CN-121978742-A - Dual-insulation material self-powered detector and production method thereof

CN121978742ACN 121978742 ACN121978742 ACN 121978742ACN-121978742-A

Abstract

The invention relates to a double-insulation material self-powered detector and a production method thereof, wherein the detector comprises a shell, an insulator, an emitter and a signal wire, the insulator is of a three-layer composite structure which is sequentially distributed along the axial direction and integrally sintered and formed, the detector comprises a first insulation layer positioned at the detector probe end, a second insulation layer positioned at the detector cable end, and a composition gradient transition layer positioned between the first insulation layer and the second insulation layer, the chemical composition of the composition gradient transition layer is continuously changed along the axial direction, and the composition gradient transition layer gradually transits from 100% magnesium oxide close to the first insulation layer to 100% aluminum oxide at the joint of the second insulation layer. The material distribution of the double-insulation material self-powered detector insulator along the axial direction is matched with the axial working condition (high temperature and high radiation at the lower end and low temperature ion pollution at the upper end) of the detector, so that the characteristics of the insulator material are fully exerted, and the service life and the detection stability of the detector are improved.

Inventors

XUE HONGYUAN
BU JIANGTAO
NI JIE
ZHU SHUJIN
WANG YANHONG
XU QINGHUA
QU HAITAO
XU MENGXUAN
CAI ZHIZHOU
LV MAOSHENG
XIE JINGJING
ZHENG MINGGUANG
WU FANGLIANG
KUANG HONGBO
XIONG WEIHUA
BI DAOWEI

Assignees

上海核工程研究设计院股份有限公司
浙江伦特机电有限公司
中核核电运行管理有限公司

Dates

Publication Date: 20260505
Application Date: 20260209

Claims (9)

1. The double-insulation material self-powered detector comprises a shell, an insulator, an emitter and a signal wire, and is characterized in that the insulator is of a three-layer composite structure which is sequentially distributed along the axial direction and integrally sintered and formed, and the double-insulation material self-powered detector comprises: the first insulating layer is positioned at the probe end of the detector and is made of magnesia ceramics; the second insulating layer is positioned at the cable end of the detector and is made of alumina ceramic; and a compositionally graded transition layer between the first insulating layer and the second insulating layer; the chemical composition of the composition gradient transition layer continuously changes along the axial direction, and gradually transits from 100% magnesium oxide at the joint of the composition gradient transition layer and the first insulating layer to 100% aluminum oxide at the joint of the composition gradient transition layer and the second insulating layer.
2. The dual insulation self-powered detector of claim 1, wherein said compositionally graded transition layer is comprised of at least 5 axially layered mixed material sublayers, each of said mixed material sublayers having a constant and different mass fraction of magnesia that decreases from layer to layer in a direction from the first insulation layer toward the second insulation layer.
3. The dual insulation self-powered detector of claim 1 or 2, wherein the purity of the magnesium oxide or aluminum oxide in the first insulation layer and the second insulation layer is not less than 99.9%.
4. The dual-insulation self-powered detector as claimed in claim 1 or 2, wherein the first insulation layer, the second insulation layer and the composition gradient transition layer all contain rare earth oxide as sintering aid and grain boundary modifier, and the addition amount of the rare earth oxide accounts for 0.1-2% of the total mass of the ceramic material.
5. A method for producing an insulator of a double-insulating-material self-powered detector is characterized by comprising the following steps: s1, slurry preparation and forming: Preparing a plurality of ceramic slurries, wherein the mass ratio of the raw materials of magnesium oxide and aluminum oxide changes along a preset gradient to form at least 7 different ratios from 100% magnesium oxide to 100% aluminum oxide; Sequentially grouting and forming in a mould according to the sequence of the magnesium oxide content from high to low to form a composite green body consisting of a first insulating layer green body, a component gradient transition layer green body and a second insulating layer green body, wherein adjacent green body layers are combined in a wet state; S2, compacting a green body: Drying the composite green body, followed by cold isostatic pressing at a pressure in the range of 150MPa to 250MPa to eliminate interlayer gaps to obtain a high density monolithic green body; s3, integral sintering: Placing the integral biscuit in a sintering furnace for co-sintering; the sintering process comprises the steps of setting a heat preservation platform in a temperature rising process at a temperature range of 1200-1400 ℃, completing final densification in a hydrogen or vacuum atmosphere at a temperature range of 1650-1800 ℃, and performing controlled rapid cooling after sintering, wherein the cooling rate is not more than 1 ℃ per minute in a temperature range of 1300-800 ℃.
6. The method of claim 5, wherein in the step S1, 7 ceramic slurries are prepared with a mass ratio of 100:0, 90:10, 70:30, 50:50, 30:70, 10:90 and 0:100 of magnesium oxide to aluminum oxide, respectively.
7. The method of producing a dual insulator self-powered detector insulator as claimed in claim 5, wherein in step S1, each ceramic slurry is formulated with rare earth oxide powder added thereto in an amount of 0.1 to 2% by mass based on the total mass of ceramic powder in the slurry.
8. The method of producing a dual-insulation self-powered detector insulator according to claim 5, wherein in step S3, when the temperature is reduced to 800 ℃ or less by controlling the temperature, the temperature reduction rate is increased to 2 ℃ per minute to 5 ℃ per minute.
9. A production method of a double-insulation self-powered detector is characterized by comprising the following steps: S1, preparing an insulator by the production method of the double-insulation material self-powered detector of any one of claims 5-8; S2, after the emitter is welded with the signal wire, penetrating into a central hole of the insulator from one end of the second insulating layer to a preset position; s3, transferring the insulator assembled with the emitter and the signal wire into the shell from one end of the first insulating layer; s4, carrying out drawing diameter reduction treatment on the shell to enable the shell to form interference fit with the outer wall of the insulator, and finally carrying out stress relief annealing on the whole component at the temperature of 600-750 ℃.

