JPH0582915B2 - - Google Patents

Description

[Detailed description of the invention] [Technical field to which the invention pertains]

The present invention relates to a seal structure for a sealed can that houses spent fuel bodies carried out from a nuclear reactor together with a cooling medium, and then immerses the spent fuel bodies in a spent fuel storage pool for cooling storage.

[Prior art and its problems]

As is well known, spent fuel bodies removed from the inside of a nuclear reactor are cleaned and then stored in a sealed can with a highly heat conductive cooling medium such as water or helium gas to ensure that the decay heat level of the fuel body is safe. Spent fuel is immersed in a spent fuel storage pool and kept cool for a long period of time until the level has dropped to a low level. Further, the sealed can used in this case is required to have high sealing performance in order to prevent leakage of the radioactive gas sealed therein. Here, the general structure of the above-mentioned sealed can is shown in the third section.
As shown in the figure, 1 is a can container with a bottom, 2 is a stopper lid that seals the opening surface of the can container 1, and 3 is a connection between the flange 1a of the can container 1 and the flange 2a of the stopper lid 2. A ring-shaped metal sealing material 4 is interposed between the overlapping surfaces, and is a tightening bolt that fastens between the flanges 1a and 2a. Cooling medium 6
By attaching the stopper lid 2 to the can container 1 and fastening it with bolts after accommodating the can container 1, the metal sealing material 3 comes into pressure contact with the flange surface to form an airtight boundary between the can container 1 and the stopper lid 2. It is sealed. Note that 7 is a leak check port opened on the flange surface to check the sealing performance of the metal seal material 3 after sealing, 8 is a rubber seal that seals the outer periphery of the open end of the leak check port, and 2b is a plug in the center of the lid. It is a handling head formed on the body. By the way, such a sealed can is carried into the canning facility from the storage standby area with the stopper lid 2 temporarily attached to the can container 1. Here, the stopper lid 2 is temporarily removed by remote control and the spent fuel is placed inside the can container. 5. Cooling medium 6
After accommodating the bottle, the bottle cap 2 is attached again and the bottle is sealed.
In this state, a leak check is performed to confirm the sealing properties of the metal seal material 3. In this case, the ring-shaped metal sealing material 3 described above is relatively easy to deform, and in order to closely adhere to the flange surface in a sealed state and exhibit high sealing performance, the metal sealing material 3 is attached to the lid 2.
It is necessary to hold it in the correct position so that it does not shift or fall off when attaching or detaching it. In response to such requirements, the conventional seal structure of a sealed can was constructed as shown in FIG. That is, the metal sealing material 3 interposed between the overlapping surfaces of the flange 1a of the can container 1 and the flange 2a of the stopper lid 2 is arranged parallel to the outer peripheral side of the sealing material 3 and interposed between the flanges 1a and 2a. The seal presser member 9 is guided and held in a predetermined position by a ring-shaped seal presser member 9, and the seal presser member 9 is fixedly supported by being screwed to the flange surface of the stopper lid 2 with set screws 10 at several locations on its circumference. There is. However, the conventional seal structure described above has the following drawbacks. That is, (1) High precision is required for the tapping position of the set screw 10 that fixes the seal presser member 9, which makes positioning difficult for the tapping process, and furthermore, there is a large amount of play between the seal presser member 9 and the set screw 10. In addition, accurate positioning of the seal presser member 9 becomes difficult. (2) Since the seal presser member 9 is arranged parallel to the outer circumferential side of the metal seal material 3 and interposed between the flanges 1a and 2a, the rubber seals 8a and 8b necessary for leak checking can be attached to the seal presser member 9. In addition, in order to install the rubber seals 8a and 8b, dovetail-shaped circumferential grooves must be formed on the flanges 1a and 1b, respectively, which is difficult to process. . (3) Metal sealing material 3 subject to leak check
On the other hand, since rubber seals are installed at two locations on the outer circumference side, the number of leakage paths for outside air increases accordingly, and the measurement accuracy of the leak check decreases.

[Object of the Invention] The present invention has been made in consideration of the above points, and it solves the difficulties of the conventional structure described above, simplifies the structure, and provides a seal that achieves high reliability due to sealing performance. The purpose is to provide a sealing structure for cans.

