JPH059680Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a support structure for a storage pit for storing radioactive waste, and in particular is an earthquake-resistant structure that takes into account heat countermeasures for the high-temperature waste being stored. This invention relates to a support structure for a storage pit.

[Prior Art] Spent fuel from a nuclear reactor is processed at a nuclear fuel reprocessing plant and stored in packages, which are stored in radiation-shielding storage cells. Specifically, as shown in FIG. 9, the package a is housed using a crane or the like in a cylindrical storage pit c that is set up in a storage cell b formed with a concrete wall in the ground. They are stored in sequential stacks.

As shown in FIGS. 9 and 10, the storage pit c is horizontally surrounded and supported by a parallel cross structure e made up of support beams d.
are arranged in multiple stages above and below. The seismic resistance in the vertical and horizontal directions is determined by the support beams d
had everything.

[Problems to be solved by the invention] In the past, since the support beam d was responsible for earthquake resistance in both the vertical and horizontal directions, the number of members was large and the weight of each member was also considerably heavy. There was a problem that the number of manufacturing steps increased and the material cost increased.

In addition, storage pit c has a high temperature due to the generation of heat from the radioactive waste stored therein.
Thermal expansion. Therefore, when supporting the storage pit c,
Careless support would generate considerable thermal stress, which was a problem in terms of ensuring structural integrity.

[Purpose of the invention] This invention was devised in view of the above-mentioned problems, and its purpose is to create a support structure for earthquake-resistant storage pits that is lightweight and inexpensive, while taking heat measures against high-temperature radioactive waste. is to provide.

[Summary of the invention] The present invention consists of a storage pit that is suspended from the ceiling of a storage cell, and whose heat dissipation temperature is gradually lowered from above to below; A sleeve-shaped protection pit that forms a cooling space is placed between the protection pit and the side wall of the storage cell in the lower half of the storage pit. It comprises a support plate for supporting these pits at two points against external forces, a support bracket for supporting the protection pits on the support plate, and a stiffening structure for reinforcing the support plate.

[Embodiment] A preferred embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

As shown in FIGS. 1 to 4, a rectangular parallelepiped storage cell 1 is formed underground or elsewhere with a concrete wall that shields radiation. Ceiling part 1a of this storage cell 1
A large number of through-holes 2 having support step portions 2a are bored in the through-holes 2, and storage pits 3 are inserted into these through-holes 2. The upper part of the storage pit 3 is the supporting stage 2.
a and is suspended into the cell 1 from the ceiling portion 1a. This storage pit 3 is formed into an elongated, low-profile cylinder shape, and inside it, packages 4 containing radioactive waste are stacked one after another and stored.

This storage pit 3 is provided with a sleeve-shaped protective pit 5 that surrounds the storage pit 3 along its longitudinal direction and at intervals radially outward.
A support plate 6 is horizontally spanned between the protection pit 5 and the side wall portion 1b of the storage cell 1 so as to divide the interior of the cell 1 into upper and lower sections. This support plate 6 is perforated to allow the protection pit 5 to pass therethrough, and is formed so as to surround the protection pit 5 in the horizontal direction. In particular, the support plate 6 is connected to the storage pit 3.
Two pieces are disposed one above the other in the lower half of the body, and are configured to support both the outer protection pit 5 and the inner storage pit 3 at two points against horizontal external forces such as seismic force. Further, on the outside of the storage pit 3, a spacer 7 is arranged in close contact with the inner surface of the protection pit 5 at a point supported at two points.

The support plate 6 configured in this way has a first
As shown in FIGS. 6 to 6, a stiffening structure 8 for reinforcing this is provided. Specifically, stiffening structure 8
is composed of a plurality of I-shaped beams 9 arranged along the width direction of the support plate between the protection pits 5. Furthermore, a support bracket 10 is provided between these I-shaped beams 9 and the protection pit 5 in a direction perpendicular to the beams 9, and these support brackets 10
is constructed so as to transmit vertical force such as the weight of the protection pit to the support plate 6 so as to be supported by the support plate 6.

By the way, regarding the support structure of the storage pit constructed as described above, first of all, the following can be said as a countermeasure against heat.

