湍球塔、穿流筛板塔对含金属粉尘废气的净化研究

动力堆燃料元件在首端切断操作过程中,产生含有放射性金属粉尘的废气。该项科研旨在研究净化这些废气的设备结构和工艺条件。本文详细介绍了用铁粉作模拟粉尘,用水作淋洗液时湍球塔、穿流筛板塔的除尘工艺试验,以及粉尘浓度、喷淋密度、液气比等因素对除尘效率的影响,从而确定了两种塔的设备结构及其较佳的除尘工艺条件。试验结果表明,在选定的工艺条件下,该两种塔均具有99.9%左右的除尘效率。     

加速器含氚废气净化系统的技术指标估算

根据加速器应用环境的要求,对建立纳秒脉冲/直流强中子发生器的含氚废气净化处理系统的主要参数、性能和技术指标进行了较为详细的分析和估算。含氚废气排放量大于4 m3/d,最大含氚浓度约1×1012Bq/m3,净化系统的除氚因子应大于1×103。建议采用国内外广泛使用的催化氧化加分子筛吸附的净化技术;结构上采用进出口都有氚浓度在线监测的装置,全自动智能控制加手动控制的三级串联的净化系统。     

用于LPCE的有序床催化剂催化活性研究

采用气-液逆流方式研究了Pt/C/PTFE有序床疏水催化剂对H_2(g)/HDO(l)体系中同位素交换的催化性能。结果表明:Pt/C/PTFE有序床催化剂不仅具有较高的催化活性和良好的疏水性,而且能够达到很高的气体流速;实验所用的两种Pt/C/PTFE的体积传质系数(K_(ya))均达1.12m~3(STP)/(s·m~3)(50mol/(m~3·s))以上,且用水浸泡35d后其催化活性无明显变化;在气液摩尔比为1∶1的条件下,气体空塔线速率达到1.0m/s时,两种填装的有序床Pt/C/PTFE均未发生液泛。     

内螺纹管中汽-液两相流体摩擦压降特性研究

在压力为9～22MPa,质量流速为600～1200kg/(m2·s),含汽率为0～1的工况范围内,对Φ38.1mm×7.5mm的6头内螺纹管中汽-液两相流体的摩擦压降特性进行了试验研究。试验段采用水平绝热布置。试验结果表明:压力对两相流摩擦压降的影响很大,随压力增加,两相流摩擦压降倍率减小,在临界压力附近,两相流摩擦压降倍率趋近于1;随含汽率增加,两相流摩擦压降倍率先增加,然后有减小的趋势;随质量流速增加,两相流摩擦压降倍率减小。用于计算单相水摩擦压降系数以及用于计算汽-液两相流体摩擦压降的试验关联式被提供。     

带自动控制功能的除氚系统

针对氚工艺尾气处理的需求和源项实际情况,根据化工原理和氚特性设计含自动控制功能除氚系统的主要部件、自动控制功能和初步性能测试,得出催化反应器、氚水吸附床等部件的结构尺寸,催化剂、干燥吸附剂的装填量等参数及控制软件界面;通过除氘和除氚实验初步测试了除氚系统的处理性能。结果表明,在循环处理模式下,1m3密闭容器中氘体积比6.0×10–4–2.8×10–2范围内时,35min内氘气浓度降低两个量级;5次对30L密闭容器内不同浓度的含氚气体处理,60min内对氚的去除效率均达到95%以上。     

衡阳市大气颗粒物中~(210)Po的活度-粒径分布测量

利用大流量撞击式分级采样器、放化分离提纯技术和α谱仪测量技术,建立了针对大气颗粒物中210Po的活度及活度-粒径分布的测量方法,并应用该方法分别于春季和秋季对衡阳市城区大气颗粒物中210Po的活度及活度-粒径分布进行了测量。实验测量结果表明,衡阳市城区大气颗粒物中210Po的含量处于正常水平;总体积比活度和质量比活度的分布范围分别为:0.012 5 m Bq·m-3~1.165 8m Bq·m-3、0.459 7 Bq·g-1~13.859 8 Bq·g-1,体积比活度含量占TSP中总含量93%的210Po存在于粒径范围小于3.0μm(PM3.0)的颗粒物中;雾霾天气会提高公众所接受的天然内照射剂量;同时发现雨水对大气颗粒物中210Po的净化作用较为明显。     

