Tracer Study on Catalytic Hydrogen Exchange Reactions over Nickel Catalyst

In heterogeneous catalysis it is important to know the reactivity of C-H bond in the hydrocarbon molecules. Experiments have been performed to obtain information about the exchange reaction of adsorbed hydrogen with methane and ethylene. In order to reduce the probability of forming products which contain more than one tritium atom, hydrogen labelled with H³ with low activity has been used.     

Facility for preparation of gas mixture in muon catalyzed fusion experiments

A facility is described that allows safe handling of high tritium gas activity as dozens kilocuries in a regular laboratory environment. It is used to make and deliver into the target a mixture of specific isotopic composition with the contamination requirement of 10^-7 v.f. for Z>1 elements, and recover it upon completion of operation. With this facility, efforts have been accomplished to investigate into the muon catalyzed fusion on two targets – liquid tritium and high-pressure tritium types. Also, the operation range was 0.1–120 MPa for pressure and 20–800 K for temperature and the amount of tritium used was about 100 kCi. The facility showed reliability in operation without indications of radiation beyond the safety level. This revised version was published online in August 2006 with corrections to the Cover Date.     

Time-of-flight measurement of resonant molecular formation in muon-catalyzed dt fusion

Preliminary results are reported for an experiment at TRIUMF where a time-of-flight technique was tested for measuring the energy dependence of the rate for muon-catalyzed dt fusion. Muonic tritium atoms were created following transfer of negative muons from muonic protium in a layer of solid hydrogen (protium) containing a small fraction of tritium. The atoms escaped from the solid layer via the Ramsauer-Townsend mechanism, traversed a drift region of 18 mm, and then struck an adjacent layer of deuterium, where the muonic atom could form a molecular system. The time of detection of a fusion product (neutron or alpha) following muon arrival is dependent upon the energy of the muonic tritium atom as it traverses the drift region. By comparison of the time distribution of fusion events with a prediction based on the theoretical energy dependence of the rate, the strength of resonant formation can in principle be determined. The results extracted so far are discussed and the limitations of the method are examined.     

Increasing of registering capacity of nuclear emulsion for autoradiography

The ways of increasing detecting power of the type M nuclear emulsion gel have been investigated in these studies. There have been found conditions under which type M emulsion sensitivity increased by 15–20% without increasing fog grain background. The stability of photographic sensitivity during emulsion gel storage increased by two times. The prevention of latent image fading (by means of layer moisture content) decreased to 1.2% and increasing the detecting power of the emulsion (by means of exposure temperature) by up to 37°C). The exposure time of tritium labelled autographs has been decreased to about 20%.     

Tritium Burn-up Depth and Tritium Break-Even Time

Similarly to but quite different from the xenon poisoning effects resulting from fission-produced iodine during the restart-up process of a fission reactor, we introduce a completely new concept of the tritium burn-up depth and tritium break-even time in the fusion energy research area. To show what the least required amount of tritium storage is used to start up a fusion reactor and how long a time the fusion reactor needs to be operated for achieving the tritium break-even during the initial start-up phase due to the finite tritium breeding time that is dependent on the tritium breeder, specific structure of breeding zone, layout of coolant flow pipe, tritium recovery scheme, extraction process, the tritium retention of reactor components, unrecoverable tritium fraction in breeder, leakage to the inertial gas container, and the natural decay etc., we describe this new phenomenon and answer this problem by setting up and by solving a set of equations, which express a dynamic subsystem model of the tritium inventory evolution in a fusion experimental breeder （FEB）. It is found that the tritium burn-up depth is 317g and the tritium break-even time is approximately 240 full power days for FEB designed detail configuration and it is also found that after one-year operation, the tritium storage reaches 1.18kg that is more than the least required amount of tritium storage to start up three of FEB-like fusion reactors.     

球环型产氚聚变堆中子学分析

对球环型产氚聚变堆概念设计中的中子学设计进行了计算分析。此设计利用了球形环的先进等离子体物理性能和紧凑的结构特征,并尽量利用真空室内的空间安置氚生产包层以减少氚泄漏而提高氚增殖率,达到年产氚量1kg的目标。2D中子学计算得到的氚增殖率高于1．68的设计是其它类似设计没有达到的,进一步体现出球环型产氚聚变堆的先进性。     

Z箍缩驱动聚变-裂变混合堆氚燃料循环系统氚盘存量与氚自持初步分析

为研究氚自持条件,建立了Z-FFR氚分析模型,基于理论方程和氚平均滞留时间方法进行计算,得到稳态运行时排灰气处理系统、氚增殖提取系统、同位素分离系统、水去氚化系统的氚质量流分别为52.30,25.40,81.30,3.60 g/day,对应的氚盘存量为52.30,25.40,8.13,1.80 g。同时以氚质量流推导出氚自持判断条件,分析了设计参数能够满足氚自持要求,同时获得了燃烧效率、氚增殖率、提取效率与氚自持的互补关系,三者作为关键参数相互依存,于临界值、设计值、理想值之间分析了氚的自持情况。     

FEB—E氚循环系统的计算机模拟

对聚变实验增殖堆（ＦＥＢ）工程概要设计的氚燃料循环构造了一个动态子系统模型，研制了模拟氚燃料循环系统的计算机程序ＳＷＩＴＲＩＭ，计算运行一年后１０个子系统中的氚投料量和整个推系统总的氚投料量，这对预示起动一个聚变热功率的１５０ＭＷ量级的实验增殖堆所需的最少初始氚投料量有参考价值，计算结果表明，要求的最少初氚贮备量除了与燃料气体净化系统和同位互分离系统中氚的平均逗留时间有关外，还与包层液态锂中提取氚     

Technogenic Tritium in Central European Precipitations

An overview of environmental aspects of the tritium method is given. Temporal and local variations of the specific tritium activity of precipitations, particularly the decay of the bomb peak as well as the continential and latitude effects, are used to subdivide the tritium content of precipitations in bomb tritium and technogenic tritium for the example of the measurement series of Freiberg. Technogenic tritium is shown to have prevailed from the beginning of the eighties, whereas the emission of technogenic tritium has strongly decreased in Europe since the middle of the seventies.     

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基于ITERCHHCSBTBM的设计特点,设计了相关的氚工艺辅助系统。描述了氚提取系统(TES)、冷却剂纯化系统(CPS)、氚测量系统(TMS)的功能、设计参数和工艺流程等。TES用于氚提取、储存、同位素的分离;CPS实现氧氮等杂质和氚的去除及冷却剂的定量处理和分析等功能;TMS不仅可以定量分析氚含量,而且必要时可替代TES。氚渗透及氚安全的分析表明,通过CHHCSBTBM以及辅助系统向环境释放的氚可控制在ITER的氚安全限度内。     

LiAlO_2陶瓷小球的堆外放氚行为

将LiAlO2陶瓷小球置于裂变反应堆中辐照,采用热解吸技术研究该类产氚材料的堆外放氚特性,考察了升温速率、载气组分、催化活性元素和提氚温度对氚释放行为的影响;采用电子自旋磁共振(ESR)实验技术研究了辐照缺陷的顺磁特征。结果表明:LiAlO2中氚的扩散速度慢,热解吸活化能高,氚释放主要分布在750~1000K;表面氢同位素交换反应贡献大,释氚形态受载气条件的影响较大,当氦气中添加H2时,会增大HTO转化成HT的比例;中子辐照会在LiAlO2中诱生F+,O-和O2-等缺陷色心,其退火湮灭行为与氚释放过程存在一定关系。     

ITER气体注入系统含氚管道的等效漏率评估

氚的泄漏会对公众安全和环境造成危害,有必要对含氚管道的泄漏进行分析。对ITER气体注入系统的含氚管道进行分析,对触发系统氚报警阈值(3×10⁵Bq·m^-3/环境安全值,1×10⁸Bq·m^-3/系统安全值)时,氚送气管、离子源管以及中性化管泄漏的等效空气漏率进行了计算。结果表明,氚送气管泄漏的风险最高。虽然氚送气管的气体压力低于包容管的夹层压力,但由于管道的氚浓度高,漏率大于3.2×10^-8 Pa·m³·s^-1时会触发报警。而在离子源管中虽然氚浓度低,但管道的气体压力远高于包容管的夹层压力,漏率大于6.1×10^-6 Pa·m³·s^-1时会触发氚报警。气体注入系统含氚管道泄漏的氚危害不可忽视,必须进行实时监测和防护。     