Since the radioactive waste stored in the storage pit 3 generates heat, the atmosphere around the storage pit 3 is at a high temperature. A rise in ambient temperature can be suppressed by providing protective pits 5 surrounding the storage pits 3 at intervals to form a cooling space S that performs cooling by natural convection of air between the storage pits 3. . This can reduce adverse thermal effects on the structural members. Further, due to such a cooling space S, the storage pit 3 has a temperature distribution T in which the heat radiation temperature gradually decreases from the top to the bottom, as shown in FIG. Therefore, although the storage pit 3 undergoes considerable thermal expansion due to the presence of the cooling space S, the storage pit 3 is simply suspended from the ceiling 1a, and therefore almost no thermal stress occurs and the pit structure is Soundness is maintained. On the other hand, the protective pit 5 also expands at ambient temperature. On the other hand, since the protection pit 5 is supported by the lower half of the storage pit 3 where the temperature difference is relatively small, the thermal stress caused by restraint due to the support can be suppressed as much as possible. Further, the upper portion of the protective pit 5, where the temperature difference is relatively large and the strain is large, is unsupported and unrestrained, and almost no thermal stress is generated. Therefore, the structural integrity of the protective pit 5 can also be ensured.

As described above, the seismic support structure for the storage pit has heat countermeasures for the main components, and the flat support plate 6 effectively supports the pits 3 and 5 even when horizontal external forces such as seismic forces act from any direction. can support. In particular, as shown in FIG. 8, two-point support is provided at the bottom end of the protection pit 5 and the upper part of the lower half of the storage pit 3, which is set based on heat countermeasures, so that vibration modes such as those shown in the figure can be avoided. On the other hand, it can be supported while suppressing the generated stress. Furthermore, support at the lowest end is advantageous in terms of earthquake resistance.

Furthermore, since the protective pit 5 is supported by the support plate 6 via the beam 9 by the support bracket 10, the vertical force such as the weight of the pit itself can be dispersed and transmitted to the support plate 6, and the required strength of the plate 6 can be reduced. .

In addition, by adopting the support plate 6, the number of members for supporting horizontal external forces can be significantly reduced, and the combination of the plate 6, bracket 10, and beam 9 achieves strength while reducing the weight of each individual member. Therefore, it is possible to reduce production man-hours and costs.

Note that the support plate 6 can also be used as a mounting base for a heat insulating material. In addition, 11 is a seal lid, 1
2 is a shielding plug. Further, a flange portion 5a is formed at the upper end of the protection pit 5, and a shielding plate 13 is placed on these flange portions 5a so as to span between them.

[Effects of the Invention] In summary, the present invention provides the following excellent effects.

(1) By creating a cooling space using protective pits and reducing thermal stress by using a support structure that responds to temperature distribution, adverse thermal effects on the structure can be suppressed and the soundness of the seismic support structure can be improved.

(2) Since the horizontal external force is supported by the support plate, the number of parts can be significantly reduced, and the number of manufacturing steps can be reduced.

(3) Since it is composed of a combination of a support plate, a support bracket, and a stiffened structure, the weight of each structural member can be reduced, material costs can be reduced, and construction can be made at low cost.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a preferred embodiment of the present invention;
FIG. 2 is a side sectional view thereof, FIG. 3 is a plan sectional view thereof, FIG. 4 is an enlarged side sectional view of the storage pit, FIG. 5 is a sectional view taken along the line - in FIG. 4 is a sectional view taken along the - line, and FIG. 7 is a graph showing the atmospheric temperature distribution around the storage pit.
FIG. 8 is a schematic view showing the basic vibration modes of the storage pit and the protection pit, and FIGS. 9 and 10 are a side sectional view and an enlarged plan view of the main parts showing a conventional example. In the figure, 1 is a storage cell, 1a is its ceiling, 1b
3 is a storage pit, 5 is a protection pit, 6 is a support plate, 8 is a stiffening structure, 10 is a support bracket, and S is a cooling space.

Claims (1)

[Scope of utility model registration request] A storage pit is suspended from the ceiling of the storage cell and the heat radiation temperature is gradually lowered from above to below, and a sleeve-shaped sleeve is provided surrounding the storage pit to form a cooling space between them. Between the protection pit and the side wall of the storage cell in the lower half of the storage pit, two plates are placed between the protection pit and the side wall of the storage cell, surrounding the protection pit from the horizontal direction, and extending over and under against horizontal external forces. A storage device comprising: a support plate for supporting the pits at two points; a support bracket for supporting the protection pits on the support plate; and a stiffening structure for reinforcing the support plates. Pit support structure.