Risk acceptance criteria

A numerical level of risk acceptance is specified where quantitative evaluation of the probabilities and consequences of an accidental event have been performed. The documentation may also be used by senior management as a justification for budgetary decisions. The values of risk for many industries and daily personal activities have published and are readily available for comparison. This comparison has formed the basis of risk acceptance levels that have been applied to the hydrocarbon industry in various projects. 

Usually the petroleum industry level of risk for a particular facility is may be based one of two parameters. The average risk to the individual (FAR or PLL) or the risk of a catastrophic event at the facility (QRA). The risk criteria can be specified in two manners. Risk per year (annual) or facility risk (lifetime). For purposes of Consistency and familiarity all quantifiable risks are normally specified as annually. Where value analysis is applied for cost comparisons of protection options, a lifetime risk figure is normally used. 

It has been commonly acknowledged in the hydrocarbon industry the average risk to an individual at a facility should generally not exceed a value in the order of 1 x 10 per year. The facility risk is the total frequency of an accidental event for each main type of incident. Similarly for most oil and gas facilities, the facility risk should generally not exceed a value in the order of 1 x 10 4 per year. 

Where risks are higher that normally acceptable and all reasonable mitigation measures have been examined to find out value and practicality, the principal of risk as low as reasonably practical applies. Where the available risk protection measures have been exhausted and the risk level is still higher that the accepted numerical value, the risk would be considered As Low As Reasonably Practical (ALARP). 

In the petroleum industry, insurance agents will typically estimate the maximum losses a facility may suffer by performing a calculation of a potential vapor cloud explosion at the facility (where this is applicable). By examining the high loss explosion potentials, a maximum risk level can be determined and therefore insurance coverages that are necessary will be defined. 

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The remaining step in the hazard identification and risk assessment procedure shown in Figure 1 is to decide on risk acceptance. For this step, few resources are available and analysts are left basically by themselves. Some companies have formal risk acceptance criteria. Most companies, however, use the results on a relative basis. That is, the results are compared to another process or processes where hazards and risks are weU-characterized. 

Miller, B. and R. E. Hall, Index of Risk Exposure and Risk Acceptance Criteria, February... 

Review Against Risk Acceptance Criteria - The comparison of an incident risk which is supplemented by the selected safety measures to achieve the requirements for company safety levels. 

The accepted risk is a risk inferior to a level defined in advance either by law, technical, economical, or ethical considerations. The risk analysis, as it will be described in the following sections, has essentially a technical orientation. The minimal requirement is that the process fulfils requirements by the local laws and that the risk analysis is carried out by an experienced team using recognized methods and risk-reducing measures that conform to the state of the art It is obvious that non-technical aspects may also be involved in the risk acceptation criteria. These aspects should also cover societal aspects, that is, a risk-benefit analysis should be performed... 

For a summary of these efforts, see Philipson, Lloyd L (1983) Risk Acceptance Criteria and Their Development. Journal of Medical Systems 7(5) 437—456. 

The CRM Policy, terms of reference and definitions Process overview Risk acceptability criteria... 

Risk acceptance criteria can be defined relative to the risk matrix. The as-low-as-reasonably practicable (ALARP) approach may be chosen, defining three risk levels [4] ... 

Provide reasoned arguments and judgments about the risk acceptance criteria including the rationale for their acceptance, references used, and details of the risk acceptance studies conducted into potential major accident events that may occur during the life of the facility. 

A survey has been made of the regulatory and industry requirements in the Oil and Gas industry for defining Risk Acceptance Criteria (RAC). The focus has been on Norwegian and UK offshore oil industry. RAC may be quahtative or quantitative, and are known variously in the Oil and Gas industry as, e.g., risk criteria , decision criteria , screening criteria , tolerability criteria . 

The NORSOK standards are developed by the Norwegian petroleum industry, and the NORSOK standard Z-013 presents some general requirements regarding the formulation of RAC, see NORSOK (2001). This standard does not provide any guidelines on what actual values to choose for RAC, which is in line with the basic Norwegian PSA requirements, which require that the operators should formulate their own risk acceptance criteria. 

