基于RELAP5的CFETR氦冷陶瓷增殖包层模块热工安全分析

本文对中国聚变工程实验堆(CFETR)氦冷陶瓷增殖(HCCB)包层进行热工安全分析。采用大型反应堆瞬态分析程序RELAP5对HCCB包层建模,并进行稳态分析和假设事故的模拟。计算结果表明,CFETR HCCB包层在真空室内氦气泄漏和增殖区盒内氦气泄漏事故中均未出现结构材料熔化,同时各部分的压强变化情况均未超出设计阈值,包层系统在事故发生后均能有效快速地排出余热。CFETR HCCB包层的设计满足热工安全方面的要求。     

Thermal Hydraulic Design and Analysis of a Water-Cooled Ceramic Breeder Blanket with Superheated Steam for CFETR

The water-cooled ceramic breeder blanket (WCCB) is one of the blanket candidates for China fusion engineering test reactor (CFETR). In order to improve power generation efficiency and tritium breeding ratio, WCCB with superheated steam is under development. The thermal-hydraulic design is the key to achieve the purpose of safe heat removal and efficient power generation under normal and partial loading operation conditions. In this paper, the coolant flow scheme was designed and one self-developed analytical program was developed, based on a theoretical heat transfer model and empirical correlations. Employing this program, the design and analysis of related thermal-hydraulic parameters were performed under different fusion power conditions. The results indicated that the superheated steam water-cooled blanket is feasible.     

Analysis of Time-Dependent Tritium Breeding Capability of Water Cooled Ceramic Breeder Blanket for CFETR

Attaining tritium self-sufficiency is an important mission for the Chinese Fusion Engineering Testing Reactor(CFETR) operating on a Deuterium-Tritium(D-T) fuel cycle. It is necessary to study the tritium breeding ratio(TBR) and breeding tritium inventory variation with operation time so as to provide an accurate data for dynamic modeling and analysis of the tritium fuel cycle. A water cooled ceramic breeder(WCCB) blanket is one candidate of blanket concepts for the CFETR. Based on the detailed 3D neutronics model of CFETR with the WCCB blanket,the time-dependent TBR and tritium surplus were evaluated by a coupling calculation of the Monte Carlo N-Particle Transport Code(MCNP) and the fusion activation code FISPACT-2007.The results indicated that the TBR and tritium surplus of the WCCB blanket were a function of operation time and fusion power due to the Li consumption in breeder and material activation.In addition, by comparison with the results calculated by using the 3D neutronics model and employing the transfer factor constant from 1D to 3D, it is noted that 1D analysis leads to an over-estimation for the time-dependent tritium breeding capability when fusion power is larger than 1000 MW.     

Neutronics Comparison Analysis of the Water Cooled Ceramics Breeding Blanket for CFETR

China Fusion Engineering Test Reactor(CFETR) is an ITER-like fusion engineering test reactor that is intended to fill the scientific and technical gaps between ITER and DEMO.One of the main missions of CFETR is to achieve a tritium breeding ratio that is no less than 1.2to ensure tritium self-sufficiency.A concept design for a water cooled ceramics breeding blanket(WCCB) is presented based on a scheme with the breeder and the multiplier located in separate panels for CFETR.Based on this concept,a one-dimensional(1D) radial built breeding blanket was first designed,and then several three-dimensional models were developed with various neutron source definitions and breeding blanket module arrangements based on the 1D radial build.A set of nuclear analyses have been carried out to compare the differences in neutronics characteristics given by different calculation models,addressing neutron wall loading(NWL),tritium breeding ratio(TBR),fast neutron flux on inboard side and nuclear heating deposition on main in-vessel components.The impact of differences in modeling on the nuclear performance has been analyzed and summarized regarding the WCCB concept design.     

