JPH034954Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a jig for testing spring characteristics of an upper nozzle spring of a fuel assembly for a pressurized water reactor.

[Prior art]

Fuel assemblies have traditionally been used in pressurized water reactors. As shown in FIG. 4, this fuel assembly has an upper nozzle 1 and a lower nozzle 2 arranged vertically apart, and a predetermined interval between them, and has a lattice space. A plurality of support grids 3 and control rods inserted into the grid spaces at predetermined intervals, fixed to fixed parts of the support grids 3, and further connected at their upper and lower ends to the upper nozzle 1 and the lower nozzle 2. It has a guide tube 4, a large number of fuel pellets 5 sealed in a cladding tube, and a pressing spring 6 for these, and is inserted into a predetermined location in the lattice space of the support lattice 3. It is composed of a large number of supported fuel rods 7.

Such fuel assemblies are installed in parallel between upper and lower core plates of a pressurized water type light water reactor, thereby forming a nuclear reactor core.

In a pressurized water reactor, high-temperature, high-pressure cooling water flows at a high flow rate from the lower nozzle 2 to the upper nozzle 1 of the fuel assembly. Therefore, this cooling water flow applies a force that lifts the fuel assembly from the lower core plate. Therefore, in order to stably hold the fuel assembly, an upper nozzle spring 8 is attached to the upper surface of the upper nozzle 1, and this upper nozzle spring 8 pushes the fuel assembly downward against the upper core plate. There is.

By the way, as mentioned above, in order to know whether the upper nozzle spring 8 can sufficiently press downward the fuel assembly that is about to be lifted by the cooling water flow, the spring characteristics of the upper nozzle spring 8 can be checked. I need to test it.

However, in the past, there was no suitable test means, and it was not possible to accurately understand the behavior of the upper nozzle spring 8 in a nuclear reactor.

[Problems that this invention attempts to solve]

The problem that the present invention aims to solve is to make it possible to apply a stable load to the upper nozzle spring in the same state that the upper nozzle spring is actually assembled in the fuel assembly, thereby making it possible to apply a stable load to the upper nozzle spring. The objective is to obtain highly accurate characteristic test results.

[Means for solving problems]

In order to solve this problem, the present invention has been developed by attaching a slide table to a slide table fixture in a freely sliding manner to form a slide head, attaching the upper nozzle spring to the top surface of the upper nozzle spring mounting jig, and attaching the upper nozzle spring to the slide table. The upper nozzle spring mounting surface and the lower surface of the upper nozzle spring mounting jig are parallel planes. .

[Effect]

For example, attach the slide table fixture to a tensile testing machine, place the upper nozzle spring mounting jig on the load converter of this tensile testing machine, attach the upper nozzle spring to this, and attach the upper nozzle spring to the slide table through the slide head. When pressed downward, the upper nozzle spring is displaced downward while the upper nozzle spring mounting jig remains stable. At this time, the slide table moves appropriately, so that the point of application of the pressurized load to the upper nozzle spring does not move, and the pressurized load and the displacement amount of the upper nozzle spring are proportional.

[Effect of idea]

When the upper nozzle spring is pressurized, the upper nozzle spring mounting jig is stable and the slide table slides, so the point of application of the pressurized load on the upper nozzle spring is always constant regardless of fluctuations in the pressurized load, and the The proportional relationship between the amount of pressure load and the amount of displacement of the upper nozzle spring is maintained accurately, and a stable load can be applied to the upper nozzle spring. Characteristic test results can be obtained easily and quickly, and the spring characteristic tests of several types of upper nozzle springs can be performed using the same jig.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

Reference numeral 11 in FIG. 1 is a tensile testing machine, and this tensile testing machine 11 is provided with arms 13 and 14 spaced apart from each other vertically and fixed horizontally via a column 12.

A rectangular board 15 is horizontally fixed to the arm 14, and a load converter main body 16 is attached to the four corners of this board 15. A load reader 17 is connected to the load converter main body 16, and the load converter main body 16 and the load reader 17
8 are made up.

On the other hand, a slide head 19 is attached to the arm 13. This slide head 19 is
As shown in the figure, the slide table fixture 21 is formed into a U-shaped cross section and has a recess 20 and is attached to the arm 13, and the oid parts 22, 23, 24, 2.
5 and a guide bearing 26, and a slide table 27 fitted into the recess 20 and slidably attached to the slide table fixture 21 via the guide parts 22, 23, 24, 25 and the guide bearing 26. ing. The guide bearing 26 is rotatably provided between the guide parts 22 and 23 and between the guide parts 24 and 25. When the slide head 19 is attached to the arm 13, the slide table 27 is moved as shown by the arrow in FIG.
It is said to be able to slide freely in the AB direction.

