JP2015102359A - Radioactive waste underground storage facility and construction method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an underground storage facility having a large disposal space for efficiently performing burial disposal (geological disposal/marginal depth disposal) of radioactive waste.SOLUTION: In a method, vertical shafts 1 are formed down to a predetermined depth, each of which has a diameter enough to locate and drive a drilling unit 3 for constructing disposal tunnels 2 by using a shield method, and the disposal tunnels 2 are constructed from the respective vertical shafts by using the shield method of machine-drilling and assembling concrete segments. The disposal tunnel 2 is constructed to form a disposal space having a perfect water-shielding structure which includes: a primary lining having a water-shielding structure formed by attaching sealing materials in advance around the entire periphery of end surfaces of the segments used in the shield method; a continuous water-shielding layer formed by heat welding water-shielding sheets on the inner wall surface of the primary lining; and a secondary lining with concrete inside the water-shielding layer.

Description

  The present invention relates to a radioactive waste underground storage facility and a construction method thereof.

  Radioactive waste from nuclear power plants and reprocessing facilities is divided into high-level radioactive waste and low-level radioactive waste, and high-level radioactive waste is used as spent fuel itself to be disposed of as well as spent fuel. It consists mainly of fission products that remain after recovery and recovery of uranium and plutonium. This high-level radioactive waste is currently mixed and melted with borosilicate glass, poured into a stainless steel container (canister), solidified, and stored as waste. This storage means that the geological disposal to store in the deep underground (depth of 300m or more from the ground) after cooling and storing for a certain period is stipulated by law.

  Among the low-level radioactive waste, wastes with relatively high levels of radioactivity, such as reactor structures and used control rods, are sealed in a predetermined container to form a waste body, which can be disposed at a sufficient depth ( 50-100m buried disposal).

  The typical example of the underground storage facility used as the geological disposal facility is shown in Patent Documents 1 and 2. This facility is equipped with a stand to carry waste (canister) underground, and a large number of storage horizontal tunnels connected to the vertical shaft. Disposal holes drilled downward are intermittently formed on the bottom of each horizontal tunnel (disposal tunnel). The waste is buried and disposed in a state in which each disposal hole is covered with an artificial barrier material (such as bentonite). In addition, as an example of a low-level radioactive waste embedding disposal means, Patent Document 3 discloses a configuration in which a disposal tunnel formed in the rock is used as a disposal space, waste is multi-layered, and the surroundings are filled with low-diffusion materials. ing.

  In addition, the above-mentioned patent document 1 discloses that a supporting structure is formed by a segment in which a steel frame is filled with granite as a structure of a disposal tunnel.

  Furthermore, in the underground storage facility, as a means for preventing contaminants from stored waste and the like from penetrating into the groundwater, Patent Document 2 discloses disposal through a fault crushing zone existing between healthy rocks as a conventional example. It has been shown that a water stop plug made of clay material is constructed in a mine shaft, and as a countermeasure against this, it is proposed to construct a disposal mine shaft in the rock mass while avoiding a fault fracture zone.

  Further, Patent Document 3 discloses that a bentonite block is disposed on an inner wall surface of a disposal mine formed by a concrete lining constructed by a conventional method to provide a water permeable layer, and a reinforced concrete segment is provided inside the low water permeable layer. A method for arranging and constructing a disposal space is disclosed.

JP 2002-250795 A. JP-A-2005-331313. JP 2004-298822 A.

  High-level radioactive waste is geologically disposed as a predetermined waste body, but the disposal tunnel of the previous underground storage facility is premised on the formation of the rock layer, and further, a disposal hole is drilled downward from the disposal tunnel. It is necessary to excavate many disposal tunnels and disposal holes, and it cannot be said that the construction of facilities is necessarily efficient.

  Also, as a water-blocking structure for disposal tunnels and waste storage, tunnel wall formation with bentonite blocks and means for filling the surroundings with waste have been proposed. The volume ratio becomes large, and the utilization rate of the disposal space is not good.

  Therefore, the present invention proposes a novel radioactive waste underground storage facility and a method for constructing it, which can efficiently carry out the disposal of radioactive waste (geological disposal and marginal depth disposal).

In the underground storage facility for radioactive waste according to claim 1 of the present invention, a shaft having a diameter in which a predetermined excavation device can be arranged and a plurality of appropriate branches from the shaft in an appropriate direction are provided in the facility construction area. A primary lining of a water-blocking structure with a concrete segment fitted with a water-stop sealant around the entire end surface, a water-blocking layer formed of a water-blocking sheet on the inner wall surface of the primary lining, and an inner side of the water-blocking layer It is characterized by comprising a disposal tunnel with a disposal space that has a triple water-tight structure by secondary lining with concrete.
It is what.

