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NASA-FTA-1.1

NASA-FTA-1.1
  • Version
  • 322 Downloads
  • 1.65 MB File Size
  • 1 File Count
  • March 30, 2016 Create Date
  • March 30, 2016 Last Updated
Scroll for Details

Fault Tree Handbook

NASA-FTA-1.1 Fault Tree Handbook

Foreword

NASA has been a leader in most technologies it has employed in its programs over the years.
One of the important NASA objectives is now to add Probabilistic Risk Assessment (PRA) to its
repertoire of expertise in proven methods to reduce technological and programmatic risk.

Fault Tree Analysis (FTA) is one of the most important logic and probabilistic techniques used
in PRA and system reliability assessment today.

Methods to perform risk and reliability assessment in the early 1960s originated in US aerospace
and missile programs. Fault tree analysis is such an example that was quite popular in the mid
sixties. Early in the Apollo project the question was asked about the probability of successfully
sending astronauts to the moon and returning them safely to Earth. A risk, or reliability,
calculation of some sort was performed and the result was a mission success probability that was
unacceptably low. This result discouraged NASA from further quantitative risk or reliability
analysis until after the Challenger accident in 1986. Instead, NASA decided to rely on the use of
failure modes and effects analysis (FMEA) and other qualitative methods for system safety
assessments. After the Challenger accident, the importance of PRA and FTA in systems risk and
reliability analysis was realized and its use at NASA has begun to grow.

The nuclear industry began to utilize probabilistic risk assessment to assess safety following the
Three Mile Island accident in 1979. In 1981, the US Nuclear Regulatory Commission (NRC)
issued the Fault Tree Handbook, NUREG-0492. Over the past two decades, this document has
become the leading technical information source on how FTA should be performed. Although
originally intended for nuclear power applications, the Fault Tree Handbook has been
extensively used in all fields where this powerful systems analysis methodology was applied.

Over the past two decades, probabilistic risk assessment and its underlying techniques, including
FTA, has become a useful and respected methodology for safety assessment. Because of its
logical, systematic and comprehensive approach, PRA and FTA have been repeatedly proven

capable of uncovering design and operational weaknesses that escaped even some of the best
deterministic safety and engineering experts. This methodology showed that it was very
important to examine not only low-probability and high-consequence individual mishap events,
but also high-consequence scenarios which can emerge as a result of occurrence of multiple
high-probability and nearly benign events. Contrary to common perception, the latter is
oftentimes more detrimental to safety than the former.

A foremost strength of PRA and its underlying analysis techniques, including FTA, is that it is a
decision support tool. In safety applications, this methodology helps managers and engineers find
design and operational weaknesses in complex systems and then helps them systematically and
efficiently uncover and prioritize safety improvements.

In order to best benefit from PRA and PTA in management decisions, it is important that
managers and their support staffs be familiar with the value and application of these methods. In
addition, there should be a small but robust group of in—house technical experts that understand
the methods used in a PRA or FTA study, can explain its meaning and applicability to given
problems to management and serve as in-house technical advisers to the management decision
process for safety improvement. If these in-house experts do not exist initially, they should be
hired or groomed through training and transfer of technology, becoming part of the corporate
resources and memory that will help shape the organization, taking advantage of the PRA and
FTA methods and results and the expert knowledge of the external consultants. In-house experts
will help build risk-based knowledge and experience and stimulate cultural changes so that a
progressive organization can use these resources to make sound and cost—effective safety
improvement decisions.

FileAction
NASA-FTA-1.1 Fault Tree Handbook.pdfDownload 

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NASA-FTA-1.1

NASA-FTA-1.1
  • Version
  • 322 Downloads
  • 1.65 MB File Size
  • 1 File Count
  • March 30, 2016 Create Date
  • March 30, 2016 Last Updated
Scroll for Details

Fault Tree Handbook

NASA-FTA-1.1 Fault Tree Handbook

Foreword

NASA has been a leader in most technologies it has employed in its programs over the years.
One of the important NASA objectives is now to add Probabilistic Risk Assessment (PRA) to its
repertoire of expertise in proven methods to reduce technological and programmatic risk.

