JPS59128487A - 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] In conventional pressurized water type light water reactors, the coolant that has risen in the axial direction of the reactor core flows radially outward (laterally) in the upper plenum directly above the core. ) and flows towards the exit nozzle and out of the reactor vessel.

A guide tube that guides the control rod assembly of the core is installed in this upper plenum, but this guide tube surrounds and protects the control rod assembly so that it is not directly exposed to the lateral flow of coolant. It is something to do.

However, if the number of control rods or their aggregates is very large, the number of guide tubes will be large or the size of the guide tubes will need to be increased, making it impossible to secure a flow path area toward the outlet nozzle. In order to solve this problem, it has been proposed to install a calandria section directly above the core exit that diverts the coolant toward the exit nozzle. The control rods are inserted through the fuel assembly into the fuel assembly so that the control rods are not directly exposed to the lateral flow of coolant. However, even in this case, if there are many control rods, only small-diameter protection tubes can be used, and there is still the risk of damage to the protection tubes due to fluid vibration caused by radial flow, or damage to the control rods due to this. .

The present invention has been made in view of the above-mentioned problems.

That is, the present invention provides a lower guide structure directly above the reactor core that mainly surrounds and protects the control rod assemblies individually and has an assembly guide pipe that allows coolant to flow vertically upward.
Furthermore, the gist is that an upper guide structure is provided above which protects tubes that individually surround the drive shafts of the control rod assembly, and guides the coolant in the radial direction and directs it toward the coolant outlet nozzle. As a result, regardless of the increase in the number of control rods, an increase in the number of protection tubes receiving a lateral flow of coolant can be suppressed, a sufficient coolant flow path can be secured, and the strength and soundness of the protection tubes can be significantly improved.

Hereinafter, the present invention will be explained based on illustrated embodiments.

In FIG. 1, a reactor vessel 1 is provided with a coolant inlet nozzle 3 and an outlet nozzle 5 at its upper part, and these communicate with a primary cooling system piping (not shown).

The container 1 is supported by a building at the lower part of the nozzles 3 and 5, and the upper part is closed with a removable upper lid body 7.

The core shaft 9 suspended and supported inside the vessel 1 defines an annular flow path 11 through which the coolant descends between it and the vessel 1, has a lower core support plate 13 at the lower part, and a lower plenum 15 at the lower part. Form.

A large number of fuel assemblies 17 are mounted on the core support plate 13 to form a core 19 . The fuel assembly 17 is made up of a large number of parallelly arranged fuel rods and control rod guide tubes bundled together by a support grid. The core support plate 13 includes a large number of through holes (not shown) through which coolant passes,
The coolant enters from the inlet nozzle 3 as shown by the arrow and flows down the annular channel 11 to the lower plenum 15. Thereafter, it passes through the core support plate 13 and enters the core 19.

The inner cylinder 21 supported inside and above the core shell 9 constitutes a guide structure as described later.

The guide structure is recognized as being divided into a lower part and an upper part, and is located in the core 19.
The upper core plate 23, the intermediate support plate 25, and the lower solid part 27 of the inner cylinder 21 are positioned directly above the fuel assembly 17.
And an assembly guide tube 29 that individually surrounds control rod guide tubes, which will be described later, constitutes a lower guide structure.

FIG. 2 shows an example of a control rod assembly 30, in which the upper ends of a plurality of control rods 31 containing a neutron absorbing material are configured as one assembly via a spider 33 and a drive shaft 35.

Returning to FIG. 1 again, the protective tubes 41 that individually surround the drive shafts 35 cooperate with the intermediate support plate 25, the upper part 43 of the inner cylinder having a number of flow holes, and the upper support plate 45 to form an upper guide structure. forming the body.

There are a large number of control rod assemblies 30, which are individually connected to drive devices 47 and 49 provided at the upper part of the upper cover body 7. The control rods 31 of the control rod assembly 30 are inserted into the control rod guide tube of the fuel assembly 17, and are moved up and down in a predetermined pattern by drive devices 47 and 49 to control the reactivity of the reactor core 19 during operation of the reactor. do.

As described above, the coolant that has flowed into the core 19 flows outside the fuel rods, absorbs the heat of the nuclear reaction, increases its temperature, and flows through the guide tubes 2.
9 and flows upward.

Furthermore, it passes over the intermediate support plate 25 and reaches the upper plenum 51, where it changes direction and flows radially outward (laterally).
It flows out from the outlet nozzle 5 through a hole in the upper part 43 of the inner cylinder 21.

According to this embodiment, the coolant flows along the axial direction around the control rod 31, which is thin, that is, has low rigidity, so that no fluid vibration occurs and wear due to vibration is prevented.

In addition, since the coolant flows from the upper guide structure to the outlet nozzle 5 located at the same height as the upper guide structure, the flow is smooth and there is little pressure loss. Even if this occurs, the coolant circulates naturally within the vessel 1, and cooling of the core 19 can be ensured.

Furthermore, in the upper plenum 51 where the ascending coolant flows sideways, the protection tube 41 surrounds the drive shaft 35, which is much smaller in number than the control rod 31, so even though the diameter is large and the strength and rigidity are large, First, the coolant flow path is large, allowing the coolant to flow smoothly.

Furthermore, because of this, the fluid force acting on the protection tube 41 is also small, so the excitation force is also small and the integrity is high.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention, and FIG. 2 is a side view showing one component of the embodiment. 1...Reactor vessel, 9...Reactor core, 17...Fuel assembly, 19...Reactor core drawing A; Tsukasa 0; (No change in content) Figure 1 procedural amendment (method) Showa Indication of the May 10, 1958 incident Patent Application No. 4006 of 1982
Relationship with famous cases that amend the name of the invention No. 2 Nuclear Reactor Patent Applicant Address 2-5-1 Marunouchi, Chiyoda-ku, Tokyo Name (620) Representative of Mitsubishi Heavy Industries, Ltd. Person Address 2 Marunouchi, Chiyoda-ku, Tokyo Chome 5@11
3 (No change in content 7) is attached.

Claims (1)

[Claims] A reactor core consisting of a plurality of fuel assemblies, a reactor core containing and supporting the core in its lower part, and a reactor vessel that suspends and supports the reactor core inside and forms a coolant descending annular space between the reactor core and the reactor core. , an upper lid body that closes the upper part of the vessel, a lower guide structure located directly above the core and including a control rod assembly guide tube, an upper guide structure located above the lower guide structure, and the upper guide structure. A nuclear reactor, characterized in that it has a coolant nozzle provided on the upper side of the vessel in correspondence with the vessel.