Consistent consequence severity estimation

Abstract

Most risk analysis methods rely on a qualitative judgment of consequence severity, regardless of the analysis rigor applied to the estimation of hazardous event frequency. As the risk analysis is dependent on the estimated frequency and consequence severity of the hazardous event, the error associated with the consequence severity estimate directly impacts the estimated risk and ultimately the risk reduction requirements. Overstatement of the consequence severity creates excessive risk reduction requirements. Understatement results in inadequate risk reduction.Consistency in the consequence severity estimate can be substantially improved by implementing consequence estimation tools that assist process hazards analyses/layers of protection analysis (PHA/LOPA) team members in understanding the flammability, explosivity, or toxicity of process chemical releases. This article provides justification for developing semiquantitative look-up tables to support the team assessment of consequence severity. Just as the frequency and risk reduction tables have greatly improved consistency in the estimate of the hazardous event frequency, consequence severity tables can significantly increase confidence in the severity estimate.

A security risk analysis model for information systems: Causal relationships of risk factors and vulnerability propagation analysis

“…As the risk analysis is dependent on the estimated occurrence probability and consequence severity of security risks, the error associated with the consequence severity evaluation directly impacts the estimated security risk and ultimately the risk reduction requirements. To address the qualitative biases for consequence severity estimation, a semi-quantitative approach [41] is adopted to support the assessment of consequence severity of security risk.…”

Risk assessment challenges to 20:20 vision

“…A lack of understanding of how a process misbehaves or a refusal to believe that harm is possible inherently limits the capability of responsible personnel to correctly assess and manage risk. A big risk is not addressed by a big list of poorly managed safeguards or a list of nothing; it is addressed by the right list of rigorously designed and managed safeguards .…”

“…Do not use conditional modifiers in the risk analysis without justification. The rationale should consider event dispersion and flammability analysis, assessment of the loss prevention and emergency response plan, and the site culture in controlling and monitoring the conditions that increase the likelihood of the worst‐credible scenario . Dr. Clifford Nass, a Stanford professor who pioneered research into how humans interact with technology warned, “denial is the greatest enabler.” Every effort should be made to install equipment that has a reduced potential to serve as an ignition source, but during a loss of containment ignition sources are freely available.…”

Risk criteria, protection layers, and conditional modifiers

“…As consequence severity is often used to screen events for further analysis, it is important that the documentation reflect the hazardous situation without consideration of any safeguards including proactive, reactive, and emergency response activities. Consequence modeling can be used to better understand the hazardous situation and impact zone [4–6].…”

“…This article is primarily focused on frequency estimation and the different techniques in evaluating its acceptability. However, consequence severity is often used to screen events for more rigorous frequency analysis [6]. The PHA team is generally asked to estimate the consequence severity without the operation of safeguards.…”