Description

Dual-insulation material self-powered detector and production method thereof Technical Field The invention relates to the technical field of nuclear measuring instruments, in particular to a double-insulation material self-powered detector and a production method thereof. Background The self-powered detector is used for neutron flux detection of a nuclear reactor core, and mainly comprises a shell, an emitter, an insulator and a signal wire, wherein two ends of the detector are a probe end and a cable end respectively, the emitter arranged in the probe end is subjected to beta decay after absorbing neutrons to release electrons, a current signal is generated through charge accumulation, the current signal is transmitted to a potentiometer or a ammeter through the signal wire penetrating out of the cable end to realize measurement, and the insulator is used for realizing electric isolation between the emitter and the shell. In the existing self-powered detector, the insulator is generally a magnesia ceramic tube, because magnesia has the characteristics of extremely high resistivity, good irradiation performance, excellent thermal stability and the like, when the detector is placed in a high-temperature high-radiation reactor core environment to work, the stability and the accuracy of the detector can be ensured, but in practical application, the probe end of the detector is placed in the reactor core environment, the cable end of the detector is placed in a containment environment, the temperature in the containment environment is lower (generally not more than 100 ℃ and more stable) than that in the reactor core environment, neutron flux and radiation level are also lower than that in the reactor core environment, the magnesia ceramic tube generates performance redundancy in the containment environment, and a large amount of alkali metal ions such as sodium ions and potassium ions exist in the containment environment, and the metal ions migrate into a sensitive active area through the insulator to cause the performance drift and failure of the detector. Disclosure of Invention Accordingly, the present invention is directed to a dual-insulation self-powered detector and a method for manufacturing the same, which solve the above-mentioned problems. Based on the above object, the present invention provides: The utility model provides a self-powered detector of double insulation material, includes shell, insulator, emitter and signal line, the insulator is along the axial in proper order distribution and integrative sintered's three-layer composite structure, includes: the first insulating layer is positioned at the probe end of the detector and is made of magnesia ceramics; the second insulating layer is positioned at the cable end of the detector and is made of alumina ceramic; and a compositionally graded transition layer between the first insulating layer and the second insulating layer; the chemical composition of the composition gradient transition layer continuously changes along the axial direction, and gradually transits from 100% magnesium oxide at the joint of the composition gradient transition layer and the first insulating layer to 100% aluminum oxide at the joint of the composition gradient transition layer and the second insulating layer. Preferably, the compositionally graded transition layer is comprised of at least 5 axially stacked mixed material sublayers, each having a constant and different mass fraction of magnesia that decreases from layer to layer in a direction from the first insulating layer toward the second insulating layer. Preferably, the purity of the magnesium oxide or aluminum oxide in the first insulating layer and the second insulating layer is not less than 99.9%. Preferably, the first insulating layer, the second insulating layer and the composition gradient transition layer all contain rare earth oxide serving as a sintering aid and a grain boundary modifier, and the addition amount of the rare earth oxide accounts for 0.1-2% of the total mass of the ceramic material. A method of producing an insulator for a dual-insulation self-powered detector, comprising the steps of: s1, slurry preparation and forming: Preparing a plurality of ceramic slurries, wherein the mass ratio of the raw materials of magnesium oxide and aluminum oxide changes along a preset gradient to form at least 7 different ratios from 100% magnesium oxide to 100% aluminum oxide; Sequentially grouting and forming in a mould according to the sequence of the magnesium oxide content from high to low to form a composite green body consisting of a first insulating layer green body, a component gradient transition layer green body and a second insulating layer green body, wherein adjacent green body layers are combined in a wet state; S2, compacting a green body: Drying the composite green body, followed by cold isostatic pressing at a pressure in the range of 150MPa to 250MPa to eliminate interlayer gaps to obt