JPH11295490A - Facility for storage of radioactive material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain the performance of heat removal and increase the storage capacity by minimizing the rise of construction costs in a facility for the dry storage of spent fuels and the like. SOLUTION: A facility 26 for the dry storage of radioactive material has the structure where an air outlet 31 and an air exhaust passage 27 formed like a stack communicating with the outlet 31 are located in the center, storage chambers 29 are formed under the surface of the earth communicating to the outlet 31 and the passages 27 and air inlets 35 opening in the air and air ducts 33 are placed on both sides symmetrically. Then the ceiling floors of the storage chambers 29 equipped with shield lids 37 that can be freely removed and attached are straddled by gate-type travelling cranes 39 located on the ground, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a facility for storing exothermic radioactive substances or objects, such as so-called spent fuel, which has been burned in a nuclear reactor, and in particular, uses air as a cooling medium. To dry storage facilities.

[0002]

2. Description of the Related Art Spent fuel removed from a nuclear reactor, such as a light water reactor, continues to emit intense radiation and significant decay heat, and is therefore stored or stored in the water of a cooling pool, commonly referred to as a spent fuel pool. When the levels of the radioactivity and the calorific value reach a predetermined value or less, they are sent to a nuclear fuel reprocessing facility for processing. However, dry spent fuel storage equipment that does not use water as a cooling medium has recently attracted attention because of its low construction cost. Due to the nature of such dry spent fuel storage equipment, cooling performance and radiation confinement function that remove decay heat and keep the temperature below an allowable value are required, and low cost of construction and operation is low. Considered. FIG. 2 conceptually shows the structure of a typical typical dry storage facility that has been conventionally proposed.

Referring to FIG. 2, the structure of a spent fuel storage facility 1 will be outlined. A concrete frame 7 is formed so that a storage chamber 3 for storing a spent fuel storage container C is located below the ground surface 5. Have been. Concrete skeleton 7
A ventilation path 9 communicating with the storage chamber 3 is formed at one end side of the storage chamber 3 and opens to the atmosphere through an air intake 11 above the ground surface 5. A chimney-shaped exhaust passage 13 communicating with the storage chamber 3 is formed on the other end side of the concrete body 7,
The uppermost air outlet 15 communicates with the atmosphere. An entrance / exit 19 to which a detachable shielding lid 17 is attached is formed in the ceiling of the storage chamber 3, and a portal crane 18 is provided across the upper part thereof. In the figure, one spent fuel storage container C is shown in a suspended state, but the spent fuel storage container C is put in and out of the storage chamber 3 in such a manner. The spent fuel storage container C in the storage chamber 3 dissipates the decay heat of the spent fuel and warms the surrounding air. The warmed air flows through the chimney-shaped exhaust passage 13 and flows out of the air from the air outlet 15 into the atmosphere. By this chimney effect, relatively low-temperature air is sucked from the air intake 11 through the ventilation passage 9, Natural convection of air occurs. In short, the spent fuel storage container C is thermally cooled by the natural convection air.

[0004]

Since the dry spent fuel storage facility 1 as described above utilizes natural convection to drive the cooling air, it does not require the driving power of the cooling medium and is further discharged. Since soil is used to shield radiation, the thickness of the concrete frame can be reduced, and the construction and operation costs can be kept low. However, when increasing the capacity of the storage facility for storing the spent fuel storage container, if the distance between the ventilation path and the chimney-shaped exhaust path is increased, the ventilation resistance of natural convection increases, and the cooling performance is reduced. The capacity cannot be increased. Therefore, an object of the present invention is to provide a storage facility capable of accommodating a large amount of radioactive material while maintaining the advantages of low construction cost and operation cost.

[0005]

According to the present invention, there is provided, in accordance with the present invention, an air inlet and an air outlet which are open to the atmosphere and a storage chamber which communicates therewith and is formed below the ground surface. In the radioactive material storage facility whose main component is an air outlet and a chimney-shaped exhaust passage communicating with it, the two storage chambers and the air intake are symmetrical with the chimney-shaped exhaust passage interposed. It is arranged and configured. Then, a portal traveling crane for handling radioactive materials is disposed on the ground, each straddling the ceiling floor of the storage chamber provided with a detachable shielding lid.

