摘要:

Nearly ten years have passed since the publication in August 1974 of the draft Reactor Safety Study (WASH 1400), the first detailed attempt to apply probabilistic risk assessment (PRA) techniques to estimate the public risks posed by commercial nuclear power plants. Now is an opportune time to look back and see how PRA has fared over these ten years. We will not attempt to pass judgement on how the Reactor Safety Study report itself has withstood the test of time, as that task is best left to others less directly involved in preparing the report. Instead, we will examine advances in the understanding, acceptance, and utilization of PRA techniques, as well as technical advances in PRA methods. Some of the significant insights gained from PRAs will be discussed. Finally, some observations on the future of PRA will be offered.

ISSN:0272-4332    

DOI:10.1111/j.1539-6924.1984.tb00944.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

A large number of PRA studies have been completed for specific plants at specific sites. From these studies, taken individually or collectively, many significant insights have evolved into items important to risk and safety. The content of this paper is primarily based on the material contained in the EPRI funded review of five PRA studies: Big Rock Point, Zion, Limerick, Grand Gulf, and Arkansas Nuclear One. The first three were the utility sponsored studies publicly available at the time of project initiation while the other two were deemed representative of the NRC's RSSMAP and IREP programs respectively. The results of PRA studies are usually expressed in terms of core melt frequencies, radionuclide release frequencies, and frequencies of occurrence of different reactor accident consequences (e.g., early and latent fatalities) depending on the level of PRA. These subjects are prominently addressed in this paper. One of the results of a PRA study is identification of a relatively small number of accident sequences that represent the dominant contributors to core melt. An analysis of the salient features of the dominant accident sequences from eleven PRA's yielded a characterization of accident sequence categories discussed at some length. Impact of external events is discussed very briefly. Next to an explicit quantification of public risk or core melt frequency, the identification of specific safety concerns and the evaluation of possible solutions to implement risk management are probably the best recognized and most widely used applications of PRA. Several illustrative examples are briefly discussed. Human interactions are extremely important contributors to safety and reliability of the plants. A review of PRA studies concluded that it was necessary to account for five types of human interactions; some of which may mitigate while others may exacerbate an accident sequence.

ISSN:0272-4332    

DOI:10.1111/j.1539-6924.1984.tb00945.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

During the period from 1977 to 1984, Pickard, Lowe and Garrick, Inc., had the lead in preparing several full scope probabilistic risk assessments for electric utilities. Five of those studies are discussed from the point of view of advancements and lessons learned. The objective and trend of these studies is toward utilization of the risk models by the plant owners as risk management tools. Advancements that have been made are in presentation and documentation of the PRAs, generation of more understandable plant level information, and improvements in methodology to facilitate technology transfer. Specific areas of advancement are in the treatment of such issues as dependent failures, human interaction, and the uncertainty in the source term. Lessons learned cover a wide spectrum and include the importance of plant specific models for meaningful risk management, the role of external events in risk, the sensitivity of contributors to choice of risk index, and the very important finding that the public risk is extremely small. The future direction of PRA is to establish less dependence on experts for in‐plant application. Computerizing the PRAs such that they can be accessed on line and interactively is the ke

ISSN:0272-4332    

DOI:10.1111/j.1539-6924.1984.tb00946.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Probabilistic risk assessment (PRA) is a relatively new tool in the nuclear industry. The Reactor Safety Study started the present trend of conducting PRAs for nuclear power plants when it was published in 1975. Now, nine years later, those in the industry currently using PRA techniques are frequently asked the same question: Why should the nuclear utility industry, with so many accepted analytical tools already available, invest the time and manpower to develop a new technique with so many uncertainties?

ISSN:0272-4332    

DOI:10.1111/j.1539-6924.1984.tb00947.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The historical basis and more recent activities and products of probabilistic risk analysis (PRA) in the Atomic Energy Commission and Nuclear Regulatory Commission (NRC) are reviewed. Current NRC program activities and objectives are described. The author's opinions on the best uses of PRA are presented.

ISSN:0272-4332    

DOI:10.1111/j.1539-6924.1984.tb00948.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

A synopsis is given of research projects on probabilistic systems analysis conducted by the Risk Assessment Program of the Electric Power Research Institute. A brief outline of the value of systems analysis both within PRA and as a stand‐alone discipline is used to show how the objectives of the research program are related to industry needs. Research projects and their deliverables are discussed in relation to three objectives: (1) to improve the credibility of the methods and results, (2) to provide computer tools and technology transfer, and (3) to develop use of the methods to improve safety and availability in operation. Recent achievements and future plans are briefly described and an up to date list of relevant EPRI publications is provide

ISSN:0272-4332    

DOI:10.1111/j.1539-6924.1984.tb00949.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

There are many uncertainties in a probabilistic risk analysis (PRA). We identify the different types of uncertainties and describe their implications. We then summarize the uncertainty analyses which have performed in current PRAs and characterize results which have been obtained. We draw conclusions regarding interpretations of uncertainties, areas having largest uncertainties, and needs which exist in uncertainty analysis. We finally characterize the robustness of various utilizations of PRA results.

ISSN:0272-4332    

DOI:10.1111/j.1539-6924.1984.tb00950.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

This article discusses the methodologies presently available for analyzing the contribution of “external initiators” to overall risks in the context of PRA (probabilistic risk assessment) of large commercial nuclear power reactors. “External initiators” include earthquakes, fires and floods inside the plant, external floods, high winds, aircraft, barge, and ship collisions, noxious or explosive gases offsite, and so on. These are in contrast to “internal initiators” such as active or passive plant equipment failures, human errors, and loss of electrical power. The ability to consider external initiators within PRA has undergone major advances in recent years. In general, uncertainties associated with the calculated risks from external initiators are much larger than those associated with internal initiators. The principal uncertainties lie with development of hazard curves (such as the frequency of occurrence of an event exceeding a given size: for example, the likelihood of a hurricane with winds exceeding 125 knots). For assessment of earthquakes, internal fires and floods, and high winds, the methodology is reasonably mature for qualitative assessment but not for quantitative application. The risks from other external initiators are generally considered to be low, either because of the very long recurrence time associated with the events or because the plants are judged to be well designed to wit

ISSN:0272-4332    

DOI:10.1111/j.1539-6924.1984.tb00951.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY