JPS6262288A - Control rod for high-conversion type light water reactor - 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 of the Invention] The present invention relates to a control rod for a high conversion type light water reactor, which is used in a high conversion type light water reactor that is composed of a fuel assembly having a regular hexagonal cross section.

[Technical background of the invention and its problems] Conventionally, high conversion light water reactors in which fuel assemblies with a regular hexagonal cross section are arranged densely have adopted so-called cluster control rods in which a group of control rods are inserted inside the fuel assemblies. has been done.

When cluster control rods are installed inside a fuel assembly in this way, it is important to ensure the mechanical integrity of the fuel rods during control rod operation, especially when considering control rod movement within a short period of time required during load following operation. It is necessary to design the fuel assembly taking this into account. Therefore, the fuel design becomes complicated, and as a result, the manufacturing cost of not only the fuel assembly but also the entire reactor core increases.

[Object of the Invention] The present invention has been made in view of the above circumstances, and its purpose is to reduce the weight of the control rod for a high conversion light water reactor, thereby reducing the weight of the entire reactor core, and to provide a high-performance, high-conversion light reactor with high mechanical strength and low cost. The purpose of the present invention is to provide control rods for convertible light water reactors.

[Summary of the Invention] In order to achieve the above object, the present invention provides a control rod for a high conversion type light water reactor that is used in a high conversion type light water reactor consisting of a fuel assembly with a regular hexagonal cross section. In addition, the control rod is configured to be controlled by a control rod drive mechanism disposed at the bottom of the reactor core. The control rod has a single layer of neutron absorption rods filled with neutron absorption material arranged in an equilateral triangle shape, and the periphery is covered with a flat metal plate. Furthermore, the control rod and the control rod drive mechanism are connected by three rod-shaped struts so that core cooling water can pass through the inside of the control rod.

[Embodiments of the invention] Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a cross-sectional view of the core according to the present invention, and as shown in the figure, part of the side surfaces of adjacent channel boxes 2 of a plurality of fuel assemblies 1 having regular hexagonal cross sections constituting the core are mutually connected to each other. By arranging the channel boxes 2 so as to be in contact with each other, an equilateral triangular space 3 is formed between the channel boxes 2 adjacent to each other. In other words, the fuel assemblies 1 having a regular hexagonal cross section are arranged in a staggered manner to provide an equilateral triangular space 3.

A control rod 4, which will be described later, is inserted into this equilateral triangular space 3 to control the core power. Therefore, as shown in FIG. 2, this control rod 4 is constructed by arranging neutron absorbing rods 5 with a circular cross section in a layer so that the cross section forms an equilateral triangle, and surrounding the neutron absorbing rods 5 with stainless steel, etc. It is covered with a metal plate 6.

Therefore, an equilateral triangular space is created inside this control rod, and the surrounding area is covered with a metal plate 6 made of stainless steel or the like, so that this control rod 4 has a structure that is resistant to corrosion and has a well-distributed strength. . Further, as shown in FIG. 3, the main control rod 4 is connected to a control rod drive mechanism support 8 at the lower part of the reactor core by three supports 7 extending from each triangular vertex at its lower end.

Next, the operation of this embodiment will be explained.

By using the control rods 4 of this embodiment described above, there is no need to provide passage holes for cluster control rods inside the fuel assembly, and the fuel assembly 1 can be made into a uniform lattice in which only fuel rods are arranged. Therefore, the distribution of local power inside the fuel assembly is made flatter, and the degree of margin for operational restrictions on linear power density can be improved. Separation of the control rods also allows rapid control rod operations required during load following operations without compromising the mechanical integrity of the fuel. Moreover, since water can pass through the inside of the control rod 4 and the space is sufficiently larger than the deceleration distance of neutrons, the high-speed neutrons passing through the control rod 4 are decelerated and absorbed by the control rod 4. The effectiveness is improved compared to when there is no water inside the control rod. Furthermore, since the control rod 4 has a triangular cross section, it is expected to have sufficient mechanical strength and deformation due to stress will be sufficiently small. In addition, since the inside of the control rod 4 is composed of the neutron absorption rod 5, it can be manufactured using conventional manufacturing technology for control rods for boiling water reactors. Since the equipment used for this purpose can be used as is, it is expected that the cost of developing equipment for this purpose will be reduced.

FIG. 4 is a sectional view of another embodiment of the present invention, and the same reference numerals are given to the same components as in the above embodiment, and the explanation thereof will be omitted. In this embodiment, a metal structural member 11 is arranged at each of the three corners 10 of a control rod 9 having a triangular cross section, and three breathing plates 12 shown in FIG. 5 are welded to the structural member 11. It is configured to be fixed.

Therefore, according to this embodiment, the strength is further improved by the corner support material 13, and the corner support material 13 is
Since it is divided into the breathing plate 1 and the breathing plate 12, manufacturing is also simplified.

[Effects of the Invention] As described above, according to the present invention, the control rods can be installed outside the fuel assembly, and the fuel rods can be arranged uniformly within the fuel assembly, so that the power distribution can also be made uniform. Therefore, the degree of margin for thermal limit values during operation is improved. Also, the presence of water inside the control rod improves the value of the control rod. Furthermore, since the control rod of the present invention has a triangular structure as a whole, there are sufficient bullet holes, and since the fuel and control rod are separated, there is no need to consider the effect on the fuel assembly during rapid control rod drive. Furthermore, since neutral dried persimmons are used, conventional boiling water reactor control rod manufacturing technology can be used, and since the lower control rod is driven by am, conventional boiling water reactor technology can be used. It has a great effect.

[Brief explanation of drawings]

FIG. 1 is a top view of a core according to the present invention, FIG. 2 is a sectional view of an embodiment of the present invention, FIG. 3 is a schematic perspective view of an embodiment of the present invention, and FIG. FIG. 5 is a cross-sectional view of the corner member of FIG. 4. 1... Regular hexagonal fuel assembly 3... Control rod insertion hole 4.9... Control rod 5... Neutron absorption rod 6... Metal plate 7... Branch 8... Control rod Drive Mechanism Strut (8733) Agent: Yoshiaki Inomata, Patent Attorney (and 1 others)
Figure 1 Figure 2 Figure 3

Claims (3)

[Claims] (1) In a high conversion light water reactor control rod used in a high conversion light water reactor consisting of a fuel assembly with a regular hexagonal cross section, the control rod is a control rod with an equilateral triangular cross section, and the control rod is located at the bottom of the reactor core. A control rod for a high conversion light water reactor, characterized in that the control rod is configured to be controlled by a control rod drive mechanism. (2) The control rod is for a high conversion light water reactor according to claim 1, in which neutron absorption rods filled with neutron absorption material are arranged in a single layer in an equilateral triangular shape, and the periphery of the control rod is covered with a flat metal plate. control rod. (3) A control for a high conversion light water reactor according to claim 1, wherein the control rod and the control rod drive mechanism are connected by three rod-shaped struts so that core cooling water can pass through the inside of the control rod. rod.