CHAPTER 12 - RISK ASSESSMENT Flashcards
Originated in the aerospace industry and has been used extensively by the
nuclear power industry to qualify and quantify the hazards and risks associated with
nuclear power plants.
C. Fault trees
____________ begin with an initiating event and work toward the top event.
B. Event Trees
. __________ is a semi-quantitative tool for analyzing and assessing risk. This method
includes simplified methods to characterize the consequences and estimate the frequencies.
C. LOPA
The actual risk of a process or plant is usually determined using _________.
C. QRA or LOPA
A method that identifies where operations, engineering, or management systems can be
modified to reduce risk.
D. QRA
Events in a fault tree are not restricted to hardware failures. They can also include
______________
software, human, and environmental factors.
A fault event that needs no further definition.
B. BASIC Event
The resulting output event requires the occurrence of any individual input event
D. OR Gate
The resulting output event requires the simultaneous occurrence of all input events
B. AND Gate
The event that results from the interaction of a number of other events.
A. INTERMEDIATE EVENT
Failures that are immediately obvious.
B. Revealed failures
Sum of the period of operation and downtime.
D. MTBF
A failure of equipment without the operator being aware of the situation.
A. Unrevealed failure
All process components demonstrate unavailability as a result of a failure.
A. Probability of Coincidence
The loss of electrical power or a loss of instrument air. A utility failure of this type can
cause all the control loops to fail at the same time.
B. Common mode failure
The approach offers details on the possibility of a failure as well as how it could happen.
A. Event trees
Depends on the hazards of the process and on the potential for economic losses.
D. Degree of Redundancy
__________ lines are drawn from these two states to the next safety function.
B. Horizontal
The event trees is written from left to ______.
A. Right
Among the 4 Safety Functions, which function is the high-temperature alarm?
A. First safety function
_____ are collected on the failure rate of a particular hardware component
A. Data
on average, the component fails after a certain period of time.
A. Average failure data
The complement of the reliability.
C. Failure Probability
The __________ is defined as the derivative of the failure probability.
B. Failure Density Function
This means that a failure of any single component in the ______ of components will
result in failure of the process.
D. Series
___________ would depend on the manufacturer, materials of construction, the design,
the environment, and other factors.
C. Actual Values
______ is the reliability of an individual process component.
A. Ri
_______is the failure probability of each component.
Pi
_______ represents the fraction of the total area under the failure density function
between time to and t1 .
A. Integral
The time interval between two failures of the component is called the ___________.
C. MTBF
The consequences and effects are approximated by categories, the frequencies are estimated, and the effectiveness of the protection layers is also approximated.
B. LOPA
It begins with a top event and works backward toward the initiating event. (deduction)
C. Fault Trees
In short terms, it means “LOPA”
A. Layer of Protection Analysis
In short terms, it means “QRA”
C. Quantitative Risk Analysis
The independent protection layer (IPL) varies from
A. 10^-1 to 10^-5
The results should always be more conservative than those from a QRA.
A. LOPA
if the LOPA results are unsatisfied or if there is any uncertainty in the results, then a
full ____ may be justified
D. QRA
The primary purpose is to determine whether there are sufficient layers of protection
against a specific accident scenario.
A. LOPA
study the consequences of these releases are quantified using dispersion modeling and a
detailed analysis to determine the downwind consequences as a result of fires, explosions,
or toxicity.
D. QRA
The concept of ___ is also used when designing emergency shutdown systems called
safety instrumented functions. (SIFs)
B. PFD
