SAPHIRE

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SAPHIRE is a probabilistic risk and reliability assessment software tool. SAPHIRE stands for Systems Analysis Programs for Hands-on Integrated Reliability Evaluations. The system was developed for the U.S. Nuclear Regulatory Commission (NRC) by the Idaho National Laboratory.

Development began in the mid-1980s when the NRC began exploring two notions: 1) that Probabilistic Risk Assessment (PRA) information could be displayed and manipulated using the emerging microcomputer technology of the day and 2) the rapid advancement of PRA technology required a relatively inexpensive and readily available platform for teaching PRA concepts to students.

Contents

The history of SAPHIRE

1987 Version 1 of the code called IRRAS (now known as SAPHIRE) introduced an innovative way to draw, edit, and analyze graphical fault trees.

1989 Version 2 is released incorporating the ability to draw, edit, and analyze graphical event trees.

1990 Analysis improvements to IRRAS led to the release of Version 4 and the formation of the IRRAS Users Group.

1992 Creation of 32-bit IRRAS, Version 5, resulted in an order-of-magnitude decrease in analysis time. New features included: end state analysis; fire, flood, and seismic modules; rule-base cut set processing; and rule-based fault tree to event tree linking.

1997 SAPHIRE for Windows, version 6.x, is released. Use of a Windows user-inferface makes SAPHIRE easy to learn. The new "plug-in" feature allows analysts to expand on the built-in probability calculations.

1999 SAPHIRE for Windows, version 7.x, is released. Enhancements are made to the event tree "linking rules" and to the use of dual language capability inside the SAPHIRE database.

2005 SAPHIRE for Windows, version 8.x, undergoes development.

2008 SAPHIRE for Windows, version 8.x, release as a beta version.

The evolution of software and related analysis methods has led to the current generation of the SAPHIRE tool. The current SAPHIRE software code-base started in the mid-1980s as part of the NRC’s general risk activities. In 1986, work commenced on the precursor to the SAPHIRE software – this software package was named the Integrated Reliability and Risk Analysis System, or IRRAS. IRRAS was the first IBM compatible PC-based risk analysis tool developed at the Idaho National Laboratory, thereby allowing users to work in a graphical interface rather than with mainframe punch cards. While limited to the analysis of only fault trees of medium size, version 1 of IRRAS was the initial step in the progress that today has led to the SAPHIRE software, software that is capable of running on multiple processors simultaneously and is able to handle extremely large analyses.

NASA Use with SAPHIRE

Historically, NASA relied on worst-case Failure Modes and Effects Analysis for safety assessment. However, this approach has problems, such as it is qualitative and does not aggregate risk at a system or mission level. On October 29, 1986, the investigation of the Challenger accident criticized NASA for not “estimating the probability of failure of the various [Shuttle] elements.” Further, in January 1988, the Post-Challenger investigation recommended that “probabilistic risk assessment approaches be applied to the Shuttle risk management program."

Consequently, probabilistic methods are now being used at NASA. Specifically, the following projects have all used the SAPHIRE software as the primary analysis tool for risk:

  • PRA for the International Space Station
  • PRA for the Space Shuttle
  • PRA studies in support of nuclear missions
  • PRA for conceptual designs (e.g., Constellation)
  • PRA for the Mars Exploration Rover

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