多参量数据的离线分析

本文介绍了一种适用于ND620系统的多参量数据离线分析程序,采用FORTRAN—77语言可运用于PDP11系列的计算机,本文并讨论了粒子的鉴别和二维符合谱本底扣除等问题。     

大面积双维位置灵敏电离室离线数据分析程序

本程序是为离线分析由大面积双维位置灵敏电离室采集的多参数核事件数据设计的。程序是在PDP-11/44计算机上,用FORTRAN IV-plus语言写成,程序采用多级命令调用,方便灵活,结构的模块化易于按不同的要求组装。     

Remaining life prediction methods using operating data and knowledge on mechanisms

It is important to be able to predict the remaining life of components and structures in a power plant, both for nuclear and fossil units. The information needed can be obtained from controlled laboratory experiments and the plant operating data. On materials degradation, large amounts of data from both sources are available. However, it is essential to formulate the best methodology to utilize this information so that our needs can be met. In this paper, the methods currently used for remaining life prediction are discussed with typical results. For components with multi-subcomponents such as globe valves, it is not possible to predict the remaining life using operating data, even though useful information related to aging characteristics can be obtained. On the other hand, operating data can be used to predict the remaining life of a steam generator (SG), since the degradation of the tubes is the life limiting factor for a SG. It is shown in this paper that Weibull statistics is a useful tool in predicting the remaining life of a component utilizing the operating data. Mechanistic approaches are also necessary in formulating the working hypothesis, which can be validated by experiments and in some cases by utilizing the operating data.     

MAPPIX: A software package for off-line micro-pixe single particle aerosol analysis

In the framework of a multiannual experiment performed at Baia Terra Nova, Antarctica, size-segregated aerosol samples were collected by using a 12-stage SDI impactor (Hillamo design). Approximately 2800 particles, belonging to the first four supermicrometric SDI stages – 8.39, 4.08, 2.68, 1.66 μm dynamic aerosol diameter cuts – were analyzed at the INFN-LNL micro-PIXE facility, a three lens Oxford Microprobe (OM) product, installed in the early nineties. Four regions on each of the 12 sub-samples were measured; 60 aerosol particles were detected on average in each of the analyzed regions.The off-line single aerosol particle (SAP) analysis of such big amount of data required software that is able to rapidly handle the acquired data, with a simple and fast area selection procedure; the subsequent automated PIXE spectra analysis with a specialized code was also needed.The MAPPIX 2.0 software was designed to make easier and faster the user jobs during the SAP analysis. The package is composed of two separate routines: the first one is devoted to data format conversion (OM-LMF file format to MAPPIX format), while the second one is devoted to micro-PIXE maps graphical presentation and aerosol particle selection procedure.The MAPPIX data format and software features will be discussed; a short report of the speed performances will be presented.     

Overview of the RPV-2 and INTERN-1 packages: From primary damage to microplasticity

In the framework of the European project PERFECT, four multiscale simulation packages dedicated to the prediction of evolution of material properties were developed. Among them, the RPV-2 and INTERN-1 are two simulation sequences of similar structure dealing with radiation damage in the reactor pressure vessel and the reactor internal structures, respectively. Both start at the atomic scale, where the neutron spectrum of the specified reactor is used to determine the energy distribution of the primary knocked-on atoms (PKA). A database of molecular dynamics results is then used to integrate the instantaneous production of defect clusters resulting from the displacement cascades initiated by each PKA. Depending on the type of calculation chosen to model long-term diffusion and reactions of defect clusters, precipitates and mixed-clusters, this primary damage enters either in rate equations or in Object Kinetic Monte Carlo simulations. The later correspond to a more accurate (but also more computationally demanding) physical model for diffusion as positions of objects on a lattice are explicitly treated. Finally, the increase of critical resolved shear stress is estimated from these cluster distributions either using an analytical model, taking into account the self and mutual dipole interactions of dislocations pinned on randomly dispersed unshearable obstacles, or by simulating the glide of a single dislocation line in its main slip system. Dislocation dynamics simulations were already used to validate some of the assumptions of the latter models, and will be fully integrated in the next versions of the packages.     

利用PC/Linux处理BES实验数据的可行性研究及PC/Linux在BES粲介子物理研究中的应用

简要地介绍了利用ＰＣ／Ｌｉｎｕｘ实现对北京谱仪（ＢＥＳ）数据的离线重建、蒙特卡罗数据的产生和探测器模拟的可行性研究结果及ＰＣ／Ｌｉｎｕｘ在Ｄ／Ｄｓ物理研究等方面的应用情况,并就ＰＣ／Ｌｉｎｕｘ和ＨＰ工作站对ＢＥＳ数据的处理能力及处理结果的一致性进行了详细的比较。结果表明,ＰＣ／Ｌｉｎｕｘ完全可以用于北京谱仪数据的离线处理和物理分析工作,并在运算速度和价格上占有很大的优势。     

