Risk ranking methodology for chemical release events
Risk ranking schemes have been used in safety analysis to distinguish lower risk accidents from higher risk accidents. This is necessary to identify those events that might warrant additional study or quantitative analysis and to ensure that any resources allocated for risk reduction are properly directed. A common method used for risk ranking utilizes risk matrices. These are typically 3x3 or 4x4 matrices having event consequences along one axis and event frequency along the other. Each block on the risk matrix represents some level of risk, and blocks presenting similar risk are often grouped together into one of three or four risk regions. Once a risk matrix has been identified, events are placed on the matrix based on an estimate of the event consequence and event frequency. Once the risk of each block on the matrix is defined, the relative risk of the events can be found based on where they are placed on the matrix. In most cases, the frequency axis of the matrix has numerical values associated with it, typically spanning several orders of magnitude. Often, the consequence axis is based on a qualitative scale, where consequences are judgment based. However, the consequence scale generally has implicit quantitative values associated with it, which may or may not be recognized. Risk regions are often arbitrarily assigned (or assigned on the basis of symmetry). This presents a problem in that if the blocks Of the risk matrix are incorrectly grouped, then incorrect conclusions can be drawn about the relative risk presented by events at a facility. This paper first describes how risk matrices have typically been established in the past. Problems associated with these risk matrices are identified and discussed. A methodology for logically establishing risk matrices, with specific application to chemical risk, is provided.
- Research Organization:
- Lawrence Livermore National Lab., CA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 292198
- Report Number(s):
- UCRL-JC--128510; CONF-980907--; ON: DE98057738; BR: 39DP02000
- Country of Publication:
- United States
- Language:
- English
Similar Records
Methodology for the relative risk assessment in the NIF Preliminary Safety Analysis Report
Methodology for the relative risk assessment in the LDF safety analysis report