JPS60214295A - Measuring device for nuclear 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 (Technical Field of the Invention) The present invention relates to a nuclear reactor measuring device in which an electrically insulating insulator for electrical insulation is improved.

[Technical Background of the Invention] For example, neutron detectors, gamma ray detectors, and detection signals from these detectors that directly measure radiation levels, etc. in radiation utilization facilities such as nuclear power plants, reprocessing facilities, or radiation irradiation facilities are used. Transmission signal cables are required to have radiation resistance characteristics.

Of the above-mentioned detectors, in-reactor neutron detectors and thermocouples in particular are used under the most severe conditions, and therefore active measures are taken to make these detectors radiation-resistant. It is constructed so that it does not operate stably for a long period of time in the furnace.

Hereinafter, an in-core neutron detector will be explained as an example with reference to FIG. FIG. 1 is a longitudinal cross-sectional view showing a part of the in-core neutron detector, and the upper part of the figure indicates the ionization chamber, and the upper part of the figure shows the ionization chamber part, and the symbol -?
- indicates the signal cable section. The ionization chamber 8IIL is composed of an ionization chamber case 3, an anode 4 arranged at a distance within the ionization chamber case 3, and a cathode 5 attached to the inner peripheral surface of the ionization chamber case 3. ing. The ionization chamber case 3' is made of a metal having heat resistance, contact resistance, and radiation resistance, such as austenitic stainless steel. The anode 4 is supported at both ends by the ionization chamber case 3 via anode support members 7A and 7B. The anode support members 7A and 7B are made of ceramic and not only support the anode 4 but also provide electrical insulation. Examples of the above-mentioned ceramics include alumina (8β203), magnesia (Mill
O), silica (SiO2), etc. Further, the ionization chamber case 3 is filled with inert gas and sealed with an insulating seal 11A. This insulating seal 11A is also made of ceramics like the supporting members 7A and 7B. On the other hand, the signal cable section? - consists of a signal cable sheath 8 connected to the ion chamber case 3 and a signal cable core 9 housed in the signal cable sheath 8 and connected to the anode 4; An insulator 10 is filled between the cable sheath 8 and an insulating seal 11B between the insulator 10 and the upper side of the ionization chamber. This insulating seal 11B is configured to prevent moisture from entering into the insulator 10.

These insulators 10 and insulating seals 11B are also made of ceramics, similar to the anode support parts U7A and 7B. The above-mentioned ceramics can sufficiently maintain their performance even when used in a nuclear reactor for a long period of time, so the in-reactor neutron detector can perform highly reliable detection for a long period of time inside a nuclear reactor. .

[Problems with the Background Art] In the above configuration, there is generally a volumetric expansion phenomenon due to neutron irradiation in the furnace, and the above-mentioned ceramics have a problem in this respect. 10 and insulation seal 11
Insulating seals 11A and 11B may expand in volume and lose their performance after long-term use, especially insulating seals 11A and
When B expands, cracks occur, and as a result, the filled inert gas flows out or moisture flows into the insulator 10, making detection impossible.

(Object of the Invention) The present invention has been made based on the above points, and its purpose is to provide an electrically insulating insulator that can maintain its integrity even under long-term neutron irradiation. The object of the present invention is to provide a nuclear reactor measurement device that has improved performance.

[Summary of the invention]

The nuclear reactor measuring device according to the present invention is a nuclear reactor measuring device that performs various measurements in a nuclear reactor, and is characterized in that an electrically insulating insulator for electrical insulation is made of spinel ceramics. It is.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 2 and 3. Note that the same parts as in the prior art are designated by the same reference numerals, and their explanations are omitted. The anode support members 107A and 107B, the insulator 110, and the insulating seals 111A and 111B according to this embodiment are made of spinel type ceramics, such as MQAr1204. This MCI
The properties of Al2204 are shown in Table 1 below in comparison with conventional alumina and magnesia.

