JPS5838894A - Abnormality detecting device - 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 The present invention relates to a nuclear reactor abnormality detection device for detecting a normal state caused by a rise in temperature of coolant within a fuel assembly, and in particular,
The present invention relates to a nuclear reactor abnormality detection device that can simplify the structure of a nuclear reactor.

In fast breeder reactors that use liquid metal as a coolant.

In order to ensure the reliability of nuclear reactors and ensure smooth operation,
Various measuring equipment is installed inside the furnace vessel, e.g.
As shown in FIG. 1, a core upper mechanism J is provided above a large number of fuel assemblies installed in the reactor core l. In order to constantly monitor the cooling status of the fuel assembly during operation, each fuel assembly is provided with a set of flowmeters, thermometers, etc. Therefore.

The upper core mechanism 3 is a very large-scale transverse frame in the reactor, and is located directly above the fuel assemblies 3 and 3, so it has complex shadowing effects on the flow of coolant. It has become a part that requires advanced technology in the structural design of nuclear reactors.

The fuel assembly and core upper mechanism 3 are housed in a reactor vessel 10, a rotary plug is attached to the upper opening of the reactor vessel 10, and a cooling inlet nozzle is installed at the bottom of the reactor vessel 10. Also, a coolant outlet nozzle/J is provided on the side.

Therefore, an object of the present invention is to provide a reactor abnormality detection device with a simple structure that has the same function as the complex and large-scale upper core mechanism as described above. , the above object is achieved by providing a temperature-sensitive deformable body attached to the top of each of a large number of fuel assemblies loaded in the reactor core, and an ultrasonic fluoroscopy device that detects thermal deformation of the temperature-sensitive deformable body. achieved.

Embodiments of the present invention will be described below with reference to FIGS. 2 to 1.

In Fig. 1, the symbol sIP indicates a temperature-sensitive deformable body, and in this figure 1, the sIP is attached to the top of a fuel assembly containing a large number of fuel bottles j, .

The assembly is a single-layer flexible base body installed coaxially with the fuel assembly core, and its internal space, which is kept airtight, contains:
A gas or liquid with a large coefficient of thermal expansion is enclosed.

On the other hand, the reactor vessel IO is inherently equipped with an ultrasonic fluoroscopy device for confirming that the fuel assembly is inserted to the proper position when replacing the fuel assembly. As shown in FIG. 3, this ultrasonic fluoroscopy device includes an ultrasonic transmitter/receiver t attached to the inner wall surface of the reactor vessel/θ, which is slightly above the fuel assembly inserted into the normal position; This ultrasonic transmitter/receiver has a reflecting plate 7 provided on the inner wall surface of the reactor vessel facing it at the same height as the ultrasonic transceiver. And fuel assembly-,
Ultrasonic waves are emitted so as to skim the top of the fuel assembly, and the floating cape of the fuel assembly is detected by the change in the signal of one reflected wave. The reactor abnormality detection device according to the present invention utilizes an ultrasonic fluoroscopy device, which originally detects an abnormality in the degree of insertion of a fuel assembly, as its own component.

The nuclear reactor abnormality detection device according to one embodiment of the present invention configured as described above operates the ultrasonic fluoroscopy device regularly or intermittently, and checks the received signal of the ultrasonic transceiver B. , it is possible to detect an abnormality caused by a rise in the temperature of the coolant inside the fuel assembly. In other words, the temperature of the coolant flowing inside the fuel assembly is within the range set in the pan. In addition to the temperature-sensitive deformable body attached to the top of each fuel collection body 2, the elongation of the fuel assemblies in the axial direction is also almost the same. For example, ultrasonic waves oscillated in a pulsed manner are unobstructed by anything and are transmitted to the fuel poultry house body 1. The beam passes over the top of the beam and enters the reflection plate 7, is reflected by the reflection plate 7, becomes an echo, and is received by the ultrasonic transmitter/receiver s1. In this case, since the distance between the ultrasonic transmitter/receiver 4 and the summer radiation [7] and the propagation speed of the ultrasonic wave in the coolant are fixed t, the reception timing of the reflected echo from the first reflecting plate 7 is fixed t9. Sh.

Therefore, it can be seen that there is no abnormality in the temperature of the coolant.

On the other hand, a large number of fuel assemblies 2. If there is a local decrease in the flow rate of coolant or a summer-related increase in f'T in the fuel house KsIP, the temperature of the coolant flowing through the fuel assembly will be Rise.