质量流速对两相压降的影响

在对空气-水在水平放置的圆管内流动时的两相压降实验的基础上,分析质量流速对两相压降的影响。在质量流速G=2102.6—3546kg/m·s和重量含汽量x<1％的范围内,观察到:(1)当x为给定值时,两相摩擦压降倍率φ~2_(f0)随质量流速G的增加而减少;(2)当G为给定值时,φ~2_(f0)随x的增加而增加。本文所得到的结果和巴罗塞(Baroczy)以及马斯塞托拉(Muscettola)(意大利情报研究中心)以垂直圆管内汽水流动时所得到的结论是一致的。最后,将实验所得到的、当G=2550kg/m~2·s时的数据整理成一个公式。即: φ~2_(f0)=1.43[1 ν_(fg)/ν_f x]~(2.48)[1 (μ_(fg)/μ_(5g))x]~(-1/4     

谱估计方法在大型实验装置地基振动测量中的应用

大型物理实验装置为获得高品质的强流脉冲电子束流,通常对地基振动都有较高的要求。详尽的地质振动状况分析是装置选址的重要前提。本文针对某装置待勘区域实际地质条件和周围人文环境,首先简要介绍了测点布设、振动测试系统的基本组成,然后通过分阶段测试比对试验对某装置待勘区域进行实际振动测量,最后应用谱分析的方法对区域内不同时间段、不同方向的测量数据进行分析,评估选址位置是否合理。数据结果表明,待勘区域在5μm·s~(-1)以上速度被95%概率检测,垂直方向位移振幅谱在185 nm,水平方向大于垂直方向约60 nm,物理实验表明,进一步基建过程中应采取适当的减震措施降低垂直位移幅度。     

CO_2对活性炭捕集氙工程的影响

很多核设施会产生放射性水平较高的氙等稀有气体同位素,须经过特殊处理后才能向环境排放,研究以空气或其它气体为介质的氙的吸附净化方法具有较强的实用价值。研究了常温下多组分气体在活性炭上直接吸附时,杂质组分CO2对捕集氙效果的影响,比较了多级柱和单级柱两种方案的效果和活性炭用量,以及条件参数的影响。结果表明:相比较多级柱除杂质吸附氙的方法,单级柱直接吸附氙更易于实现工程应用;在流速约0.33cm/s下,活性炭单级柱常温常压吸附对氙捕集效率达到90%;在一定流速(0.02~1.2cm/s)范围内,可以忽略炭床阻力的影响。     

核设施退役放射性结构解体切割气溶胶与烟尘净化装置设计

针对核设施退役放射性结构解体切割产生的大量气溶胶和烟尘问题,以通用气溶胶净化装置为基础,采用机械过滤方法和多级过滤原理,设计开发了烟尘预处理模块,并通过优化净化工艺和整体结构,研制了一种可同时实现放射性气溶胶和烟尘净化的装置。性能检测和工程应用表明:该装置的烟尘预处理模块能充分过滤金属切割过程中产生的细小金属颗粒或气溶胶悬浮物,放射性气溶胶和烟尘经过滤净化后,排出空气所含烟尘粒径不大于0.3μm,净化效率在85%以上。     

Experimental study on toluene removal by a two-stage plasma-biofilter system

Volatile organic compounds (VOCs) are typical pollutants that affect air quality. Discharge plasma is thought to be a potential method that can remove VOCs from flue gas. In this experiment, pulsed corona discharge plasma combined with a biological tower was carried out to remove the benzene series, and toluene was selected as the typical VOC. The results indicated that the removal efficiency of toluene by pulsed corona plasma was slightly higher than that of direct current (DC) corona plasma, while its energy efficiency was much higher than DC corona plasma. Under the optimal experimental conditions of pulse voltage 8.5 kV, initial toluene concentration 1400 mg m−3, and toluene flow rate of 12 l h−1, the toluene removal efficiency reached 77.11% by the single method of pulsed corona discharge plasma, and the energy efficiency was up to 1.515 g/(kW·h) under the pulse voltage of 4.0 kV. The trickling biofilter was constructed by using the screened and domesticated Acinetobacter baumannii, and the highest toluene removal efficiency by the pulsed corona discharge plasma combined with the trickling biofilter rose up to 97.84%. Part of the toluene was degraded into CO2, H2O, and some intermediate products such as o-diphenol under the influence of Acinetobacter baumannii. When the remaining waste gas passed through the discharge plasma reactor, the benzene ring structure could be directly destroyed by the collision between toluene and plasma. Meanwhile, O·, OH·, and some other oxidizing radicals generated by the discharge also join into the oxidative decomposition of toluene and its intermediate products, thereby further improving the removal efficiency of toluene. Therefore, the two-stage plasma-biofilter system not only showed a high toluene removal efficiency, but also had a good energy efficiency. The results of this study will provide theoretical support and technical reference for industrial VOC treatment.     

基于氢同位素研究商用钯银合金膜的渗氚性能

钯银合金膜可用于熔盐堆尾气中气态氚（HT和T₂）的分离与纯化。本文研究了厚度为80 μm的钯银合金膜在纯H₂气氛中及Ar气存在下对H₂的分离效果。结果表明,渗氢过程中氢原子在膜内部的体相扩散是控制速率的关键。Ar气存在时,在钯银合金膜工作温度为480 ℃、混合气体进气流速为100 mL/min、氢分压差为20～100 kPa的条件下,钯银合金膜对H₂气的渗透通量随氢分压差的增大而增加,随Ar气浓度的升高而减小。在氢分压差相同的条件下,纯氢的渗透通量明显高于Ar-H₂混合气的渗透通量,说明钯银合金膜受Ar气的影响分离效果变差。渗氢后的钯银合金膜表面变得光滑,有晶界形成。     

裂变气体分离器气泡分离轨迹的数值模拟

钍基熔盐堆是我国重点开发的第四代核反应堆之一,其裂变反应产生的中子俘获截面大的Kr、Xe等裂变气体以微气泡的形式存在于熔盐冷却剂中,对裂变气体的分离是提高熔盐堆中子经济性、实现燃料深燃耗的重要环节。为定量地获得分离器内气泡的分离行为,采用数值模拟和理论建模相结合的方法,得到旋流场的流场分布特征;通过建立旋流场中气泡运动控制方程,分析并计算不同旋流度和气泡直径下的分离长度。与实验数据对比发现,数值模拟结果和实验数据吻合良好,表明数值模拟方法可以用于气液分离器的优化设计。     

Regulation characteristics of oxide generation and formaldehyde removal by using volume DBD reactor

Discharge plasmas in air can be accompanied by ultraviolet(UV) radiation and electron impact,which can produce large numbers of reactive species such as hydroxyl radical(OH·),oxygen radical(O·),ozone(O3),and nitrogen oxides(NOx),etc.The composition and dosage of reactive species usually play an important role in the case of volatile organic compounds(VOCs) treatment with the discharge plasmas.In this paper,we propose a volume discharge setup used to purify formaldehyde in air,which is configured by a plate-to-plate dielectric barrier discharge(DBD) channel and excited by an AC high voltage source.The results show that the relative spectral-intensity from DBD cell without formaldehyde is stronger than the case with formaldehyde.The energy efficiency ratios(EERs) of both oxides yield and formaldehyde removal can be regulated by the gas flow velocity in DBD channel,and the most desirable processing effect is the gas flow velocity within the range from2.50 to 3.33 m s-1.Moreover,the EERs of both the generated dosages of oxides(O3 and NO2) and the amount of removed formaldehyde can also be regulated by both of the applied voltage and power density loaded on the DBD cell.Additionally,the EERs of both oxides generation and formaldehyde removal present as a function of normal distribution with increasing the applied power density,and the peak of the function is appeared in the range from 273.5 to 400.0 W l-1.This work clearly demonstrates the regulation characteristic of both the formaldehyde removal and oxides yield by using volume DBD,and it is helpful in the applications of VOCs removal by using discharge plasma.     

北京谱仪Ⅲ束流铍管环形窄通道冷却优化设计

北京谱仪Ⅲ(BESⅢ)要求束流铍管部分物质量尽可能少,同时要求将束流铍管内部产生的热负荷通过冷却介质带走,精确控制外壁温度。本文结合理论分析和有限元数值模拟对束流铍管的冷却环形窄通道尺寸进行优化设计,确定了窄通道最佳间隙,研究了集中热负荷对内外壁温度场的影响,并确定了冷却液最佳工作流速。根据设计结构,制作出束流铍管实际尺寸实验模型。实验测量结果表明,束流铍管冷却结构设计合理,最佳流速满足冷却要求。     

Evaluation of the fraction of delayed photoneutrons for TMSR-SF1

The 10 MW_(th) solid-fueled thorium molten salt reactor(TMSR-SF1) is a FLi Be salt-cooled pebble bed reactor to be deployed in 5–10 years, designed by the TMSR group. Due to a large amount of beryllium in the core, the photoneutrons are produced via(γ , n) reactions.Some of them are generated a long time after the fission event and therefore are considered as delayed neutrons. In this paper, we redefine the effective delayed neutrons into two fractions: the delayed fission neutron fraction and the delayed photoneutron fraction. With some reasonable assumptions, the inner product method and the k-ratio method are adopted for studying the effective delayed photoneutron fraction. In the k-ratio method, the Monte Carlo code MCNP6 is used to evaluate the effective photoneutron fraction as the ratio between the multiplication factors with and without contribution of the delayed neutrons and photoneutrons. In the inner product method, with the Monte Carlo and deterministic codes together, we use the adjoint neutron flux as a weighting function for the neutrons and photoneutrons generated in the core. Results of the two methods agree well with each other, but the k-ratio method requires much more computing time for the same precision.     

