Research and development on nuclear hydrogen production using HTGR at JAERI

JAERI has been conducting R&D on HTGR and on hydrogen production using HTGR. The reactor technology has been developed using HTTR installed at Oarai site of JAERI. HTTR reached its full power operation of 30MW in 2001 and demonstrated reactor outlet helium temperature of 950°C in April 2004. As for the hydrogen production technology, the thermo-chemical IS process is under study. The process control method for continuous hydrogen production has been examined using a bench-scale apparatus. Also, studies are underway on process improvement and on materials of construction to be used in the corrosive environment. As for the system integration of HTGR and the hydrogen production plant, R&D is underway aiming to develop technologies for safe and economical connection. It covers safety technology against explosion, safety technology against radioactive materials release, control technology to prevent the thermal disturbance from hydrogen production plant to reactor, etc.     

Study on efficiency of DCP for nuclear hydrogen production

With many advantages, hydrogen is considered as the fuel of the future. But there is no natural resource of hydrogen and it must be produced by other kinds of energy. As for the primary energy, nuclear energy is a promising alternative. Using heat from nuclear reactor to produce hydrogen is receiving more and more concerns in recent years. This paper mainly emphasizes the study of the direct contact pyrolysis （DCP） of methane using heat from nuclear reactor. A facility was designed to investigate the efficiency of DCP process in certain conditions. The experimental results show that this process produces only hydrogen and carbon. The conversion efficiency increases with temperature and residence time, but decreases as flow rate increases. The highest efficiency of DCP obtained in this exoedment is about 22%.     

高温和超高温气冷堆动力转换方案研究

动力转换单元是高温和超高温气冷堆的重要组成部分。本文对高温和超高温气冷堆的动力转换单元进行研究。从4个关键参数（反应堆出口温度、反应堆入口温度、压缩比和主蒸汽参数）入手,对5个循环方案进行比较分析。综合考虑各种工程因素,上位循环为简单氦气透平循环、下位循环为有再热的蒸汽轮机循环的联合循环方案是具有竞争力的,其中下位循环在高温气冷堆范围是亚临界参数循环,在超高温气冷堆范围是超临界参数循环。联合循环可实现高温和超高温气冷堆热量的高效率转化,且反应堆入口温度在反应堆压力壳材料允许的范围内,具有足够的安全性。     

高温气冷堆用石墨材料氧化行为研究进展

核级石墨是高温气冷堆重要的慢化剂、反射层和结构材料,其氧化腐蚀性能对反应堆安全运行至关重要,因此已成为核材料学科的研究热点之一。本文综述了国内外在核级石墨氧化腐蚀领域的研究现状,总结了核石墨氧化的化学动力学模型、失重率影响因子模型以及模拟计算模型,提出了高温气冷堆用石墨材料氧化腐蚀的研究方向。     

Development of high temperature gas-cooled reactor (HTGR) fuel in Japan

This paper describes experiences and present status of research and development works for the high temperature gas-cooled reactor (HTGR) fuel in Japan. Recently, Very High Temperature Reactor (VHTR) is evaluated highly worldwide, and is a principal candidate for the Generation IV reactor systems. In Japan, HTGR fuel fabrication technologies have been developed through the High Temperature Engineering Test Reactor (HTTR) project in Japan Atomic Energy Agency since 1960’s. In total about 2 tons of uranium of the HTTR fuel has been fabricated successfully and its excellent quality has been confirmed through the long-term high temperature operation. Based on the HTTR fuel technologies, SiC TRISO fuel has been newly developed for burnup extension targeted VHTR. For ZrC-TRISO coated fuel as an advanced fuel designs, R&Ds for fabrication and inspection have been carried out in JAEA. The irradiation with the Japanese uniform stoichiometric ZrC coating has been completed in the cooperation with Oak Ridge National Laboratory of the United States.     

球床式高温气冷堆球流及球床辐射的理论与实验研究进展

球床堆芯的球流及等效导热系数是直接影响球床式高温气冷堆设计、运行和安全的重要依据,具有重要的意义。清华大学核能与新能源技术研究院近年对球流和球床等效导热系数进行了实验测量、理论研究和数值模拟,全面深入地揭示了球流规律、球流纺及径向内扩散规律、球床几何优化、物性参数影响、球流流态表征及刻画、球床等效导热系数建模等。本文对此进行了回顾总结,并指出了下一步的研究方向。     

聚变高温制氢反应堆概念设计研究

在深入分析相关领域研究发展状况的基础上,提出了具有较好技术可行性的聚变高温制氢反应堆概念(称之为FDS-Ⅲ),包括具有先进等离子体物理和技术水平的聚变堆芯、先进高温锂铅包层(HTL)、可减少热流分布密度的"垂直靶板"偏滤器以及相应的功率转换系统。尤其是提出了HTL包层新概念,其特点是选用技术基础相对成熟的低活化铁素体/马氏体钢作结构材料,在锂铅流道中使用可耐高温的多层流道插件,实现约1000℃的出口温度,可应用于制氢。初步性能分析表明FDS-Ⅲ制氢堆及其包层概念具有较好的技术可行性。     

