JPS6139359Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a simulated fuel rod structure used in a nuclear reactor simulation test device.

For example, a test device for conducting a simulation test of a fast breeder reactor has a large number of simulated fuel rods consisting of sheathed heaters, which correspond to nuclear fuel rods, arranged inside a test vessel in a manner that corresponds to the actual reactor structure. The test is conducted by heating liquid metal such as sodium contained in the test container using the heat generated by a simulated fuel rod, that is, a sheathed heater.

Therefore, in this test device, a gap is provided between each of the simulated fuel rods that are collectively arranged in the test container to allow sodium to flow, similar to the actual fuel rod arrangement structure. Conventionally, as one means of maintaining the gap between the simulated fuel rods, a wire spacer made of a metal wire having a diameter corresponding to the cross section of the gap was spirally placed outside the outer tube of the simulated fuel rod, similar to the actual structure. Wrapping is being done.

In addition, each simulated fuel rod is equipped with a thermocouple to measure the surrounding sodium temperature, and this thermocouple is attached to the outside of the outer tube of the simulated fuel rod so that it is located in the gap between each simulated fuel rod. .

However, since the actual fuel rods are not equipped with thermocouples for measurement and there are no thermocouples in the gaps between the fuel rods, by attaching thermocouples to the outside of the outer tube of the simulated fuel rod, it is possible to The cross-sectional area of the gap between the rods will be different from the actual cross-sectional area of the gap between the fuel rods. For this reason, the arrangement structure of the simulated fuel rods cannot faithfully simulate the arrangement structure of actual fuel rods, which causes problems in conducting accurate simulation tests. Furthermore, a problem may occur in which the thermocouple similarly gets entangled with the wire spacer provided outside the simulated fuel rod and is cut off.

The present invention was developed in view of the above circumstances, and it improves the structure in which thermocouples are installed in simulated fuel rods, and the size of the cross-sectional area of the gap between the simulated fuel rods is made equal to the cross-sectional area of the gap between the actual fuel rods. A simulated fuel rod structure that allows thermocouples to be installed as close together as possible, supports thermocouples with simple means without interfering with temperature detection, and prevents thermocouples from being cut by wire spacers. The purpose is to provide the following.

That is, the simulated fuel structure of the present invention uses a wire spacer at least partially made of a pipe, a thermocouple inserted through the pipe, and a support wire attached to the detection end of the thermocouple. is fixed to the end of the pipe of the wire spacer, and a through hole is formed in the peripheral wall of the pipe to correspond to the detection end of the thermocouple.

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

Figures 1 and 2 show a nuclear reactor simulation test device, in which A is a test vessel, B is a sealing member that seals the end of test vessel A, and C is a member that fills the inside of test vessel A with, for example, sodium. It is a distribution outlet for The simulated fuel structure of the present invention is installed inside a test container A, and includes a simulated fuel rod 1 that is a sheathed heater, a wire spacer 2 wrapped around the outside of the simulated fuel rod 1, and a wire spacer 2 that is inserted into the interior of the wire spacer 2. It consists of a thermocouple 3. Inside the test container A, a large number of simulated fuel rods 1 are arranged in a bundle along the longitudinal direction of the container A, and the base end of each simulated fuel rod 1 penetrates one of the sealing members B. It protrudes outside and is connected to the power supply. Each of the assembled simulated fuel rods 1 maintains a gap therebetween by having the wire spacer 2 wound thereon contacting the other simulated fuel rods 1. Then, the simulated fuel rod 1, that is, the sheathed heater, is energized to generate heat, thereby heating the sodium contained in the test container A.