聚变增殖堆液态金属Li自冷包层的热工水力分析

完成了托卡马克商用混合堆 TCB(Tokamak Commercial Breeder)Li 自冷包层设计的热工水力分析,讨论了热工水力设计中的一些关键问题。用两维有限元热传导程序 AYER 计算了 TCB 包层的温度分布,用液态金属 MHD(Magnetohydraudynamic)压降公式计算了包层的压降。同时,还分析了包层冷却剂丧失事故 LOCA 的瞬态热工过程。分析表明,正常工况下,包层结构材料最高温度,结构材料与冷却剂界面最高温度,以及包层总压降都满足堆设计要求。在 LOCA 工况下,如果停堆后1小时内包层中的燃料球能够借助重力卸出包层,第一壁和包层是安全的,并且不会受到损伤。     

Flow Distribution Analysis of Water-Cooled Solid Breeder Test Blanket Module

Blanket system is one of the most important systems in a fusion reactor, which plays an important role in heat removing, radiation shielding and tritium breeding. Water-cooled ceramic breeder (WCCB) blanket module (BM) is one of tritium breeding blanket module concepts for Chinese Fusion Engineering Testing Reactor. According to the preliminary design of WCCB BM, there are complicated cascade and parallel cooling channels, in which maybe exists the nonuniform distribution of flow rate, and resulting adverse effect on heat transfer and safety. In this paper, the whole model of one BM is built by thermal hydraulic analytical code named Relap 5 and the flow distribution issue of water-cooled solid breeder (WCSB) test blanket module (TBM) is analyzed. The systematic analysis results show that the flow rate differences of most parts of the WCSB TBM are less than 4 % in a steady state. Start-up, operational transient and loss of flow accident are also studied, and flow instability in these transient cases is found and needs for further analysis. Three dimensional local model of First Wall is also built by CFX, to investigate flow characteristics at partial WCSB TBM, which shows that flow distribution calculated by CFX is consistent with the results from the thermal hydraulic analytical code. Both of the results of the steady state and transient analysis show that the thermal hydraulic analytical code is appropriate in analyzing the flow distribution and transient issue from the systematic view.     

Activation and Environmental Aspects of In-Vacuum Vessel Components of CFETR

The water-cooled ceramic breeder(WCCB) blanket is one of the three candidates of China's Fusion Engineering Test Reactor(CFETR). The evaluation of the radioactivity and decay heat produced by neutrons for the in-vacuum vessel components is essential for the assessment of radioactive wastes and the safety of CFETR. The activation calculation of CFETR in-vacuum vessel components was carried out by using the Monte Carlo N-Particle Transport Code MCNP, IAEA Fusion Evaluated Nuclear Data Library FENDL2.1, and the nuclear inventory code FISPACT-2007 and corresponding EAF-2007 libraries. In these analyses, the three-dimensional(3-D) neutronics model was employed and the WCCB blanket, the divertor, and the shield were modeled in detail to provide the detailed spatial distribution of the neutron flux and energy spectra. Then the neutron flux, energy spectra and the materials specification were transferred to FISPACT for the activation calculation with an assumed irradiation scenario of CFETR. This paper presents the main results of the activation analysis to evaluate the radioactivity, the decay heat, the contact dose, and the waste classification of the radioactive materials. At the time of shutdown, the activity of the WCCB blanket is 1.88×10~(19)Bq and the specific activity, the decay heat and the contact dose rate are 1.7×10~(13)Bq/kg, 3.05 MW, and 2.0×10~3Sv/h respectively. After cooling for 100 years, 79%(4166.4 tons) radioactive wastes produced from the blanket, divertor,high temperature shield(HTS) and low temperature shield(LTS) need near surface disposal, while21%(1112.3 tons) need geological disposal. According to results of the contact dose rate, all the components of the blanket, divertor, HTS and LTS could potentially be recycled after shutdown by using advanced remote handling equipment. In addition, the selection of Eurofer97 or RAFM for the divertor is better than that of SS316 because SS316 makes the activity of the divertor-body keep at a relatively high level.     