CFETR氦冷固态增殖包层多物理场氚输运分析

针对中国聚变工程实验堆(CFETR)外中平面氦冷固态增殖包层模块,开展了包层热、流、氚的多物理场耦合模拟分析,获得包层模块的氚分布、氚滞留量及氚渗透量。分析结果显示,在包层球床区无因吹洗气体流动滞缓而造成的氚滞留现象,其吹洗气体流道设计合理。同时,开展了入口吹洗气体掺氢量的参数敏感性分析。分析显示吹洗气体掺氢可以降低材料表面氚浓度,从而降低结构材料中的氚浓度梯度,抑制氚渗透;入口氢气浓度从 1ppm 增加到 1000ppm 时,氚渗透量降低为 1/20。     

聚变堆氚系统设计中的一些重要问题研究(Ⅱ)

在文献[1]中,计算了FEB-E 聚变堆PFC 材料内的氚滞留量、堆系统总的氚投料量、启动运行开始阶段的氚坑深度和氚坑时间大小。这里将讨论在ITER 的TBM 氚增殖包层内固体氚增殖剂中的氚如何高效率地被载氚气体带出并且以高效率地提取回收。本部分将进行创新的探索性研究并且提出某些减少氚滞留量和改善氚提取回收效率的新方案,例如：基于氘饱和的海绵效应;第一壁表面建立氘和铍的伴同沉积层;基于在低频外电场作用下载氚气分子和硅酸锂颗粒电极化旋转催化同位素交换速率的增强载氚气提取氚效率“SPB 方法”。     

脉冲条件下ITER HCCB TBS动态氚输运分析

在ITER脉冲运行条件下对中国氦冷固态增殖剂实验包层系统(HCCB TBS)动态氚输运进行了分析,利用Modelica语言开发了一套动态氚分析程序.对比了在脉冲运行工况及连续运行工况下TBS流体中的氚浓度和分压的动态变化、固体材料中氚盘存量的动态变化以及氚渗透通量的动态变化.脉冲运行下TBS系统氚变化趋势与物理分析结果...     

氚安全防护研究进展

本文简要介绍了与氚气所接触者的防护重点、防止氚气内照射毒害的首选措施、氚气内照射剂量监测的特殊规律、氚致非随机辐射效应的首要受累器官等方面的研究工作和一些新认识． We have made wide researches on the safety protection on tritium in order toprevent the tritium radioactive toxicity. Systematic and comprehensive understanding isachieved in many aspects like the protection emphasis on tritium gas contactors, the mostpreferable measurement for the protection of tritium gas internal irradistion toxicity, the particular law of tritium gas internal irradiation dosage monitoring, and the principal involvedorgans of tritium-induced non-random radiative effects...     

中国聚变工程实验堆启动氚投料量与氚平衡分析

根据中国聚变工程实验堆(CFETR)堆芯设计参数及燃料系统流程模型,采用平均停留时间方法,建立燃料循环子系统的氚转移模型用来描述氚在各子系统之间的输运、滞留等过程。采用该模型,分析了不同聚变功率水平、运行因子以及燃烧率对中国聚变工程实验堆的氚平衡以及启动氚投料量的影响。     

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In part one published in the last issue, the tritium retention and the total tritium inventory in PFC materials of FEB-E fusion reactor had been calculated. The tritium well depth, tritium well time during the FEB-E fusion reactor start-up and initial operation phase had been obtained. In this part, how to improve tritium recovery efficiency in the ITER TBM solid breeder blanket with using purge gas has been discussed. Some new innovative schemes for reducing tritium retention and improving tritium recovery efficiency are proposed. Such as, sponge mechanism based on deuterium saturated PFC materials; deuterium and beryllium co-deposition layer created on first wall surface; SPB scheme for enhancing tritium recovery efficiency of purge gas in ceramic breeder blanket based on the electrical polarization rotations catalyzing isotope exchange rate enhancement resulted from applied low frequency electric-field, of Li4SiO4 grain and purge gas molecular particles and so on, are explored.     

In-situ X-ray photoelectron spectroscopy study of supported gallium oxide

In-situ XPS study of supported gallium oxide catalysts prepared by impregnation of different metal oxides supports (SiO₂, γ-Al₂O₃, TiO₂, and MgO) has been performed. It has been found that the formation of metallic gallium takes place upon high-temperature reduction of the catalysts in flowing hydrogen. Relative concentrations of metallic gallium were most high in the cases of alumina- and titania-supported catalysts. It was suggested that interaction of gallium oxide with a support surface favors the formation of metallic gallium upon high-temperature reduction. A possible mechanism of metallic gallium formation upon the reduction is discussed.