.

The invention therefore allows the safe closure by a suitable cut of the repository of the stored waste before contact with water or saline solutions. In addition, there are additional Active countermeasures are possible, which prevent the liquid from penetrating from the shaft area into the underground Preventing cavities and even reversing them in the event of water ingress should. Should a water ingress from other mountain areas than directly in the shaft occur, what at Corresponding, unscratched safety zones around the immediate repository are much less likely when water access through the shaft tube is to be assumed, it is possible according to the invention to also in this case to block large parts of the repository from the ingress of liquids. this happens in such a way that the entire storage field is divided into separate sub-stores, which are below each other are not connected by horizontal stretches at the same level.

The invention is illustrated below on the basis of an exemplary embodiment explained in more detail by means of a schematic figure

As can be seen from the figure, the shafts 4, 7 required for the operation of the repository 10 are sufficient considerably lower than level 11 of the actual storage area 2 and have a sufficient safety distance to the fields of storage field 2. in the Case of the largest accident to be assumed (GAU)

ίο can be used in the highly radioactive for final disposal Waste 2 used part 1 of the repository 10 to create an air bubble which is below the hydrostatic This ensures that the water masses 12 to 14 do not have any direct pressure Have access to repository areas 1. Experience has shown that rock salt formations are impermeable in the mountain range for gases.

The shafts 4, 7 required for the repository 10 are at some distance (approx. 200 m) from the actual one Repository area for highly radioactive, heat-generated waste 2 sunk After this Shafts 4, 7 sunk to a depth of approx. 1000 m are, fill points and horizontal connecting lines 3 are driven. The actual storage Field 1 is created approx. 200-300 m above level 15 and is only accessible via spiral and / or blind shafts with the lower connecting sections 3 or 16 5, 6 connected. In the event of a water ingress, the water 12 to 14 first rises into the lower one Divide the mine building and compresses the air in the bearing sections 1,5 and 6 up to hydrostatic pressure of the water column.

The to keep away the penetrated water 12 up to 14 required additional air volume can be in the shafts 4 or 7 and routes 3 or 16 Pipelines 9 laid in the repository area 1 by above-ground compressor stations (not in detail shown).

By introducing a gas phase, the direct Contact of the water 12 to 14 which has penetrated into the repository 10 with the waste 2 is prevented. The possibility a leaching and subsequent spread of radioactivity will be reliable and long-term prevented.

As shown in dashed lines in the figure, the connecting lines 3 can be designed in such a way that one or more of a line 16 with a depression 8 forms. This design has the advantage that with certainty it is prevented that z. B. in the case of strong water ingress, the water in the spiral section 5 or the Blind shaft 6 does not go up first. By means of the depression 8 it is accordingly achieved that it is first filled and the air (gas) in the repository 1 or the accesses 5, 6 remains until the water 13 also these blocked.

In the meantime, underground personnel can in any case leave the repository via one of the horizontal connecting routes.
As shown in dashed lines in the figure, further cavities 17 can be created from the spiral section 5 or the Lindschacht 6, which cavities initially absorb the water masses in the event of a very rapid ingress of water. The air displaced from these additional volumes escapes into the storage area 1 and is compressed there. Even if all of the overactive compressors fail, the storage section 1 will not be able to be flooded.
In addition to this advantage, there are also other technical

5

see possibilities for long-term securing of the repository 10, which in the designs discussed so far the repository were not possible. By precautionary built-in pipelines 9, which in normal operation as cooling, fresh weather or material transfer 5

port lines can be used in the ^J

Air volumes under increased pressure are pulpy Pump in VerfüUmassen, which gradually solidify and ultimately to one with solid masses tight sealed repository 10 even after an unexpected 10 seen water ingress.

In order to reduce the air-filled scale production for the repository horizon 11, the bearing sections 1 can gegebe- ψ appropriate, additionally with low and intermediate level radioactive; | Waste 2, e.g. B. in barrels are filled. is f.

