移动式反应堆运输安全风险评价

目的在移动式反应堆现有研发水平无法满足《放射性物品安全运输规程》(GB 11806—2019)的背景下,本研究提出通过风险评价的方法对移动式反应堆运输的安全性进行研究。方法风险评价的内容主要包括计算移动式反应堆在运输中遇到假想事故的概率和事故后果,本研究根据美国联邦法规10CFR71中§12条款的相关要求对移动式反应堆在运输中可能遇到的事故种类进行梳理,并以事故后果最为严重的与油罐车发生撞击作为极端的假想事故,通过五因子计算公式的方法对假定热功率为20 MWt的移动式反应堆在假想事故下的事故后果进行计算。结果计算得出移动式反应堆在每年运输1次的条件下假想事故的发生概率为9.7×10^(–6)次/年,反应堆冷却1年后在假想事故下对工作人员的辐照剂量为810 mSv;冷却5年后在假想事故下对工作人员的辐照剂量为590 mSv。结论假想事故下移动式反应堆的事故后果远超过Advisory Material for the IAEA Regulations for the Safe Transport of Radioactive Ma-terial(SSG-26)和《电离辐射防护与辐射源安全标准》(GB 18871—2002)中工作人员受到的辐照剂量限值,并且假想事故的发生概率没有满足我国核安全导则对超设计基准事故10–7次/年的筛选要求。因此有必要在移动式反应堆运输过程中采取包括武装押运和路线规划在内的管理措施以降低假想事故的概率并采取相应的应急措施减轻假想事故的事故后果以满足核安全部门的监管要求。

羊运输应激反应的预防措施

在羊的运输过程中,由于外界刺激因素的影响,羊会出现一系列病理变化,这被称为羊运输应激反应。这些应激症状包括流泪、口腔溃疡、咳嗽、感冒、厌食和腹泻等。据相关数据显示,新引进的羊群中有70%左右的羊只会呈现不同程度的应激反应。因此,采取正确的处理措施针对应激反应对养殖户后续的羊群生产发展具有实质性的指导意义。本文结合实际工作经验,探讨了羊运输应激反应产生的原因以及危害临床症状,并提出了相应的预防措施,希望通过研究对更好的控制该种疾病的发生流行有一定帮助。

肉用种犬运输反应的处理方法

犬是神经敏感动物,在运输途中主要表现是晕车、呕吐、精神沉郁,一般入舍后要经过数天才能恢复正常的体力和精神状态。如果不及时处理还会继发其它疾病。

降低牛运输应激反应八措施

在养牛生产中,为了引种、出售、肥育、屠宰等,经常长途运输活牛。在运输过程中牛出现应激反应,抵抗力降低,食欲变差,体重损失,甚至发病或死亡。降低牛运输应激反应可采取下列技术措施。

运输应激反应诱发小猪水肿病及其防治

通过流行病学调查,临床症状、发病原因及病理学变化分析,确定为小猪水肿病。为此提出了相应的防制措施,为今后预防和防制此类疾病发生提供借鉴。

小型移动式铅铋堆整堆运输临界安全问题研究

作为近年来核能领域研究热点方向之一的小型移动式铅铋堆,为便于应用在偏远地区或海岛等条件恶劣的场景,可运输性成为其设计目标之一.由于使用将全部核燃料放置在堆本体内的整堆运输方式,因此,有必要进行整堆运输过程的临界安全问题研究,分别研究小型移动式铅铋堆运输过程中不同工况下的堆芯临界安全问题,并分析水密度变化和湿沙含水量变化的影响.经过计算得到最恶劣事故工况下的堆芯有效增殖因数大于次临界限值的结果,不满足临界安全要求,并且分析采用其他运输方式的可能性.

Hydrodynamic Instabilities Driven by Acid-base Neutralization Reaction in Immiscible System

The hydrodynamic instabilities driven by an acid-base neutralization reaction, in contact along a plane interface, placed in a Hele-Shaw cell under the gravitational field are reported. The system consists of the heavier aqueous tetramethyle-ammonium hydroxide below the lighter layer of organic phase with propionic acid as reacting specie. The effect of chemical composition on hydrodynamic instabilities during interfacial mass transfer accompanied by a neutralization reaction is investigated. Depending on the initial concentration of the reacting species, Marangoni convection in the form of roll ceils or trains of waves is observed. Mach- Zehnder interferometer is used to measure the change in base concentration at the time of instability formation. The results show that the instabilities resulted from the convection flow are more efficient to the mechanism of mass transfer and can drastically alter pattern formation in the system.

Vapor-Phase Transport Synthesis of MnSAPO-34 and Its Catalytic Properties

MnSAPO-34 molecular sieves were synthesized by vapor-phase transport （VPT） method using triethylamine （Et3N） as a structure directing agent （SDA）, and were characterized by XRD, BET, SEM, UV-Vis, FT-IR, and TG analy- ses. The influence of the zeolite crystallization conditions and the dry-gel composition were investigated. The results showed that the synthesis conditions had an effect on the crystalline phase. Pure MnSAPO-34 had been obtained when it was crystallized at 140 C for 18 hours. The ratio of MnO/A1203 in the starting gel ranging from 0.1 to 0.2 resulted in pure MnSAPO-34 with a CHA topology. Beyond this scope, MnSAPO-5 with an AFI topology structure was obtained as an impurity substance. UV-Vis spectroscopy and FT-IR spectroscopy study indicated that manganese was incorporated into the framework of the molecular sieve. The catalytic performance of MnSAPO-34 molecular sieve was tested by ketalization reaction of l, 2-propanediol with cyclohexanone. High yield of cyclohexanone-1, 2-propanediol ketal was obtained.

小型移动式铅铋堆运输过程堆芯进水事故工况下临界安全问题研究

小型移动式铅铋堆由于在海岛、偏远地区等场景的应用需要,整堆运输的安全可行性成为必要设计目标之一。基于小型移动式铅铋堆自身特点,采用谱移吸收材料的反应性控制手段进行反应性控制方案研究,以确保整堆运输的临界安全。利用MCNP软件计算在运输过程、堆芯进水事故工况下表面涂覆不同厚度Gd_(2)O_(3)涂层的燃料芯块的有效增殖系数(k_(eff)),其中涂层厚度为50μm时满足临界安全要求;分析加入谱移吸收材料后堆芯的燃耗特性、功率分布和传热,验证表明其不影响堆芯正常运行,确定了此种反应性控制方案的可行性。

Effect of Transport Time and Handling on Physiological Responses of Cattle

The objective of this work was to determine the effect of transport time （up to 11 hours） on animal welfare. 540 animals （cows, bulls and calves）, three transport times of 2, 4 to 6, and 10 to 11 hours, and two space allowances （2 m2 and 1.5 m2 per animal for cows and bulls; and 1.2 m2 and 0.8 m2 per animal for calves） were used for the experiment during transport from farms to the abattoir in Uppsala, Sweden. Measurements were made on five animals on each trip. Stress response parameters considered were cortisol, glucose, lactate, creatine kinase and heart rate. Blood samples were taken before and after transport. Heart rate sensors were mounted on the animals at least 30 minutes before loading and measurements were made continuously from farms to the abattoirs until stunning. The results of heart rate measurement indicated that loading, un-loading and forced movement in the stunning box were the most stressful events. However, the results of statistical analysis confirmed that transport time doesn＇t have significant effect （P 〈 0.05） on heart rate. Concentration level of cortisol increased by 10 folds during short transport. However, cortisol concentration decreased with an increase of transport times （P 〈 0.01）. Glucose concentrations increased with transport time in all animal categories （P ≤ 0.01）. Transport time has significant effect on concentration levels of glucose （P ≤ 0.01）, creatine kinase （P 〈 0.001） and lactate （P 〈 0.01） particularly after 6 hours journey time.

Selective Removal of Nitrogen-Containing Heterocyclic Compounds from Transportation Diesel Fuels with Reactive Adsorbent

This paper presents a new selective adsorbent to remove nitrogen-containing heterocyclic compounds from model and commercial transportation diesel fuels based on characteristic reaction designed to occur in the pores of substrate.This reactive adsorbent is composed of formaldehyde,phosphotungstic acid and Santa Barbara USA(SBA)-15.The experiment was based on assumed hydroxymethylation reaction of nitrogen-containing heterocyclic compounds with formaldehyde using phosphotungstic acid as catalyst in batch and fixed-bed systems.The nitrogen concentration in the model fuel was 237.33 ng.μl-1,carbazole and toluene were used as model nitrogen-containing heterocyclic compound and solvent,respectively.The effectiveness of reactive adsorbent for removal of nitrogen-containing heterocyclic compounds from commercial 0# diesel fuel containing 224.86 ng.μl-1 nitrogen was examined in a fixed-bed reactor at 70 ℃.The results showed that nitrogen in the model fuel was very low and the nitrogen concentration in the commercial diesel reduced to 2.44 ng.μl-1.The demand for transportation fuel with ultra-low nitrogen is satisfied.

Coupled Transport Phenomena in Corrugated Photocatalytic Reactors

Corrugated reactors are known for their use in applications requiring UV-exposure, whereby media flowing within the corrugated channel react with a photo-active catalyst impregnated on the surface （i.e. TiO2）. The performance in these systems is dependent on catalyst properties and reactivity for a given light source, in conjunc-tion with the coupled transport of reactants within the media and photons falling incident to the catalyst surface. Experimental and computational analyses of local mass transfer and radiation pattems for a broad range of corrugation angles, depths, and non-idealities introduced during manufacture （i.e. fold curvature） are thus integrated to the design and optimization of these systems. This work explores techniques for determining incident energy distribu-tions on the surface of corrugated reactor geometries with non-ideal cross-sectional profiles, and the local and overall mass transfer rates obtained using computational fluid dynamics and experimental analysis. By examining the reaction kinetics for the photo-degradation of 4-chlorophenol over a TiO2 catalyst, the effects of surface area, energy incidence with photon recapture, and local mass transfer on overall reactor performance are presented to highlight ootimization concerns for these tvoes of reactors.

