JPS5935191A - Fuel transporting pipe - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is characterized in that materials having a radiation shielding effect such as lead and iron are integrated in advance into the main body of the fuel transfer pipe that transfers spent fuel from a nuclear reactor etc. from a containment vessel to a spent fuel pit. This installation relates to fuel transfer pipes intended to protect against leakage radiation.

Conventionally, this type of fuel transfer pipe 1 has a cavity 2 in the containment vessel and a cavity 3 on the spent fuel bit side in the peripheral auxiliary equipment building, as shown in the example of a nuclear power plant having a steel containment vessel in Fig. 1. When loading nuclear fuel into a nuclear reactor or discharging spent fuel, nuclear fuel assemblies are transferred throughout the fuel transfer pipe 1.

Between the cavity 2 in the containment vessel and the spent fuel bit side cavity 3, a secondary shielding wall 4, a steel plate 5 for the containment vessel,
There is an external shielding wall 6 and a peripheral auxiliary line concrete floor 7, a gap 8 between the steel plate 5 and the primary shielding wall 4, a gap 9 between the steel plate 5 and the external shielding wall 6, and an external shielding wall 6. There is a gap 1o between the peripheral auxiliary equipment line and the concrete floor 7. These gaps 8.9.1 (1: h) are about 5 to 103, but when the nuclear fuel assembly passes through the fuel transfer pipe main body la during fuel transfer, Since radiation leaks through all of these gaps to the upper operation floor 11, there are problems such as workers being exposed to radiation.

Therefore, measures have been taken to reduce leakage radiation, such as filling the gaps with shielding material.
This gap fluctuates due to the vibration of concrete walls during earthquakes, etc., so there are problems such as the need to use elastic materials as shielding materials, and the materials are extremely expensive. Ta.

In the figure, 12, 13, and 14 are sleeves that support and fix the fuel transfer pipe main body 1at and also function as a pressure boundary.

The present invention has been made in view of the above-mentioned circumstances, and the present invention is made by directly wrapping a radiation shielding material around the main body of the fuel transfer pipe, or by forming a U-shaped VC and covering it from above. What do you mean by totally attenuating leakage radiation based on the principle of shielding as close to the radiation source as possible?
The objective is to provide a fuel transfer pipe for this purpose.

Hereinafter, embodiments according to the present invention will be explained in detail based on FIGS. 2 and 3. In the figure, are the parts corresponding to the conventional structure the same symbols? The explanation will be omitted.

A radiation shield 15 is installed around the outer periphery of the fuel transfer pipe main body 1a in the vicinity of the penetration part of the fuel transfer pipe 1 through the containment vessel steel plate 50 and in an area that sufficiently covers the gap between the peripheral auxiliary equipment line concrete floor 7 and the external shielding wall 6. It is configured to be fully installed.

The radiation shield 15 is made of steel, lead, or a material with an equivalent radiation shielding effect, and the thickness of the radiation shield 15 is set as appropriate depending on the conditions of the intended installation location. Fig. 2 is a sectional view showing the state in which the radiation shield 15 is attached inside the sleeves 12.13 and 14, etc., but if there is space, the sleeves 12.13, etc.
, and 14, or may be modified by using both the inside and outside.

FIG. 3 is a perspective view of the main parts of an embodiment of the pond according to the present invention, in which the radiation shielding f*15Th is formed into a U-shape, and the fuel transfer pipe main body 1a and the sleeves 12, 13 and 14 can be covered from above. May be installed.

Note that welding and gluing methods are available for attaching the radiation shield to the 15ft fuel transfer pipe or sleeve.

Therefore, in a fuel transfer pipe configured as described above, radiation leaking from spent fuel, etc. containing a large amount of radioactive materials, is absorbed by the steel or lead pipe in an area that sufficiently covers the gaps 8, 9, and 10 of the fuel transfer pipe. Since a radiation shield such as the one shown in FIG.

There is no need to fill the gap with an expensive shield as in the conventional method, and radiation protection can be provided at low cost.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a main part of a fuel transfer pipe having a steel containment vessel according to a conventional embodiment, FIG. 2 is a cross-sectional view of a main part of a fuel transfer pipe according to the present invention, and FIG. FIG. 2 is a perspective view of a fuel transfer pipe showing an embodiment of a pond. 1...Fuel transfer pipe, 1a...Fuel transfer pipe body, 2.
... Containment vessel internal cavity, 3... Spent fuel bit side cavity, 4... -Second shielding wall, 5... Containment vessel steel plate, 6... External shielding wall,
7...Auxiliary equipment line concrete floor, 8.9.10...Gap, 11...Operation floor surface, 12.13.14...Sleeve, 15...Radiation shielding body. Patent Applicant Mitsubishi Atomic Crab Industry Co., Ltd. Agent Patent Attorney Hide Sato 5-

Claims (1)

[Claims] A fuel transfer pipe for a nuclear power plant, characterized in that a radiation shield is attached to the outer periphery of the fuel transfer pipe.