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.     

变压器绝缘电阻低于允许值的处理

本文就一台主变压器绝缘电阻低于“规程”允许值的问题，进行了原因分析，提出了简易的处理方法，取得了较好效果，同时提出了几个值得探讨的问题，对提高变压器的安全运行水平有一定的现实意义。     

收尽铁路油槽车底油的措施

介绍了造成铁路油槽车底油收不尽的原因，一是节约意识差；二是设备设施陈旧或维护不够；三是操作不当。提出了增强节约意识，挖掘设备潜力，采用合理的吸油方法的对策。     

建筑砖砌体裂缝产生的因素及控制措施

根据温度变化、对砖墙体在地基不均匀沉降、材料自身、施工经验、建筑设计所引起的各种裂缝进行分析研究，并提出控制的措施和建议。     

设计监理在工程建设中的意义及应用探讨

对我国目前建设工程的监理概况进行了分析,指出推行设计监理是社会经济发展的必然趋势,探讨了推行工程设计监理的意义,就如何做好设计监理工作,详细阐述了具体的应对措施.     

新型清洁压裂液的实验室合成

研制出一种新型的双子季铵盐表面活性剂———N,N-双十八烷基-N,N,N,N-四醇乙基-二溴乙二铵(Gemini-OHAB),对用Gemini-OHAB及其它辅剂配制的新型压裂液体系性能进行了研究。结果表明:该体系具有良好的粘弹性、悬砂性能、低温溶解性以及抗温稳定性能;而且由于双子季铵盐表面活性剂中引入了醇乙基,该新型压裂液体系解决了传统季铵盐类清洁压裂液体系的低温不溶性及高生物毒性,也克服了甜菜碱类清洁压裂液体系抗温性能低的缺点,具有良好的市场应用前景。     

浅谈沥青混凝土桥面铺装

通过对钢筋混凝土桥面柔性铺装的早期病害及其产生原因的分析,从桥面设计、材料和施工三方面提出了预防措施,对混凝土桥面沥青铺装的设计与施工有重要的参考价值。     

Robust estimation for circular data

The problems arising when there are outliers in a data set that follow a circular distribution are considered. A robust estimation of the unknown parameters is obtained using the methods of weighted likelihood and minimum disparity, each of which is defined for a general parametric family of circular data. The class of power divergence and the related residual adjustment function is investigated in order to improve the performance of the two methods which are studied for the Von Mises (circular normal) and the Wrapped Normal distributions. The techniques are illustrated via two examples based on a real data set and a Monte Carlo study, which also enables the discussion of various computational aspects.     

Environmental assessment of an uncontrolled sanitary landfill,Pocos de Caldas,Brazil

There are more than 20,000 uncontrolled sanitary landfill areas in Brazil. The paper reports an integrated study undertaken to develop an environmental assessment of the uncontrolled sanitary landfill area of the city of Po?os de Caldas, State of Minas Gerais, Brazil. A number of remedial alternatives were evaluated. The USGS modular 3D finite difference groundwater flow model (Modflow) and Modular 3D Finite Difference Mass Transport Model (MT3D) software were used to simulate groundwater flow and contaminant transport modelling, as well as to predict changes due to the proposed remediation measures. The remedial alternatives considered for normal conditions from 20 to 40 year periods were waste removal, vertical cut-off barriers, extraction wells and top capping. The results indicated that extraction wells and waste removal are the best alternatives because they significantly reduce both the extension and levels of the contamination plume even after 5 years. The extraction well proved a less expensive remedial alternative than waste removal.      

沥青质沉积引起的储层损害与对策

综述了近年来受到国际石油界普遍关注的沥青质沉积引起近井地带储层损害的问题。综述论题有：前言；原油沥青质吸附沉积过程及其对产能的影响；沥青质沉积的清除方法；结论：沥青质沉积对储层的损害和对产能的影响是不可忽视扩要损害形式为孔喉堵塞，润湿反转和微粒运移等，沥青质沉积主要是原油所处热力学条件变化，原油中沥青质絮凝并沉降的结果。这类储层损害应以早期预防为主，一旦发生严重损害，应采取有效方法清除沉积的沥青质，使油井恢复产能。