Structural analysis of W7-X: Overview

The Wendelstein 7-X (W7-X) modular stellarator is in the assembly phase at the Max-Planck-Institut für Plasmaphysik (IPP) in Greifswald, Germany. The goal of the project is to demonstrate that this type of machine is a viable option for a fusion power-plant. The “pentagonal” magnet system of the machine encompasses 50 non-planar and 20 planar superconducting coils with sophisticated support structure. Structural reliability of components as well as resulting deformations and displacements during various modes of operation have to be considered not only for the magnet system but also throughout the whole cryostat whose main components are the plasma vessel, outer vessel, ports, and thermal insulation.A reliable prediction of the W7-X structural behaviour is only possible by employing complex finite element (FE) simulations with a hierarchical set of FE models. A special strategy has been developed and implemented for the task.The design is basically completed, main parameters are defined, and most of the W7-X components are manufactured. Therefore, the focus in the analysis is being shifted to the creation of parametric FE models which allow performing fast analyses of possible non-conformities, changes in the assembly procedure, and future exploration of operational limits.This paper gives an overview of the implemented analysis strategy, the applied safety margins, and focuses on the most remarkable results.     

Performance of real-time neutron/gamma discrimination methods

Nuclear security usually requires the simultaneous detection of neutrons and gamma rays.With the development of crystalline materials in recent years,Cs₂Li La Br₆ (CLLB) dual-readout detectors have attracted extensive attention from researchers,where real-time neutron/gamma pulse discrimination is the critical factor among detector performance parameters.This study investigated the discrimination performance of the charge comparison,amplitude comparison,time comparison,and ...     

Numerical methods for the prediction of thermal fatigue due to turbulent mixing

Turbulent mixing of hot and cold flows is one of the possible causes of thermal fatigue in piping systems. Especially in primary pipework of nuclear power plants this is an important, safety related issue. Since the frequencies of the involved temperature fluctuations are generally too high to be detected well by common plant instrumentation, accurate numerical simulations are indispensable for a proper fatigue assessment. In this paper, a link is made between two such numerical methods: a coupled CFD-FEM model and a sinusoidal model. By linking these methods, more insight is obtained in the physical phenomenon causing thermal fatigue due to turbulent mixing. Furthermore, useful knowledge is acquired on the determination of thermal loading parameters, essential for reducing overconservatism, as currently present in simplified fatigue assessment methods.     

Fracture toughness prediction for highly irradiated RPV materials: From test results to RPV integrity assessment

New fracture toughness data are represented for highly irradiated RPV materials that were obtained by testing standard compact specimens with thickness of 12.5 mm and 25 mm and pre-cracked Charpy specimens machined from the RPV decommissioned. Two advanced engineering methods, the Master Curve and the Unified Curve, are applied for treatment of the test results. Application of the dependence of fracture toughness K_JC on test temperature T predicted with the Master Curve and the Unified Curve methods on the basis of surveillance specimens testing is discussed for RPV integrity assessment when the reference K_JC(T) curve is recalculated to the crack front length of the postulated flaw that is considerable larger than thickness of surveillance specimens. The prediction of the K_JC(T) curve transformation caused by neutron irradiation is considered.     

Post-dryout heat transfer: Physical mechanisms and a survey of prediction methods

Significant thermal non-equilibrium has been observed in the post-dryout regime. The degree of thermal non-equilibrium depends primarily on liquid-vapor interaction, and the heated surface temperature is controlled by the near-wall vapor velocity, vapor superheat and liquid-wall interaction. The possible mechanisms of post-dryout heat transfer and the state of the art for predicting post-dryout temperatures are described. The semi-theoretical approach is the most promising for simple geometries. Four empirical methods of predicting post-dryout temperatures are discussed. A bibliography and a table of all known post-dryout heat transfer correlations are presented.     

Structural analysis of W7-X: From design to assembly and operation

The Wendelstein 7-X (W7-X) modular stellarator is in the assembly phase at the Max-Planck-Institut für Plasmaphysik in Greifswald, Germany. The design of the “basic machine”, i.e. without in-vessel components, diagnostics and periphery, is largely completed, structural parameters such as bolt preload, initial conditions for contact elements, etc. are defined, and most of the components are manufactured and partly assembled. Therefore, the focus of structural analysis was shifted towards fast analyses of non-conformities, changes in the assembly procedure, and exploration of operational limits. Assembly-related work is expected to continue until commissioning of the machine, however, with decreasing intensity. In parallel the analysis requirements for in-vessel components, diagnostics and periphery will increase.This paper focuses on the most remarkable results, on special problems which had to be solved, on strategic issues like parameterization, complex finite element model structuring and benchmarking with alternative models in different codes, on assumptions of reasonable safety margins and expected tolerances, and on confirmation of analysis results by tests. Finally it highlights some lessons learned so far, which might be relevant also for other large fusion machines, and gives an outlook on future work.     

