JPS59137885A - Nuclear fuel assembly - 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 [Technical Field] The present invention relates to a structure of a nuclear fuel assembly that can be easily identified (rubbed) at the time of fuel exchange.

[Conventional technology and problems]

In nuclear reactors, fuel is replaced periodically, but
In order to identify the fuel body at the time of replacement (when manufacturing this fuel body, for example, in BWR fuel bodies, conventionally, the handle G of the upper tie plate is engraved with alphanumeric characters).

However, with the above method, when the vessel is loaded approximately 10 meters below the water surface, reading the inscription becomes extremely difficult. Therefore, people use binoculars or the like to magnify and read the image.

In addition, in the reactor secondary cooling water, crud is generated due to corrosion of the structural materials of equipment such as the main condenser and feedwater heater of the condensate water supply system during plant operation. This crud flows into the reactor during plant operation and adheres to the fuel assembly in significant amounts. Since the engraved part has a concave shape, the crud tends to clump together, which is one reason why it is difficult to read.

[Structure of the invention]

The present invention has been made in view of the above points, and its configuration will be explained based on the drawings.

FIG. 1 shows an upper tie plate 11, a handle portion 2. Lower tie plate 3. Spacer 4. A nuclear fuel assembly composed of fuel elements 5 and the like is shown.

FIG. 2 is a view of the nuclear fuel assembly shown in FIG. 1 viewed from above (main view A in FIG. 1), and 6 indicates the engraved surface.

FIG. 3 shows a vertical sectional view of the engraved portion on the upper surface of the handle according to an embodiment of the present invention. 7 indicates a recessed portion of the engraved portion, and the surface may be coated with a fluorescent substance or may be plated with metal. 8 indicates a transparent protective surface, which is made of a radiation-resistant material such as inorganic glass.

This protective surface has a structure that protrudes above the upper surface of the handle.

In FIG. 4, the transparent protective surface 8 of FIG. 3 is changed to a protective surface 9 with an acute angle.

As the fluorescent substance, metal sulfides such as zinc sulfide, which are generally used as luminous paints, are used.

These metal sulfides include zns, CdS and Ca
It is possible to use S.

Although the metal sulfide is poorly soluble in water and sublimable, both the melting point and the sublimation point are considerably higher than the reactor water temperature during reactor operation, M20C. However, it has the disadvantage that it hydrolyzes and generates hydrogen sulfide when it comes into contact with high-temperature water.

Therefore, a protective film is required to prevent water from coming into contact with the engraved surface coated with a fluorescent substance. This protective film needs to be transparent, heat resistant, and radiation resistant.

Therefore, inorganic glass such as silicate glass is used as the protective film. Further, the protective film has a structure in which it bulges out from the handle surface around the engraved portion. This is to reduce the amount of cladding adhering to the surface of the protective film.

The protective film is attached by making a cut in the engraved part so that it widens at the bottom, inserting the end of the protective film into the engraved part, and fixing it to the engraved part by dissolving the rear end.

Next, in the case of metal plating, metals having a different luster than the SUS member, such as hard chrome, nickel, and nickel chrome, are plated. However, during reactor operation, there is a risk that the plating may become oxidized or the cladding may adhere, making the markings unclear. Therefore, a protective film is required to protect the plated surface.

Therefore, an inorganic glass made of silicate glass is used as the protective film, and its structure and installation are the same as in the case of coating with a fluorescent substance.

(Effects of the Invention) The effects of the present invention are as follows: (1) By coating the engraved surface with a phosphor or plating with different gloss, the engraved characters can be easily read from a distance.

(2) By covering the coated or plated surface of the phosphor with a substance such as glass, chemical reactions between said surface and reactor water can be prevented. (3) Glass surfaces are cleaner than metal surfaces. Furthermore, since it is electrochemically inert and has a shape that is convex upward with respect to the engraved surface, it is less likely to accumulate on the cladding or its upper part.

etc.

[Brief explanation of the drawing]

Figure 1 is an overall view of the nuclear fuel assembly, Figure 2 G is A in Figure 1.
The main figure, which is a top view of the nuclear fuel assembly, and FIGS. 3 and 4 are vertical sectional views of the engraved portion of FIG. 2. 1... Upper tie plate, 2... Handle, 3...
Lower tie plate, 4... Spacer, 5... Fuel element, 6... Engraved portion, 7... Coating with fluorescent substance, and C
Metal-plated engraved surface, 8, 9... Protective film such as glass to protect the engraved surface.

Claims (1)

[Claims] 1. Coat the engraved surface of the upper tie plate handle with a fluorescent material or apply metal plating to the engraved surface, and make sure that the fluorescent material or metal plated surface is covered with a transparent material such as glass. A nuclear fuel assembly characterized by: