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| Probabilistic Risk and Safety
Assessment - PRA, PSA a website created by Relex Software Corporation
Probabilistic Risk Assessment and Probabilistic Safety Assessment (PRA and PSA) are reliability assessment methods used to analyze systems where safety is a critical factor. They determine the reliability of a product or system based on the probability of component or system failure. A PSA generally deals with safety-related issues, while a PRA may deal with other non-safety issues. Two reliability analysis methods that provide this information are the Fault Tree Analysis (FTA) and Event Tree Analysis (ETA). Fault Tree Analysis (FTA)Fault Tree analysis is one of the most widely-used methods in system reliability analysis. It is a deductive procedure for determining the various combinations of hardware and software failures, and human errors that could result in the occurrence of specified undesired events (referred to as top events) at the system level. A deductive analysis begins with a general conclusion, then attempts to determine the specific causes of this conclusion. This is often described as a "top down" approach. Click here to see an example screen of a fault tree. (Click your browser's "Back" button to return.) The main purpose of a fault tree analysis is to evaluate the probability of the top event using analytical or statistical methods. These calculations involve system quantitative reliability and maintainability information, such as failure probability, failure rate, or repair rate. FTA can provide useful information concerning the likelihood of a failure and the means by which such a failure could occur. Efforts to improve system safety and reliability can be focused and refined using the results of the FTA. Event Tree Analysis (ETA)An event tree is a visual representation of all the events which can occur in a system. As the number of events increases, the picture fans out like the branches of a tree. Click here to see a simple example of an event tree. (Click your browser's "Back" button to return.) The goal of an event tree analysis is to determine the probability of an event based on the outcomes of each event in the chronological sequence of events leading up to it. By analyzing all possible outcomes, you can determine the percentage of outcomes which lead to the desired result. PRA, PSA, and Reliability SoftwareRelex Software Corporation produces software that enables users to easily perform fault tree analysis and event tree analysis, which are important elements in both PRA and PSA. Relex Software is a leader in RAM (Reliability and Maintainability) software analysis tools. We specialize in software, training courses, and seminars covering all aspects of reliability engineering. Our products are used by thousands of engineers worldwide in a variety of businesses. For More InformationPlease visit the Links page for more online information about the Relex Software visual reliability software modules, and about PRA and PSA in general. If you are a Relex user, thank you for your support. If you are evaluating our software for future use, we hope to welcome you soon to RELiability EXcellence with Relex. Contact UsPhone: 724.836.8800 Copyright © 2001, Relex Software Corporation. All Rights Reserved. |
