Conference Paper

QRAS - the Quantitative Risk Assessment System

Maryland Univ., College Park, MD
DOI: 10.1109/RAMS.2002.981666 Conference: Reliability and Maintainability Symposium, 2002. Proceedings. Annual
Source: IEEE Xplore


This paper presents an overview of version 1.6 of QRAS, the
Quantitative Risk Assessment System. QRAS is a PC-based software tool
for conducting probabilistic risk assessments (PRA), which was developed
to address needs held by NASA, but can be used in a wide range of
industries. The software is different from other PRA tools in three key
areas. First, QRAS bridges communication and skill gaps between
managers, engineers, and risk analysts by using representations of the
risk model and analysis results that are easy to comprehend by each of
those groups. For that purpose, event sequence diagrams (ESD) are used
as a replacement for event trees (ET) to model scenarios, and the
quantification of events is possible through a set of quantification
models familiar to engineers. In addition, QRAS' graphical user
interface provides a more structured guidance than other tools in order
to facilitate its use by nonexpert users. Second, QRAS includes a strong
support for modeling approaches not typically found in tools developed
for the nuclear industry, such as phased-mission modeling. Finally, QRAS
applies leading edge reduced ordered binary decision diagram (ROBDD)
technology for the accurate and efficient computation of risk results

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