Fault Tree Analysis (FTA) is one of the most important logic and probabilistic techniques used
in PRA and system reliability assessment today.

Methods to perform risk and reliability assessment in the early 1960s originated in US aerospace
and missile programs. Fault tree analysis is such an example that was quite popular in the mid
sixties. Early in the Apollo project the question was asked about the probability of successfully
sending astronauts to the moon and returning them safely to Earth. A risk, or reliability,
calculation of some sort was performed and the result was a mission success probability that was
unacceptably low. This result discouraged NASA from further quantitative risk or reliability
analysis until after the Challenger accident in 1986. Instead, NASA decided to rely on the use of
failure modes and effects analysis (FMEA) and other qualitative methods for system safety
assessments. After the Challenger accident, the importance of PRA and FTA in systems risk and
reliability analysis was realized and its use at NASA has begun to grow.

The nuclear industry began to utilize probabilistic risk assessment to assess safety following the
Three Mile Island accident in 1979. In 1981, the US Nuclear Regulatory Commission (NRC)
issued the Fault Tree Handbook, NUREG-0492. Over the past two decades, this document has
become the leading technical information source on how FTA should be performed. Although
originally intended for nuclear power applications, the Fault Tree Handbook has been
extensively used in all fields where this powerful systems analysis methodology was applied.

Over the past two decades, probabilistic risk assessment and its underlying techniques, including
FTA, has become a useful and respected methodology for safety assessment. Because of its
logical, systematic and comprehensive approach, PRA and FTA have been repeatedly proven

capable of uncovering design and operational weaknesses that escaped even some of the best
deterministic safety and engineering experts. This methodology showed that it was very
important to examine not only low-probability and high-consequence individual mishap events,
but also high-consequence scenarios which can emerge as a result of occurrence of multiple
high-probability and nearly benign events. Contrary to common perception, the latter is
oftentimes more detrimental to safety than the former.

A foremost strength of PRA and its underlying analysis techniques, including FTA, is that it is a
decision support tool. In safety applications, this methodology helps managers and engineers find
design and operational weaknesses in complex systems and then helps them systematically and
efficiently uncover and prioritize safety improvements.

In order to best benefit from PRA and PTA in management decisions, it is important that
managers and their support staffs be familiar with the value and application of these methods. In
addition, there should be a small but robust group of in—house technical experts that understand
the methods used in a PRA or FTA study, can explain its meaning and applicability to given
problems to management and serve as in-house technical advisers to the management decision
process for safety improvement. If these in-house experts do not exist initially, they should be
hired or groomed through training and transfer of technology, becoming part of the corporate
resources and memory that will help shape the organization, taking advantage of the PRA and
FTA methods and results and the expert knowledge of the external consultants. In-house experts
will help build risk-based knowledge and experience and stimulate cultural changes so that a
progressive organization can use these resources to make sound and cost—effective safety
improvement decisions.

FileAction
NASA-FTA-1.1 Fault Tree Handbook.pdfDownload 
17,005 Documents in our Technical Library
2448898 Total Downloads

Search The Technical Library

Newest Additions

NASA-RP-1060 Subsonic Aircraft: Evolution and the Matching of Size to Performance
NASA-RP-1060 Subsonic Aircraft: Evolution and the Matching of Size to Performance
AA-CP-20212-001
AA-CP-20212-001
ADPO10769 Occurrence of Corrosion in Airframes
The purpose of this lecture is to provide an overview ...
MIL-STD-1759 Rivets and Rivet Type Fasteners Preferred for Design
The purpose of this book form standard is to provide ...
MIL-STD-810G Environmental Engineering Considerations and Laboratory Tests
This standard contains materiel acquisition program planning and engineering direction ...