JP2000137089A - Core structure of pressurized water reactor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate ultrasonic inspection of a bolt fixing a core tank with a former plate by fixing the former plate positioned on the back side of a thermal shield together with a buffle plate to the core tank by a bolt from the inside. SOLUTION: In the core tank 4 of a pressurized water reactor, a former plate 13 positioned on the back side of a thermal shield 15 together with a buffle plate 11 are fixed to a core tank 4 by a long bolt 18 from the inside of the core tank 4. By such construction, ultrasonic inspection of the bolt 18 can be executed from the inside of the core tank 4, and because the thermal shield 15 is unnecessary to be detached from the core tank 4, the labor and the time required for detaching or fitting the thermal shield 15 can be omitted. Further by bolt cooling holes 19 formed on the upper face and the lower face of the former plate 13, the bolt 18 is cooled by primary cooling water, the bolt 18 can be prevented from thermally fixing to the threaded part of the bolt hole formed on the former plate 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a core structure of a pressurized water reactor.

[0002]

2. Description of the Related Art A pressurized water reactor generally has a structure as shown in FIG. In the figure, reference numeral 1 denotes a reactor vessel having an inlet nozzle 2 communicating with a primary coolant outlet nozzle of a steam generator (not shown) and an outlet nozzle 3 communicating with a primary coolant inlet nozzle of the steam generator as well. A core vessel 4 is provided in the reactor vessel 1.

[0003] The core tank 4 has a cylindrical shape, and a plurality of control rod cluster guides for guiding control rod clusters into a fuel assembly 16 are provided on an upper core support plate 5 closing the upper end of the core tank 4. A tube 6 is attached. The core tank 4 defines an annular downcomer 7 with the reactor vessel 1, and the primary cooling water flowing into the reactor vessel 1 from the inlet nozzle 2 flows downward in the downcomer 7. Thus, it flows into the core tank 4 from the lower end of the core tank 4.

A lower core plate 8 and an upper core plate 9 are provided inside the core tank 4 so as to face each other. Many cooling water circulation holes are formed in the lower core plate 8 and the upper core plate 9, and primary cooling water flowing out of the cooling water circulation holes formed in the upper core plate 9 is formed in the core tank 4. The cooling water flows into the outlet nozzle 3 through the cooling water outlet nozzle 10.

A plurality of baffle plates 11 are provided between the lower core plate 8 and the upper core plate 9 inside the core tank 4. These baffle plates 11 define a fuel assembly loading area inside the core tank 4 and include a plurality of baffle former bolts 12 (see FIG. 6).
Is fixed to the former plate 13.

The former plate 13 defines a fuel assembly non-loading region between the baffle plate 11 and the core tank 4, and is spaced apart from the baffle plate 11 and the core tank 4. It is arranged horizontally. Also,
As shown in FIG. 6, the former plate 13 is connected to the core tank 4 by a number of barrel former bolts 14.
Is fixed from the outside.

On the other hand, a plurality of heat shields 15 made of a thick steel plate are provided outside the core vessel 4. These heat shields 15 heat the side surfaces of the fuel assemblies 16 located near the core tank 4 from the outside of the core tank 4 in the fuel assemblies 16 (see FIG. 5) loaded in the fuel loading region described above. It is shielded, and is fixed to the outer peripheral surface of the core vessel 4 by a plurality of bolts 17 shown in FIG.

Incidentally, in the pressurized water reactor having such a structure, it is required to periodically inspect the inside of the reactor vessel 1. Therefore, when the barrel former bolt 14 described above is subjected to ultrasonic inspection, the reactor vessel 1
The ultrasonic inspection of the barrel former bolt 14 is performed by suspending the ultrasonic inspection apparatus on the outer peripheral surface of the core tank while taking out the core tank 4 from the core tank 4 and temporarily placing the core tank 4 on a temporary holding stand.

[0009]

However, since some of the barrel former bolts 14 are located behind the heat shield 15, in order to ultrasonically inspect all the barrel former bolts 14, the heat shield from the core tank 4 is required. The body 15 needs to be removed. For this reason, it takes time and effort to remove and attach the heat shield 15, and ultrasonic inspection of the bolts for fixing the former plate 13 to the core tank 4 requires much time and cost.

The present invention has been made in view of the above points, and has an object to provide a core structure of a pressurized water nuclear reactor capable of easily performing an ultrasonic inspection of bolts for fixing a core tank and a former plate. It is intended to provide.

