Gaseous products generated by radiation degradation of N,N-diethylhydroxylamine aqueous solution

In this paper,gaseous products generated by radiation degradation of N,N-diethylhydroxylamine (DEHA) in aqueous solution are studied.The results show that by 10～1000 kGy irradiation of the solution in DEHA concentration of 0.1～0.5 mol·L^(-1),the gaseous products were mainly hydrogen,methane,ethane and ethene.The volume fraction of hydrogen did not change much with different concentrations of DEHA.The volume fraction of methane and ethane decreased,but that of ethene increased,with increasing DEHA concentration.The volume fraction of hydrogen,methane and ethane increased with the dose.The relationship of the volume fraction of ethene with the dose had something to do with the DEHA concentration.

Gaseous products of aqueous N,N-dimethyl hydroxylamine degraded by radiation

In this work,the 0.1-0.5 mol·L-1 N,N-dimethylhydroxylamine(DMHA) were irradiated to 5-25 kGy,and gaseous products of mainly hydrogen,methane,ethane and n-butane were measured by gas chromatography.The results show that the volume fraction of hydrogen and methane increases with the concentration of DMHA and dose,and the latter does not change markedly at high doses.

基于光通量计量法的紫外辐射测定方法建立及其应用研究

近年来,我国大气一次污染颗粒物的浓度逐渐下降,二次生成的气溶胶已经成为了大气颗粒物的主要组成部分。新粒子生成作为二次生成气溶胶的重要来源,本世纪以来受到的关注也越来越高。而气态硫酸作为新粒子生成化学过程中一种极为重要的前体物,由于其浓度极低,检测所需的仪器灵敏度极高,因此如何准确定量气态硫酸是新粒子形成机制研究中最大的难点。现有的气态硫酸的定量方法主要是基于光化学法,利用紫外辐射光解水汽产生OH自由基后与过量的二氧化硫反应最终生成气态硫酸,气态硫酸的浓度由紫外光强与水汽浓度共同决定。其中紫外光强的直接测量存在着较大的不确定性,这主要是由于光强在气态硫酸标定装置的反应腔体中分布不均匀,此外,在实际大气条件下标定时还会受到背景气溶胶的散射、吸收作用的影响。因此,此研究建立并比较了两种分别基于臭氧和氧化亚氮光通量计量法的紫外辐射测定的间接测量方法。结果表明:基于臭氧的间接测量法的主要误差来自于氧气的吸收截面,理论误差>60%,实际实验室的重复实验误差约为12%;基于氧化亚氮的间接测量法的主要误差来自于二级反应速率kn的测量误差、反应产物检测仪器及流量控制装置的不确定性,理论误差<16%,实际实验室的重复实验误差<1%。将基于氧化亚氮的间接测量法应用于外场观测的气态硫酸检测时,在为期半个月每天一次的定标气态硫酸中,气态硫酸的测量误差约为24%,接近或优于国外观测结果,证明基于氧化亚氮的光通量计量法对于紫外辐射的测定方法具有较好的准确性和稳定度,可以有效应用于气态硫酸的定量测量。

基于自发辐射分析的燃煤锅炉内温度及气相钠同时在线监测

准东煤燃烧过程中释放的碱金属极易导致炉膛受热面沾污、结渣等问题,影响锅炉运行的安全性,开展燃烧过程中碱金属定量测量对优化燃烧有重要意义。基于自发辐射光谱分析(Flame emission spectrometry,FES)技术开展燃煤锅炉内温度和气相钠浓度同时在线监测研究,首先提出了采用火焰光度计检验FES技术测量燃烧火焰中气相钠浓度的试验方法,并开展了气相Na浓度测量的验证试验,在0~12.2 mg/m^(3)测量值与实际值具有较高精度,最后研制了一套燃烧温度/气相钠浓度在线监测系统并应用于大型火电机组煤粉锅炉现场。连续在线监测结果表明:气相Na浓度、火焰温度与机组参数具有正相关性且同步变化,测点区域最高温度和气相Na质量浓度分别为1220℃和2.3 mg/m^(3)。基于在线监测结果能为后续炉内受热面沾污、结渣预报和锅炉燃烧调整提供指导。

Total Heat Exchange Factor Based on Non-Gray Radiation Properties of Gas in Reheating Furnace

Modified mathematical models based on imaginary plane zone method in reheating furnace were developed in which non-gray radiation properties of gas were considered,and the Newton＇s method and the finite difference method were adopted. Effects of productivity,fuel consumption,fuel-air ratio,calorific value of fuel and inserting depth of thermocouple on total heat exchange factor along the length of reheating furnace were investigated. The results show that total heat exchange factor increases with productivity or inserting depth of thermocouple,and it decreases when fuel consumption,fuel-air ratio or calorific value of fuel increases. The results are valuable for dynamical compensation of total heat exchange factor for online control mathematical models in reheating furnace.

基于BIXS方法的高浓度气态氚探测器设计

近年来,氚的监测在确保反应堆的安全运行、工作人员的健康安全有着重要作用,特别是对以氚为核燃料的聚变反应堆。基于β射线诱发的韧致辐射X射线谱仪(BIXS)由于记忆性效应低、探测器尺寸小已逐渐成为国内外研究的热点。利用蒙特卡洛方法(MCNP)对BIXS探测器的尺寸以及材料进行了优化设计。结果表明,在0.5 MPa的工作压力下,铍窗厚度为0.1 mm、铍窗镀金层厚度为125 nm的小型BIXS测量系统可实现氚气的在线测量和探测器的小型化,其中100 s探测限为1.79×108Bq。

Mathematical Models Developed by Zone Method Considering Non-Gray Radiation Properties of Gas in Combustion Chamber

Water vapour and carbon dioxide as the main products in combustion chamber have strong non-gray radiation properties. Multidimensional mathematical models were developed by zone method considering the non-gray radiation properties of gas in combustion chamber. Edwards exponential wide band model （EBWM） was adopted to calculate the non-gray radiation properties of gas, and the three-point Gauss-Legendre integral formula was used to calculate direct radiation exchange areas. Reflected radiation heat fluxes were obtained by Gauss elimination method, and energy balance equations were solved by main variable correction method. An example was given to validate the developed models, and further investigation of effects of flame distribution on heat transfer was carried on.

烃类流体火灾伤害破坏作用定量分析

对烃类流体火灾的伤害破坏作用进行正确的定量分析是开展重大消防目标火灾风险评估工作的基础。针对烃类流体火灾伤害破坏作用定量分析中存在的问题,系统论述烃类流体火灾伤害破坏作用的定量分析方法,分析并讨论火球、池火、喷射火和蒸气云火灾等不同火灾形式的热辐射通量计算模型及其前提条件,对不同热辐射伤害破坏作用准则及伤害概率模型的适用条件和模型基础进行了论述。

氚自发光标志牌轫致辐射特性的实验测定

主要介绍了氚气发光管及其指示标志牌的结构性能和标准规定的辐射剂量限制,探讨了对氚气发光管轫致辐射的能量与外表面剂量率的测量方法,给出了实际测量的初步结果并进行了讨论。

燃煤发电厂气态流出物辐射环境影响研究

目前,燃煤发电厂对环境和公众产生的辐射影响引起了广泛关注。本文选择长江沿岸具有代表性的三家燃煤发电厂为研究对象,基于电厂气态流出物中主要放射性核素的年排放量,采用烟囱直接排放和沉降进入水体两种途径的评价方法,评估燃煤发电厂气态流出物对周围环境造成的辐射影响。结果表明:三家燃煤发电厂气态流出物排放造成80km范围内辐射影响很小,归一化最大个人年有效剂量分别为3.02×10^(-4)、4.32×10^(-5)、8.50×10^(-5 )Sv/GW;辐射剂量主要来自^(210)Po和^(210)Pb直接排放通过食入照射途径的贡献,远大于其进入水体及222Rn排放对剂量的贡献。由于210Pb具有相对较长的半衰期,导致其在土壤中的比活度增加;基于文中210Pb沉积浓度的分析,建议相关研究关注燃煤发电厂下风向30km范围内210Pb的长期辐射影响。本研究结果可为类似厂址的辐射影响评价提供技术支持,为内陆核电建设中公众沟通和技术研究工作提供基础数据,也为政府相关部门的决策提供参考。

