Risk criteria in EU

This paper focuses on risk criteria used in the EU for population living in vicinity of hazardous facilities. The criteria vary from fully risk-based and goal setting to the prescriptive consequence based criteria. In spite of the philosophical differences in the formulation of risk criteria, there is a single EU Directive (Seveso 2) on the control of major accident hazards involving chemicals which applies to every member state and clearly the level of safety across the EU should be very similar if not the same. Therefore the first aim of the paper was to minimise the differences between the variety of safety approaches across the EU in order to develop risk acceptance criteria with the potential to converge to a unified set. The second aim was to develop societal risk criteria completely consistent with the legally applied individual risk criteria. public is As Low As Reasonably Practicable (ALARP). The Health and Safety Executive (HSE) publishes from time to time the risk levels it considers as intolerable or tolerable under certain circumstances and while these risk levels cover all industrial activities in the UK, the primary instrument for risk control is ALARP dynamics. Table 1 Comparison of Individual Risk Criteria IRPA UK The Netherlands Hungary Czech Republic 10 Intolerable limit for members of the public 10 Risk has to be reduced to the level As Low As Reasonably Practicable (ALARP) Limit for existing installations. ALARA principle applies Upper limit Limit for existing installations. Risk reduc tion must be carried out 3 x 10 LUP limit of acceptability (converted from risk of dangerous dose of 3 x 10) 10 Broadly acceptable level of risk Limit for the new installations and general limit after 2010. ALARA applies Lower limit Limit for the new installations 10 Negligible level of risk 10 Negligible level of risk The situation in other countries is not very clear; for example in the Netherlands, two regions Rijmond and Schiphol are excluded from the new criteria (in force after 2010), while if there is a lower risk situation than the norms require, the Authorities can allow building up to the norm; the enforcement of ALARA is questionable. It can be seen from Table 1 that individual risk of 10 per year represents the upper limit in Europe for existing installations, while in the UK the intolerable limit is 10 but ALARP is strictly imposed, meaning that in reality the risk is well below the limit. The upper limit for individual risk for new installations in Czech Republic and in the Netherlands after 2010 is 10 per year. It should also be noted that the individual risk in the LUP guidelines in the UK, HSE 2004a, in terms of a dangerous dose of 3 x 10 per year can be converted to individual risk of death of 3 x 10 per year. The quoted value for the Netherlands (10 and 10) represent so called location risk (risk contour), or the individual risk to a person who is permanently at the particular location. In addition, in the case of the Netherlands, the risk value corresponds to one establishment (facility), and the cumulative risks from several establishments are not taken into account. The negligible risk levels specified in the UK as 10 per year and in the Netherlands as 10 per year are not questionable and it will be assumed that 10 value can be accepted across the EU for the time being. 2.2 Impact Criteria The example of the consequence (impact) based criteria used in France, Salvi & Gaston 2004, is presented in Table 2. These criteria apply to the list of reference or predefined scenarios such as boiling liquid expanding vapour explosion (for liquefied combustible gases), unconfined vapour cloud explosion (for liquefied combustible gases), total instantaneous loss of containment (for liquefied, nonliquefied and toxic gases), instantaneous rupture of the largest pipeline leading to the highest mass flow (toxic gas installations), fire in the largest tank (for flammable liquids), etc. Table 2 Impact Thresholds