A graphical method for breaking logical loops based on multi-tree structure

Kerntechnik ◽  
2020 ◽  
Vol 85 (2) ◽  
pp. 122-130
Author(s):  
A. Yang ◽  
H. Miao ◽  
N. Li
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Safety Assessment ◽  
Graphical Method ◽  
Tree Structure ◽  
Industrial Systems ◽  
Probabilistic Safety Assessment ◽  
Minimal Cut Sets ◽  
Minimal Cut

Abstract Logical loops or circular logics, interpreted as circular supporting relations among systems, remain a longstanding challenge in the probabilistic safety assessment (PSA). Logical loops are commonly found in complex industrial systems. Due to the existence of the logical loops, the minimal cut sets cannot be directly obtained. In order to solve this problem, the logical loops should be broken properly. This paper proposes a graphical method based on multi-tree structure. By constructing the simplified multi-tree, logical loops both in linearly and non-linearly interrelated systems are solved. To illustrate this method, examples of linearly interrelated systems and non-linearly interrelated systems are given in this paper. As a supplement, this method is applied to the well-known complex logical loops in the nuclear power plant. It shows that this method is highly intuitive and efficient by means of graphs.

scholarly journals The Importance of Probabilistic Safety Assessment in the Careful Study of Risks Envolved to New Nuclear Power Plant Projects

2021 ◽  
Vol 9 (2A) ◽  
Author(s):  
Jônatas Franco Campos da Mata ◽  
Amir Zacarias Mesquita
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Safety Assessment ◽  
Nuclear Reactors ◽  
The United States ◽  
Careful Study ◽  
Tree Analysis ◽  
Probabilistic Safety Assessment ◽  
Probabilistic Safety

The Fukushima Daiichi nuclear accident in Japan in 2011 has raised public fears about the actual safety of nuclear power plants in several countries. The response to this concern by government agencies and private companies has been objective and pragmatic in order to guarantee best practices in the several phases of nuclear reactors. In countries where the nucleo-electric matrix is consolidated, such as the United States, France and the United Kingdom, the safety assessment is carried out considering deterministic and probabilistic criteria. In the licensing stages of new projects, it is necessary to analyze and simulate the behavior of the nuclear power plant, when subjected to conditions that can lead to sequences of accidents. Probabilistic Safety Assessment (PSA) is fundamental in this process, as it studies in depth the sequences of events that can lead to damage to the reactor core. Such sequences should be quantified in terms of probability of occurrence and your possible consequences, and organized through techniques such as Fault Tree Analysis and Event Tree Analysis. The present work will describe the procedures for the realization of PSA and its applicability to the assurance of the operational reliability of the nuclear reactors, as well as a brief comparative between the approaches used in some countries traditionally users of thermonuclear energy and Brazil. By means of this analysis, it can be concluded that nuclear power is increasingly reliable and safe, being able to provide the necessary tranquility for the population of the countries where it is inserted.

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