Prospect of RBMK-NPPS strength monitoring system on-line module development

System for strength monitoring and residual lifetime (SMS) assessment of NPP equipment makes it possible to improve safety and effectiveness of operation.

According to SMS concept it includes two main modules: for on-line data acquisition and diagnostic and for off-line date processing and lifetime assessment.

Algorithm for RBMK SMS on-line module is proposed to be based on the basis of “DASHA” expert system shell.

Universal expert shell “DASHA” was created using the original matrix method of image identification theory and can be used for on-line diagnostic system development for any complex technological object of arbitrary physical nature.     

Lifetime and ageing management of nuclear power plants: A brief overview of some light water reactor component ageing degradation problems and ways of mitigation

The susceptibility and tendency for nuclear power plant (NPP) components to undergo changes in their mechanical and physical properties in the course of the NPP lifetime is generally termed as “ageing”. The light water reactor (LWR) nuclear environment is not a begnign one; it is characterized not only by fast neutrons, which can degrade metallic structures, but also relatively high temperatures of coolant water (around 300°C) which may contain impurities (e.g. sulphate, chloride, peroxides) which can cause corrosion. The hydrodynamical conditions of the coolant in steam generators, for example, can cause thermal fatigue, erosion and corrosion; suspended particulate matter can accelerate erosion processes which can lead to wall thinning and lowering of safety margins. Ageing is, therefore, a very complex mixture of factors concerned with materials, temperatures, times of exposure to environments which vary with time and with respect to chemical composition and flow charactertistics.

The paper describes a few ageing phenomena which can be considered important due to their impact on nuclear safety issues; their influence on economic aspects (availability) of NPP is outlined. Mitigation measures for NPP component ageing problems are given together with recommendations for addressing such issues in NPP now and in the future.     

安全仪表系统在二次再热机组的应用研究

  目的  安全性是电力行业永恒的主题,安全仪表系统是保证机组安全性的重要手段之一。国际上,安全仪表系统已有较为成熟的标准体系且得到广泛应用,而在国内火电行业的应用仍处于探索阶段。为推广安全仪表系统在电力行业应用,将描述其在火电二次再热机组的实际应用案例,为其它火电工程的设计、采购和运行维护提供参考。  方法  首先详细介绍和分析了相关国际规范,然后介绍了安全仪表系统在二次再热1 000 MW机组电厂项目的应用情况,并使用风险图表法对电厂进行安全完整性等级分析。  结果  通过分析等级并应用于二次再热1 000 MW机组电厂的设备招标、设计、调试、运行等,有效提高了电厂运行的安全稳定。  结论  在电力工程前期对机组安全仪表系统进行分析有利于电厂全生命周期的管理设计过程,应广泛应用于电力行业。     

智慧型海上风电场一体化监控系统方案设计

  [目的]  针对海上风电场的运行管理情况,整合了海上风电机组、海上升压站、陆上集控中心的监控系统,提出了全面的智慧型海上风电场一体化监控系统方案。  [方法]  方案分析了其体系架构、功能要求、数据处理以及安全分区,以实现风电场海上升压站无人值守,陆上集控中心少人运行的运营模式。方案有效地整合了风机监控、升压站监控、视频及环境监控、风电功率预测、海缆故障监测、设备状态监测等多个子系统。  [结果]  对海上风电场内各主要电气设备提供了完善的监控功能,可实现运行监视、操作与控制、信息综合分析与智能告警、运行管理、辅助功能这五大应用。  [结论]  方案可有效降低风电场运营成本,达到技术先进、功能完备、性能可靠、经济合理的智能化运营要求。     

Safety-enhancing electrode additives for Li-ion batteries

分别以α-Al₂O₃和Li₂TiO₃作为锂离子电池正极和负极中的安全添加剂,提出了安全添加剂的作用模型,系统比较了有无安全添加剂的两组电池的电化学性能和安全性能。电化学性能测试结果表明,安全添加剂的加入会很小幅度降低锂离子电池的能量密度;电池的倍率性能不受影响,其在5 C放电倍率时容量保持率达到82.3%（以1 C为基准）;电池的预期循环寿命达2409次（按照80% DOD计算）,相比对比组电池的896次预算寿命大幅增加。安全性能测试结果表明,添加了安全添加剂的电池能够通过严苛的穿刺测试、重物撞击测试和外短路测试等安全测试,安全添加剂的存在可以有效避免电池内部局部热点的产生,使不可控的内部短路转变为可控的低倍率放电,显著提高电池的安全性能,在商业化方面展示出良好的应用前景。     

海上风电机组辅助监控系统方案设计

  [目的]  考虑海上风电场生产监控与运营管理的需求,分析海上风电机组辅助监控系统总体设计、功能要求、子系统要求。  [方法]  整合风机状态监测系统(含振动在线状态监测系统、风机基础监测系统、螺栓载荷在线监测系统、桨叶状态监测系统、发电机绝缘电阻自动监测系统、雷电远程监测系统、齿轮箱润滑油质在线监测系统、箱变运行状态监测系统)、视频监控系统、风机IP电话系统、扩展功能等,实现风机动力设备、环境、安防的统一监控。  [结果]  该系统结合多参数信息融合,实现电气及机械特征量的风机故障诊断,为广东省海上风电大数据中心的风机性能比较提供支撑。  [结论]  辅助监控系统方案可实现预防性的运营维护,使风电场智能化监控和故障早期预警成为可能。     

Applicability of pipelocks as a remedy for intergranular stress corrosion cracking in BWRs

Design, analyses and first application of the Pipelock as a novel long-term multicycle protection for piping systems in Boiling Water Reactor plants damaged by Intergranular Stress Corrosion Cracking in BWRs is described. Confirmatory tests simulating all design and operating conditions including LOCA are also discussed.

Pipelocks are mechanical devices which prevent pipe break even if it is assumed that intergranular stress corrosion cracking penetrates through-the-wall and around the entire circumference of the pipe weldment. With a fully cracked weldment, the entrapped wedges lock the pipes together, preventing the ends from separating.

In addition to providing defense-in-depth against pipe breaks, pretightening of the Pipelock bolts produces axial and circumferential compressive stresses in the pipe wall at the weldment, thus tending to retard or eliminate crack growth during operation after installing the Pipelock.

Pipelocks are designed to meet regulatory requirements 10CFR50—Appendix B and ASME Code Section III requirements for long-term multicycle operation.

Installed Pipelocks can be disassembled to permit inservice inspection of the weldment. They therefore can be used through several outages subsequent to the installation, thereby eliminating or postponing the need for pipe changeout. The design of the Pipelock also enables their use on weldments which were previously overlaid.     

区域综合能源管控与服务管理系统设计与应用

  [目的]  在节能降耗与区域综合能源受到广泛关注的背景下,为满足区域综合能源管控与服务需求,设计提出一套区域能源综合管控与服务管理系统架构方案,并进行实际应用。  [方法]  基于电、热、气、水等多种类型能源系统综合管控与服务的实际业务需求,结合大数据、云平台、物联网、移动互联、智慧城市等新技术新理念,设计提出一套主要包括能源监控、能源分析、能源管理、运维检修、交易结算、增值服务等应用的区域能源综合管控与服务管理系统。  [结果]  基本形成面向能源供给侧及需求侧的综合能源监控、管理与服务的完整业务,并以实际案例应用阐明该系统可满足企业级、园区级、区域级三类典型应用场景的综合能源管理与服务需求。  [结论]  所提方案经实践应用可有效支撑区域能源综合管控与服务业务开展。     

双机回热系统小汽机仪控设计及控制策略研究

  目的  双机回热系统可以提升机组的能级效率,如何设计双机回热系统的控制策略并确保其安全、经济、有效一直是我们关注的重点问题。  方法  针对双机回热系统的功能要求,设计了相应的双机回热系统的仪表测点布置方案,并系统性地提出了双机回热小机的启动、转速控制、系统保护及背压控制的策略。  结果  该双机回热控制策略已在超超临界1 000 MW机组中成功应用,可使双机回热控制系统在满足给水转速控制的同时,也满足双机回热小机的抽汽、排汽,溢流等协调控制要求,以确保系统稳定、可靠、经济运行。  结论  所提出的控制策略,对后续双机回热系统的控制策略研究具有参考借鉴意义。     

储能技术应用场景和发展关键问题

  [目的]  储能是能源互联网的重要组成部分和关键支撑技术,能够提供调峰、调频等多种服务,是提升传统电力系统灵活性、经济性和安全性的重要手段。  [方法]  综述了现有主要储能技术的特点,分析了电源侧、用户侧和电网侧应用场景下储能的作用和需求。根据应用现状,指出影响储能进一步发展应用的安全性、经济性和商业模式关键问题。  [结果]  最后从储能应用方角度提出应加强储能运行模拟、多重组合利用、集中和分散相结合等建议。  [结论]  研究结论可为储能技术的应用研究和发展提供参考。     

Measurement of physical properties of refrigerant mixtures. Determination of phase diagrams

Accurate knowledge of high pressure phase equilibrium is of utmost interest in designing chemical processes and separation units operating at high pressures. Moreover, these data are essential to develop optimized models in order to provide continuous representation of high pressure phase equilibrium. The best models are required to permit process simulators to be the most accurate as possible. There are many experimental ways to obtain information about the phase behaviour of fluid mixtures. They can be classified into two main categories: open and closed circuit methods. Closed circuit methods are composed of two main categories: the synthetic methods where compositions are known a priori and analytic methods where samplers are needed. The laboratory has published several data sets concerning refrigerant systems (binaries and ternaries). The more recent are:

– binary and ternary systems with 1,1,1,2,3,3,3-heptafluoropropane (R227ea), difluoromethane (R32) (two hydrofluorocarbons) and propane (R290),

– binaries of R227ea or R32 with CO₂ (R744) and an old refrigerant SO₂ (R764),

– ternary system composed of dimethyl ether (DME), pentafluoroethane (R125) and 1,1,1,2-tetrafluoroethane (R134a),

– binary systems involving DME with R134a and R32.

In this paper we have focused our attention on two types of models:

– the first one is a thermodynamic model implying equations of state and several mixing rules,

– the second one is a neural network model. It is not a “thermodynamic” model, but it can be used to calculate thermodynamics properties like enthalpy, entropy from density values. It has been used to represent density data of the R134a + R125 + DME ternary system.

In-service determination of acceptable defect sizes in VVER-1000 reactor vessel metal

This paper discusses NPP vessel equipment strength, reliability and operation problems.

Urgent questions of essential pressure vessel operation are considered, in particular, the determination of volume of work related to the removal of defects, detected in the course of in-service reactor vessel metal state inspection. Accomplished calculation assessment of reactor vessel metal defect acceptable sizes allows to take well-grounded decisions on reconditioning necessity and its date. The performed analysis takes into account most dangerous design conditions of vessel loading as well as defect depth and form.     

超超临界机组水汽质量控制研究

[目的]超超临界机组是国内发电主力机组,对水汽质量要求严格,文章提出水汽质量控制措施以防止热力系统产生结垢和腐蚀,保证机组安全经济运行.[方法]为控制超超临界机组水汽质量,应该选择恰当的除盐水生产工艺、可靠的凝结水精处理系统、采取给水加氧处理(OT)、设置合理的在线监测表计、选择合适的凝汽器管材及做好停炉保护.[结果]...     

A further study on the theory of “falling ponds”

The theory of “falling pond” is investigated and the stability requirements of such ponds are discussed. Based on the possible maximum temperature gradients, curves determining the regions of operation of stable falling solar ponds are presented. Also the effects of the thickness of the non-convecting layer and the bottom temperature on the stability of such ponds are discussed. Comparison between a MgCl₂ and NaCl falling solar pond is made and typical profiles for concentration are presented.     

基于固定翼无人机激光雷达点云数据的输电线路三维建模与树障分析

  [目的]  针对当前输电线路树障巡检周期长、作业强度大、无法保证巡检结果客观性与完整性的问题,提出了一套基于固定翼无人机三维激光点云数据进行输电线路三维建模及树障隐患智能识别的方法。  [方法]  通过固定翼无人机搭载三维激光扫描仪获取输电线路点云数据,提取点云中电力线点并模拟出完整电力线,计算电力线与电力线保护区范围内植被的欧式距离,将计算的结果与电力线安全规范比较得到树障点或预警点等信息。  [结果]  试验结果表明:自动拟合的电力线误差较小,满足树障检测的要求。  [结论]  研究方法可自动、快速、完整地提取电力线,且提取精度满足树障检测的精度要求,可大幅提升现有输电线路树障隐患检测的质量与效率。     

Managing your process hazards as a means of conforming to ohsa requirements

There is considerable evidence that improper changes have directly caused or through the “domino sequence” led to many of the major accidents that have occurred in the chemical process industry and related industries that use hazardous chemicals and technology. Central Government has recognised the importance of careful management of change(MOC) for ensuring the safety of chemical operations and the quality of manufactured goods by the proposed adding of the Major Hazardous Installation Regulation to the OHSA (Act 85 of 1993).

The concept and the need to properly manage change are not new; many companies have adopted MOC procedures. It is common practice nowadays to perform detailed risk assessments on any new or intended project to ensure safety and reliability of the project. Yet, incidents and near misses attributable to inadequate management of changes on existing systems and processes continue to occur. To improve the performance of MOC systems throughout industry, managers need advice on how to better institutionalise MOC systems within their companies and plants.

The purpose of this paper is to define the important features of MOC systems and to assist in the implementation and management of process hazards. MOC systems help ensure that changes to design and operation of company facilities will not adversely affect employees, the public, or the environment. This document outlines a process that can be used for designing, developing, installing, operating, and maintaining MOC systems at individual company sites.

This paper is intended for an audience ranging from plant and corporate managers of process safety to workers who have differing levels of knowledge about the principles of safely managing change. It is primarily designed to equip people responsible for MOC systems with new ideas for implementing and improving MOC systems. It was indeed a privilege to have met the personnel of JBF Associates, Inc. and Process Safety Institute in Knoxville, Tennessee, USA, without whose lectures and study material (including the book “Managing process changes”) this paper would never have seen the light. They have succeeded in putting me firmly on the “process safety road”.     

Nuclear methane reforming for coal gasification

The G.E.G.N. (Groupement pour l'Etude de la Gazéification Nucléaire) is a group which will study nuclear coal gasification and which is formed by “Commissariat à l'Energie Atomique”, “Gaz de France”, “Charbonnages de France”, “Creusot-Loire” and “Novatome”. The G.E.G.N. was created in 1976, with the approval of the French government, to determine a coal gasification process, to define a R & D programme and to evaluate the cost of the process.

The nuclear steam reforming of methane and the hydrogasification of coal were chosen as preliminary options. The hydrogasification was also chosen because the temperatue level of the steam reforming is lower than that of the coal steam gasification.

Therefore, it seems reasonable to limit the core outlet temperature to 850°C, although the core can deliver higher helium temperatures.

The use of an intermediate circuit allows a great flexibility in the reformer design and makes it easier to handle the catalyst.

In this paper the reasons for these choices are explained and the technological solutions are discussed.     

Fitness-for-service assessment of spherical pressure vessels with hot spots

Spherical shapes are used in industry as hemispherical vessel heads or high-pressure storage vessels due to the inherent strength associated with the shape. Structural integrity of such components needs to be evaluated periodically to prevent failure of the vessels under operating conditions. The paper develops a method for Level 2 (as defined by API 579 [(2000). Fitness-for-service, API 579. Washington, DC: American Petroleum Institute]) fitness-for-service estimation of spherical shapes subject to local hot spots where the temperatures are elevated due to local damage. The decay length for spherical shells is determined, and the size of hot spot to be identified as local is proposed. A lower bound “remaining strength factor” (RSF) for spherical pressure vessels containing hot spots is formulated by the application of Mura's variational formulation and the m-multiplier method. The effectiveness of the proposed Level 2 method is evaluated and demonstrated through an example.     

Facility risk review as a means to addressing existing risks during the life cycle of a process unit, operation or facility

In today's process industry environment, it is becoming more and more important for companies to manage the risks associated with their plants. Amongst others, some reasons for this are that 1) Process Safety is featuring high on the agenda of Trade Unions; 2) that Management is coming under increased pressure to provide a safe workplace; 3) that Companies are trying to survive in the current competitive environment by adopting the “zero accidents” ideal; 4) because the effects of accidents that do occur are becoming more devastating due to increased inventories and the exotic nature of products and 5) the fact that overseas companies are looking at safety and conservation track records before choosing business partners or considering trade agreements.

