蒸汽发生器蒸汽管箱的应力分析

高温一级部件的应力分析涉及载荷控制的应力限值及应变和变形限值的计算。本文描述了蒸汽发生器蒸汽管箱的高温应力分析方法、步骤,并给出了最终评价结果。     

某内陆核电厂正常工况下放射性液态流出物排放的适应性分析

介绍了国家重新修订并即将颁布的GB 6249和GB 14587新标准对核电厂液态流出物排放的新要求,通过一个内陆滨河电厂初可研阶段AP1000机组放射性液态流出物排放的环境影响评价实例,分析了内陆核电厂选址过程中放射性液态流出物排放对相关法规的适应性,并提出在AP1000机组设计过程中需要关注的问题。     

浓缩回收铀的M级联的近似算法

浓缩回收铀最有效的级联形式是带附加供料流的级联,它以天然铀为主供料,回收铀为附加供料。基于回收铀浓缩的特殊性,提供一种用于浓缩回收铀的带附加供料流的M级联的近似算法。数值计算表明,近似算法与工程优化算法得到的结果非常接近,最大相对偏差不超过0.1%。近似算法相对于工程优化算法更简单、方便和快速。     

Operations strategy for workload balancing of crews in an advanced main control room

The advanced main control room (advanced-MCR) is the one that allows for reactor operations based on digital instrumentation and control (I&C) technology. Thus, the operators of an advanced-MCR operate the plant through digital I&C interfaces, and for this purpose, an additional digital manipulation task for the operating equipment should be performed that cannot be observed in a conventional-MCR. As a prior study proposing the cognitive, communicative, and operational activity measurement approach (COCOA), COCOA enables an evaluation of the operator's workload in an advanced-MCR, which includes newly generated tasks for Man-Machine Interface System based secondary operation under a digital environment, which does not exist in a conventional-MCR. As a result of observations on the workload level by utilizing COCOA for a reference plant with an advanced-MCR when conducting an emergency operating procedure, it was observed that the workload of the shift supervisor is about two times greater than that of other operators. This is because operators therein stuck to the old guidelines customized to a conventional-MCR and failed to accomplish load balancing in consideration of the operation environment that an advanced-MCR provides. In this context, it would be imperative to develop and apply an operations strategy for an advanced-MCR operation. This study proposes an operations strategy in an attempt to make a balanced workload of operators in an advanced-MCR.     

半球形CdZnTe伽马谱仪在放射性"热点"测量中的应用

核设施退役过程中,对退役场所进行"热点"调查(包括"热点"定位,活度测量等)是非常重要的.为了配合伽马相机在热点调查后对"热点"进行更为精确的测量,建立了一套配有铅屏蔽准直器的CdZnTe伽马能谱系统,用Visual c#语言编写了便于现场操作的谱分析软件MiniAnalysis,对现场用CdZnTe谱仪测得的能谱进行...     

沉积有机质痕量元素的中子活化分析及其在有机质类型研究中的应用

采用中子活化技术测定了沉积有机质中的无机组分－痕量元素，并以此作为划分有机质类型的依据，以松辽盆地北部深层高成熟度有机质为例进行了探索，结果表明沉积有机质中Ｖ，Ｎｉ等元素的丰度与有机质母质类型的关系密切，特别是当有机质的演化程度很高时，这些元素的丰度仍有十分显著的差异，这就工分高成熟度沉积有机质类型提供了一种新的方法。     

The expansion of a cylinder under conditions of finite plane strain

The problem of the expansion of an initially thick-walled cylinder due to an internal pressure under conditions of plane strain is considered. The cylinder is composed of an elasto-plastic, Tresca material with an associated flow rule. No restriction is placed on the magnitude of the deformation or on the magnitude of the material parameters. Solutions are presented for a particular initial (stress free) geometry and it is shown that the maximum value of the internal pressure is a function of the deformation to strength parameter ratio.     

北京市地铁站台及车箱内氡浓度水平调查

地铁作为城市公共交通系统的重要组成部分,发挥着越来越大的作用.由于地铁所处地下环境的特殊性,其空间氡浓度水平及其对健康的可能影响受到越来越多的关注.本文介绍了近年北京市地铁氡浓度监测与调查工作的开展情况,汇总了地铁站与车箱内的氡浓度监测结果,分析了地铁工作人员与日常乘地铁出行公众的受照剂量水平,并提出了今后对地铁环境氡...     

核电设备公路运输的风险分析与控制

核电设备公路运输过程是设备制造完成后到安装投入使用前的一个重要环节,是设备制造价值向安装使用价值转化的一个必要阶段;在运输各环节,存在不同的风险因素。本文以秦山二期扩建工程3号机组稳压器运输过程为例,对核电设备公路运输各阶段的风险因素进行分析,提出相应的风险控制措施,以期完善核电设备公路运输过程的质量控制。     

Formal qualification of the various sources of an uncertainty employed in the level 2 PSA and the underlying issues

In the Level 2 PSA, a probabilistic treatment of complex phenomenological accident pathways inevitably leads to two sources of an uncertainty: (a) an incomplete modeling of these accident pathways and their subsequent impacts on the Level 2 risk, and (b) an expert-to-expert variation in the their probabilistic estimates. The impacts of the foregoing sources of an uncertainty on the Level 2 risk measures are different from each other, thus leading to a different conclusion in the decision-making process. An important aspect of the foregoing distinction of an uncertainty is that it plays an essential role in identifying what sources of an uncertainty impact more on the Level 2 risk and what sources among them should be focused on for a greater reduction of the overall Level 2 uncertainty. Another aspect is closely related to its importance in combining the Levels 1 and 2 uncertainties. A primary objective of this paper is to qualify formally the typical sources of an uncertainty that would often be employed in the Level 2 PSA and the underlying issues for a further clarification.     

Detailed Evaluation of the Natural Circulation Mass Flow Rate of Water Propelled by Using an Air Injection

One-dimensional (1D) air-water two-phase natural circulation flow in the “thermohydraulic evaluation of reactor cooling mechanism by external self-induced flow—one-dimensional” (THERMES-1D) experiment has been verified and evaluated by using the RELAP5/MOD3 computer code. Experimental results on the 1D natural circulation mass flow rate of water propelled by using an air injection have been evaluated in detail. The RELAP5 results have shown that an increase in the air injection rate to 50% of the total heat flux leads to an increase in the water circulation mass flow rate. However, an increase in the air injection rate from 50 to 100% does not affect the water circulation mass flow rate, because of the inlet area condition. As the height increases in the air injection part, the void fraction increases. However, the void fraction in the upper part of the air injector maintains a constant value. An increase in the air injection mass flow rate leads to an increase in the local void fraction, but it has no influence on the local pressure. An increase in the coolant inlet area leads to an increase in the water circulation mass flow rate. However, the water outlet area does not have an influence on the water circulation mass flow rate. As the coolant outlet moves to a lower position, the water circulation mass flow rate decreases.     

Development and validation of a heuristic model for evaluation of the team performance of operators in nuclear power plants

The global concerns about safety in the digital technology of the main control room (MCR) are growing as domestic and foreign nuclear power plants are developed with computerized control facilities and human–system interfaces. In a narrow space, the digital technology contributes to a control room environment, which can facilitate the acquisition of all the information needed for operation. Thus, although an individual performance of the advanced MCR can be further improved; there is a limit in expecting an improvement in team performance. The team performance depends on organic coherence as a whole team rather than on the knowledge and skill of an individual operator. Moreover, a good team performance improves communication between and within teams in an efficient manner, and then it can be conducive to addressing unsafe conditions. Respecting this, it is important and necessary to develop methodological technology for the evaluation of operators’ teamwork or collaboration, thus enhancing operational performance in nuclear power plant at the MCR.     

Qualification of the neutronic efficiency of erbium at zero burnup

The main asset of erbium as an alternative burnable poison to gadolinium is that it has a much lower thermal absorption efficient cross section that contributes to giving it much slower consumption kinetics than gadolinium, and also helps to generate much lower perturbation in the power distribution. The calculations performed with the APOLLO code and its associated library must be qualified and validated with an experiment in order to obtain a sufficient degree of confidence to envisage an industrial application of this poison. For this purpose the MIRTE UOX and MOX experiments were performed in the critical reactor EOLE at Cadarache within the framework of the EROÏNE programme. These experiments concern the neutronic assessment of a (U,Er)O₂ rod in a representative core of a pressurised water reactor lattice with an enhanced moderation ratio. The purpose of this paper is to show that the APOLLO2 code associated with its APOLLIB CEA 93 library is perfectly qualified at time zero to calculate erbium reactivity worth.     