On the other hand, as shown in FIG. 1, a square-shaped mounting plate 32 is fixed on the rectangular plate 31 in parallel with the rectangular plate 31 via sleepers 33, 34, and 35. Screw holes 36 are drilled at both ends of the mounting plate 32, and a bolt 38 is inserted into one of these screw holes 36 through a washer 37.
is screwed in. Two rectangular holes 39 are formed between both screw holes 36. And rectangular board 3
1, mounting plate 32, sleepers 33, 34, 35, washer 3
7. The bolt 38 constitutes an upper nozzle spring mounting jig 40. In addition, the rectangular plate 32
is set to have the same size as or slightly larger than the board 15 so that the load is evenly applied to the load converter 18 during testing.

A substantially L-shaped upper nozzle spring 41 is attached to the upper surface of the mounting plate 32 . This upper nozzle spring 41 has its tip loosely fitted into the rectangular hole 39, and the bolt 38 inserted through the base of the upper nozzle spring 41 is inserted into the screw hole 39.
6, the base is fixed to the mounting plate 32. The bolt 38 has the same specifications, material, strength, etc. as the bolt used for the fuel assembly. The state of attachment of the upper nozzle spring 41 is the same as the state of attachment of the upper nozzle spring 41 to the upper nozzle of the fuel assembly. That is, the contact area of the upper nozzle spring 41 with the mounting plate 32 is the same as the contact area of the upper nozzle spring 41 with the upper nozzle, and the tip of the upper nozzle spring 41 is in a free state.

Next, the operation of the upper nozzle spring characteristic testing jig constructed as described above will be explained. When performing a characteristic test of the upper nozzle spring 41, (1) Attach the upper nozzle spring 41 to be tested to the upper nozzle spring mounting jig 40 as described above.

(2) Attach the slide table fixture of the slide head 19 to the arm 13 of the tensile tester 11 as shown in FIG.

(3) Place the upper nozzle spring mounting jig 40 to which the upper nozzle spring 41 is attached on the four load converter bodies 16. (As a result, the slide table 27 and the upper nozzle spring 4
Opposed to 1. ) (4) Lower the slide head 19 together with the arm 13, and lower the slide table 2 as shown in FIG.
The slide head 19 is set so that approximately the center of the lower surface of the nozzle 7 contacts the compressive load application point P of the upper nozzle spring 41. The two-dot chain line shown in FIG. 3 shows a state in which the upper nozzle spring 41 is displaced by a compressive load. Third
In the figure, L indicates the amount of displacement.

(5) Apply a compressive load to the upper nozzle spring 41. Then, the upper nozzle spring 41 is displaced downward.

(6) Read the amount of displacement of the upper nozzle spring 41 using a commonly used scale.

(7) The compressive load applied to the upper nozzle spring 41 is read by the load reader 17.

(8) When a compressive load is applied to the upper nozzle spring 41, the upper nozzle spring mounting jig is in a stable state, and the point of application of the compressive load to the upper nozzle spring 41 is always constant regardless of fluctuations in the compressive load. ), and a stable load can be applied to the upper nozzle spring 41, and the amount of displacement of the upper nozzle spring 41 and the amount of load applied to the upper nozzle spring 41 are proportional. From this, the spring constant of the upper nozzle spring 41 is calculated from the amount of displacement of the upper nozzle spring 41 and the amount of load applied to the upper nozzle spring 41, and its spring characteristics are obtained. As a result, highly accurate spring characteristic test results that are closest to the true spring characteristics of the upper nozzle spring can be obtained easily and quickly, and the behavior of the upper nozzle spring 41 in the nuclear reactor can be accurately understood.

In the above embodiment, the two screw holes 36 of the mounting plate 32 were used to enable the spring characteristics of two types of upper nozzle springs to be tested using the same upper nozzle spring mounting jig 40. However, the spring characteristics of several types of springs can be tested depending on the shape of the upper nozzle spring.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing one embodiment of the present invention;
The figure is a partially omitted perspective view of the slide head.
The figure shows that the point of application of the compressive load does not change even if the upper nozzle spring is displaced when the upper nozzle spring is pressurized. Figure 4 shows an example of a fuel assembly, with some parts omitted and some notches cut away. FIG. 19...Slide head, 21...Slide table fixture, 27...Slide table, 40
...Upper nozzle spring installation jig, 41...Upper nozzle spring.

Claims (1)

[Scope of utility model registration request] A slide head consisting of a slide table fixture and a slide table slidably attached to the slide table fixture; an upper nozzle spring of a fuel assembly facing the slide table; and a tip end of the upper nozzle spring. In the free state, the base end can be detachably attached to the upper surface of the upper nozzle spring by the same means used for attaching the upper nozzle spring to the upper nozzle of the fuel assembly, and the upper nozzle spring mounting surface of the fuel assembly and the upper nozzle spring mounting surface of the fuel assembly are connected to each other. and an upper nozzle spring mounting jig whose lower surface is parallel to the upper nozzle spring mounting jig. A jig for testing the characteristics of an upper nozzle spring of a fuel assembly, characterized in that the jig can be pressed toward the lower surface of the fuel assembly.