  According to a fifth aspect of the present invention, there is provided a method for constructing an underground storage facility for radioactive waste, wherein a shaft having a diameter on which a predetermined excavator can be disposed is formed to a predetermined depth in a facility construction area, and a machine is formed from the shaft. When constructing a disposal tunnel by shield method by excavation and assembly of concrete segments, a water-blocking seal is preliminarily attached to the entire periphery of the end face of the segment to perform primary lining of the water-blocking structure. Forming a water-impervious layer with a continuous water-impervious sheet by thermal welding on the wall surface, and performing secondary lining with concrete inside the water-impervious layer to form a disposal space with a triple completely impermeable structure It is characterized by this.

  Thus, the excavation depth of the shaft is determined depending on whether the disposal target is geological disposal of high-level radioactive waste waste or low-level radioactive waste waste with relatively high radioactivity level. . In addition, the diameter of the shaft is the same as that used for the shield method used for excavation of disposal tunnels (sealed type, open type, sealed / open switching type, etc.). The size is such that it can be placed at the bottom and can be started, and after the shaft excavation, a disposal tunnel is excavated from the shaft with the excavator. Furthermore, a plurality of the disposal tunnels can be formed by making the excavation direction and the excavation height different, and a wide disposal space in the facility construction area can be easily secured. However, the above-mentioned legal disposal tunnel is a disposal space with a triple completely impermeable structure in which the entire disposal tunnel is prevented by the primary lining, the shielding layer, and the secondary lining. The vertical shaft is a waste carrying-in route.

  The underground storage facility for radioactive waste and the construction method thereof according to claims 2 and 6 of the present invention, particularly in the underground storage facility and construction method thereof, are a plurality of constructions separated at an appropriate distance in the facility construction area. Forming shafts and forming disposal tunnels that are connected to connect the shafts. Set the shaft position according to the terrain and ground conditions within the facility construction area, and connect multiple shafts between them. By constructing a disposal tunnel, simultaneous construction of a plurality of disposal tunnels can be easily performed, and a wide disposal space can be efficiently constructed.

  Further, the radioactive waste underground storage facility and the construction method thereof according to claims 3 and 7 of the present invention, particularly in the underground storage facility and construction method thereof, are particularly about 40 m in diameter of the shaft and about 16 m in diameter of the disposal tunnel. The disposal tunnel has a multi-layered structure, and it is possible to perform full automation of waste storage work, such as carrying in radioactive waste, for each level, realizing efficient storage work. it can.

  Further, the radioactive waste underground storage facility according to claim 4 of the present invention is formed to have a predetermined thickness with an appropriate cushioning material on each floor of the disposal tunnel, particularly when a multi-level structure is adopted for the disposal tunnel. A disposal hole for high-level radioactive waste is formed on the storage floor, and a large-scale geological disposal of high-level radioactive waste can be realized.

  Moreover, the construction method of the underground storage facility of the radioactive waste according to claim 8 of the present invention is a method in which a cement crystal growth agent is applied to the inner wall surface of the segment in the primary lining and densification treatment is performed. Increases the robustness and waterproofness of the lining.

  The configuration of the present invention is as described above, and a large-capacity underground disposal space for burying radioactive waste can be easily constructed.

The whole explanatory view of the underground storage facility of the embodiment of the present invention. FIG. The perspective view of the segment used for the disposal tunnel. Sectional drawing of the disposal tunnel. The aa sectional view taken on the line. Explanatory drawing of the storage example.

  Next, an embodiment (construction method) of the present invention will be described in the order of the steps. The construction of the underground storage facility for radioactive waste shown in the embodiment is constructed in a predetermined facility construction area, and the vertical interval is about several hundred to 2 km according to the topography and ground conditions of the construction area. A shaft position is set in the inside, and a plurality of shafts 1 are formed by excavation.

  As for the shaft 1, the excavation depth of the shaft is determined by the geological disposal of the waste of high-level radioactive waste or the marginal depth disposal of the waste of low-level radioactive waste having a relatively high radioactivity level. In the former case, the depth is usually 300 m or more, and in the latter case, the depth is 50 to 100 m.

  Moreover, the diameter of the shaft 1 is about 40 m, and the excavator 3 for excavating the disposal tunnel 2 can be disposed on the shaft bottom and can be started.