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Claims (3)

Patent Claims: 1. Final repository for radioactive waste in a mine, a) that has been driven into a salt dome or an equivalent geological formation, b) where the waste is housed in storable shielded containers, c) and stored in a storage section (1) of the salt dome or the geological formation are, d) wherein the storage section (1) for receiving the waste is arranged in such a way that its level (11) is at a sufficient distance above the (15) of a connecting section (3) e) in which the storage section (1) with the connecting section (3) via at least one of the Connection route (3) to the storage route (1) ascending connection, for example one Blind shaft (6) is connected, characterized in that el) the storage section (1) is only accessible via the ascending connections (5,6), e2) the connections (5,6) can also consist of ascending spiral stretches, and f) in the storage section (1) for receiving the waste a gas can be supplied from above ground via pressure lines (9). 2. repository according to claim 1, characterized in that dl) the connecting section (3) between two shafts (4 and 7) is formed into a depression (8) is or has a depression (8). 3. repository according to claim 1 or 2, characterized in that f 1) the bearing line (1) and the connections (5,6) in the event of a shutdown or after a water ingress via the pressure lines laid in advance (9) Can be completely or partially sealed from the surface with suitable materials are. The invention relates to a repository for radioactive waste in a mine, which is in a salt dome or an equivalent geological formation was excavated, with the waste in storable shielded containers housed and in a storage line of the salt dome or the geological formation are stored, the storage line for receiving the waste is arranged such that its level in sufficient distance is above that of a connecting section, in which the bearing section is at least a connection ascending from the connecting section to the storage section, for example a blind shaft, connected is. Such a repository is from "Umschau" 67.Jg. 1967, issue 7, pages 219-244 and issue 11, 1975, Pages 344-345 known The emplacement of radioactive waste in geological formations is recognized worldwide as the best method Safely keep the substances that have been dangerous for thousands of years out of the life-filled zone of the earth. This exclusion from the biosphere must take place until the radioactivity has decayed to harmless levels. Depending on the composition and category of the waste ίο are time periods from a hundred to a few hundred thousand Years required. In the case of storage in geological formations, the filling of a repository with water and the subsequent Penetration of leached radioactivity into the groundwater is the most dangerous path of spread represent. Attempts to solve the problem have so far provided that the radioactive waste is as good as possible against leaching protected by water or aqueous solutions of natural salts. This is done through the Use of high quality fixing materials such as glass, ceramics, bitumen, plastics and hydraulic binder In addition, the storage chambers are sealed with salt and hydraulic binders, as are the interstices between waste drums filled with loose salt. Waste brought into boreholes should be plugged can be protected from different materials such as salt, cement or bitumen. In all of these cases it will but in the case of the "largest assumed accident" (GAU) assumed water ingress, a direct one Contact of part or all of the stored waste with penetrating aqueous solutions is possible drawn. The considerations are that a fraction of the stored radioactivity is leached out becomes and by convection and diffusion over a more or less large area of the underground Voids is distributed. Under unfavorable conditions, it cannot be ruled out that parts of the contaminated After more or less long periods of time, saline solutions also with the groundwater at shallower depths come into contact. This case would be the desired goal of the final disposal, the long-term safe one Completion of radioactivity from the biosphere, questioning and endangering. For the emplacement of highly radioactive, heat-generating waste are specially produced for this purpose Final repositories are provided which, in principle, correspond to conventional mines in terms of their layout. The highly radioactive Waste makes up around 99% of the activity for final disposal. The ones in a glass matrix melted-down waste is to be packed in stainless steel containers and brought to final storage in boreholes will. So far, however, no measures are known to reduce the waste during or after the operating phase can with certainty prevent contact with water. In the previous concepts, the Connection of the repository level (bottom of the repository) horizontally and directly with the day shafts via a bottom stop in the same depth. The possibility of the repository becoming full is also being considered with water during or after the operating phase, albeit with only a very minor one Probability is to be assumed. The direct, horizontal connection planned in the previous concepts the bottom of the repository on day shafts would cause the radioactivity to spread as a result of convection.