The role of probabilistic methods in the development of regulations for nuclear power plant design — assessment and projections — in the Fed. Rep. Germany

Some views on present use and future potential of both reliability and risk analysis in reactor safety assessment and licensing are given. Although the deterministic approach is still dominating, the part of probabilistic methods in the process of regulating nuclear power plants is steadily increasing. Both methods are complementing one another.     

Seismic probabilistic safety analysis of unit 1 of the Loviisa nuclear power plant

The seismic probabilistic safety assessment consists of five phases. In the seismic hazard analysis the seismicity of the plant site is quantified. In the second phase, the structural response of plant buildings is evaluated. On the basis of structural response, the seismic fragilities of selected plant components are developed. In the following phase, the plant logic in the form of fault trees and event trees is established. In the last step, quantification of the core damage risk on the basis of the above information is carried out. For the median value of the annual core damage frequency, a value of 4.4 × 10⁻⁷ was determined.     

Low-cycle deformation of the structures in a nuclear power plant and methods for calculating them

It is proposed that the fatigue strength of structures in nuclear power plants with a quite long service life be analyzed in two stages: first, the type and location of the process and the effect of basic factors are determined by method of direct analysis of stable cycles and then a more accurate stepped analysis of the deformation kinetics is performed. The real properties of a material are systematized, taking account of creep, in ways that depend on the different types of processes. The methods for calculating the conditions and mechanisms of the progressing shape change and alternating-sign flow are refined. An example of the instability of the processes of cyclic deformation, which limits the possibility of operating structures beyond the limits of elastic adaptability, is examined. The possibilities and conditions for algorithmitization of the choice of material models and ensuring computational accuracy in calculations of deformation kinetics are discussed.     

Application of thermal comfort theory in probabilistic safety assessment of a nuclear power plant

Human factor errors in probabilistic safety assessment(PSA) of a nuclear power plant(NPP) can be prevented using thermal comfort analysis.In this paper,the THERP+HCR model is modified by using PMV (Predicted Mean Vote) and PPD(Predicted Percentage Dissatisfied) index system,so as to obtain the operator cognitive reliability,and to reflect and analyze human perception,thermal comfort status,and cognitive ability in a specific NPP environment.The mechanism of human factors in the PSA is analyzed by operators of skill,rule and knowledge types.The THERP+HCR model modified by thermal comfort theory can reflect the conditions in actual environment,and optimize reliability analysis of human factors.Improving human thermal comfort for different types of operators reduces adverse factors due to human errors,and provides a safe and optimum decision-making for NPPs.     

信息资源保障对我国核电发展的重要作用

当前,我国核电处于陕速发展阶段,而信息情报工作可以为核电的建设、持续发展提供必要的保障作用。本文在对核电发展的现状、前景进行分析的基础上,重点介绍了核领域信息资源——INIS数据库的基本隋况和利用,并举实例说明INIS工作在和平利用核能的事业中发挥越来越重要的作用。     

实时风险监测系统在田湾核电站的研发与应用

风险监测系统是概率安全分析最重要的应用工具之一,在全球各核电站风险决策领域中得到了广泛应用。本文详细介绍了田湾核电站风险监测模型的研发与管理,系统网络架构与多用户应用、实时监测研发与应用、计划自动导入和计算时效性提升等重要特征,以及在电站的针对性应用方案研究,最后讨论了风险监测系统存在的问题与挑战。     

The development of a thermal performance diagnostics expert systemfor nuclear power plant

This paper describes the development of a computerized Thermal Performance Diagnostics Expert System (TPDES) designed to assist performance engineers at nuclear power plant. The TPDES is the second phase product of the ChinShan plant performance Monitoring, Analysis and Diagnostics Expert System (CS-MADES) project. The objective of this system is to serve as a powerful tool in diagnosing the heat rate degradation problems found in nuclear power plant through man-machine intercommunications. The whole system framework was developed on a personal computer to provide an integrated, user-friendly and menu-driven environment in meeting the operator's requirements. Moreover, it can be actuated either in Chinese or English mode. Some visible benefits have been gained so far through the prototype system installed at the Chinshan nuclear power station. It is believed that TPDES could successfully reduce lost megawatts and save maintenance cost through the early detection of thermal performance deviations     

Ecology and stable development of the region containing the novovoronezh nuclear power plant

Risk analysis applied to public health is used to evaluate the ecological safety of the territory of Voronezh Oblast, where the Novovoronezh nuclear power plant is located and a new plant is under construction. It is found that for the population of the territory of Voronezh the individual risk of developing cancer because of the contamination of air by chemical carcinogens and the risk of death due to pollutants are 1000–10000 times higher than the risk of developing cancer from the additional irradiation of the population of Novovoronezh associated with the operation of the nuclear power plant. The results obtained showed that modern nuclear technologies have no effect on the public health as compared with sources of chemical risk.     