  When the construction of the shaft 1 is completed, the disposal tunnel 2 having a drilling diameter of about 16 m is constructed. The tunnel excavation employs a well-known shield method composed of a combination of the excavator 3 and the segment 21 used for the primary lining, The excavator 3 is selected according to the formation state, such as a sealed type, an open type, and a closed / open switching type.

  The segment 21 used for the tunnel formation of the disposal mine tunnel 2 is a concrete segment, and in particular, the segment 21 includes a segment joint 211 for potato splicing, a transmission strip 212 that is a connecting means in the tunnel direction, and a HOZO 213. In addition, the inner and outer double sealing material 214 is mounted on the entire periphery of the end surface. The sealing material 214 is of a high-performance anchor type having an anchor portion that bites into the segment body 21. Further, a cement crystal growth agent is applied on the inner surface side of the tunnel of the segment 21 and subjected to a densification treatment, thereby improving the water shielding performance in the primary lining described later.

  Thus, excavation is performed from the vertical shaft 1 to the other vertical shaft 1 by a known shield method in the lateral direction (not necessarily horizontal) with respect to the rock A.

  That is, as the excavator 3 moves forward, the segment 21 is assembled with the potato joint and lining is performed. In particular, the lining by the segment 21 is a primary lining, and the water shielding layer 22 is formed on the inner wall surface of the primary lining by the segment 21. The water shielding layer 22 is formed by continuously forming a water shielding sheet made of a high density polyethylene sheet by thermal welding. Further, a secondary lining 23 made of concrete is applied to the inner wall surface of the water shielding layer 22. This triple complete water-blocking structure realizes underground construction of disposal space (disposal tunnel) that does not cause groundwater contamination.

  After the secondary lining 23 is completed, the disposal mine 2 is a primary lining by a densified segment 21 assembled into a water-blocking structure with a rock mass A, a backfill material B, and a double seal material 214, and a water-blocking sheet By providing the triple water-impervious cross-sectional structure of the water-impervious layer 22 and the secondary lining 23, the disposal tunnel 2 becomes a disposal space 24 having a completely impermeable structure. This completely impermeable disposal tunnel 2 is constructed with a large number of connections between the vertical shafts 1, and is a radioactive waste with a wide disposal space that is constructed according to the topography and ground conditions within the range of a predetermined facility construction area The entire basic structure of the underground storage facility of (Waste Body C) is completed.

  In order to make the plurality of vertical shafts 1 and disposal tunnels 2 concrete storage facilities, the disposal tunnel 2 has a large diameter of about 16 m. Therefore, in order to efficiently store waste, the disposal tunnel 2 The concrete floor 25 and the column 26 are built inside, and the inside of the disposal tunnel 2 is made into a multi-layered structure (for example, a three-story structure).

  Further, the vertical shaft 1 is equipped with various equipment necessary for carrying in the waste C, such as an elevator, and the disposal mine 2 is equipped with an unmanned transport cart D, or appropriate so that unmanned carry-in and storage management is possible. An automatic carry-in device and a monitoring device are provided as necessary.

  Further, in the case of low-level radioactive waste having a relatively high radioactivity level, the disposal tunnel 2 itself has a completely water-impervious structure, so that it can be stacked and stored on the floor surface of each floor as it is. However, in the case of storage of high-level radioactive waste (canister) C, accumulation storage is difficult, so the concrete floor 25 of each floor of the disposal tunnel 2 has a predetermined thickness with an appropriate cushioning material such as clay. The storage floor 27 is formed and a large number of disposal holes 28 are provided, and the high-level radioactive waste C is stored and stored in the disposal holes 28.

1 shaft 2 disposal tunnel 21 segment (primary lining)
211 Segment joint 212 Transmission strip 213 Hozo 214 Sealing material 22 Water shielding layer 23 Secondary lining 24 Disposal space 25 Concrete floor surface 26 Column 27 Storage floor surface 28 Disposal hole 3 Excavator A Rock bed B Backfill material C Waste body D Unmanned Transport cart

The radioactive waste underground storage facility according to claim 1 of the present invention is constructed at an appropriate distance in the facility construction area and has a plurality of diameters capable of arranging the excavator used in the shield method . A primary lining of a water-blocking structure with a concrete segment that is branched from each shaft so as to connect the vertical shafts to each of the vertical shafts, and is provided with a water sealing material around the entire end surface, and the inner wall surface of the primary lining. A water-impervious layer formed of a water sheet, and a plurality of disposal tunnels equipped with a disposal space having a triple water-impervious structure by secondary lining with concrete inside the water-impervious layer. It is.

