气冷快堆温度反馈效应优化及堆芯方案优化设计  

Optimization of reactivity temperature feedback and core design of GFR

作　　者：周梦飞 易璇 刘国明 ZHOU Mengfei;YI Xuan;LIU Guoming(China Nuclear Power Engineering Co.Ltd.,Beijing 100840,China)

机构地区：[1]中国核电工程有限公司,北京100840

出　　处：《核技术》2025年第1期176-184,共9页Nuclear Techniques

摘　　要：气冷快堆的堆芯安全设计是制约其研发进度的关键技术难点之一,而增强温度负反馈效应是提高堆芯固有安全性的有效手段。针对气冷快堆堆芯能谱较硬、反应性温度系数小、温度负反馈效应弱的问题,本文提出了一种增强温度负反馈的气冷快堆堆芯优化设计方案。通过合理布置慢化材料、优化活性区高径比、优化燃料富集度等手段,达到了调节堆芯能谱、强化多普勒效应、增强活性区中子泄漏,进而增强堆芯温度负反馈的优化效果。采用三维蒙特卡罗输运程序对上述气冷快堆堆芯方案进行模拟分析,结果表明:优化后的堆芯具有均匀的功率分布和充足的安全裕量,且能够在温度限值内仅依靠温度负反馈效应实现自动安全停堆,验证了优化手段的有效性和堆芯方案的安全可靠性。[Background]Gas-cooled fast reactor(GFR)is one of the six recommended nuclear reactor types of Generation IV Forum(GIF)with the lowest technical maturity.Cooled by inert gas like helium and super critical carbon dioxide which performs not so good as water or liquid metal in heat transfer,GFR has been challenged by safety issues especially in Loss-Of-Coolant-Accident(LOCA)events.It has been considered to be an effective way to improve the core inherent safety of GFR by strengthening the temperature feedback on reactivity in the core.However,with no moderating materials and low neutron reaction rates which cause a harder neutron spectrum than other reactor types,GFR has very weak negative temperature feedback.[Purpose]This study aims to optimize nuclear design of GFR core by increasing the negative temperature feedback.[Methods]Firstly,moderating materials were utilized in the fuel assemblies(FAs)in order to get a softer neutron spectrum in the core and increase both the doppler effect of the fuel and the temperature feedback on reactivity.Four moderators including graphite,beryllium oxide,zirconium carbide and zirconium hydride were used in the FA with different geometric structures such as uniformly mixing in the fuel pellets,separate rods distributed in the fuel rod bundles and thick layer outside the fuel rod bundles.Then,Monte Carlo(MC)calculation software RMC was employed to carry out neutronics analysis of the GFR core.Neutronics characteristics of these FA models was comparatively analyzed in details to find the best performance FA model.Finally,a 10-megawatt-power micro GFR core design was given based on the selected FA structure.Effects of the High-to-Diameter ratio(H/D)value as well as the uranium enrichment of fuel on the temperature feedback of the core were thoroughly studied and optimization of the GFR nuclear design was conducted.[Results]The MC simulation results show that the optimized GFR core has a more than twice larger reactivity temperature coefficient value compared to the general core desig

关 键 词：气冷快堆 温度负反馈 能谱调节 堆芯设计 固有安全性 

分 类 号：TL329[核科学技术—核技术及应用] TL43+3TL424