核电站风险监测系统恢复分析方法及其应用

核电站概率安全评价中一般都包含恢复分析的内容,作为概率安全评价技术高级应用的风险监测系统同样也需要恢复分析.在分析风险监测系统实时风险计算特点及要求的基础上,总结了风险监测系统恢复分析特点,并以秦山三核风险监测系统恢复分析为例进行详细介绍.研究给出一般性指导原则,并为核电站概率安全评价模型的建立提供了参考建议.     

Operating procedure automation to enhance safety of nuclear power plants

Use of logic statements and computer assist are explored as means for automation and improvement on design of operating procedures including those employed in abnormal and emergency situations. Operating procedures for downpower and loss of forced circulation are used for demonstration. Human-factors analysis is performed on generic emergency operating procedures for three strategies of control; manual, semi-automatic and automatic, using standard emergency operating procedures. Such preliminary analysis shows that automation of procedures is feasible provided that fault-tolerant software and hardware become available for design of the controllers. Recommendations are provided for tests to substantiate the promise of enhancement of plant safety. Adequate design of operating procedures through automation may alleviate several major operational problems of nuclear power plants. Also, automation of procedures is necessary for partial or overall automatic control of plants. Fully automatic operations are needed for space applications while supervised automation of land-based and offshore plants may become the thrust of new generation of nuclear power plants.     

Seismic safety of nuclear power plants in eastern Europe

This paper summarizes the work performed by the International Atomic Energy Agency in the areas of safety review and applied research in support of programmes for the assessment and enhancement of seismic safety in Eastern Europe and in particular, WWER type nuclear power plants during the past seven years. Three major topics are discussed; engineering safety review services in relation to external events, technical guidelines for the assessment and upgrading of WWER type nuclear power plants, and the Coordinated Research Programme on "Benchmark study for the seismic analysis and testing of WWER type nuclear power plants". These topics are summarized in a way to provide an overview of the past and present safety situation in selected WWER type plants which are all located in Eastern European countries. The main conclusion of this paper is that even though there is now a thorough understanding of the seismic safety issues in these operating nuclear power plants, the implementation of seismic upgrades to structures, systems and components are lagging behind, particularly for those cases in which re-evaluation indicated the necessity to strengthen the safety related structures or install new safety systems.     

Analyzing the decision making process of certifying digital control systems of nuclear power plants

Safety-critical computing systems need regulators’ approval before operation. Such a permit issue process is called “certification”. Digital instrumentation and Control (I&C) certification in the nuclear domain has always been problematic and lengthy. Thus, the certification efficiency has always been a crucial concern to the applicant whose business depends on the regulatory decision. However, to our knowledge, there is little basic research on this topic. This study presents a Regulatory Decision-Making Model aiming at analyzing the characteristics and efficiency influence factors in a generic certification process. This model is developed from a dynamic operational perspective by viewing the certification process as an evidence–confidence conversion process. The proposed model is then applied to previous nuclear digital I&C certification experiences to successfully explain why some cases were successful and some were troublesome. Lessons learned from these cases provide invaluable insights regarding to the regulatory review activity. Furthermore, to utilize the insights obtained from the model, a prototype of a computer-aided licensing support system has been developed to speed up review evidence preparation and manipulation; thus, regulatory review efficiency can be further improved.     

Regenerative cesium-vapor-supply systems for thermal-emission nuclear power plants

Scientific-Industrial Organization Red Star. Translated from Atomnaya Énergiya, Vol. 71, No. 6, pp. 573–575, December, 1991.     

Fuzzy methodology applied to Probabilistic Safety Assessment for digital system in nuclear power plants

A fuzzy inference system (FIS) modeling technique to treat a nuclear reliability engineering problem is presented. Recently, many nuclear power plants (NPPs) have performed a shift in technology to digital systems due to analog obsolescence and digital advantages. The fuzzy inference engine uses these fuzzy IF-THEN rules to determine a mapping of the input universe of discourse over the output universe of discourse based on fuzzy logic principles. The risk priority number (RPN) (typical of a traditional failure mode and effects analysis - FMEA) is calculated and compared to fuzzy risk priority number (FRPN), obtained by the use of the scores from expert opinions. It was adopted the digital feedwater control system as a practical example in the case study. The results demonstrated the potential of the inference system to this class of problem.     

