Level 2 Probabilistic Risk Assessment Using Dynamic Event Tree Analysis

Author(s):  
Douglas M. Osborn ◽  
Tunc Aldemir ◽  
Richard S. Denning ◽  
Diego Mandelli
2017 ◽  
Author(s):  
Timothy A. Wheeler ◽  
Matthew R. Denman ◽  
R. A. Williams ◽  
Nevin Martin ◽  
Zachary Kyle Jankovsky

2011 ◽  
Vol 6 (7) ◽  
pp. 340-348 ◽  
Author(s):  
Zhongbao Zhou ◽  
Xuan Zeng ◽  
Haitao Li ◽  
Siya Lui ◽  
Chaoqun Ma

2021 ◽  
Author(s):  
Zlatko Zafirovski ◽  
Vasko Gacevski ◽  
Zoran Krakutovski ◽  
Slobodan Ognjenovic ◽  
Ivona Nedevska

The intense demand and construction of tunnels is accompanied by uncertainties. The reason for appearance of uncertainties are the complex solutions and conditions for these structures. Location and dimensions are becoming more challenging, and the construction is predicted in complexed geological conditions, leading to application of new approaches, methodologies and technologies by the engineers. Most of the uncertainties and unwanted events in tunnelling occur in the construction phase, which generally leads to economic consequences and time losses. For easier handling of the uncertainties, they should be anticipated and studied within a separate part of each project. One of the newer approaches to dealing with uncertainties is hazard and risk assessment and defining ways to deal with them i.e. management. Hazards and risks can be analysed qualitatively and quantitatively. The quantitative analysis, examines the causes and consequences in more detail way and gives explanation of the dependencies. With the quantitative approach, a more valuable information for decision-making can be provided. There are various models and methods used for the quantification of hazards and risks. This paper presents a methodology in which the fault tree analysis and event tree analysis are used in combination to obtain quantitative results. The fault tree analysis is used for assessment of various hazards and the different ways and reasons that cause them. The event tree analysis is a method for assessing the possible scenarios, which follow after a certain hazard i.e. the consequences that may occur in the project. These trees represent graphic models combined with a mathematical (probabilistic) model, which give the probability of occurrence of the risks.


2019 ◽  
Author(s):  
RAFAE ANTONIO BRISEÑO-RAMIRO ◽  
VÍCTOR HUGO ALCOCER-YAMANAKA ◽  
ADRIÁN PEDROZO-ACUÑA ◽  
JOSÉ AGUSTIN BREÑA-NARANJO ◽  
RAMÓN DOMÍNGUEZ-MORA

Author(s):  
Petr Trávníček ◽  
Luboš Kotek ◽  
Tomáš Koutný ◽  
Tomáš Vítěz

Biogas plants are a specific facility from the QRA (Quantitative Risk Assessment) methodologies' point of view, especially in the case of the determination of the event frequency of accident scenarios for biogas leakage from a gas holder and subsequent initiation. QRA methodologies determine event frequencies for different types of accident events related to vessels made of steel. Gas holders installed at biogas plants are predominantly made of other materials and are often integrated with the fermenter. It is therefore a specific type of gas holder, differing from that which is commonly used in the chemical industry. In addition, long-term experience is not available for the operation of biogas plants, unlike in the chemical industry. The event frequencies listed in the QRA methodologies are not relevant for the risk assessment of biogas plants. This work is focused on setting the prerequisites for QRA of biogas storage, including for example: information on hazardous chemical substances occurring at biogas plants, their classification, and information on the construction of integrated gas holders. For the purpose of the work, a scenario was applied where the greatest damage (to life or property) is expected. This scenario is the leakage of the total volume of hazardous gas substance from the gas holder and subsequent initiation. Based on this information, a "tree" was processed for "Fault Tree Analysis" (FTA), and frequencies were estimated for each event. Thereafter, an "Event Tree Analysis" was carried out. This work follows up on a discussion by experts on the determination of scenario frequencies for biogas plants that was conducted in the past.


Author(s):  
Oskars Podziņš ◽  
Andrejs Romānovs

There are numerous methods for risk identification and risk assessment phases. Which for risk identification includes historical and systematic approach and inductive or theoretical analysis. One of the main reasons why risk identification is very helpful is that it provides justification in many cases for any large IT investment and other large undertakings. Without it organization probably wouldn’t be able to come to conclusion. Also in this phase business recognize the threats, vulnerabilities, and assets associated with its IT systems. Together with risk assessment phase risk management specialist is responsible for determining asset value, what's the value of the asset business is protecting, and risk acceptance level. Risk assessment on the other hand examines impact or consequence, as well as examines and evaluates the likelihood or probability of that adverse event happening. Risk assessment includes methods like Bayesian analysis, Bow Tie Analysis, brainstorming or structured interviews, business impact analysis, cause and consequence, cause-and-effect analysis, Delphi method, event tree analysis, fault tree analysis, hazard analysis, hazard and operational studies, and finally structured what if technique or SWIFT process. Risk assessment has two distinctive assessment types- quantitative and qualitative assessment. Quantitative assessment tries to put a monetary value on all risks. Qualitative assessment on the other hand rather look at it from a range of values like low, medium, high. The results of these phases are going to be documented in the risk assessment report and reported to senior management.


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