袖珍核电站

安全、可靠和廉价地和平利用核能,一直是全球关注的问题。曾有无数的方案,而开发与研究中的袖珍核电站乃其中之一。该方案的核心技术是易于运输的、一次性使用的、全密封的以及高度自动化的长寿命轻便型反应堆,它可连续使用30年无须添加燃料。这就增加了今后在偏远地区和发展中国家应用的吸引力和可行性。

The transport of water in subduction zones

The transport of water from subducting crust into the mantle is mainly dictated by the stability of hydrous minerals in subduction zones. The thermal structure of subduction zones is a key to dehydration of the subducting crust at different depths. Oceanic subduction zones show a large variation in the geotherm, but seismicity and arc volcanism are only prominent in cold subduction zones where geothermal gradients are low. In contrast, continental subduction zones have low geothermal gradients, resulting in metamorphism in cold subduction zones and the absence of arc volcanism during subduction. In very cold subduction zone where the geothermal gradient is very low(?5?C/km), lawsonite may carry water into great depths of ?300 km. In the hot subduction zone where the geothermal gradient is high(>25?C/km), the subducting crust dehydrates significantly at shallow depths and may partially melt at depths of <80 km to form felsic melts, into which water is highly dissolved. In this case, only a minor amount of water can be transported into great depths. A number of intermediate modes are present between these two end-member dehydration modes, making subduction-zone dehydration various. Low-T/low-P hydrous minerals are not stable in warm subduction zones with increasing subduction depths and thus break down at forearc depths of ?60–80 km to release large amounts of water. In contrast, the low-T/low-P hydrous minerals are replaced by low-T/high-P hydrous minerals in cold subduction zones with increasing subduction depths, allowing the water to be transported to subarc depths of 80–160 km. In either case, dehydration reactions not only trigger seismicity in the subducting crust but also cause hydration of the mantle wedge. Nevertheless, there are still minor amounts of water to be transported by ultrahigh-pressure hydrous minerals and nominally anhydrous minerals into the deeper mantle. The mantle wedge overlying the subducting slab does not partially melt upon water influx for volcanic arc magmatism, but it is hydrated at first with the lowest temperature at the slab-mantle interface, several hundreds of degree lower than the wet solidus of hydrated peridotites. The hydrated peridotites may undergo partial melting upon heating at a later time. Therefore, the water flux from the subducting crust into the overlying mantle wedge does not trigger the volcanic arc magmatism immediately.

Single-step chemistry model and transport coefficient model for hydrogen combustion

To satisfy the needs of large-scale hydrogen combustion and explosion simulation,a method is presented to establish single-step chemistry model and transport model for fuel-air mixture.If the reaction formula for hydrogen-air mixture is H2+0.5O2→H2O,the reaction rate model is ?? =1.13×10?5[H2][O2]exp(?46.37T0/T) mol(cm3 s)?1,and the transport coefficient model is ?=K/CP=ρD=7.0×10?5T 0.7 g(cm s)?1.By using current models and the reference model to simulate steady Zeldovich-von Neumann-Doering(ZND) wave and free-propagating laminar flame,it is found that the results are well agreeable.Additionally,deflagration-to-detonation transition in an obstructed channel was also simulated.The numerical results are also well consistent with the experimental results.These provide a reasonable proof for current method and new models.

Nano-Morphology of a Polymer Electrolyte Fuel Cell Catalyst Layer Imaging, Reconstruction and Analysis

The oxygen reduction reaction （ORR） in the cathode catalyst layer （CCL） of polymer electrolyte fuel cells （PEFC） is one of the major causes of performance loss during operation. In addition, the CCL is the most expensive component due to the use of a Pt catalyst. Apart from the ORR itself, the species transport to and from the reactive sites determines the performance of the PEFC. The effective transport properties of the species in the CCL depend on its nanostructure. Therefore a three-dimensional reconstruction of the CCL is required. A series of two-dimensional images was obtained from focused ion beam- scanning electron microscope （FIB-SEM） imaging and a segmentation method for the two-dimensional images has been developed. The pore size distribution （PSD） was calculated for the three-dimensional geometry. The influence of the alignment and the anisotropic pixel size on the PSD has been investigated. Pores were found in the range between 5 nm and 205 nm. Evaluation of the Knudsen number showed that gas transport in the CCL is governed by the transition flow regime. The liquid water transport can be described within continuum hydrodynamics by including suitable slip flow boundary conditions.