Introduction to Risk and Reliability concepts Flashcards
1
Q
Risk definition
A
The probability/possibility of incurring loss
2
Q
Calculating risk
A
Risk = Consequence * Frequency
3
Q
Categories of risk
A
- community risk
- occupational risk
- economic risk
4
Q
Community risk
The three types of risk
A
- Unavoidable - without any compensating benefits
- In principle avoidable but have direct compensating benefits. In practise, unavoidable in modern society
- Avoidable - people expose at will
5
Q
Farmer Curve
A
- Below the line - acceptable
- Above the line - unacceptable
6
Q
ALARP
A
- As Low As Reasonably Practicable
7
Q
4 basic stages of Quantitative Risk Assessment(QRA)
A
- identification of potential safety hazawrds
- estiamtion of the consequences of each hazard
- estimation of the probability of occurence of each hazard
- comparison of the results of the analysis against the acceptability criteria
8
Q
Qualitative risk assessment tools
A
- Checklists
- used to identify hazards
- HAZOP
- applies a set of guidewords to determine the consequences of operating outside the design intention
- FMEA
- step by step procedure for the systematic evaluation of the severity of potential failure modes in a system
9
Q
Quantitative Reliability Tools
A
The most appropriate tool is chosen depending on the characterisitics of the system
10
Q
Definition of Reliability
A
- Reliability of a component or system = R(t)
- It is defined as the probability that the component or system remains operating from time 0 to time t, given that it was operating at time 0.
11
Q
Definition of Unreliability
A
- Unreliability of a component or system = F(t)
- It is defined as the probability that the component or system has failed once or more times from time zero to time t, given that it was operating at time zero
- R(t) + F(t) = 1
12
Q
Definition of Availability
A
- Availability of a component or system = A(t)
- It is defined as the probability that the component or system operating at time t given that it was operating at time zero.
13
Q
Definition of Unavailability
A
- Unavailability of a component or system = Q(t)
- It is defined as the probability that the component or system is not operating at time t, given that it was operating at time zero
- A(t) + Q(t) = 1
14
Q
Qualitative methods in risk assessment
A
- applied during feasability and conceptual phases
- identify and rank by importance the potential hazards, equipment types, operating/maintenance procedures which may critically affect safety or reliability
- significant reductions in risks and improved reliabiliyu
- provide input into more detailed quantitative studies
15
Q
3 key stages of risk management
A
- Risk identification
- Risk analysis
- Risk evaluation