SSE在中子脉冲序列核信号实时频谱分析中的应用

为解决中子核信号频谱分析中快速傅立叶变换(FFT)高速计算的实时性关键技术问题,本论文针对用于频谱分析的中子脉冲序列信号本身所具有特殊"0、1"结构的特点,构造旋转因子表,采用SSE指令对算法优化设计,研究了一种仅需加法和寻址运算的FFT快速算法,实现了基于PC平台,在1 GHz采样率下中子脉冲序列信号的FFT实时频谱分析处理工作.性能测试结果表明,在中子脉冲计数率为3×106 s-1时,与相应的FFTW算法相比较,该算法所需的计算时间(效率)提高了517%.其中,SSE指令的优化设计可使算法的计算效率提升209%,满足了中子脉冲序列核信号频谱分析时对实时性的要求.     

Application of virtual machine technology to real-time mapping of Thomson scattering data to flux coordinates for the LHD

This paper presents a system called “TSMAP” that maps electron temperature profiles to flux coordinates for the Large Helical Device (LHD). Considering the flux surface is isothermal, TSMAP searches an equilibrium database for the LHD equilibrium that fits the electron temperature profile. The equilibrium database is built through many VMEC computations of the helical equilibria. Because the number of equilibria is large, the most important technical issue for realizing the TSMAP system is computational performance. Therefore, we use multiple personal computers to enhance performance when building the database for TSMAP. We use virtual machines on multiple Linux computers to run the TSMAP program. Virtual machine technology is flexible, allowing the number of computers to be easily increased. This paper discusses how the use of virtual machine technology enhances the performance of TSMAP calculations when multiple CPU cores are used.     

Design of FPGA based high-speed data acquisition and real-time data processing system on J-TEXT tokamak

Tokamak experiment requires high-speed data acquisition and processing systems. In traditional data acquisition system, the sampling rate, channel numbers and processing speed are limited by bus throughput and CPU speed. This paper presents a data acquisition and processing system based on FPGA. The data can be processed in real-time before it is passed to the CPU. It provides processing ability for more channels with higher sampling rates than the traditional data acquisition system while ensuring deterministic real-time performance. A working prototype is developed for the newly built polarimeter–interferometer diagnostic system on the Joint Texas Experimental Tokamak (J-TEXT). It provides 16 channels with 120 MHz maximum sampling rate and 16 bit resolution. The onboard FPGA is able to calculate the plasma electron density and Faraday rotation angel. A RAID 5 storage device is adopted providing 700 MB/s read–write speed to buffer the data to the hard disk continuously for better performance.     

A review of creep-fatigue life prediction methods: identification and extrapolation to long term and low strain cyclic loading

Eight creep-fatigue interaction models are identified on a set of LCF experimental data.The material is 316 L type stainless steel, the temperature is 600°C. The general agreement between tests and predictions is good in the experimental range.Tentative extrapolations are made toward low strain and long dwell.Opposite trends are then pointed out on stress dependent and strain range dependent models.The final results are still encouraging and general rules are given concerning the long term life prediction.     

LHAASO地面簇射粒子阵列在线实时分布式数据处理

高海拔宇宙线观测站(Large High Altitude Air Shower Observatory,LHAASO)是十二五批复立项的国家重大科技基础设施,是我国海拔最高的大科学基础设施之一,核心目标是探索高能宇宙线。作为LHAASO的重要组成,地面簇射粒子阵列(square KiloMeter detector Array,KM2A)建成探测阵列面积高达1 km~2。不同于大多高能物理实验,KM2A共约6 500路通道,总输入约546 MB·s~(-1),没有硬件触发功能,因此,需要软件完成触发与数据处理。采用基于标准以太网和TCP/IP协议的数据传输方案,接收包括所有探测器单元同一时间的全部组包数据,利用配置的触发算法对数据包进行在线处理与计算,将具有物理意义的数据提取、打包,组成不同的有物理标签的事例,并按照配置的输出规则将这些事例送出至不同的接收方,实现了实时分布式算法调度与数据处理。软件可以实时触发筛选,降低数据量,减轻传输与存储的负担。软件已在4 410 m海拔实验现场的数据中心投入使用,至今为止一直运行良好。     

Database application research in real-time data access of accelerator control system

The control system of Shanghai Synchrotron Radiation Facility (SSRF) is a large-scale distributed real-time control system. It involves many types and large amounts of real-time data access during the operating. Database system has wide application prospects in the large-scale accelerator control system. It is the future development direction of the accelerator control system, to replace the differently dedicated data structures with the mature standardized database system. This article discusses the application feasibility of database system in accelerators based on the database interface technology, real-time data access testing, and system optimization research and to establish the foundation of the wide scale application of database system in the SSRF accelerator control system. Based on the database interface technology, real-time data access testing and system optimization research, this article will introduce the application feasibility of database system in accelerators, and lay the foundation of database system application in the SSRF accelerator control system.