Suggestion of a new definition of risk in the frameworks regulations: possible implications for the process of establishing fire and explosions loads to be used as a basis for design

Abstract

The Petroleum Safety Authority Norway has suggested an update of the definition of risk in the regulations that concerns the health, safety and environment for Norwegian petroleum operations. The prevailing definition of risk, given in the guidelines to Section 11 in the Frameworks Regulations, is that “Risk means a combination of probability and consequence” (Petroleum Safety Authority Norway, 2011c). The suggestion for a new definition is that: “Risk means the consequences of the activity with associated uncertainty” (Petroleum Safety Authority Norway, 2013). This thesis will not address the wide range of potential implications of the new definition, but focus on the process of establishing accidental loads from explosions and fires that a facility shall be designed to withstand. This thesis suggests some principles and ideas related to two new methods of establishing the fire and explosion loads that an installation should be able to withstand, that will be in compliance with the suggested new definition of risk. The suggestions acknowledges that the accidental loads cannot be selected based alone on results from quantitative risk analyses, and that there are uncertainties that have to be assessed that is not reflected on computed probabilities and expected values. In addition, it is shown in this thesis that there is confusion surrounding the terminology used to describe these loads, and a suggestion is given on how to clear up this confusion.