Inservice measurements on piping systems and components in nuclear power plants

A special program has been developed and applicated by TÜV Rheinland to control the behaviour of pipes in power plants during service. Therefore on one hand it is possible to demonstrate the safe behaviour of the pipe on the other hand it is possible to find out unexpected loads before leading to problems. Measurements are taken over years and therefore moreover long time changes can be detected. The four phases of the program allow its application to the actual problem with basic measurements, temporary measurements or continuous measurements.     

New generation of boiling-water-reactor nuclear power plants of increased safety

Scientific-Research Construction Institute of Power Engineering. Russian Scientific Center Kurchatov Institute. Special Design Office of Industrial Organization Izhorskii Plant. All-Union Scientific-Research and Design Institute of Power Engineering Scientific-Industrial Organization. Translated from Atomnaya Énergiya, Vol. 73, No. 1, pp. 13–19, July, 1992.     

Methodology to evaluate the effectiveness of fire protection systems in nuclear power plants

A methodology for the evaluation of a fire protection system in a nuclear power plant is described. A system of Monte Carlo simulation modules has been developed, divided into the four phases of a fire scenario: ignition, detection, suppression and propagation. An interactive graphics computer program, FIRES, has been written to support these models. The system has been applied in a test case analysis of several zones of an operating plant. The models appear capable of providing interpretable and useful results.     

A neural network based operation guidance system for procedure presentation and operation validation in nuclear power plants

An operation guidance system (OGS) was developed to regulate and supervise operators’ actions during abnormal environments in nuclear power plants (NPPs). The system integrated a primitive computerized procedures system (CPS) and an operation validation system (OVS) imbedded in a virtual simulated operational environment. As the key component of the OGS, OVS provided two important functions for the operators: validated check of operations, and qualitative and quantitative effects analysis of operations. Each of operators’ action was evaluated by the system and possible results were simulated by using artificial neural networks (ANN). Finally, corresponding suggestion or warning was provided to operators. This should reduce human errors during operation in emergency scenarios.     

Recommended research for improving seismic safety of light-water nuclear power plants

Recommendations for research to improve the seismic safety of Light Water Reactors (LWR) are presented in this paper, based on analysis of the answers to a questionnaire returned by 55 persons or groups working in the area of seismic safety of nuclear power plants. In addition to the questionnaire results, the recommendations also include ideas expressed at a meeting of an ad hoc group of professionals, formed by Sandia Laboratories; a review of literature, current research programs, and engineering judgment.     

Development and application of filters for air cleaning in nuclear power plants

The development of filter systems for air cleaning in nuclear power plants will be briefly described. The result of research work on iodine filters was the basis for the use of gasketless deep-bed filters and of the multiway sorption filter in German reactor stations. The composition of the iodine release to the environment was validated with the “discriminating iodine species sampler”. The main sources for the release of elemental iodine from BWR and PWR were discovered and finally suppressed. The mechanical strength of HEPA filters is being tested at high temperatures and humidities. Prototype HEPA filters have been developed with much higher resistance against humidity, differential pressure, and corrosion. A filter for the removal of particles during extreme operating conditions such as containment venting was developed using stainless steel fibers for the filter medium. The first filter of this type has already been built and installed in a modern German PWR as a part of the containment-venting system for serious accidents.     

Deterministic safety study of advanced molten salt nuclear systems for prospective nuclear power

The inter-comparative analysis of the deterministic safety potential of innovative molten salt systems with critical and sub-critical cores is presented for both fast and thermal neutron spectra. The analysis includes two aspects: the choice of an initial level of sub-criticality and the study of multiple unprotected transients which have been simulated on the basis of one-point kinetics and two-point thermo-hydraulic schemes considering realistic feedback effects. Our preliminary results show that even small levels of sub-criticality (2–3 dollars) of cores can improve their safety characteristics significantly.     

A pragmatic pairwise group-decision method for selection of sites for nuclear power plants

A pragmatic pairwise group-decision approach is applied to compare two regions in order to select the more suitable one for construction of nuclear power plants in the Kingdom of Saudi Arabia. The selection methodology is based on pairwise comparison by forced choice. The method facilitates rating of the regions or sites using simple calculations. Two regions, one close to Dhahran on the Arabian Gulf and another close to Jeddah on the Red Sea, are evaluated. No specific site in either region is considered at this stage. The comparison is based on a set of selection criteria which include (i) topography, (ii) geology, (iii) seismology, (iv) meteorology, (v) oceanography, (vi) hydrology and (vii) proximetry to oil and gas fields. The comparison shows that the Jeddah region is more suitable than the Dhahran region.