The risk acceptance criteria used by the UK petroleum industry have mainly been formulated by the UK Health and Safety Executive (HSE) and are embodied in statutory legislation. The Offshore Installations Safety Case Regulations 2005 (SCR05), see HSE... 

Figure 3. Risk acceptance criteria for 3rd party societal risk (Norwegian continental shelf).

Risk acceptance criteria have been used in offshore risk analysis for many years. A common thinking has... 

However, there has also been some discussions about the suitabihty of risk acceptance criteria to assess and control risks, see Aven and Vinnem (2005). One concern is that the introduction of pre-determined criteria may give the wrong focus to risk assessment activities, i.e., on meeting risk criteria rather than on obtaining overall safe and cost-effective solutions and measures. 

When we are communicating risk and risk acceptance criteria to the public, the figures as we present them in technical risk analyses and in e.g., Fig. 1 will often not be very informative. One way to visualise the actual risk for the activity (LNG facility) and the risk acceptance criteria is to plot known events in the risk... 

The use of risk acceptance criteria is, despite the critique raised to this approach, one possible approach to ensure that safety is reasonable accounted for. Common practice in Norway is that the enterprises themselves define the RAC even in the case of societal risk. This practice has been questioned, and a broader principal discussion is on the way in Norway. The recent developments in the UK and the Netherlands in relation to land-use planning are believed to also improve the Norwegian thinking. 

Aven, T, and Vinnem, J.E. 2005. On the use of risk acceptance criteria in the offshore oil and gas industry. Reliability Engineering System Safety, Volume 90, Issue 1, Pages 15-24... 

Hokstad, P, Vatn, J, Aven, T. and Scrum, M. 2003. Use of risk acceptance criteria in Norwegian offshore industry. Dilemmas and challenges. Risk Decision and Policy... 

Problem definition and setting of boundaries Ship category ship systems and ftmctions, ship operation, external influences of ship, accident categories, risks associated with consequences Defining scope of assessment and system border Describing system IdentiAing relevant stakeholders Defining risk acceptance criteria V.4R, S.4R. tolerance for disturbance... 

As a comprehensive view of the LNG supply chain was intended, a life-cycle view of the system was considered appropriate. To test the methodology, initial smdies were performed on a fictive case, involving only one vessel. The step 0 part of defining system borders, describing relevant stakeholders, and risk acceptance criteria had to be divided into four distinct phases Charter-party, construction, operation and termination. 

Societal risk acceptance criteria expressed reluctance to accidents with more than one fatality. The FN curves for different ships types based on Loyds accident database together with tolerable curves are presented in Fig. 3 (Skjong 2002). 

Skjong R. 2002. Risk Acceptance criteria Current proposal and IMO Position. Surface transport technologies for sustainable development EU Commission Conference. Valencia. 

The purpose of the system safety program plan (SSPP) is to identify the specific system safety requirements for a given project, to include specified system safety tasks, risk assessment methodology and risk acceptance criteria, system safety products and milestones, and system safety organization. 

System Safety Requirements. Specify the system safety products to be produced, the risk assessment code matrix to be used, risk acceptability criteria, and residual risk acceptance procedures. 

The subsystem hazard analysis report contains a description of the subsystem and a narrative summary of key findings that specifically address the adequacy of the controls placed on any high hazards associated with the end products, the level of residual risks that remain after controls have been applied, and recommendations for further analysis or testing. The report should also describe the techniques and methodology used in performing the analysis, including risk assessment and risk acceptance criteria. The report should also contain the hazard report worksheets used in the study. 

Review the Total Risk Exposure Code matrix and risk acceptance criteria in Chapter 11. Adopt the risk assessment and acceptance criteria and methodology (as presented or as modified by the planning group) or develop and adopt alternatives. 

Not only changes in variables and associated risks are examined but also the baseline assumptions made in the risk assessment process (total exposure, number of products, product life, failure rates, and so on) are validated or adjusted, as well the risk acceptability criteria. 

Facility Risk Acceptance. The following risk acceptability criteria are typical of those in MIL-STD-882B ... 

The RAC matrix and the risk acceptability criteria described in this example are representative of many of the risk assessment efforts presently in use and are consistent with the MIL-STD-882B approach to risk assessment. 

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