水冷包层模块第一壁流动传热特性初步分析

本文基于我国聚变工程实验堆水冷包层优化设计与安全分析的要求,针对水冷包层模块第一壁的流动传热特性进行三维数值模拟研究。采用计算流体力学方法,建立了水冷包层模块第一壁的三维数值模型,研究流量分配的特点以及温度分布情况,分析与评估在稳态工况、瞬态工况及失流事故下的水冷包层模块第一壁传热能力。研究结果表明,不同冷却管间存在流量分配不均匀的现象;在稳态工况下,水冷包层模块第一壁具有较好的传热能力,瞬态工况下水冷包层模块能够有效地导出反应堆热量;失流事故下冷却管内温度短时间上升至系统压力下的饱和温度,有待进一步研究。相关研究为优化包层第一壁传热设计提供参考,并为今后聚变堆的安全分析提供依据。     

Steady State and Transient Analysis of Novel Design Helium Cooled Ceramic Blanket (HCCB) System of China Fusion Engineering Test Reactor (CFETR)

An upgraded form of China fusion engineering test reactor (CFETR) was investigated for the safety performance. In the current study, modification of the designs were presented with relative tolerance. The steady state were calculated for the new design using Relap5 code. Two accidents were simulated i.e., in-vessel and In-box loss of coolant accident. These accidents were simulated in helium cooled ceramic blanket (HCCB) system for the purpose to investigate the safety measures of the CFETR. It is utmost important to ensure the safety performance of the reactor. In this research, sudden break at blanket system was assumed and calculated different parameters including temperature, pressure and coolant fluxes to observe the differences in pattern during the accident under limited time domain. The research is very important because the design of HCCB is new and there is a need to conduct steady state and transient state of the reactor in order to make sure and authenticate the design and to safer the reactor.     

中国聚变工程试验堆包层的核热耦合效应研究

本文以中国聚变工程试验堆（CFETR）的氦冷固态包层和水冷固态包层为研究对象,基于蒙特卡罗程序MCNP和计算流体力学程序FLUENT,利用3D-1D-2D耦合方法和伪材料方法,分别对200 MW的氦冷固态包层和水冷固态包层及1.5 GW的水冷固态包层方案进行了核热耦合计算分析。研究结果表明,金属铍的热散射效应和轻水密度是聚变包层核热耦合效应的主要来源,核热耦合效应对氦冷固态包层的影响可忽略,对水冷固态包层的氚增殖比和温度分布有一定程度的影响。     

Availability Analysis for CFETR

Availability analysis for Chinese fusion engineering testing reactor (CFETR) is very important at the pre-conceptual phase. Availability apportion are the theoretical basis of system design of CFETR. Availability analysis informs the development of the CFETR overall system and subsystem design. Availability analysis will enable the identification of key subsystems to achieve availability targets. The duty cycle of CFETR should be at least 0.3–0.5. Such design goals require all subsystems of CFETR must have a pretty high availability. The availability of CFETR can be defined by break time analysis results. Analysis results proved that the availability of CFETR is 0.5–0.7. All availability subsystems of CFETR can be apportioned from their relevant mean time before failure (MTBF) and mean time to repair (MTTR) data to meet the availability goals. The relation between reliability, maintainability and availability indicates that a subsystem could have a high availability though its reliability is pretty low. Availability apportionment and analysis indicate that the availability of blanket and divertor should be 0.769–0.91 to meet the design requirements and their availability can be improved by increase the MTBF and reduce the MTTR of blanket and divertor with the development of remote handling or remote maintenance technology for fusion reactor.     

