Fire-induced loss of nuclear power plant safety functions

A methodology is developed for evaluating the probability for loss of nuclear power plant safety functions due to fire. A framework for the investigation of fire scenarios involving safety-related equipment is established which models fire development as an event tree consisting of a series of ignition, detection, suppression, and propagation steps. The methodology has been applied to a representative BWR. Variations in the methodology are discussed for application to specific plants. Conservative estimates of core-damage probabilities due to fire were obtained; application of the methodology to a particular BWR including specific knowledge of cable locations, fire-retardants, detectors, etc. would result in considerably lower probabilities.     

Hot particles near a nuclear power plant during a hypothetical explosive accident

Institute of Applied Geophysics, Rosgidromet. Translated from Atomnaya Énergiya, Vol. 75, No. 5, pp. 377-381, November, 1993.     

Equipment response spectra for nuclear power plant systems

An analytical method is developed whereby a simple estimate can be obtained of the maximum dynamic response of light equipment attached to a structure subjected to ground motion. The natural frequency of the equipment, modeled as a single-degree-of-freedom system, is considered to be close or equal to one of the natural frequencies of the N-degree-of-freedom structure. This estimate provides a convenient, rational basis for the structural design of the equipment and its installation.The approach is based on the transient analysis of lightly damped tuned or slightly nontuned equipment-structure systems in which the mass of the equipment is much smaller than that of the structure. It is assumed that the information available to the designer is a design spectrum for the ground motion, fixed-base modal properties of the structure, and fixed-base properties of the equipment. The results obtained are simple estimates of the maximum acceleration and displacement of the equipment. The method can also be used to treat closely spaced modes in structural systems, where the square root of the sum of the squares procedure is known to be invalid.This analytical method is also applied to nontuned equipment-structure systems for which the conventional floor spectrum method is mathematically valid. A closed-form solution is obtained which permits an estimate of the maximum response of the equipment to be determined without the necessity to compute time histories as required by the floor spectrum method.     

Investigation of the development of the 1986 accident at the Chernobyl nuclear power plant

Important results obtained from investigations of the diverse processes that occurred during the accident in the No. 4 unit of the Chernobyl nuclear power plant on April 26, 1986 are presented in a concise form. The events occurring in the unit in connection with the preparation for runout tests to be performed on a turbogenerator are examined: from the characteristics of the test program to the actions taken by the plant personnel in preparation for the these tests. The events that determined the character of the evolution and the catastrophic consequences of the accident are noted: involuntary stopping of the reactor and subsequent power increase without unpoisoning of the core, stopping of feed-water flow with increasing loop flow, operators’ lack of information about the actuation of the technological shielding of the electric drives of the main circulation pumps and electricity generator. Computational analysis of the initial phase of the accident and other computational assessments revealed new factors which with a large void effect made reactor runaway on prompt neutrons unavoidable-cavitation steam reaching the core entrance from the shutoff-regulation valve and/or the cavitation shutdown of the feed to the remaining main circulation pumps after the pumps powered by the run-out turbogenerator were disconnected. The most likely picture of the evolution of the accident is constructed on the basis of an examination of the destroyed power-generating unit. __________ Translated from Atomnaya énergiya,Vol. 100, No. 4, pp. 243–258, April, 2006.     

Active seismic response control systems for nuclear power plant equipment facilities

To sustain severe earthquake ground motion, a new type of anti-seismic structure is proposed, called a Dynamic Intelligent Building (DIB) system, which is positioned as an active seismic response controlled the structure. The structural concept starts from a new recognition of earthquake ground motion, and the structural natural frequency is actively adjusted to avoid resonant vibration, and similarly the external counter-force cancels the resonant force which comes from the dynamic structural motion energy. These concepts are verified using an analytical simulator program. The advanced application of the DIB system, is the Active Supporting system and the Active Stabilizer system for nuclear power plant equipment facilities.     

Single-loop nuclear power plant with a pressurized-water reactor

Trust Tsentroénergomontazh. Translated from Atomnaya Énergiya, Vol. 71, No. 5, pp. 458–460, November, 1991.     

Safety-related decision making at a nuclear power plant

The decision making environment of an operating nuclear power plant is presented. The organizations involved, their roles and interactions as well as the main influencing factors and decision criteria are described. The focus is on safety-related decisions, and the framework is based on the situation at Loviisa power station. The role of probabilistic safety assessment (PSA) is illustrated with decisions concerning plant modifications, optimization, acceptance of temporary configurations and extended repair times. Suggestions are made for rational and flexible risk-based control of allowed times to operate the plant with some components out of service.     

核电厂的安全文化

以DNMC(大亚湾核电站)管理干部安全文化培训教材为基础,简要地说明核电厂的安全、设计、管理、组织文化、安全文化这一系列概念的基本内容和相互之间的关系。重点解释了安全文化体系的构成要素;政策层、管理层和员工个人三层承诺的基本要求;并对典型的安全文化事项,如透明的文化、习惯性违规等进行了分析和论断。人三层承诺的基本要求;并对典型的安全文化事项,如透明的文化、习惯性违规等进行了分析和论断。     

核电运行人才的培养

以秦山第二核电厂为例,介绍了系统性培训方法SAT和运行人才培养体系、培训管理组织机构和责任、核电厂运行人才培养的逐级培训体系、在岗培训制度、运行处的岗位授权制度、人才培养的激励机制等,为核电厂运行人才培养提供参考。     

On the implementation of disturbance analysis systems for detection and diagnosis of safety-related transients in a nuclear power plant

Considerable interest has developed in the last few years in the possible applications of a computerized disturbance analysis system (DAS) to nuclear power plant fault detection and diagnosis. The present paper, after introducing some general aspects of the DAS methodology, focuses specifically on the problems associated with its application to safety related malfunctions and transients. An approach called ‘significant event analysis’ is proposed for possible application when considerable diagnostic depth is deemed necessary from the DAS. A fairly detailed application of this approach to a particular class of disturbances potentially associated with power supply systems is then described. Finally, consideration is given to the relation between the specific types of failures actually recorded in electrical systems and the potential benefits from implementation of a DAS in those systems.     

Choice of the unit power-generating capacity of a nuclear power plant

A characteristic of the present status of nuclear power in Russia is that in the next few years it will be necessary to make basic technological and economic decisions that will have long-term consequences. These decisions must concern all aspects of the nuclear-power complex. Specifically, at the present time there is no validation of the present and future requirements for the capacity of serially manufactured power-generating units of nuclear power plants with VVER or fast reactors. The problem of choosing the unit capacity of a nuclear power plant must be examined taking account of different factors and not solely from the standpoint of minimizing the capital and operational components of the cost of electricity. The main objective of this work was to develop recommendations for validating the optimal capacity of powergenerating units in nuclear power plants (capital costs, construction time, harm due to unanticipated stoppage of the power-generating units, unification, manufacturing quality, harm due to accidents, and so forth), the possibilities of electric grids, and the regional demand for electricity. Translated from Atomnaya énergiya, Vol. 105, No. 5, pp. 243–248, November, 2008.