Contribution information

Title	Risk assessment matrix Absolute vs. Relative approach
Status	Accepted
Final type	Lecture
Final session	Risk management and process safety
Authors	M., Krško1 1 Department od Process Safety & Environment, VURUP, Bratislava, Slovakia
Uploaded abstract	link
Brief content	Risk assessment matrix – absolute vs. relative approach In general, to qualitatively evaluate the risk of an unwanted event means to evaluate the combination of the Likelihood of the unwanted event’s causes and the Consequence severity of the unwanted event’s consequences. Risk matrices combining Likelihood and Consequence severity have been invented to visually represent the extent of such qualitative risk. However Risk assessment team members seldom fully understand how to use Risk matrices correctly. Even though companies invested into Risk matrix calibration, and Tolerable risk level definition, subjective attitudes stealthily enter the risk evaluation causing the Risk assessment to appear unreliable, and untrustworthy in the eyes of the managerial decision makers as well as useless in the eyes of simple operators. This situation is caused by the fact that the Risk assessment team members rely heavily on the Absolute risk value resulting from the Risk matrix given by the simple combination of Likelihood and Consequence Severity. Furthermore, considering Safeguards provides opportunities for a very subjective reasoning. The Risk assessment team members forget never take into account that there is also a Tolerable risk level definition to be accounted for. We present an alternative approach to Risk matrix utilization, taking the Risk assessment aa step further – the assessed Absolute risk has to be compared relative to the Tolerable risk level. This relative Risk assessment approach has been designed so that it fits into a wide range of Risk assessment methods e.g. HAZID, HAZOP, LOPA and FMEA.
ID	49