Table 1 As shown in Table 1, Mill Aff204, like alumina and magnesia, has excellent properties as a neutron detector insulator. Next, when we look at the volumetric expansion of MgAu204 due to neutron irradiation, we find that it is extremely low compared to alumina and the like, as shown in FIG. In addition, in Figure 3, the horizontal axis shows the neutron irradiation amount and the vertical axis shows the volumetric expansion coefficient, 1100K [(1100-273)'C],
1015K [(1015-273>'CI and 925
Alumina at K [(925-273) °C], MU
It is a diagram showing changes in the volumetric expansion coefficient of Aj2204, where the case of alumina is shown by a broken line and the case of MgAu204 is shown by a solid line. Further, the case of 1100 is shown in the mouth, the case of 1015 is shown by O mark, and the case of 925 is shown by Δ mark. That is, in the case of alumina, the coefficient of volumetric expansion increases as the amount of neutron irradiation increases, and this tendency becomes more pronounced as the temperature increases. On the other hand, MgAu
It can be seen that the volumetric expansion coefficient of No. 204 is approximately zero regardless of the increase in the neutral preheating 11mlt and the temperature rise, indicating that it hardly expands. In this way, the supporting members 107A and 10 are made of MgAl2204, which hardly expands in volume when irradiated with neutrons.
7B, insulating seals 111A, 111B, and insulator 110, there will be no structural change even if it is used in a nuclear reactor for a long time, and its performance such as maintaining insulation and preventing mechanical damage will be maintained. It is possible to provide an in-core neutron detector that can be maintained reliably and is highly reliable. In particular, by configuring the insulating seals 111A and 111B with MgAl2204, it is possible to reliably prevent the occurrence of cracks, which had been a concern in the past. Situations such as inflow can be prevented and the integrity of the detector can be reliably maintained.

In the above embodiment, the case where the present invention is applied to an in-reactor neutron detector has been described, but the present invention is not limited to this, and can be applied to various radiation detectors such as a gamma ray detector, a beta ray detector, an alpha ray detector, etc. can also produce the same effect. Mata1i11
It is applicable not only to the 11-box type but also to the proportional counter type, Geiga tube type, Muller tube type, and semiconductor type. Furthermore, in addition to radiation detectors, the same effect can be achieved even when applied to thermal lightning pairs for temperature measurement or eddy current detectors for detecting flow velocity.

〔Effect of the invention〕

As detailed above, the nuclear reactor measurement device according to the present invention has the following features:
A nuclear reactor measuring device for performing various measurements in a nuclear reactor is characterized in that an electrically insulating insulator for electrical insulation is made of spinel type ceramics.

Therefore, it is possible to reliably maintain its performance even during long-term neutron irradiation, and it is possible to provide a highly reliable nuclear reactor measurement device.

[Brief explanation of the drawing]

Fig. 1 is a partial side view of a conventional in-core neutron detector, and Fig. 3 shows alumina and M! It is a diagram showing a comparison of the volumetric expansion coefficient with J Al2O2. 1-... Electric box part 1. ? -...Signal cable section, 3.
...Ionization chamber case, 4...Anode, 5...Cathode, 10
7A, 107B...1ilII support member, 8...Signal cable covering, 9...Signal cable core wire, 110.
...Insulator, 111A. 111B...Insulating seal. Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 2154

Claims (5)

[Claims] (1) A nuclear reactor measuring device for performing various measurements in a nuclear reactor, characterized in that an electrically insulating insulator for electrical insulation is made of spinel type ceramics. (2) The above nuclear reactor measurement device is a neutron detector, and a spinel type ceramic is used to connect the ionization chamber case with a cathode on the inner peripheral surface and the anode housed at a distance within the ionization chamber case. 2. The nuclear reactor measuring device according to claim 1, wherein the measuring device is insulated and supported by a supporting member. (3) The above-mentioned neutron detector has a signal cable connected to the anode and a signal cable sheathing connected to the ionization box case on the outer periphery of the signal cable. 3. The nuclear reactor measuring device according to claim 2, wherein the space between the two is insulated by an insulating material made of spinel type ceramics. (4) The nuclear reactor measuring device according to claim 1, wherein the nuclear reactor measuring device is a thermal lightning pair for temperature measurement. (5) The nuclear reactor measuring device according to claim 1, wherein the nuclear reactor measuring device is an eddy current detector for detecting flow velocity.