核技术利用项目环保验收中的放射性流出物监测问题探讨

建设项目竣工后应该进行环境保护验收监测,对于向环境排放放射性物质的建设项目,在验收监测过程中需要进行放射性流出物监测。本文总结了北京市核技术利用项目在环保验收中放射性流出物(废水、废气)监测所遇到的困难和解决措施,为今后解决这些问题提出了针对性建议。

γ射线辐照对煤中自由基浓度变化和电解加氢液化的影响

利用电子顺磁共振(ESR)波谱仪对γ射线辐照前后的煤样进行了自由基的测试,结合气相色谱分析研究了辐照对煤结构的影响,并对辐照前后的煤样进行了电化学测试。结果表明,辐照可以促进煤中大分子烷烃链及杂原子的断裂,并产生氢气、甲烷等小分子量的气体,当辐照剂量为40 kGy时,自由基浓度达到最大。而自由基浓度的增大有利于煤的电解加氢液化,且当辐照剂量为40 kGy时,电流密度达到最大。

核电站气载放射性流出物环境辐射剂量计算

计算大亚湾核电站正常工况下气载放射性流出物对80km的大气环境防护距离内的公众所致辐射剂量。根据大亚湾核电站2001年气载放射性流出物排放量,逐时观测气象数据及相关参数,选用修正的高斯烟羽模型和美国核管会导则1.109的食物链模型,运用美国橡树岭国家实验室编制的AIRDOS-EPA程序,程序经修改后适合于中国核设施的计算。计算得到2001年大亚湾核电站气态放射性流出物对周边80km范围内的公众所致的年均集体剂量为4.722E-3人·希,最大个人有效剂量为1.362E-8希。结果表明,2001年大亚湾核电站正常工况下,气载放射性流出物对周围公众造成的剂量当量远低于国家标准,对周边地区居民健康几乎没有影响。

非灰气体离散坐标法模型的比较

将求解气体辐射传递方程的离散坐标法与描述非灰气体辐射特性的灰气体加权和模型结合,来研究气体介质参与的辐射换热问题.不同的坐标离散方法———SN法、TN法、SRAPN法与灰气体加权和模型结合,得到不同的非灰气体离散坐标法.分别用非灰气体的SN法、TN法、SRAPN法对一个三维炉况进行模拟,得到炉膛内介质的温度分布及壁面热流分布,比较了不同非灰气体离散坐标法的计算时间和精度.结果表明,SN法和TN法与灰气体加权和模型结合能较好地模拟气体介质参与的辐射换热问题.

丙烷/氢气混合燃烧的火焰特征与辐射特性试验研究

针对丙烷和氢气混合气体燃烧的火焰特征与辐射特性开展试验研究。根据不同的混合比进行了10组试验,分析火焰高度、火焰中心线温度、火焰外部辐射通量、火焰内部辐射通量的变化。研究发现,随着混合气体中丙烷气体组分的比例不断下降,混合燃烧时的平均火焰高度逐渐下降。丙烷/氢气的混合比例大于50%时,火焰内部辐射通量随着总热释放速率的增大而显著下降;当丙烷/氢气的混合比例小于50%时,火焰内部辐射通量基本保持一致。

基于全光谱关联k分布模型的加压富氧燃烧烟气辐射特性研究

在加压富氧燃烧中,烟气介质的热辐射是炉膛中换热的主要形式之一。气体与粒子的非灰辐射特性导致辐射换热研究需要耗费过多的计算资源,加剧了燃烧、流动及传热多场耦合的难度,忽略气体与粒子非灰特性的双灰体假设模型的计算精度不能满足辐射传热研究要求。全光谱关联k分布模型(Full Spectrum Correlated k-distribution,FSCK)兼顾精度和效率,在非等温非均匀介质的辐射传热中具有很高的应用前景。本文在全光谱关联k分布模型的基础上,结合加压富氧燃烧下的烟气特性,构建适用于加压富氧燃烧气氛下的FSCK气体辐射模型及数据库,并将该模型下的辐射换热计算结果与逐线法及灰气体加权和模型进行比对,对加压富氧燃烧下气体介质的辐射换热特性进行研究;对于吸收散射性介质,将气体与粒子的非灰辐射特性参数进行归一化处理,结合气体FSCK模型与粒子Mie理论,建立了吸收散射性介质全光谱关联k分布计算模型,探究了加压富氧燃烧下包含飞灰颗粒的烟气辐射传热特性。

