Development of Online Sipping Detection Device Based on β-γ Coincidence Method
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摘要: 反应堆运行期间燃料包壳时常会发生破损，当燃料组件发生破损后，核电厂通常会在换料过程中使用在线啜吸装置对每个燃料组件进行啜吸试验，通过裂变产物分析确定被测组件是否发生破损，然而受核岛内过强的辐射环境干扰影响，传统单一β或单γ粒子检测设备的检测结果时有误判或漏判发生。本文设计了一种基于β-γ符合法测量技术的在线啜吸检测装置，装置含有β和γ粒子探测器，并构建了β-γ符合检测通道，融合了现有β、γ破损判断技术，同时增加了基于β-γ符合判断的结果。相关应用结果表明：在核岛内较强辐射干扰下，本系统符合测量本底计数率可达到0.04 s–1，装置对133Xe最小可探测活度（MDA）达23.7 Bq，检测灵敏度优于单一β粒子或γ粒子检测模式；3种判断模式的应用大幅提升了破损判断结果的可靠性。该装置可以替代现有单一粒子检测模式的在线啜吸检测装置应用于核电厂开展相关检测工作。
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关键词:
- 组件破损 /
- 符合法 /
- 在线啜吸检测 /
- 最小可探测活度（MDA）
Abstract: The fuel cladding tubes damage often occurs during the operation of the reactor. When a fuel assembly is damaged, the power plant usually performs a sipping test on each fuel assembly using an online sipping device during the re-fueling process, and determines whether the tested assembly is damaged. However, due to the influence of the strong radiation in the island, misjudgment and missed judgment may occur in the detection results by detecting single β or γ particle. In this paper, an online-sipping detection device based on β-γ coincidence measurement technology is designed, which contains β and γ particle detectors, and a β-γ coincidence detection channel. It combines existing β and γ damage judgment technologies and adds the results based on β-γ coincidence judgments. The results of the applications show that the device background counting rate can reach 0.04 s–1 and the Minimum Detectable Activity (MDA) of 133Xe can reach 23.7 Bq under the environmental radiation in the nuclear island. The detection sensitivity is better than that of a single β or γ particle detection mode. The application of the three judgment modes significantly enhances the reliability of damage determination results. This device can replace the existing online sipping detection device of single particle detection mode and be applied to the nuclear power site to carry out relevant detection work. -
图 2 在线啜吸装置气体回路系统原理图
Figure 2. Schematic Diagram of the Air Circuit of Online Sipping Device
表 1 不同探测方法下Nb测量结果及MDA计算结果对比
Table 1. Comparison of Nb and MDA Results under Different Detection Methods
测试条件 β测量道 γ测量道 β-γ符合道 测量时间/s 300 自然Nb 151 24 2 MDA/Bq 30.3 7.2 14.6 
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表 2 不同装置MDA结果对比
Table 2. Comparison of MDA Results of Different Devices
测试装置 筒内啜
吸装置镜式啜
吸装置本文符合测量装置 β测量道 γ测量道 β-γ符合道 自然nb/s–1 0.8 50 50.3 0.8 0.007 采样体积/L 2 0.06 0.63 MDA/Bq 20.0 35.1 30.3 7.2 14.6 MDC/(Bq·L−1) 10 585 48 11.4 23.2
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表 3 本装置在某现场本底计数率nb′测量结果及MDA计算值
Table 3. Comparison of Background Counting Rate nb′ and MDA Results of the Device in Field
测量指标 测量方式 β测量道 γ测量道 β-γ符合道 某现场nb′/s–1 121.5 22.5 0.04 MDA/Bq 43.0 33.5 23.7 MDC/(Bq·L−1) 68.3 53.2 37.6
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