[Key points of the invention]

In order to achieve the above object, the present invention disposes a seal presser member on the inner circumferential side of a metal sealing material, and fits and supports the seal presser member on the circumferential surface of the stopper lid, thereby creating a seal. In addition to improving the positioning accuracy of the holding member, it is possible to simplify the structure and improve the leak check measurement accuracy by installing only one rubber seal for leak check.

[Embodiments of the invention]

FIG. 1 shows a sectional view of a seal structure according to an embodiment of the present invention, and the same members corresponding to FIGS. 2 and 3 are given the same reference numerals. That is, according to the present invention, the sealing material 3 is positioned at a predetermined position with respect to the ring-shaped metal sealing material 3 interposed between the overlapping surface between the flange 1a of the can container 1 and the flange 2a of the stopper lid 2. A seal pressing member 9 for holding the seal member 3 is disposed on the inner peripheral side of the seal material 3,
At this position, it is fitted and supported on the outer periphery of the stopper lid 2, particularly the stopper body portion forming the handling head 2b. Further, the seal holding member 9 includes a presser metal fitting 11 which also serves as a stopper cover guide and which is attached to the outer periphery of the stopper body of the stopper lid 2 and fixed with a set screw 10.
It is clamped and fixed between the flange 2a. On the other hand, a rubber seal 8 for leak checking is located on the outer peripheral side of the metal sealing material 3 and is installed in a mounting groove 1c formed on the flange surface of the stopper lid 2. Note that the mounting groove 1c is formed so that one side of its cross-sectional shape forms a right angle to facilitate cutting of the groove. According to the above structure, first, the seal presser member 9 is attached to the central stopper part of the stopper lid in a fitting manner, so that assembly is easy and the metal sealing member 3 is positioned at a predetermined position with high positioning accuracy. be able to hold it. In addition, since the seal holding member 9 is placed on the inner circumferential side of the metal sealing material 3, the rubber seal 8 required for leak checking can be installed in one place instead of the need to provide it in two places as in the conventional structure shown in Fig. 2. This improves the measurement accuracy of the leak check for checking the sealing performance of the metal seal material 3, and simplifies the seal structure including the processing of the rubber seal mounting groove.

【Effect of the invention】

As described above, according to the present invention, the seal pressing member is disposed on the inner peripheral side of the metal sealing material, and the seal pressing member is fitted and supported on the circumferential surface of the stopper lid. In addition to improving the positioning accuracy of the seal material and the reliability of the seal, compared to conventional seal structures, the rubber seal required for leak check only needs to be installed in one place, simplifying the structure and manufacturing cost, including the machining of the mounting groove. This provides advantages such as a reduction in

[Brief explanation of the drawing]

1 and 2 are sectional views of an embodiment of the present invention and a conventional seal structure, respectively, and FIG. 3 is a sectional view showing the overall structure of a sealed can for a spent fuel body. In each figure, 1... can container, 2... stopper lid,
1a, 1b...flange, 3...metal sealing material,
4... Tightening bolt, 5... Spent fuel body, 6...
Cooling medium, 8... Rubber seal for leak check, 9... Seal holding member, 11... Holding fitting.

Claims (1)

[Scope of Claims] 1. Consisting of a bottomed flanged can container for accommodating spent fuel bodies carried out from a nuclear reactor, and a flanged cap lid for sealing the opening surface of the can container, the can A ring-shaped metal sealing material is interposed between the overlapping surfaces of the flanges of the container and the cap lid, and the metal sealing material is held in a predetermined position by a seal presser, and then the can container and the cap lid are bolted together to form a can. The container is sealed with a stopper lid, characterized in that the seal pressing member is disposed on the inner circumferential side of the metal sealing material, and the seal pressing member is fitted and supported on the circumferential surface of the stopper lid. Seal structure of a sealed can for spent fuel bodies. 2. In the seal structure as set forth in claim 1, it is noted that the seal presser member is clamped and fixed between the presser metal fitting that is attached to the circumferential surface of the stopper lid and that also serves as a stopper lid guide, and the flange of the stopper lid. Features a seal structure for sealed cans for spent fuel bodies.