Calculation of the probabilistic characteristics of the heat-engineering parameters of a nuclear power plant under emergency regimes

A probabilistic model of the thermohydraulic processes occuring during accidents in water-moderated water-cooled reactors is studied. Computational schemes and an algorithm for calculating the probabilitistic characteristics of the heat-engineering parameters of reactors in accident regimes are proposed on the basis of the theory of multidimensional Markov processes. Examples of the application of the probabilistics approach in the analysis of accidents in nuclear power plants are presented. 9 figures. 3 tables, 6 references. Deceased. Special Design Office of Machine Building. Translated from Atomnaya énergiya, vol. 88, No. 1, pp, 21–34, January, 2000.     

基于朴素贝叶斯的核电厂事故诊断方法研究

本文将机器学习领域的贝叶斯技术应用于核应急中的电厂状态诊断,提出了基于朴素贝叶斯分类器的核电厂事故诊断方法。利用压水堆核电厂仿真机获取事故案例数据,对朴素贝叶斯分类模型进行训练,实现了对核电厂多类事故(LOCA、SGTR、MSLB)的诊断。测试结果表明,基于朴素贝叶斯分类器的核电厂事故诊断方法在诊断精度、诊断效率、事故类型可扩展性以及程序自主化诊断上有显著优势,并且模型训练中不同事故类型先验分布对诊断结果影响较小,具有较好的适用性。     

Fuzzy probability on reliability study of nuclear power plant probabilistic safety assessment: A review

Fault tree analysis (FTA) is a graphical model which has been widely used as a deductive tool for nuclear power plant (NPP) probabilistic safety assessment (PSA). The conventional one assumes that basic events of fault trees always have precise failure probabilities or failure rates. However, in real-world applications, this assumption is still arguable. For example, there is a case where an extremely hazardous accident has never happened or occurs infrequently. Therefore, reasonable historical failure data are unavailable or insufficient to be used for statistically estimating the reliability characteristics of their components. To deal with this problem, fuzzy probability approaches have been proposed and implemented. However, those existing approaches still have limitations, such as lack of fuzzy gate representations and incapability to generate probabilities greater than 1.0E-3. Therefore, a review on the current implementations of fuzzy probabilities in the NPP PSA is necessary. This study has categorized two types of fuzzy probability approaches, i.e. fuzzy based FTA and fuzzy hybrid FTA. This study also confirms that the fuzzy based FTA should be used when the uncertainties are the main focus of the FTA. Meanwhile, the fuzzy hybrid FTA should be used when the reliability of basic events of fault trees can only be expressed by qualitative linguistic terms rather than numerical values.     

加快核电标准建设 促进核电健康发展

论述了尽快建立和完善我国核电标准体系的重要意义,分析了我国核电标准建设取得的成绩和存在的问题,提出了积极推进我国核电标准建设的建议,表明了中国核工业集团公司将进一步加强标准化工作,加强与核电标准相关行业的协调配合,共同促进我国核电标准建设。     

核动力装置运行过程可靠性研究现状与发展

核动力装置运行过程的可靠性研究是保障装置安全，提高装置效能的重要基础，本文从运行过程可靠性问题的背景出发，研究了可靠性分析方法的适应性，并论述了问题研究的技术途径。     

Prospects for the development of nuclear power in Russia

Conclusions Nuclear power has completed the initial stage of development. An efficient international collaboration of scientists and specialists has been instituted, and this has made it possible to develop and formulate generally accepted requirements and the necessary conditions for further development. Despite the fact that Russia has a quite powerful scientific and technical potential, there are no significant reserves in different directions of application of nuclear power, no real plan for the development of nuclear power in Russia even in the next 15 years. This is apparently explained by the overall state of the economy of the country. Journal variant of a report at the Seventh Conference of the Nuclear Society of Russia "New Energy technologies and the role of nuclear fission and fusion power," October 14–18, 1996, Moscow. Special Office of Machine Design N. N. Ponomarev-Stepanoi Russian Science Center "Kurchatov Institute". Translated from Atomnaya énergiya, Vol. 81, No. 3, pp. 163–170, September, 1996.     

Safety goals for nuclear power plant regulation

A survey and comparison has been made of 10 widely disseminated safety goal proposals originating in Canada, the U.K. and the U.S. When the proposals are placed in a directly comparable numerical context, they are remarkably similar in the inferred levels of safety. The development of quantitative safety goals by the U.S. Nuclear Regulatory Commission is also reviewed. While progress has been made in structuring technically and politically defensible goals, because of the way the regulatory philosophy has evolved in the U.S. the implementation of such goals could well turn out to be more difficult than defining the goals themselves.The safety goals are useful in providing guidance to the designers, operators and regulators of nuclear power plants with regard to public safety concerns as well as plant reliability and engineering considerations.     

我国核电产业发展的铀资源保障

叙述了国内外铀资源的探明储量、供应能力、消耗量等情况,根据我国核电发展的现状和未来核电发展的规划,分析了我国核电发展的铀资源保障情况,提出了铀资源保障的有关建议。