Updated neutronics analyses of a water cooled ceramic breeder blanket for the CFETR

The water cooled ceramic breeder (WCCB) blanket employing pressurized water as a coolant is one of the breeding blanket candidates for the China Fusion Engineering Test Reactor (CFETR).Some updating of neutronics analyses was needed,because there were changes in the neutronics performance of the blanket as several significant modifications and improvements have been adopted for the WCCB blanket,including the optimization of radial build-up and customized structure for each blanket module.A 22.5 degree toroidal symmetrical torus sector 3D neutronics model containing the updated design of the WCCB blanket modules was developed for the neutronics analyses.The tritium breeding capability,nuclear heating power,radiation damage,and decay heat were calculated by the MCNP and FISPACT code.The results show that the packing factor and 6Li enrichment of the breeder should both be no less than 0.8 to ensure tritium self-sufficiency.The nuclear heating power of the blanket under 200 MW fusion power reaches 201.23 MW.The displacement per atom per full power year (FPY) of the plasma-facing component and first wall reach 0.90 and 2.60,respectively.The peak H production rate reaches 150.79 appm/FPY and the peak He production reaches 29.09 appm/FPY in blanket module # 3.The total decay heat of the blanket modules is 2.64 MW at 1 s after shutdown and the average decay heat density can reach 11.09 kW m-3 at that time.The decay heat density of the blanket modules slowly decreases to lower than 10 W m-3 in more than ten years.     

Neutronics Analysis of Water-Cooled Ceramic Breeder Blanket for CFETR

In order to investigate the nuclear response to the water-cooled ceramic breeder blanket models for CFETR, a detailed 3D neutronics model with 22.5otorus sector was developed based on the integrated geometry of CFETR, including heterogeneous WCCB blanket models,shield, divertor, vacuum vessel, toroidal and poloidal magnets, and ports. Using the Monte Carlo N-Particle Transport Code MCNP5 and IAEA Fusion Evaluated Nuclear Data Library FENDL2.1,the neutronics analyses were performed. The neutron wall loading, tritium breeding ratio, the nuclear heating, neutron-induced atomic displacement damage, and gas production were determined.The results indicate that the global TBR of no less than 1.2 will be a big challenge for the watercooled ceramic breeder blanket for CFETR.     

An Analysis of Ripple and Error Fields Induced by a Blanket in the CFETR

The Chinese Fusion Engineering Tokamak Reactor(CFETR) is an important intermediate device between ITER and DEMO. The Water Cooled Ceramic Breeder(WCCB)blanket whose structural material is mainly made of Reduced Activation Ferritic/Martensitic(RAFM) steel, is one of the candidate conceptual blanket design. An analysis of ripple and error field induced by RAFM steel in WCCB is evaluated with the method of static magnetic analysis in the ANSYS code. Significant additional magnetic field is produced by blanket and it leads to an increased ripple field. Maximum ripple along the separatrix line reaches 0.53% which is higher than 0.5% of the acceptable design value. Simultaneously, one blanket module is taken out for heating purpose and the resulting error field is calculated to be seriously against the requirement.     

Feasibility study of applying the passive safety system concept to fusion–fission hybrid reactor

The fusion–fission hybrid reactor can produce energy, breed nuclear fuel, and handle the nuclear waste, etc., with the fusion neutron source striking the subcritical blanket. The passive safety system consists of passive residual heat removal system, passive safety injection system and automatic depressurization system was adopted into the fusion–fission hybrid reactor in this paper. Modeling and nodalization of primary loop, partial secondary loop and passive core cooling system for the fusion–fission hybrid reactor using relap5 were conducted and small break LOCA on cold leg was analyzed. The results of key transient parameters indicated that the actuation of passive safety system could mitigate the accidental consequence of the 4-inch cold leg small break LOCA on cold leg in the early time effectively. It is feasible to apply the passive safety system concept to fusion–fission hybrid reactor. The minimum collapsed liquid level had great increase if doubling the volume of CMTs to increase its coolant injection and had no increase if doubling the volume of ACCs.     

