导　　师： 王侃

学科专业： 0827

授予学位： 博士

作　　者： ;

机构地区： 清华大学

摘　　要： 超临界水堆是六种第四代核能系统中唯一的水冷堆，与传统轻水堆相比，超临界水堆由于能谱变化范围更广，因此可以实现热谱、快谱等不同设计。这一方面增加了超临界水堆物理设计的灵活性，从而为多种燃料的利用以及核素嬗变提供了条件；另一方面，却使得采用多群常数库的传统轻水堆确定论分析程序在几何处理及能谱适用性方面面临较大挑战。 在反应堆物理分析中，蒙卡方法强大的几何处理能力及连续能量中子截面库的应用，使其成为新型核能系统研究的理想工具，但影响其广泛大量使用的最主要原因是其计算耗时长，效率低。本论文提出了一种基于蒙卡组件多群截面统计，采用多群蒙卡进行堆芯物理分析的方法，并研究了相应的等效均匀化方法，大量数值验证证明其具有良好的精度，同时计算效率有了较大的提高。本论文据此建立了蒙卡堆芯燃耗分析计算程序系统，为超临界水堆物理特性研究打下了基础，同时也为其它新型核能系统的物理分析以及等效均匀化方法的研究提供了很好的借鉴。 本论文分别对热谱和快谱两种典型超临界水堆设计进行了研究，同时分析了不同燃料的应用特性。 热谱超临界水堆设计的关键在于组件设计，通过对现有设计的对比分析，本文提出了一种新型含环形慢化剂通道的组件设计，可以使组件内慢化更均匀；进一步地，进行了不含Gd与含Gd可燃毒物的堆芯优化设计，分析了堆芯的平衡循环特性；之后，在组件和堆芯两个层面上对不同燃料的应用特性进行了对比分析，发现其主要与易裂变核素成分相关。 对于快谱超临界水堆，在综合考虑已有设计特点的基础上，本论文针对一种冷却剂“两次流通”的堆芯方案进行了研究，重点分析了不同类型燃料的转换性能、冷却剂空泡反应性、堆芯多循环燃耗特性以及MA和LLFP的嬗变性能，发现MOX燃料的转换性能较好而空泡反应性较差，含Th燃料的转换性能稍差但空泡反应性较好，由于嬗变目标核素对堆芯的安全性能影响较大，因此综合来看含Th燃料优势明显。 本论文的研究成果为将来超临界水堆专用分析工具的研发，以及不同能谱超临界水堆方案设计和燃料的选择，都打下了良好的基础。 Super-Critical Water-cooled Reactor /(SCWR/) is the only one with water ascoolant among the six Generation-IV nuclear energy systems. Comparing withthe traditional light water reactor /(LWR/), SCWR features larger spectrumchange. Thus, it can be designed with thermal spectrum /(SCWR-T/) or fastspectrm /(SCWR-F/), which increases the flexibility of physics designs andprovides good conditions for the utilization of different nuclear fuels and thetransmutation of long-lived radioactive waste. On the other hand, it also forcesthe traditional deterministic neutronics analysis methods of LWR to face thegreat challenges in geometry processing and the multi-spectrum applicability oftheir multi-group cross section libraries. Due to its strong geometry modeling capability and the application ofcontinuous energy neutron cross section libraries, the Monte Carlo /(MC/) methodhas been widely used in reactor physics calculations and it is the ideal tool foranalyzing the innovanent nuclear energy systems. However, MC suffers mostlyfrom its ultra-long simulation time, which prevents it from being used widelyand frequently. To solve this problem, a two-step MC core calculation scheme isproposed in this thesis. Firstly, the group cross sections are tallied for thetypical lattices; secondly, the multi-group MC core simulation is performed withthe group cross sections tallied at the first step. The suitable equivalencehomogenization method is also studied. The precision of the new scheme isconfirmed in many numerical tests, and the calculation efficiency is greatlyimproved at the same time. Furtherly, a MC core burnup analysis code system isdeveloped, which will be the basic SCWR simulation tool in this thesis. It willprovide good references for the neutronics simulations of other newly developednuclear systems and for the research of equivalence theory as well. Both SCWR-T and SCWR-F designs are studied in this thesis and theutilization of different fuels are discussed at the same time. For SCWR-T, the key point lies in the assembly design. According to theanalyses of various existing designs, a new assembly design with an annular moderator channel is proposed, which is demonstrated to have uniformmoderation. The assembly with Gadalinia /(Gd/), the widely used depletablepoison, is also studied. After that, the core loading pattern with and without Gdare designed, and their equilibrium cycle characteristics are compared. Theutilization analysis of different fuels is performed both at the assembly and corelevel, which reveals that the difference is mainly caused by the fissile nuclidecontents. As for SCWR-F, the design with double-pass flow diagram is chosen forstudy, considering the features of many similar existing designs. The workmainly concentrates on the fuel conversion ratio /(CR/), coolant void reactivity/(CVR/), multi-cycle core burnup characteristics and the transmutation of MA andLLFP. It is concluded that MOX fuel has higher CR and also higher CVR, whileTh-based fuels show a little lower CR but much lower CVR. Since the additionof transmutation target nuclides in the fuel will result in worse safety features,Th-based fuels show big advantages over MOX fuel at this point. The research results of this thesis will provide good references for thedevelopment of SCWR-specialised neutronics analysis tools, and also for theSCWR core and fuel designs with various spectrums in future.

关 键 词： 超临界水堆 能谱 蒙卡 均匀化

分 类 号： [TL32]

领　　域： [核科学技术]