The reactor nuclear instrumentation system measures the reactor neutron flux rate through a series of neutron detectors placed outside the reactor to provide initial measurement signals for reactor start-up,operation and safety.The measurement range of the intermediate range neutron flux rate exceeds 6 orders of magnitude,and the current output by the detector is very weak,the minimum reaches 10 pA,and the requirements for measurement technology are relatively high.The traditional linear current measurement method produces measurement errors caused by range switching,which affects the stability of the reactor cycle measurement and thus affects nuclear reactor safety.In this paper,the logarithmic measurement principle was analyzed in detail,and the logarithmic measurement scheme was proposed.Symmetric compensation technology,temperature compensation technology and full temperature range resistance matching technology were proposed.The neutron flux rate measurement with a wide dynamic range was realized,which avoids the measurement value jump caused by the range switching,and improves the accuracy of the neutron flux rate measurement and the period calculation.The analog detector signal was input with a micro-current of 10 pA-100 μA.The results show that for input exceeding 7 orders of magnitude,the error is less than 0.5％,this scheme is applicable to the intermediate range measurement of the reactor neutron flux rate.
关键词
中子注量率/对数放大/微电流/中间量程/动态范围
Key words
neutron flux rate/logarithmic amplification/micro-current/intermediate range/dynamic range
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