CFETR第一壁及赤道面外包层中子辐照损伤初步分析

中国聚变工程实验堆(Chinese Fusion Engineering Testing Reactor,CFETR)的包层和偏滤器第一壁面向堆芯等离子体,第一壁辐照损伤分析对于托克马克安全运行至关重要。赤道面外包层较其它包层距离堆芯等离子体中心更近,其结构材料承受中子辐照大。因此,进行中子辐照损伤评估十分必要。基于此目的,采用计算机辅助设计(Computer Aided Design,CAD)模型和蒙特卡罗中子学建模转换接口Mc CAD完成中子学建模,并用蒙特卡罗方法的粒子输运程序计算第一壁和氦冷固态外包层结构材料辐照损伤。此外,对比了铍和钨作为面向等离子体材料两种情况下第一壁的受损情况。计算结果表明,氦冷固态包层模型下结构材料可以满足CFETR一期的运行要求。     

cosRMC复杂曲面开发及在聚变中子学的应用

中国聚变工程实验堆（CFETR）是我国自主设计和研制的重大科学工程,CFETR旨在与ITER相衔接和补充,为研制DEMO级别聚变堆电站提供必要的技术。蒙特卡罗方法在聚变中子学与屏蔽设计等方面具有重要作用。本文基于自主化蒙特卡罗程序cosRMC,研究了蒙特卡罗复杂曲面建模的数学模型和计算方法,开发了复杂曲面建模功能,并通过PPCS（power plant conceptual study）模型验证了该功能实现的正确性。然后构建了CFETR的三维精细化模型,并利用该模型对CFETR包层设计中的关键中子学参数进行计算分析。结果表明,cosRMC对中子学参数氚增殖比、中子壁载荷和核热沉积的计算结果与MCNP的计算值吻合良好,相对偏差均小于5%,满足工程设计需求。研究证明了cosRMC应用于聚变堆包层中子学分析的正确性和有效性。CFETR中子学参数的计算分析,也为其设计和优化提供了参考。     

CFETR氦冷陶瓷增殖包层在等离子体主破裂时的电磁结构耦合分析

增殖包层作为中国聚变工程实验堆(China Fusion Engineering Test Reactor,CFETR)的核心部件,承载着能量转换和氚增殖的重要作用。中国科学院等离子体物理研究所在之前增殖包层设计的基础上,又提出了氦冷陶瓷增殖(Helium Cooled Ceramic Breeder,HCCB)包层的概念设计。为评估电磁载荷对HCCB包层结构安全性的影响,借助通用有限元软件ANSYS,研究计算了在等离子体主破裂时包层中产生的感应涡流、洛伦兹力和力矩。通过多物理场耦合分析方法,获取了包层中产生的等效应力和形变位移。结果表明,在等离子体电流指数衰减时,HCCB包层模型上产生的最大等效应力和形变位移满足包层结构设计的要求,同时模拟分析结果也为未来的包层结构优化以及支撑结构设计提供了必要的数据支撑。     

Impact Analysis of Helium Cooled Solid Blanket Structures on the Tritium Breeding Performance in CFETR

Chinese Fusion Engineering Test Reactor (CFETR) is a test tokamak reactor to bridge the gap between ITER and future fusion power plant. As its objectives are to demonstrate generation of fusion power and to realize tritium self-sufficiency, the tritium breeding ratio (TBR) is a key design parameter. In the blanket design and optimization, the structures such as the first wall (FW), cooling plate (CP), stiffening plate (SP), cap and some other design parameters in detailed 3-D model have significant impacts on the tritium breeding performance. Based on a helium cooled solid breeder blanket option for CFETR, the impact analysis of the helium cooled solid blanket structures on tritium breeding performance was performed in this paper. Firstly, the detailed 3D neutronics model was built by using of a CAD to Monte Carlo Geometry conversion tool McCad. Then based on the detailed 3D neutronics model, the impact analyses of the blanket structures on tritium breeding performance were carried out, which include the FW, CP, SP, cap and side wall. By the sensitivity study of the blanket structures on the TBR, it gave the TBR variation trend and references for the blanket design and optimization.