不同热电转换系统的热管堆反应性引入事故特性研究

Characteristics of reactivity insertion accident of heat pipe reactors using different thermoelectric conversion systems

热管堆具有固有安全性高、结构紧凑等特点,拥有广阔的应用前景。热电转换系统是热管堆中将热能转换成电能的关键系统,其形式和工作原理对热管堆的事故安全特性和动态响应特性具有非常重要的影响。自主研发的热管堆系统分析程序TAPIRS-D已经拥有静态热电转换模块和动态斯特林循环模块,本文在此基础上开发了动态热电转换模块(开式布雷顿循环),结合热管冷却空间反应堆(Space Advanced Reactor with Integrated Cooling System,SAIRS-C)的反应堆设计,开展了热管堆系统在反应性引入事故发生时的系统安全特性研究,并横向对比了不同类型、不同原理热电转换模块对于热管堆系统事故安全特性的影响。计算结果表明:当对热管堆系统的反应性引入相同时,在堆芯功率变化方面,与斯特林热电模块进行耦合的热管堆系统在事故后堆芯功率的变化幅度最小,其缺点是斯特林热电转换模块的热端温度上升幅度较大;在输出功率方面,与开式布雷顿循环模块和半导体热电转换模块相耦合的热管堆系统的输出功率变化幅度相当,均大于斯特林热电转换模块;在循环效率提升方面,与半导体热电转换模块耦合的热管堆系统效率提升幅度最大,其缺点是需要额外关注半导体热电转换模块中的电路负载的安全情况。

[Background]The heat pipe reactor(HPR)is characterized by inherent safety and a compact structure,which making it widely applicable.The thermoelectric conversion system(TEC)is a key system in the HPR that converts thermal energy to electrical energy.Its form and operational principles significantly impact the accident safety characteristics and dynamic response of the HPR.A self-developed analysis code TAPIRS-D for HPR systems has already incorporated stirling cycle with semiconductor thermoelectric conversion system at the Nuclear Safety and Operations Research Laboratory of Xi'an Jiaotong University,China.[Purpose]This study aims to develop a new dynamic thermoelectric conversion module suitable for open Brayton cycle on the basis of the TAPIRS-D code.[Methods]Firstly,an open Brayton TEC model was developed for code TAPIRS-D,making it capable of analyzing heat pipe reactor system coupled with different thermoelectric conversion systems,such as stirling cycle,open Brayton TEC as well as semiconductor thermoelectric conversion system.Then,maximum relative errors in temperature prediction,pressure prediction and maximum flowrate prediction were obtained by comparison between the calculated results of the newly developed open Brayton TEC model and the experimental data to confirm the rationality of the model.Finally,the upgraded TAPIRS-D were applied to evaluate the reactivity insertion accident of SAIRS-C reactor concept,and the transient performance of SAIRS-C coupling with different thermoelectric conversion system were analyzed and compared.[Results]Comparison results show that the newly developed open Brayton TEC model has a maximum relative error of 2%in temperature prediction,a maximum relative error of 3%in pressure prediction and maximum relative error of 15%in flowrate prediction.Under the same accident conditions involving the introduction of reactivity,the calculation results indicate that the reactor using the Stirling conversion system has the smallest change in core power after an accident while the temperature rise of the Stirling machine's hot end is relatively high.[Conclusions]Results of this study demonstrate that the output power of open Brayton cycle and thermoelectric conversion system has a similar variation change,which are both larger than that of stirling conversion system whilst heat pipe reactor system coupling with semiconductor thermoelectric conversion system has the largest cycle efficiency gain.However,special attention should be pay on the circuit load of semiconductor thermoelectric conversion system under reactivity insertion accident.