声学共鸣法实时测量高温气冷堆堆芯温度机理研究

The real-time measurement of the core temperature of the high temperature gas-cooled reactor is an unresolved problem until now. Due to the high radiation, high temperature and high carburizing of the reactor core, none of the traditional temperature measurement techniques can meet the requirement under the whole temperature range. Problems of temperature drift or even device failure will occur when they are used for a long time. In this subject, a method based on the acoustic resonator method is proposed to measure the temperature in the reactor core or the nearby region. The basic idea is to use graphite and helium, which are totally compatible with the reactor, to produce the temperature measurement device. The sound speed in the helium inside the enclosed cavity made of graphite will be measured to obtain the average kinetic energy of the closed gas system and the thermodynamic temperature can then be calculated. In this subject, the acoustic characteristics of the graphite resonator and the interaction mechanism between it and the helium will be researched. The functional mechanism of each non-ideal disturbance factors will be studied both theoretically and experimentally. Corresponding correction methods to restrain the disturbances will be put forward. This method based on the measurement of the average kinetic energy of the gas system enclosed in a cavity can effectively avoid the high radiation and high carburizing risk in the reactor core and hence exhibits great superiority and significance in science.

高温气冷堆堆芯温度的实时测量是至今尚未解决的技术难题。由于高温堆堆芯高辐照、高温、高渗碳等条件，在全工况温度范围内，现有已知的测温手段均无法胜任实时测温的需求，存在温度漂移及测温失效等问题。本课题提出一种基于声学共鸣法测量高温堆堆芯及近堆芯处温度的测量方法，其基本思路是采用与高温堆完全相容的材料石墨和氦气，制作测温元件，安装在堆芯或近堆芯石墨层内，通过测量由石墨构成的封闭腔内氦气介质的声速，获得封闭系统的平均动能，从而获得热力学温度。本课题将研究石墨材质声学共鸣腔的声学特性，探索其与氦气工质之间的相互作用机理；对各类非理想扰动因素的作用机理分别进行理论和实验分析刻画，提出相应的抑制、消除扰动的修正方法。这种基于封闭共鸣腔内气体系统平均动能的测温方法能有效“回避”高温堆堆芯中的高辐照、高渗碳风险，不存在温度漂移的问题，具有极大的优越性和重要的科学意义。

高温气冷堆堆芯温度的实时直接测量是至今尚未解决的技术难题。由于高温堆堆芯存在高辐照、高温、高渗碳等问题，现有已知的测温手段在长期运行中测温元件受高温渗碳腐蚀，普遍存在温度漂移及测温失效等问题，均无法胜任长期稳定测温的需求。本课题提出一种基于声学共鸣法测量高温气冷堆堆芯及近堆芯处温度的测量方法，其基本思路是采用高温堆堆芯自身结构材料“石墨”和“氦气”，制作测温元件本体，安装在堆芯或近堆芯石墨层内，通过测量由石墨构成的封闭共鸣腔内氦气介质的声速，获得封闭气体系统的平均动能，从而获得热力学温度。这种新式的测温方法将能有效回避高温堆堆芯中的高温渗碳风险，避免了测温元件受腐蚀造成的温度漂移及测温失效问题，具有极大的优越性和重要的科学意义。.研究期间，本课题首先构建了高温气冷堆工况下声学共鸣法温度测量的理论模型，采用He国际标准状态方程从理论上分析计算了He声速随温度、压力变化关系，从理论上分析了采用He声速的热力学关系测量高温气冷堆堆芯温度的可行性，为实验工作奠定了理论基础。接下来，根据实际情况制订了分阶段的具体实验实施方案，进行了第一阶段实验系统的详细方案设计，完成了相应设备及材料的采购，并搭建了声学共鸣法测量实验系统。进一步，进行了多层次的实验验证，采用1 米长的两根声波导管，测量得到了无氧铜圆柱共鸣腔空气中的声学共振频率，验证了1 m长声波导管内声学衰减仍能获得共振频率；采用He在无氧铜腔体和1 m长声波导管上测量了He常温常压的声学共振频率，证明了在密度很小、声学共振频率较高的He内，仍然能够获得声学共振频率；制作了石墨材质的声学共鸣腔，采用He在石墨腔体和1 m长声波导管上测量了He常温常压的声学共振频率，证明了石墨腔的腔体自振基本不会影响He低模式的声学共振频率的测量，从而最终证明了采用He结合石墨腔测量获得声学共振频率以测量热力学温度的方案是可行的。