ITER赤道窗口生物屏蔽层特性研究

ITER赤道窗口生物屏蔽层外的窗口室是放置各种电子仪器和管道的场所,在停堆后允许人员进入其中进行维修等工作.为了保证工作人员安全,本文研究了停堆后窗口室中的剂量率分布.文中使用大型集成中子学计算分析系统VisualBUS中的建模、计算分析模块完成了停堆剂量率计算.结果表明,ITER停堆1天后赤道窗口室中剂量率高出限值(...     

ITER上窗口屏蔽中子学分析研究

利用CAD/MCNP自动建模程序MCAM建立ITER新上窗口中子学计算模型,使用中子/光子耦合输运程序MCNP/4CI、AEA聚变核数据库FENDL1.0和集成上窗口模型的ITER基本中子学模型计算并分析上窗口新的工程设计的屏蔽能力以检验设计的合理性。结果表明,与以前的上窗口设计相比,新设计的上窗口的周围剂量控制点的快中子注量率、停堆剂量率以及线圈核热等都增大了好几倍,建议进一步改进上窗口设计。     

基于SuperMC的ITER下窗口生物屏蔽插件屏蔽分析

在国际热核聚变实验堆(ITER)中,窗口生物屏蔽插件需为电子设备和工作人员提供必要的辐射屏蔽防护。基于中子学分析的生物屏蔽插件设计是ITER设计的重要内容。本文基于超级蒙卡核模拟软件SuperMC,在ITER大厅三维中子学模型中整合了ITER设计整合部门(DIN)最新设计的下窗口生物屏蔽插件模型,对四种下窗口生物屏蔽插件进行了屏蔽分析。分析结果显示,低温恒温器低温泵生物屏蔽插件中子屏蔽性能最好,室内监视系统生物屏蔽插件屏蔽性能最差;室内检视系统生物屏蔽插件停堆剂量率最小,环形低温泵生物屏蔽插件停堆剂量率最大。在SA2辐照方案下,停堆12天后,环形低温泵生物屏蔽插件处停堆剂量率超过规定限值20倍。分析结果表明,ITER下窗口生物屏蔽插件设计有待优化。     

ITER中国液态锂铅实验包层模块中子学分析

基于ITER装置全模型,借助于MCNP自动建模程序MCAM,将TBM模块插入该模型的赤道窗口,使用MCNP/4C和FENDL1.0数据库,对DLL和SLL两个典型子模块设计进行三维中子学计算和分析,给出TBM模块核热功率密度分布以及氚增殖能力.     

中国ITER固态实验包层模块活化特性计算分析

基于中国ITER氦冷固态实验包层(HCSB-TBM)3×6 模块化结构设计,对其活化特性进行了计算分析.利用蒙特卡罗程序MCNP及数据库FENDL/2进行三维中子输运计算,在此基础上,使用欧洲活化分析系统EASY-2007进行了详细的活化计算.结果表明,刚停堆时,测试包层模块(TBM)总活度为1.29×1016 Bq,总余热为2.46 kW,且均主要受低活化马氏体钢Eurofer材料控制.活度和余热值均在TBM安全设计范围内,且不会对环境造成显著影响.同时,根据计算的接触剂量率可知,TBM中的活化材料均能采取远程操作实现循环再利用.活化计算结果表明,当前的HCSB-TBM设计从中子活化角度满足ITER安全设计需求.     

中国氦冷固态实验包层2×6模块中子学计算分析

为了满足ITER对波纹度的要求,核工业西南物理研究院提出了新的减少低活化铁素体钢的氦冷固态（HCSB）实验包层模块（TBM）设计方案。采用MCNP程序及ITER全堆MCNP模型,对新设计的2×6HCSB-TBM进行三维中子学计算分析,给出了模块产氚率、核热沉积和功率密度分布等结果。在ITER运行因子为22%时,HCSB-TBM的产氚率为12.68mg/d。TBM内总核热沉积为522.5kW,最高功率密度为11.8W/cm³,出现在氚增殖区Li₄SiO₄中。计算结果可为TBM进一步的结构、热工水力学优化及其他系统设计提供中子学数据。     

MCAM4.8在ITER建筑大厅子学建模中的应用

国际热核聚变实验堆ITER的基准中子学分析模型只包含了托克马克装置.为了进行托克马克装置生物屏蔽以外的中子学分析,需要建立其建筑大厅的中子学计算模型.本文利用蒙特卡罗计算自动建模软件MCAM,在最新的ITER建筑大厅的工程CAD模型基础上,建立了ITER装置生物屏蔽层外墙的建筑大厅中子学计算模型.该模型是第一个包含托克...     

基于CAD的内耦合严格两步法停堆剂量率计算方法研究

核装置尤其是聚变装置中结构材料的辐照活化问题,对核装置的辐射安全具有重要影响。停堆剂量率是材料辐照活化计算中的重要参数,也是聚变堆设计的重要参考依据。本文基于超级蒙卡核模拟软件系统SuperMC的中子/光子输运计算功能和中子活化计算功能,开展了严格两步法停堆剂量率计算方法研究。与传统的输运-活化程序外耦合方法相比,本文发展了一种基于CAD的内耦合严格两步法停堆剂量率计算方法,直接基于CAD模型进行网格材料映射,并支持扇形圆柱源抽样,在提高易用性和灵活性的同时,消除了传统方法在圆柱坐标系活化区计算的不足和处理复杂几何时的局限性。最后利用国际热核聚变实验堆ITER发布的停堆剂量率计算基准例题进行了校核计算,计算结果表明了该方法的正确性和可靠性。     

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。     

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。     

Shielding Analysis for ITER Equatorial Port Cell During Blanket Replacement

ITER port cells are located outside the bio-shield of the Tokamak. During shutdown, the shielding blanket may be replaced and the radioactive blankets will be transported through equatorial port cells, increasing the radiation exposure in the gallery. To examine the dose rate in the gallery with respect to the dose limitation specified by ITER, the activation of typical shielding blanket was calculated using the cell based rigorous two-step method. Then the activated blankets were loaded in cask and moved to the port cell, the radiation level in the port cell and gallery during the worst case was calculated. The shielding capability of port cell door was analyzed and the design was optimized based on the present proposal. As shown from the results, the dose rate from cask is much higher than that from activated Tokamak. The main concern for port cell door should be the concrete lintel and penetrations through it, providing basis for further engineering design of the port cell shielding.     

Structural analysis of ITER TBM Frame and Dummy TBM

One of the main engineering performance goals of ITER is to test and validate design concepts of tritium breeding blankets. To accomplish these goals, three ITER equatorial ports are dedicated to the test of Test Blanket Modules (TBMs) that are mock-ups of tritium breeding blankets. These TBMs, associated with appropriate shield blocks, will also provide the same thermal and nuclear shielding as the main blanket. The main function of TBM Port Plug (PP) is to accommodate TBMs and provide a standardized interface with the vacuum vessel (VV)/port structure.The feasibility of the design concept of the Frame including two Dummy TBMs has been investigated by proposing design improvements of the reference design through an extensive set of thermal, electromagnetic (EM) and stress analyses. As well, the related static strength was evaluated in accordance with the structural design criteria for ITER in-vessel components (SDC-IC). This paper outlines the engineering aspects of the ITER TBM Frame and Dummy TBM and focuses on the feasibility of the present design by structural assessment.     

First neutronics analysis for ITER bio-shield equatorial port plug

ITER equatorial port cell outside the bio-shield plug is a place to allow personnel access after shutdown that accommodates various sensitive equipment and pipes. Gamma dose rate after shutdown of 1 day in the port cell should be within 10 μSv/h for occupational safety which is one order of magnitude less than that in the port interspace by the shielding of bio-shield plug. To verify the shielding property of the bio-shield plug, the distributions of gamma dose rates in port cell were studied. Based on the ITER neutronics model Alite4 which is a three-dimensional ITER tokomak neutronics model for MCNP calculations with a 40 degree extent in the toroidal direction and vertical reflecting bounded planes on both sides, the equatorial port was updated according to a conceptual CAD model using Monte Carlo Automatic Modeling Program for Radiation Transport Simulation (MCAM). A 2-step method of gamma dose rate calculation was used for shutdown dose rates in CAD-based Multi-Functional 4D Neutronics Simulation System (VisualBUS). The result showed that gamma dose rates in the port cell were higher than the desired limit. Refinements to the bio-shield plug design were suggested to ensure that dose rates in the port cell were within the design value for maintenance access.     

Present status of the conceptual design of the EU test blanket systems

The EU Breeding Blanket Programme aims the testing of two blankets concept in ITER in form of Test Blanket Modules. In the equatorial port #16 the two EU TBMs – a solid and a liquid blanket concept – will be exposed to the plasma and the complex system of their auxiliary systems dedicated to heat and Tritium removal will be integrated in the surrounding ITER buildings. The development of the conceptual design of the EU TBM System is the main objective of the Grant F4E-2008-GRT-09 contract launched by F4E and assigned to a European Consortium. This paper presents an overview of the results after about 20 months of activities: namely, the design of the main sub-systems of the EU TBSs and a concept of integration in ITER.     

Design update,thermal and fluid dynamic analyses of the EU-HCPB TBM in vertical arrangement

In the frame of the activities of the EU Breeder Blanket Programme and of the Test Blanket Working Group of ITER, the Helium Cooled Pebble Bed Test Blanket Module (HCPB TBM) is developed in Forschungszentrum Karlsruhe (FZK) to investigate DEMO relevant concepts for blanket modules.The three main functions of a blanket module (removing heat, breeding tritium and shielding sensitive components from radiation) will be tested in ITER using a series of four TBMs, which are irradiated successively during different test campaigns. Each HCPB TBM will be installed, with a vertical orientation, into the vacuum vessel connected to one equatorial port. As the studies performed up to 2006 in FZK concerned a horizontal orientation of the HCPB TBM, a global review of the design is necessary to match with the new ITER specifications.A preliminary version of the new vertical design is proposed extrapolating the neutronic analysis performed for the horizontal HCPB TBM. An overview of the new HCPB TBM vertical designs, as well as the preliminary thermal and fluid dynamic analyses performed for the validation of the design, are presented in this paper. A critical review of the results obtained allows us, in the conclusion, to prepare a plan for the future detailed analyses of the vertical HCPB TBM.     

