Sammendrag
This paper describes the environmental risk acceptance criteria (ERAC) currently in use in the Norwegian offshore petroleum industry, points out their shortcomings and suggests possible alternative ways of setting such criteria. An important question is how ERAC can be formulated and applied to allocate reliability requirements to safety systems that shall prevent environmental releases (e.g. blowouts). Reliability requirements for such systems, if at all established, are traditionally based on considerations related to personnel risk, with limited attention paid to environmental aspects. However, as Norwegian petroleum activities are moving further north, and as sophisticated technology permits exploration in more complex reservoirs and deeper waters, the environmental focus on the petroleum activities has sharpened. Recent accidents with large or potentially large environmental consequences are also there to remind us of the risks involved. The Norwegian offshore petroleum industry adheres to the so called MIRA guideline on environmental risk analysis. The ERAC proposed in this guideline focus on the consequences of an environmental release, but have limited or no impact on the reliability and design of safety systems implemented to prevent releases in the first place. Additional acceptance criteria, defined e.g. in terms of maximum acceptable blowout frequencies, or maximum acceptable release volumes, may turn more focus towards the barriers implemented to prevent releases and the performance requirements of such barriers. The paper also discusses the use of calibrated risk graph as a method to obtain required Environmental Integrity Level (EIL) for equipment based on e.g. released volumes, analogous to how such graphs are frequently used to obtain Safety Integrity Level (SIL). The paper builds on an ongoing research project that is performed in close collaboration with the Norwegian Research Council and the petroleum industry.