An embodiment of the simulated fuel rod structure of the present invention will be described with reference to FIGS. 3 to 5. The simulated fuel rod 1 is
As shown in FIG. 3, this is a sheathed heater constructed by inserting a heating wire 5 into the outer tube 4 and filling it with heat-resistant insulating powder 6. Terminal 7 is connected to a power supply circuit. The wire spacer 2 is the outer tube 4 of the simulated fuel rod 1
The coil is wound spirally around the entire axial direction of the coil and fixed by welding. As shown in FIGS. 4 and 5, the wire spacer 2 is formed by a hollow pipe 8 whose portion extending over a predetermined length from its base end opposite to one end of the simulated fuel rod 1 is made of metal such as stainless steel. has been done. The length of the pipe 8 is at least large enough to pass through all the locations where the temperature is to be measured by the thermocouple 3 set in the axial direction of the simulated fuel rod 1 and to be wrapped around the outer tube 1 . Therefore, as shown in the figure, the wire spacer 2 consists of a pipe 8 for at least a portion of the above-mentioned length, and the remaining portion is made of a solid wire 9, and the two are welded, crimped, etc. They may be joined together, or the entire wire spacer 2 may be constructed from a single pipe 8. Note that the outer diameter of the wire spacer 3, that is, the outer diameter of the pipe 8 and the wire 9, has a size necessary to form a gap with a predetermined cross-sectional area between each of the simulated fuel rods 1. In addition, a thermocouple 3 is attached to the wall of the pipe 8 while being wrapped around the outer tube 4 of the simulated fuel rod 1.
A plurality of through holes 10 are formed at each location where the temperature is to be measured and penetrate through the inside and outside of the pipe 8. The wire spacer 3 wraps the pipe 8 around the outer tube 4 of the simulated fuel rod 1 from one end thereof, and then wraps the wire 9 around the outer tube 4 of the test vessel A. It passes through and extends to the outside. The thermocouple 3 is a sheathed type in which a thermocouple element 12 is inserted inside a sheath pipe 11.
The wire spacer 2 is inserted into the pipe 8 and provided therein. Thermocouple 3 inserted into pipe 8
The number corresponds to the number of temperature measurement points in the simulated fuel rod 1, and the base end of each inserted thermocouple 3 is fixed through the neck body 14 provided at the base end of the pipe 8. 8 extends outside, and a thermocouple element 12 is connected to the temperature measurement circuit. Each thermocouple 3 has a different length corresponding to each temperature measurement point,
The detection end (tip) 3a of each thermocouple 3 is a pipe 8
It is located opposite each through hole 10 formed in the wall portion. In addition, the detection end 3a of each thermocouple 3 and the pipe 8
Support wires 13 made of stainless steel wire or the like are stretched under tension between the tips of the pipes (in this embodiment, the welded joints between the pipe 8 and the wire 9). The ends are fixed to the detection end 3a of the thermocouple 3 (ie, the end of the sheath tube 11) and the end of the pipe 8 by welding. Therefore, each thermocouple 3 is pulled by the support wire 13 and supported in a tensed state along the axial direction of the pipe 8.

Thus, the simulated fuel rod 1 generates heat by energizing the heating wire 5 and heats the sodium around the outer tube 4. Since through holes 10 are formed in the pipe 8 of the wire spacer 2 at each temperature measurement point, sodium flows into the pipe 8 through the through holes 10, and the thermoelectric cells located relative to the through holes 10 It is in contact with the detection end 3a of pair 3. Therefore, when sodium is heated, each thermocouple 3 at each temperature measurement point
measures the sodium temperature.

In the simulated fuel rod structure configured in this way, the thermocouple 3 is provided inside the pipe 8 of the wire spacer 2, and only the wire spacer 2 is wound around the outside of the simulated fuel rod 1. Similar to the actual gap between fuel rods, the gap between the fuel rods 1 has only a wire spacer, so that its cross-sectional area approximates the cross-sectional area of the actual gap. Moreover, since the thermocouple 3 is provided inside the pipe 8 of the wire spacer 2, it will not become entangled with the wire spacer 2 and be cut. Moreover, since the pipe 8 of the wire spacer 2 is hollow and has no filling, the thermocouple 3 can be moved and fixed freely, and can be easily positioned to correspond to a predetermined temperature measurement point. In addition, a through hole 10 is formed in the wall of the pipe 8 to allow sodium to flow into the pipe 8, and the thermocouple 3
It can be configured to easily measure the temperature of Also,
By supporting the thermocouple 3 inside the pipe 8 using the support wire 3, the configuration can be simplified.

As explained above, the simulated fuel rod structure of the present invention is used in a nuclear reactor simulation test device, and is constructed by inserting a thermocouple into the pipe of a wire spacer wrapped around the outside of the simulated fuel rod. By providing this, the gap between the simulated fuel rods can be made as close as possible to the size of the gap between the actual fuel rods where only a wire spacer exists, making it possible to conduct a simulation test that is faithful to the actual reactor. Moreover, the thermocouple does not get tangled with the wire spacer and is cut off, which improves reliability and durability.

Furthermore, since a through hole is formed in the peripheral wall of the pipe of the wire spacer, sodium flows into the pipe, making it easy to measure the temperature with a thermocouple.
Furthermore, by fixing the support wire attached to the detection end of the thermocouple to the pipe of the wire spacer, the thermocouple can be reliably supported inside the pipe with a simple structure.

[Brief explanation of the drawing]

Figure 1 is a vertical cross-sectional view showing the nuclear reactor simulation test equipment;
Fig. 2 is a cross-sectional view of the same, Fig. 3 is a partially cutaway side view showing an embodiment of the simulated fuel structure of the present invention, Fig. 4 is a side view showing a wire spacer, and Fig. 5 is a side view showing a wire spacer. FIG. 3 is an enlarged vertical cross-sectional view. 1... Simulated fuel rod, 2... Wire spacer, 3
...Thermocouple, 4...Outer tube, 5...Heating wire, 8...
Pipe, 10...through hole, 13...support line.

Claims (1)

[Scope of utility model registration request] A simulated fuel rod in which a heat-generating wire is provided in an outer tube through an insulator, a wire spacer wrapped around the outer tube of the simulated fuel rod and formed of a pipe from at least one end to an intermediate portion; a thermocouple inserted through the inner space of the pipe of the wire spacer, and the thermocouple is supported by fixing a support wire attached to the detection end to the end of the pipe of the wire spacer. . A simulated fuel rod structure, wherein a through hole is formed in the peripheral wall of the pipe in correspondence with the detection end of the thermocouple.