Shut-Down Dose Rate analysis for ITER Diagnostic Equatorial and Upper Ports

The Shut-Down Dose Rate (SDDR) is an important criterion of radiation safety for the personnel access for maintenance operations in ITER ports after the cessation of the D-T 14 MeV neutron fusion source. Therefore, the problem of the SDDR calculations attracts the attention of fusion neutronics community because SDDR in such a large and geometrically complicated fusion device as the ITER tokamak is challenging to compute. This challenge has been faced and overcome by applying dedicated methodological approaches explained in this paper. The results of the SDDR analysis allowed us to propose several design solutions for improvement of the radiation shielding of the ITER Generic Diagnostic Equatorial and Upper Port Plugs (EPP and UPP). The SDDR analysis was focused on the interspace area located between the ITER bioshield and port plugs where the personnel access is envisaged at ∼12 days after the ITER shut-down. By this analysis the radiation streaming pathways and dominant sources of decay radiation were revealed and the methods to mitigate the streaming and subsequent activation were found. The optimization of the port shielding was targeted on minimization of the SDDR in the interspace area following the ALARA principle and taking into account the feasibility to implement proposed shielding options with the actual hardware. Among them, wrapping the EPP walls with the B₄C tiles improves the EPP shielding performance. While void around the ELM/in-vessel coils and blanket manifolds leads to the performance reduction. The SDDR inside the Generic UPP interspace depends mainly on the environment (blanket, manifolds, and gaps).     

Tritium and heat management in ITER Test Blanket Systems port cell for maintenance operations

Three ITER equatorial port cells are dedicated to the assessment of six different designs of breeding blankets, known as Test Blanket Modules (TBMs). Several high temperature components and pipework will be present in each TBM port cell and will release a significant quantity of heat that has to be extracted in order to avoid the ambient air and concrete wall temperatures to exceed allowable limits. Moreover, from these components and pipes, a fraction of the contained tritium permeates and/or leaks into the port cell. This paper describes the optimization of the heat extraction management during operation, and the tritium concentration control required for entry into the port cell to proceed with the required maintenance operations after the plasma shutdown.     

Engineering studies for integration of the test blanket module (TBM) systems inside an ITER equatorial port plug

The European test blanket module (EU-TBM), first prototype of the breeding blanket concepts under development for the future DEMO power plant to produce the tritium, will be developed to be tested in three equatorial ports of ITER dedicated to this. The CEA Cadarache under the contract of Association EURATOM/CEA and in close relation with Association EURATOM/HAS works on the integration of the EU-TBM inside ITER tokamak.The installation of the TBM into the vacuum vessel is made with the help of a port plug, constituted with two components: the Shield module and the Port-Plug frame. The Shield module provides the neutron shielding inside the Port-Plug frame, which maintains in cantilever position the TBM and its shield module and closes the vacuum vessel port.This paper will describe the EU-TBM design and integration activities on the cooled shield module and on its interface with the TBM component. A particular attention, in term of thermal and mechanical studies, is dedicated to the design of the shield and test blanket module attachment, and also to the shield design and its internal cooling system.     

Design optimization of first wall and breeder unit module size for the Indian HCCB blanket module

The Indian test blanket module(TBM) program in ITER is one of the major steps in the Indian fusion reactor program for carrying out the RD activities in the critical areas like design of tritium breeding blankets relevant to future Indian fusion devices(ITER relevant and DEMO).The Indian Lead–Lithium Cooled Ceramic Breeder(LLCB) blanket concept is one of the Indian DEMO relevant TBM,to be tested in ITER as a part of the TBM program.Helium-Cooled Ceramic Breeder(HCCB) is an alternative blanket concept that consists of lithium titanate(Li_2TiO_3) as ceramic breeder(CB) material in the form of packed pebble beds and beryllium as the neutron multiplier.Specifically,attentions are given to the optimization of first wall coolant channel design and size of breeder unit module considering coolant pressure and thermal loads for the proposed Indian HCCB blanket based on ITER relevant TBM and loading conditions.These analyses will help proceeding further in designing blankets for loads relevant to the future fusion device.     

Progress in the integration of Test Blanket Systems in ITER equatorial port cells and in the interfaces definition

In the framework of the TBM Program, three ITER vacuum vessel equatorial ports (#16, #18 and #02) have been allocated for the testing of up to six mock-ups of six different DEMO tritium breeding blankets. Each one is called a Test Blanket System (TBS). A TBS consists mainly of the Test Blanket Module (TBM), the in-vessel component facing the plasma, and several ancillary systems, in particular the cooling system and the tritium extraction system. Each port accommodates two TBMs and therefore the two TBSs have to share the corresponding port cell. This paper deals with the design integration aspects of the two TBSs in each port cell performed at ITER Organization (IO) with the corresponding definition of interfaces with other ITER systems. The performed activities have raised several issues that are discussed in the paper and for which design solutions are proposed.