Taking the Risk Out of Risk Assessment
Computer Technology
Originating Technology/ NASA Contribution
The ability to understand risks and have the right
strategies in place when risky events occur is
essential in the workplace. More and more organizations
are being confronted with concerns over how to
measure their risks or what kind of risks they
can take when certain events transpire that could
have a negative impact.
NASA is one organization that faces these challenges
on a daily basis, as effective risk management
is critical to the success of its missions—especially
the Space Shuttle missions.
On July 29, 1996, former NASA Administrator Daniel
Goldin charged NASA’s Office of Safety and Mission
Assurance with developing a probabilistic risk
assessment (PRA) tool to support decisions on the
funding of Space Shuttle upgrades. When issuing
the directive, Goldin
said, “Since I came to NASA [in 1992], we’ve spent
billions of dollars on Shuttle upgrades without
knowing how much they improve safety. I want a
tool to help
base upgrade decisions on risk.” Work on the PRA
tool began immediately.
The resulting prototype, the Quantitative Risk
Assessment System (QRAS) Version 1.0, was jointly
developed by NASA’s Marshall Space Flight Center,
its Office of Safety and Mission Assurance, and
researchers
at the University of Maryland. QRAS software automatically
expands the reliability logic models of systems
to evaluate the probability of highly detrimental
outcomes occurring in complex systems that are
subject to potential accident scenarios.
Even in its earliest forms, QRAS was used to begin
PRA modeling of the Space Shuttle. In parallel,
the development of QRAS continued, with the goal
of making it a world-class tool, one that was especially
suited to NASA’s unique needs. From the beginning,
an important conceptual goal in the development
of QRAS was for it to help bridge the gap between
the professional risk analyst and the design engineer.
In the past, only the professional risk analyst
could perform, modify, use, and perhaps even adequately
understand PRA. NASA wanted to change this by developing
a PRA tool that would be friendlier, more understandable,
and more useful to the broader engineering community.
This concept ultimately led to the look, feel,
and functionality that QRAS has today.
Partnership
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The Quantitative
Risk Assessment System (QRAS) is a comprehensive
tool for conducting probabilistic risk assessment. |
In July 2003, Item
Software (USA) Inc., of Anaheim,
California, received an exclusive license for the
QRAS software. The company is a leader in providing
software solutions and services for reliability,
availability, maintainability, safety, quality
assurance, and risk assessment to government and
commercial customers in aerospace and other industries.
It built on the already-state-of-the-art features
of QRAS, preparing the software for commercial
sale as part of its suite of software and associated
services. As part of the commercialization and
distribution of QRAS, Item Software also supplies
support and training.
The license provides the basis for a potential
partnership between NASA and Item Software for
the future extension and deployment of QRAS and
related software, as may be needed for NASA purposes.
Product Outcome
Item Software developed the first commercialized
version of QRAS and released it in January 2005.
The new, enhanced QRAS 1.80 provides a cohesive
and simple-yet-powerful platform for system risk
assessment, through a large range of failure probability
characterizations for engineering and scenario-driven
applications.
The software builds a risk model of a system or
a scenario for which risk of failure is being assessed,
then analyzes the associated risk to the risk model.
It can then be used to perform sensitivity analysis
of the risk model by altering fundamental components
and quantification models. During this stage, a
fixed baseline is constructed and stored. This
baseline contains the solutions for the lowest
level scenarios, preserved in an event tree structure.
The analysis, at any level of the hierarchy, aggregates
these baseline results for risk quantitative computation
as well as ranking of a particular risk.
The commercial version introduces substantial enhancements
and includes many new features not seen in the
original version. For example, it contains fault
tree analysis, a deductive procedure for determining
the various combinations of hardware and software
failures, plus human errors that could result in
the occurrence of specified undesired events. Fault
tree analysis is one of the most widely used methods
in system reliability analysis.
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QRAS provides
a full graphical user interface, including
fault tree editors and event sequence diagrams,
plus analysis screens that provide results
in tabular and graphical formats. The screen
to the left portrays System Hierarchy Mission
Phase and event sequence diagrams that are
used to determine the consequence of an initiating
event and the expected frequency of each consequence.
For example, a leak in an aircraft fuel system
could result in the following user-defined
end states: Mission Success (MS) if the leak
is repaired, or Loss of Mission (LOM), Loss
of Crew and Vehicle (LOCV), or Mission Failure
(MF). |
A new fault tree editor with extensive editing
and user-friendly features was also added to the
commercial version to allow users to effortlessly
create, review, and analyze multiple fault trees
simultaneously. The fault trees created with the
fault tree editor can be attached to the event
sequence diagram (ESD) in QRAS projects. An ESD
is a visual representation of a set of possible
outcome scenarios originating from an event. Each
scenario in an ESD consists of a unique sequence
of pivotal events, and eventually leads to an end-state
that designates the severity of the outcome of
a particular scenario.
QRAS assesses risk at the failure mode, subsystem,
and element (i.e., a group of subsystems) levels,
based upon user-supplied quantification of failure
models, event sequence system decompositions, and
system operating time. It provides users with structured
guidance so managers, engineers, and even individuals
who may not be experienced in the field of risk
assessment can use it.
Overall, the QRAS software’s unique, patented PRA
capabilities assist risk analysts in modeling deviations
from a system’s nominal functions, the timing and
likelihood of such deviations, potential consequences,
and scenarios leading from initial deviations to
such consequences.
The U.S. Department of Homeland Security, The Boeing
Company, Booz Allen Hamilton, Inc., ITT Industries,
Inc., the European Space Agency, and the China
National Space Administration are just some of
the entities evaluating QRAS for their risk assessment
needs.
Those currently employing it—other than NASA—
include the Canadian Space Agency, AES Corporation,
and Harvard Medical School. At Harvard Medical
School’s major teaching hospital, Beth Israel Deaconess
Medical School Center, QRAS is being utilized to
determine the health care risk associated with
general surgical processes and surgical devise
use, pharmaceutical ordering, transfusion services,
and organ procurement
and transplantation.
Other examples of application include determining
the probability of airplane crashes arising from
factors such as engine failure, avionics failure,
or human-failure at the air control tower; and
train collisions caused by failures in train-signaling
systems.
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