Effect of electron beam irradiation on the viscosity of carboxymethylcellulose solution

In this study, the effects of an electron beam irradiation on the viscosity of a carboxymethylcellulose (CMC) solution were investigated. The viscosity of the CMC solution was decreased with an increase in the irradiation dose. Interestingly, the extent of the degradation of the CMC was found to decrease with an increase of the CMC concentration in the solution. The change of the average molar mass confirmed the decrease in the viscosity due to the degradation of the polymer. The energy of the electron beam also affected the degradation of the CMC. Lower degradation of the CMC was obtained with a decreasing electron beam energy due to its lower penetration. Addition of vitamin C as a radical scavenger to the solution and an irradiation at −70 °C were shown to be moderately effective in preventing a decrease in the viscosity of the solution by irradiation.     

Seismic analysis of thin shell structures

We consider in this paper a vertically erected, axisymmetric shell, resting on a horizontal foundation. The foundation is subjected to a time-dependent motion in both the vertical and horizontal directions. The motion may be produced by an event such as an earthquake or explosion. An estimate of the response of the shell to such excitation can be obtained from the solution for time-dependent boundary conditions. This solution is adapted here for an analysis with the response spectrum of earthquakes, which has been pioneered by Biot and Housner. The modes of free vibration are calculated by the multisegment, direct numerical integration method using classical shell theory. An actual design case of a containment vessel of a nuclear power plant built in the US is presented. An estimate of the dynamic response of the shell to an earthquake is obtained for all the relevant variables, such as stresses and displacements. As an example, an estimate for the axial stress of the response is given at various stations of the shell.     

Molecular dynamics simulation of interaction of H with vacancy in W

Molecular dynamics simulations were performed to investigate the interaction between H and vacancy in W using an analytical bond-order potential to describe the interactions between W-W, W-H and H-H. The most stable configuration for H in W is the tetrahedron interstitial site. We calculated the binding energies of an H and a vacancy to an H-vacancy cluster (H_nV_m) in W, respectively, where n and m ranged from 0 to 10. The binding energy was almost unchanged. The binding energy of a vacancy to H-vacancy cluster is about 0.4 eV, which is higher than the binding energy of an H to H-vacancy cluster. Vacancy is much easier to bond with H-vacancy cluster than H. And H is easier to stay in the tetrahedron interstitial site or octahedron interstitial site in bcc W.     

Development of a Cherenkov light imaging system for studying the dynamics of radiocesium in plants

High-resolution images of radiocesium (¹³⁷Cs) distribution are required to study cesium kinetics in plants. A Cherenkov light imaging system can visualize fine distributions of radionuclides emitting beta particles using an optical camera. To evaluate the linearity of the system, an imaging test was performed with point sources of ¹³⁷Cs, with a radioactivity of 10–2000 kBq. The results indicated that the system has a good linearity between the image intensity and the radioactivity of ¹³⁷Cs. We developed an imaging system for plants using this system to study radiocesium movement in intact plants. To demonstrate the ability to image radiocesium in a plant, an experiment was performed with an intact soybean plant for four days. The root of an 11-day-old soybean plant was dipped in 20 mL of a culture solution containing ¹³⁷Cs with a radioactivity of 10 MBq without potassium. After one day, the solution was replaced with one with potassium but no ¹³⁷Cs. The soybean plant was in healthy condition in the system, and the high-resolution serial images indicated that ¹³⁷Cs was transported to the shoot and accumulated in the node. Therefore, Cherenkov light imaging is promising for imaging radiocesium in intact plants.     

U型管阵流体弹性不稳定性分析

从U型管振动方程出发,推导出 U 型管阵流体诱发振动方程,给出了管阵出现流体弹性不稳定性临界流速的计算方法及算例。结果表明:管阵的临界流速与其频率取 U 型管阵中各管子一阶频率平均值的直管管阵的流速基本一致。     

压水堆核电站大破口失水事故分析

压水堆核电站安全分析报告是核安全监管部门对其进行安全审查的重要文件,大破口失水事故是核电站运行的设计基准事故,是安全分析报告中的重要内容。本文使用RELAP5/MOD3.2进行压水堆冷管段大破口失水事故的计算,对比发现一回路冷管段发生双端断裂大破口时燃料元件包壳温度峰值（PCT）最高,且长时间维持在较高温度,此条件下反应堆最危险。计算结果表明,事故发生后,一回路压力迅速下降,堆芯冷却剂的流动性变差,导致堆芯裸露,燃料包壳温度又重新回升。通过安注系统和辅助给水系统等一系列动作,能保证燃料元件包壳温度不超过1204 ℃的限值。     

Adaptation of RT-1 Plant Technology to Processing of New Types of Spent Nuclear Fuel

Atomic Energy - The issues of including new materials into processing at a radiochemical plant are considered. Taking by way of an example the technology of an RT-1 plant, it is shown that it can...