移动式微型裂变电离室中子探测器研制与核特性测试

Development and nuclear characteristic testing of a mobile miniature fission ionization chamber neutron detector

微型裂变电离室是一种反应堆上广泛使用的堆芯中子探测器。国内CPR1000核电机组的堆芯中子注量率测量系统采用移动式微型裂变电离室作为中子探头,在反应堆运行过程中测量反应堆中子通量,提供堆芯中子通量分布图,是核电站重要的安全仪控设备。对标现役国外产品的服役条件和技术指标要求,研制了一款移动式微型裂变电离室中子探测器,并参照国家标准GB/T 7164-2022和行业标准NB/T 20215-2013,对探测器的核特性进行了测试。测试结果表明:其核特性与国外产品相当,有望实现该反应堆安全产品的“国产替代”。

[Background]The miniature fission ionization chamber is a widely used neutron detector for the in-core neutron flux monitoring of a nuclear reactor.Typically,the in-core neutron flux rate measurement system of a domestic CPR1000 nuclear power unit adopts a mobile miniature fission ionization chamber as the neutron probe to measure the neutron flux of the reactor and provide an in-core neutron flux distribution map during the operation.Therefore,it is an important piece of safety and control equipment for nuclear power plants.[Purpose]This study aims to develope a mobile miniature fission ionization chamber neutron detector according to the service conditions and technical requirements of current foreign products.[Methods]The nuclear properties of self-made fission ionization chamber neutron detector was developed strictly following the national standard GB/T 7164−2022 and the industry standard NB/T 20215−2013.The gamma sensitivity was tested and compared with a reference commercial fission detector using a 60Co gamma source.The thermal neutron detection characteristic,including the length and slope of plateau,the thermal neutron sensitivity and linearity were tested in one test channel of the China Mianyang Research Reactor(CMRR)with neutron flux from 1×109 n∙cm−2∙s−1 to 4×1013 n∙cm−2∙s−1.[Results&Conclusions]The test results indicate that"domestic substitution"of this in-core safety product can be achieved,and the nuclear characteristics of self-developed prototypes are comparable to those of foreign products.