[0006]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Referring to FIG. 1, a storage building 21 of a dry storage facility 20 is constructed on the ground excavated from the ground surface 5 to a predetermined depth. Backfilled. A chimney-shaped exhaust passage 27 is formed substantially at the center of the storage building 21, and two storage chambers 29 communicate with each other from opposite directions. That is, two storage chambers 29 defined below the ground surface 5 by the concrete skeleton 25 are disposed symmetrically with respect to the chimney-shaped exhaust passage 27. The uppermost part of the chimney-shaped exhaust passage 27 is open to the atmosphere via an air outlet 31. A ventilation path 33 communicating with the storage chamber 29 on the opposite side of the chimney-shaped exhaust path 27 extends in the vertical direction, and is open to the atmosphere through an air inlet 35 above the ground surface 5. Further, an access hole through which a shielding cover 37 is attachable is formed on the ceiling floor of the storage chamber 29, so that the spent fuel storage container C can be put in and out of the storage chamber 29. The spent fuel container C is stored in the storage chamber 2
9 may be placed directly on the bottom surface, or may be suspended and placed on a mounting cart that is movable in a direction perpendicular to the plane of the drawing.

The procedure for carrying the spent fuel storage container C into the storage chamber 29 in the dry storage facility 20 having the above-described configuration will be described. A spent fuel storage container C is lifted from a transport vehicle such as a trailer (not shown) by a portal traveling crane 39, and the spent fuel storage container C is moved to an access hole from which a shielding cover 7 has been removed in advance. As shown in the figure. If there is a concern about excessive emission of radiation from the storage chamber 29, the spent fuel container C
The shield cover 37 may be removed after the is carried right above the entrance. Thereafter, the spent fuel storage container C is suspended and stored in the storage chamber 29. When this is completed, the access hole is closed by the shielding cover 37. On the other hand, when unloading the spent fuel storage container C, the above-described procedure is performed backward. Thus, the spent fuel storage container C accommodated in the storage chamber 29 dissipates the decay heat of the spent fuel and warms the surrounding air in the storage chamber 29. The warmed air has a reduced density due to expansion, flows into the chimney-shaped exhaust passage 27 from both sides as indicated by arrows, flows upward there, and flows out from the air outlet 15 into the atmosphere. Due to the chimney effect of the upward flow of air, relatively cool air is sucked from the two air intakes 35 through the ventilation passage 33, and thus natural convection of air occurs. Therefore, the spent fuel storage container C and the spent fuel in the inside are kept at an appropriate temperature by the natural convection flow of the air as described above. And
As described above, the warm air flowing into the chimney-shaped exhaust passage 27 from both sides flows without collision. Also, the spent fuel storage container C
Is appropriately shielded by the concrete skeleton 25, the surrounding soil layer, and the ceiling floor.

[0008]

As described above, according to the present invention,
Since the chimney-shaped ventilation passage is shared, the side walls required for individually forming the storage chambers can be omitted, so that the necessary materials are reduced and the construction cost per unit is reduced. In addition, since the distance between the air inlet and the air outlet does not change, the ventilation resistance against natural convection of the cooling air does not change, and the cooling performance is well maintained.

[Brief description of the drawings]

FIG. 1 is a sectional elevational view conceptually showing the overall structure of an embodiment of the present invention.

FIG. 2 is a vertical sectional view showing a storage facility having a conventional structure.

[Explanation of symbols]

 REFERENCE SIGNS LIST 20 Dry storage facility 21 Building 25 Concrete frame 27 Exhaust passage 29 Storage chamber 31 Air outlet 33 Ventilation passage 35 Air intake 37 Shield lid 39 Portal traveling crane

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Takeshi Yokoyama 1-1-1 Wadazakicho, Hyogo-ku, Kobe-shi, Hyogo Prefecture Inside Kobe Shipyard of Mitsubishi Heavy Industries, Ltd.

Claims (1)

[Claims] 1. A storage container mounted on a floor for storing a radioactive substance, which is cooled by introducing air from an air intake, and discharging the cooled air from an exhaust port. Using a traveling crane installed on the ceiling floor upper surface, taking in and out of the facility through the opening provided in the ceiling floor, in a radioactive material storage facility, the air intake in the traveling direction of the traveling crane A plurality of radioactive substance storage facilities, wherein the air outlet is arranged between the adjacent air intakes, and the crane is installed between the air intake and the air outlet.