This coolant whose temperature has risen abnormally is the temperature-sensitive deformable body reference 11! to extend it in the axial direction of the fuel assembly. As a result, as shown in Figure 3, the top of this fuel assembly protrudes and becomes much higher than the others. In this case, the ultrasonic wave oscillated from the ultrasonic transceiver number of the ultrasonic fluoroscope A part of the coolant is scattered at the protruding top of the fuel assembly where the coolant becomes abnormally high in temperature, and a part of it is transmitted and received as ultrasonic waves as a reflected echo different from the reflected echo from the reflecting plate 7. An abnormal temperature rise in the coolant can be detected by detecting different reflected echoes received by the refrigerant.

In order to identify the fuel assembly in which the abnormal temperature rise of the coolant has occurred, for example, for each row of fuel assemblies loaded in the reactor core l in a grid pattern, an ultrasonic transmitter/receiver 6 is installed between each row of fuel assemblies. A pair with a reflector plate 7 is provided, and the ultrasonic transmitter/receiver that receives the above-mentioned different reflectors identifies the row to which the fuel assembly belongs by distinguishing between them. By specifying the distance to the ultrasonic transmitter/receiver, or by making it possible to vary the ultra-blue line oscillation direction of a single ultrasonic transmitter/receiver, it is possible to detect the reflected echo from the fuel collector with the protruding top. It is okay to manipulate the direction of ultrasonic oscillation and timing of reception. If you can identify the fuel assembly where the abnormal temperature rise has occurred in this way, you can take the necessary measures for safe operation of the reactor. can.

Figure 2 shows a modified embodiment of the present invention, in which the temperature-sensitive deformable body is not integrally integrated into the top of the labor collector as shown in Figure 2; It is attached independently and additionally to the top.

This has the advantage that the temperature-sensitive deformable body can be easily replaced.

In addition, FIG. 1 shows another modified embodiment of the present invention, in which a so-called bimetal, which is made by integrally bonding a single metal plate having different coefficients of thermal expansion, is used as a temperature-sensitive deformable body and is attached to the top opening of the fuel assembly. This bimetallic temperature-sensitive deformable body will alert the turtle when the coolant is within a specified temperature range.
K is almost horizontal as shown by the solid line in Figure 5, but when the coolant temperature rises abnormally, it deforms as if it is curled up as shown by the dotted line, and other fuel assemblies It protrudes from the top and produces ultrasound echoes.

As is clear from the above description, 1. The present invention provides a nuclear reactor with a temperature-sensitive deformable body attached to the top of each fuel assembly, and which inherently prevents thermal deformation of the temperature-sensitive deformable body due to an abnormal temperature rise in the coolant. Since it is detected by an ultrasonic fluoroscope,
The instruments such as thermometers and flow meters, which were conventionally installed in each fuel assembly and made up the complicated upper reactor mechanism, were replaced with temperature-sensitive deformable bodies with a very simple structure. It is possible to perform the same function as.

As a result, the reactor structure can be simplified by eliminating the upper reactor mechanism, and the reliability of the reactor can be further improved. This effect is achieved.

It should be noted that the temperature-sensitive deformable body is not limited to the one shown in the illustrated embodiment, and other temperature-sensitive deformable bodies, such as a so-called memory alloy that can be restored to its original shape by thermal change, can of course be used.

[Brief explanation of the drawing]

FIG. 1 is a diagrammatic sectional view showing an example of the structure of a conventional fast breeder reactor, and FIG. Partial sectional view-1 Fig. 3 is a diagrammatic partial sectional view of a nuclear reactor for detailed explanation of the present invention, Fig.
It is a sectional view similar to the figure. l°°゛Core part, -2...Fuel assembly, 4A...Temperature-sensitive deformable body. 6...Ultrasonic transmitter/receiver, 7...Reflector. Applicant's agent Seika Inomata? M object 40'#, 5 figures

Claims (1)

[Claims] 4. A temperature-sensitive deformable body attached to the top of each of a large number of fuel assemblies loaded in the reactor core, and an ultrasonic fluoroscopy device that detects the thermal shape of this temperature-sensitive deformable body. A nuclear reactor abnormality detection device. (h) The nuclear reactor abnormality detection device according to claim 1, wherein the temperature-sensitive deformable body is a bellows body in which a gas or liquid having a large coefficient of thermal expansion is sealed. 3. The nuclear reactor normalcy detection device according to claim 7, wherein the temperature-sensitive deformable body is a bimetal.