文丘里式气泡发生器气泡碎化特性研究

熔盐堆在运行过程中须不断地去除氙等气体裂变产物。熔盐堆除气系统中气泡发生器的作用是通过向回路中注入一定量的直径为0.5 mm的小气泡,在扩散作用下吸收熔盐中的氙,最终气泡被分离出来,达到除氙的目的。在橡树岭国家实验室设计的基础上,本文为钍基熔盐研究堆设计气泡发生器,并在专门建造的水回路中对其工作特性进行了可视化研究。利用高速摄像系统跟踪气泡的运动和碎化过程,分析气液相流速对碎化后气泡尺寸的影响。结果表明：在实验条件下,当气体流量一定时,气泡尺寸随液体流量的增大而减小;当液体流量一定时,气泡尺寸随气体流量的增加而增大。     

CR-39应用于中子探测的化学蚀刻条件优化研究

CR-39化学蚀刻的主要影响因素有蚀刻温度、蚀刻液种类和浓度以及蚀刻时间等。本研究选用英国Track Analysis Systems公司的CR-39,采用正交法对蚀刻温度、蚀刻液浓度、蚀刻时间进行试验研究,并与公司推荐化学蚀刻条件下的径迹图像、径迹密度进行对比,得出的优化蚀刻条件是:蚀刻温度为85°C、Na OH蚀刻液浓度为7 mol·L ~1,蚀刻时间为90 min。实验同时发现蚀刻温度是这三个因素中对化学蚀刻后净径迹密度影响最大的因素,而蚀刻时间的影响最小。该研究为CR-39应用于中子探测提供了更好的蚀刻条件,节省了实验时间。     

Impact of photoneutrons on reactivity measurements for TMSR-SF1

The solid-fueled thorium molten salt reactor(TMSR-SF1) is a 10 MW_(th) test reactor design to be deployed in 5-10 years by the TMSR group.Its design combines coated particle fuel and molten FLiBe coolant for great intrinsic safety features and economic advantages.Due to a large amount of beryllium in the coolant salt,photoneutrons are produced by(y,n) reaction,hence the increasing fraction of effective delayed neutrons in the core by the photoneutrons originating from the long-lived fission products.Some of the delayed photoneutron groups are of long lifetime,so a direct effect is resulted in the transient process and reactivity measurement.To study the impact of photoneutrons for TMSR-SF1,the effective photoneutron fraction is estimated using k-ratio method and performed by the Monte Carlo code(MCNP5) with ENDF/B-Ⅶ cross sections.Based on the coupled neutronphoton point kinetics equations,influence of the photoneutrons is analyzed.The results show that the impact of photoneutrons is not negligible in reactivity measurement.Without considering photoneutrons in on-line reactivity measurement based on inverse point kinetics can result in overestimation of the positive reactivity and underestimation of the negative reactivity.The photoneutrons also lead to more waiting time for the doubling time measurement.Since the photoneutron precursors take extremely long time to achieve equilibrium,a "steady" power operation may not directly imply a "real" criticality.     

熔盐堆主回路系统氙的动力学特性研究

基于Mathematica7.0为熔盐堆（MSR）主回路系统建立了一套含流动项及在线去除功能的氙（135Xe）的动态分布数值分析程序,针对2?MW MSR的一种设计方案,分析了不同流量、不同启停堆功率、不同在线去除效率情况下135Xe浓度随时间的动态变化特性。结果表明:相较于静态燃耗模型,流动燃耗模型的135Xe带来的负反应性要低约32.2%;额定流量下主回路系统135Xe浓度分布均匀,只有当主回路系统体积流量小于2.24 cm3·s-1时,流动效应才会对主回路系统内135Xe浓度分布有显著影响;当鼓泡系统的在线去除份额约为0.1%时可以使堆芯135Xe带来的负反应性降低至-38.3 pcm?（1 pcm =10-5）,其总的去除效率可以达到86.0%;不同功率水平瞬时停堆工况下,堆芯135Xe浓度单调下降,停堆约50 h后135Xe基本消失,相当于引入+254 pcm反应性,停堆过程无碘坑出现,停堆后再启堆过程不必担心碘坑启动的问题。135Xe去除效率对整个系统135Xe总量有一定影响,在去除份额从0.0001%~20%的变化范围内,135Xe的总活度与静态燃耗模型相比相应增加了0.67%~8.75%。