HTGR包覆燃料颗粒碳化硅层细晶化研究

高温气冷堆(HTGR)是能适应未来能源市场的第四代先进核反应堆堆型之一,其固有安全性的第一道保障是使用的TRISO型包覆燃料颗粒。在TRISO型燃料颗粒4层包覆结构中,SiC包覆层是承受包覆燃料颗粒内压和阻挡裂变产物释放的关键层,制备高质量SiC包覆层是核燃料领域中的重大问题和关键技术之一。本文介绍高温气冷堆燃料颗粒的基本结构,详述制备SiC包覆层的流化床-化学气相沉积过程,提出SiC层细晶化这一研究方向,并系统阐述包覆燃料颗粒SiC包覆层细晶化的优势。在细晶化SiC材料制备方法方面,系统分析SiC粉体、陶瓷、薄膜和厚膜材料的研究现状,并结合本实验室前期研究成果提出制备细晶SiC包覆层的可行制备策略。     

球床式高温气冷堆MOX燃料循环优化

与压水堆相比,球床式高温气冷堆能在堆芯结构不做明显改变的情况下采用全堆芯装载混合氧化物（MOX）燃料元件。基于250 MW球床模块式高温气冷堆堆芯结构,设计了4种球床式高温气冷堆下MOX燃料循环方式,包括铀钚混合的燃料球和独立的钚球与铀球混合装载的等效方式,采用高温气冷堆设计程序VSOP进行分析,比较了初装堆的有效增殖因数、燃料元件在堆芯内滞留时间、卸料燃耗、温度系数等主要物理特性。结果表明：采用纯铀和纯钚两种分离燃料球且铀燃料球循环时间更长的方案,平均卸料燃耗较高,总体性能较其他循环方式优越。     

耦合高温堆的氦加热无机膜重整器的数值研究

基于拟均相一维模型,对耦合高温堆的氦加热无机膜重整器建立了一个稳态的数学模型,开发了相应的计算程序.结果表明:氦加热无机膜重整器的平均热流密度比常规的氦加热重整器高约25%,这样可实现紧凑的重整器结构,对于整个系统的安全性和经济性具有很重要的意义.利用氦加热无机膜重整器能获得高达95%的甲烷转化率,而压力损失只是略有增加. 当膜厚度比较小和吹扫比比较大时,甲烷转化率随着重整压力的增加而增大,这样高温堆甲烷蒸汽重整制氢系统的高压将由不利条件变为有利条件.     

高温气冷堆螺旋管式直流蒸汽发生器热工水力学

高温气冷堆蒸汽发生器具有一次侧氦气工质、二次侧直流、螺旋管结构、工作温度高等特点,其热工水力特性与传统压水堆自然循环蒸汽发生器存在很大区别。针对高温气冷堆蒸汽发生器的特点,对其基础热工水力及特有热工水力学问题进行了阐述,主要包括螺旋管内单相及两相流阻及换热计算、横掠螺旋管束流阻及换热计算、温度均匀性及两相流不稳定性等。同时介绍了清华大学核能与新能源技术研究院针对高温气冷堆蒸汽发生器热工设计、温度均匀性及两相流不稳定性等热工水力学问题所开发的一维稳态程序、一维瞬态程序、二维分析程序和方法,并对分析结果和结论进行了讨论。相关研究方法、程序和结论对其他相似参数螺旋管和直管式直流蒸汽发生器具有参考和借鉴意义。     

Performance of a transmutation advanced device for sustainable energy application

Preliminary studies have been performed to design a device for nuclear waste transmutation and hydrogen generation based on a gas-cooled pebble bed accelerator driven system, TADSEA (Transmutation Advanced Device for Sustainable Energy Application). In previous studies we have addressed the viability of an ADS Transmutation device that uses as fuel wastes from the existing LWR power plants, encapsulated in graphite in the form of pebble beds, cooled by helium which enables high temperatures (in the order of 1200 K), to generate hydrogen from water either by high temperature electrolysis or by thermochemical cycles. For designing this device several configurations were studied, including several reflectors thickness, to achieve the desired parameters, the transmutation of nuclear waste and the production of 100 MW of thermal power. In this paper new studies performed on deep burn in-core fuel management strategy for LWR waste are presented. The fuel cycle on TADSEA device has been analyzed based on both: driven and transmutation fuel that had been proposed by the General Atomic design of a gas turbine-modular helium reactor. The transmutation results of the three fuel management strategies, using driven, transmutation and standard LWR spent fuel were compared, and several parameters describing the neutron performance of TADSEA nuclear core as the fuel and moderator temperature reactivity coefficients and transmutation chain, are also presented.     