Regulatory directives such as OHSA'S (Occupational Health and Safety Act, Act 85 of 1993) Major Hazard Installation Regulation in conjunction with SABS 0228 (hazard group 1) is another newcomer entering the playing fields of South African Companies and is in the future going to have a serious impact on Company philosophies and policies. In this Regulations “Risk Assessment” is defined as “a planned programme to reduce, to remove, and to control a major incident”. This can be interpreted as having the meaning/objective to involve some type of Risk Management programme which will co-ordinate inter alia the risk assessment function. Also defined is “Major Incident”, which reads: “It is an occurrence (including in particular, a major emission, fire or explosion) resulting from uncontrolled developments in the course of an industrial activity, leading to a serious danger to persons, whether immediate or delayed, inside or outside the installation, or to the environment, and involving one or more dangerous substance”

To address this problem of managing the risks in a facility/plant/operation is no mean feat. Cost factors, time constraints, manpower availability, legislatory pressures and uncertainty on the most applicable risk assessment method to use, are just some of the problems facing management. Adding to this dilemma is the fact that the reviewing specialist has to choose from a variety of risk assessment methods that have varying degrees of complexity, cost and applicability. Past experience has however shown that Hazard and Operability Analysis (Hazop), Failure Mode and Effects Analysis (FMEA), Fault Tree Analysis and Event Tree Analysis are the most widely used and well accepted.

Choosing the right assessment method which will provide the information management needs to address the facility's risks is often the most difficult part in the whole assessment process. With this paper we are providing an overview of such a risk assessment method, namely Facility Risk Review (FRR) which uses a combination of techniques of a qualitative and quantitative nature.

These methods are similar to those currently being used with great success in the risk assessment process at the facilities of the Sasol Group of Companies. These methods are in use from the initial conceptual design stage of any project or change up to the stage where the facility has been in operation for many years.     

The second ASTM/ESIS Symposium on Constraint Effects in Fracture; an overview

The Second ASTM/ESIS Symposium on Constraint Effects in Fracture attracted a total of 24 contributions. These papers addressed various models to characterize, quantify and predict constraint effects, as well as experimental/validation studies and application studies. Available constraint models include the mechanics-based approaches of two-parameter fracture mechanics (2PFM) (i.e. J-T, J-Q, J-A₂, J-_g), statistical techniques based on the Weibull model, and micro-mechanical approaches applicable to fracture by both cleavage and ductile mechanisms. Collectively, these strategies extend significantly the range of loading conditions to which a fracture mechanics methodology can be applied to assess the integrity of an operating structure. At this stage, the following general statements can be made:

1. (1) In the lower transition regime where cleavage fracture occurs before or just shortly after the onset of ductile tearing, all of the 2PEM constraint models can be applied to parameterize the variation of critical fracture toughness with constraint. Of the various models available, the J-Q approach of O'Dowd and Shih applies rigorously to the highest deformation levels and to the broadest range of materials. Experimental evidence is available which shows the validity of this approach. All of the 2PEM approaches, however, suffer from the disadvantage that they complicate considerably the task of characterizing material toughness because toughness becomes a function of constraint at every temperature rather than a single value.

2. (2) In the lower transition regime it is also possible to predict without resort to empirical argument this variation of toughness with constraint using the results of standard fracture toughness tests coupled with the micromechanics approach of Dodds and Anderson. At the second Symposium, the applicability of this model was extended into the upper transition regime where significant stable tearing may precede the onset of cleavage. Again, experimental evidence is available which shows the validity of this approach. Certain issues remain with respect to the proper treatment of 3-D effects; these are currently under investigation.

3. (3) A “master curve” approach to the analysis of fracture toughness data in the transition regime has been proposed in a draft ASTM standard on this topic. Combination of this approach with a statistical correction for thickness effects based on the Weibull model appears to provide a powerful tool for the predicting toughness of geometrically similar specimens from one another (e.g. thick C(T)s predicted from thin C(T)s) across a wide range of thicknesses.

4. (4) 2PFM models can be applied on the upper shelf to parameterize constraint effects on R-curve behavior. However, in this application the theoretical basis of these approaches is lost as a reference infinite body field solution that is self-similar to the field solution for growing cracks in finite bodies is not available. As a consequence, it can be expected that “size effects” would likely reveal themselves in such an application. On the upper shelf the way forward appears to be through application of some form of local approach wherein sub-continuum material variables are incorporated into the models to provide a capability to predict accurately structural behavior from test results.