含氟聚合物辐射气相接枝反应研究Ⅰ.ESR研究PTFE预辐照接枝气相丙烯酸反应

以聚四氟乙烯（ＰＴＦＥ）为对象，在γ射线作用下，进行预辐照接枝气相丙烯酸反应．通过红外光谱（ＩＲ）表征，确认发生了含氟聚合物－气相有机单体的接枝共聚．用电子自旋共振（ＥＳＲ）方法，研究了ＰＴＦＥ在γ射线真空辐照作用下产生自由基浓度及特征，并用Ｘ－射线衍射仪测试了预辐照膜的结晶度变化关系，初步探讨了含氟聚合物－有机单体的辐射气相接枝引发机制。

Beam test of a one-dimensional position sensitive chamber on synchrotron radiation

A one-dimensional single-wire chamber was developed to provide high position resolution for powder diffraction experiments with synchrotron radiation. A diffraction test using the sample of SiO2 has been accomplished at 1W2B laboratory of Beijing Synchrotron Radiation Source. The data of the beam test were analyzed and some diffraction angles were obtained. The experimental results were in good agreement with standard data from ICDD powder diffraction file. The precision of diffraction angles was 1% to 4.7%. Most of the relative errors between measured values of diffraction angles and existing data were less than 1%. As for the detector, the best position resolution in the test was 138 p.m （a value） with an X-ray tube. Finally, discussions of the results were given. The major factor that affected the precision of measurement was deviation from the flat structure of the detector. The effect was analyzed and the conclusion was reached that it would be the optimal measurement scheme when the distance between the powder sample and detector was from 400 mm to 600 mm.

Investigation of GEM-Micromegas detector on X-ray beam of synchrotron radiation

To reduce the discharge of the standard bulk Micromegas and GEM detectors, a GEM-Micromegas detector was developed at the Institute of High Energy Physics. Taking into account the advantages of the two detectors, one GEM foil was set as a preamplifier on the mesh of Micromegas in the structure and the CEM pream- plification decreased the working voltage of Micromegas to significantly reduce the effect of the discharge. At the same gain, the spark probability of the GEM-Micromegas detector can be reduced to a factor 0.01 compared to the standard Micromegas detector, and an even higher gain could be obtained. This paper describes the performance of the X-ray beam detector that was studied at 1W2B Laboratory of Beijing Synchrotron Radiation Facility. Finally, the result of the energy resolution under various X-ray energies was given in different working gases. This indicates that the GEM-Micromegas detector has an energy response capability in an energy range from 6 keV to 20 keV and it could work better than the standard bulk-Micromegas.

三维航空发动机燃烧室非灰气体辐射换热数值模拟

基于自主研发的辐射计算程序应用离散坐标法和统计窄谱带吸收系数关联模型准确高效地实现了复杂几何外形内非灰气体辐射换热的数值模拟。首先,在完成了结构网格和非结构曲面网格标模验证的基础上,探究了不同角度离散格式、空间差分格式、高斯积分点类型及数目对辐射换热的影响。结果显示24个空间离散方向的角度离散格式计算精度较低,推荐使用32个离散方向的角度离散格式。不同空间差分格式和高斯积分点类型对计算结果的影响较小。接着,选取精度效率结合最优的数值方法组合,以燃烧流场数据作为输入,计算并讨论了某型航空发动机燃烧室在不同压强和壁面温度下的气体辐射换热情况。结果显示中心火焰处负辐射源项的极大值超过6 000 kW/m^(3),而低温壁面附近气体温度较高的区域辐射源项的最大值接近17 000 kW/m^(3),壁面上辐射热流密度的最大值接近88 kW/m^(2)。随着压强增大,辐射源项和壁面热流密度逐渐增大但变化速率逐渐放缓,该变化速率受参与性介质浓度的影响较大。