HTGR燃料元件包覆颗粒的穿衣主要工艺研究

高温气冷堆的商业化发展对燃料元件穿衣颗粒的规模化生产提出了更高要求。本文采用自主研发的穿衣系统,研究了穿衣鼓转速对动态表面倾角、安息角、粒径分布等参数的影响。确定了穿衣鼓转速的分段设置和最佳状态,并分析了不合格颗粒产生的原因。批量实验结果显示,穿衣颗粒成品率高且稳定,平均成品率达到93-94%,且设备易于操作控制,完全能满足规模生产的需要。     

Hydrogen production by high temperature electrolysis with nuclear reactor

High Temperature Electrolysis (HTE) is a promising method because its most parts consist of environmentally sound and common materials. Hydrogen production efficiency of HTE was evaluated about the process coupling with high temperature gas cooled reactor. This process can be expected to accomplish over 53% hydrogen production efficiency at HTE operating temperature of 800 °C. As a demonstration of hydrogen production by HTE, a unit housing 15 tubular cells, where yttria-stabilized zirconia (YSZ) was used as electrolyte, was constructed, and accomplished 130 NL/h hydrogen production. In this experiment, measured hydrogen production rate has good agreement with calculated hydrogen production rate based on applied current. To design and construct large amount of hydrogen production unit, it is important to predict the thermal and electrochemical features of the unit. To predict them, the simulation technology has been developed. From the comparison between single tubular cell experimental result and simulation result, good agreement based on current–voltage characteristic was acquired.     

高温气冷堆石墨材料的疲劳裂纹扩展综述

迄今为止,各国的高温气冷堆均采用石墨作为其堆芯活性区及反射层的主要结构材料。由于堆内的高温高辐照环境,石墨构件一般承受较高的热应力及辐照应力,这些应力的循环变化将引起疲劳载荷。     

高温堆燃料元件和包覆颗粒对裂变产物的滞留性能研究

高温气冷堆包覆燃料颗粒的包覆层是阻止放射性裂变产物释放的第一道屏障。本文在简介ＦＲＥＳＣＯ模型的基础上,采用ＦＲＥＳＣＯ２程序,计算了＾１３７Ｃｓ,＾９０Ｓｒ,＾１１０ｍＡｇ从包覆颗粒和燃料元件的释放份额,分析比较了包覆层和石墨基体对这几种核素的滞留性能,肯定了ＴＲＩＳＯ包覆层对金属裂变产物的滞留作用。     

吸附法净化高温气冷堆He载气中Kr、Xe的研究

用椰子壳活性炭吸附剂固定床吸附法去除高温气冷堆He载气中Kr、Xe杂质。获得了Kr、Xe在椰子壳活性炭上的动吸附规律。考察了吸附温度、浓度、流速及床高等因素对保护作用时间、完全饱和时间、吸容量的影响,获得最佳运行参数。结果表明：采用椰子壳活性炭可以除去高温气冷堆He载气中Kr、Xe等有害杂质,满足净化系统的要求。     

聚变制氢堆高温液态包层热工水力学新概念研究

在深入分析聚变堆包层设计要求和目前技术发展水平的基础上,根据热化学工艺制氢需要高温热的要求,提出了一个基于技术相对成熟的低活化铁素体/马氏体钢作为主要结构材料、高压氦气与液态LiPb合金作为冷却剂、具有创新性“多层流道插件”结构方案以获得高温热能的包层热工水力学概念,建立了热工水力学模型,在利用有限元数值模拟程序进行模拟计算的基础上分析了这种新概念包层的可行性。     

A general survey of the potential and the main issues associated with the sulfur–iodine thermochemical cycle for hydrogen production using nuclear heat

The thermochemical sulfur–iodine cycle is studied by CEA with the objective of massive hydrogen production using nuclear heat at high temperature. The challenge is to acquire by the end of 2008 the necessary decision elements, based on a scientific and validated approach, to choose the most promising way to produce hydrogen using a generation IV nuclear reactor. Amongst the thermochemical cycles, the sulfur–iodine process remains a very promising solution in matter of efficiency and cost, versus its main competitor, conventional electrolysis. The sulfur–iodine cycle is a very versatile process, which allows lot of variants for each section which can be adjusted in synergy in order to optimise the whole process. The main part of CEA's program is devoted to the study of the basic processes: new thermodynamics data acquisition, optimisation of water and iodine quantity, optimisation of temperature and pressure in each unit of the flow-sheet and survey of innovative solutions (membrane separations for instance). This program also includes optimisation of a detailed flow-sheet and studies for a hydrogen production plant (design, scale, first evaluations of safety issues and technico-economic questions). This program interacts strongly with other teams, in the framework of international collaborations (Europe, USA for instance).     

International cooperation on control for safe operation of nuclear research reactors

The purpose of this paper is to present some of the main reasons, objectives, planning, and recent advances of an SCK·CEN/ININ joint project, which deals with the design and application of modern/expert control and real-time simulation techniques for the safe operation of a TRIGA Mark III research nuclear reactor. This project has been proposed as the first of its kind under a general cooperation agreement between the Belgian Nuclear Research Centre (SCK·CEN) and the National Nuclear Research Institute (ININ) of Mexico.