[0011]

In order to solve the above-mentioned problems, the invention of claim 1 defines a core tank provided in a reactor vessel and a fuel assembly loading area inside the core tank. A plurality of baffle plates, a plurality of former plates defining a fuel assembly non-loading region between the baffle plate and the core tank, and a fuel assembly loaded in the fuel assembly loading region. In a pressurized water reactor having a heat shield for thermally shielding the side surface of the fuel assembly located near the core tank from the outside of the core tank, the former plate located on the back side of the heat shield is bolted. The core tank is fixed to the core tank together with the baffle plate from the inside of the core tank.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.
The same parts as those shown in FIG. FIG. 1 is a diagram showing a core structure of a pressurized water reactor according to one embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line AA of FIG. As shown in the figure, the former plate 13 located on the back side of the heat shield 15 is fixed to the core tank 4 together with the baffle plate 11 from the inside of the core tank 4 by long bolts 18.

On the other hand, the former plate 13 which is not located on the back side of the heat shield 15 is fixed to the core tank 4 from the outside of the core tank 4 by barrel former bolts 14 as in the prior art.

FIG. 3 is a sectional view taken along the line BB of FIG. 1. As shown in FIG. 3, the bolt 1 screwed into the former plate 13 is provided on the upper and lower surfaces of the former plate 13.
Bolt cooling holes 19 for cooling the cooling water 2, 14, 18 with primary cooling water are formed.

FIG. 4 is a sectional view taken along the line CC of FIG. 1. As shown in FIG. 4, the former plate 13 has a baffle for cooling the former plate 13 with primary cooling water. It is drilled at a constant pitch near the plate 11.

In the embodiment of the present invention described above, the former plate 13 located on the back side of the heat shield 15 is fixed to the core tank 4 together with the baffle plate 11 from the inside of the core tank 4 by long bolts 18. Accordingly, the ultrasonic inspection can be performed on the bolt 18 located on the back side of the heat shield 15 from the inside of the core tank 4. Therefore,
In one embodiment of the present invention, the core tank 4 and the former plate 1
Since it is not necessary to remove the heat shield 15 from the core tank 4 when performing an ultrasonic inspection of the bolts 14 and 18 for fixing the heat shield 3, the trouble and time required for removing and attaching the heat shield 15 can be omitted. Ultrasonic inspection of the bolts 14 and 18 for fixing the tank 4 and the former plate 13 can be easily performed.

In the above-described embodiment, since the bolt cooling holes 19 for cooling the bolts 12, 14, and 18 screwed into the former plate 13 with the primary cooling water are formed in the former plate 13, the former plate 13 is formed. The bolts 12, 14, 18 screwed into the former plate 13 can be prevented from being fixed to the threaded portion of the bolt hole formed in the former plate 13 by heat.

Further, in the above-described embodiment, since the former cooling holes 20 for cooling the former plate 13 by the primary cooling water are formed in the former plate 13, the former cooling water flowing through the former cooling holes 20 is used to form the former cooling water. The plate 13 can be cooled. Note that the present invention is not limited to the above-described embodiment, and various modifications and the like can be made without departing from the gist described in the claims.

[0019]

As described above, according to the present invention,
A core structure of a pressurized water reactor capable of easily performing an ultrasonic inspection of a bolt for fixing a core tank and a former plate can be provided.

[Brief description of the drawings]

FIG. 1 is a plan view showing a core structure of a pressurized water reactor according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view taken along line BB in FIG. 1;

FIG. 4 is a sectional view taken along the line CC of FIG. 1;

FIG. 5 is a longitudinal sectional view of a pressurized water reactor.

FIG. 6 is a view showing a conventional core structure.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Nuclear reactor 2 Inlet nozzle 3 Outlet nozzle 4 Core tank 6 Control rod cluster guide tube 8 Lower core plate 9 Upper core plate 11 Baffle plate 13 Former plate 15 Thermal shield 18 Bolt 19 Volt cooling hole 20 Former cooling hole

Claims (1)

[Claims] 1. A core tank provided in a nuclear reactor vessel, a plurality of baffle plates defining a fuel assembly loading region inside the core tank, and a fuel between the baffle plate and the core tank. A plurality of former plates that define an assembly non-loading region, and a side surface of a fuel assembly located in the vicinity of the core tank among the fuel assemblies loaded in the fuel assembly loading region, from the outside of the core tank. A pressurized water reactor having a heat shield for heat shielding, wherein the former plate located on the back side of the heat shield is fixed to the core tank together with the baffle plate by bolts from inside the core tank. Core structure of a pressurized water reactor.