The method of constructing an underground storage facility for radioactive waste according to Claim 4 of the present invention, a plurality facility building area until the vertical shaft a predetermined depth of apart an appropriate distance predetermined drilling device positionable diameter When a large number of disposal mine shafts are branched from each shaft so as to connect between the shafts and are constructed by shield excavation by machine excavation and assembling of concrete segments, a water-stop seal is provided around the entire end surface of the segments. The material is attached to perform a primary lining of the water-blocking structure, a water-blocking layer is formed on the inner wall surface of the primary lining by a heat-shielding sheet that is continuous by thermal welding, and a concrete-coated layer is formed inside the water-blocking layer. A secondary lining is performed to form a triple-structured disposal space that completely blocks water leakage from the disposal tunnel and inundation into the disposal tunnel .

Further, the present invention forms a plurality of shafts constructed at an appropriate distance in the facility construction area, and forms disposal tunnels provided so as to connect the respective shafts. By setting up the shaft position according to the topography and ground conditions in the range, and constructing multiple disposal tunnels connecting between them, it is easy to simultaneously construct multiple disposal tunnels and efficiently construct a wide disposal space It can be carried out.

Further, the radioactive waste underground storage facility and the construction method thereof according to claims 2 and 5 of the present invention, in particular, in the underground storage facility and construction method thereof, in particular, the shaft diameter is about 40 m and the disposal tunnel diameter is about 16 m. The disposal tunnel has a multi-layered structure, and it is possible to perform full automation of waste storage work, such as carrying in radioactive waste, for each level, realizing efficient storage work. it can.

Further, the radioactive waste underground storage facility according to claim 3 of the present invention is formed to have a predetermined thickness with an appropriate cushioning material on each floor of the disposal tunnel, particularly when a multi-level structure is adopted for the disposal tunnel. A disposal hole for high-level radioactive waste is formed on the storage floor, and a large-scale geological disposal of high-level radioactive waste can be realized.

Further, the radioactive waste underground storage facility and the construction method thereof according to claims 2 and 5 of the present invention, in particular, in the underground storage facility and construction method thereof, in particular, the shaft diameter is about 40 m and the disposal tunnel diameter is about 16 m. The disposal tunnel has a multi-level structure, and it is possible to perform full automation of waste storage work such as carrying in radioactive waste for each level, thus realizing efficient storage work. .

Claims (8)

  Within the facility construction area, a shaft with a diameter where a predetermined excavator can be placed, and several concrete branches from the shaft in an appropriate direction, and a concrete segment with a water sealant around the entire end surface. Primary lining of the structure, a water shielding layer formed of a water shielding sheet on the inner wall surface of the primary lining, and a disposal space having a triple completely water shielding structure by secondary lining with concrete inside the water shielding layer An underground storage facility for radioactive waste, characterized by comprising a disposal tunnel comprising   The underground storage facility for radioactive waste according to claim 1, comprising a plurality of vertical shafts constructed at an appropriate distance in a facility construction area, and a plurality of disposal shafts provided so as to connect the vertical shafts.   The underground storage facility for radioactive waste according to claim 1 or 2, wherein the shaft diameter is about 40 m, the disposal tunnel diameter is about 16 m, and the disposal tunnel has a multi-layered structure.   The radioactive waste according to claim 3, wherein a disposal hole for high-level radioactive waste is formed on each floor of the disposal gallery having a multi-layered structure on a storage floor surface having a predetermined thickness with an appropriate cushioning material. Underground storage facility.   In the facility construction area, a shaft with a diameter capable of placing a predetermined excavator is formed to a predetermined depth, and when constructing a disposal tunnel from the shaft using a shield excavation method by machine excavation and assembly of a concrete segment, A water-blocking structure is primary-covered by attaching a water-proof seal material to the entire circumference of the end surface in advance, and a water-blocking layer is formed on the inner wall surface of the primary lining by a heat-shielding sheet that is continuous by thermal welding. A method for constructing an underground storage facility for radioactive waste, characterized in that a secondary lining with concrete is carried out inside the water layer to form a triple completely impermeable disposal space.   The underground storage facility for radioactive waste according to claim 5, wherein a plurality of shafts constructed at an appropriate distance in the facility construction area are formed, and a disposal tunnel provided so as to connect the shafts is formed. Construction method.   The method for constructing an underground storage facility for radioactive waste according to claim 5 or 6, wherein the shaft diameter is about 40 m, the disposal tunnel diameter is about 16 m, and the disposal tunnel has a multi-level structure.   The construction method of the underground storage facility of the radioactive waste in any one of Claim 5 thru | or 7 which apply | coats a cement crystal growth agent to the inner wall surface of the segment in a primary lining, and performs the densification process.

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