(47x) Economical Approach Quantification of Impacts in Major Accidents

In the industry field, the nature of certain processes has always represented an inherent threat not only to humans but also to the environment in which they are executed. Although the frequency of scenarios that lead to the occurrence of major accidents in facilities is considerably low, their consequences are usually catastrophic. Experience has demonstrated that high level impacts occurred during the development of industrial activities imply significant financial losses. Therefore, one of the main interests for risk assessment results in the economical estimation of these consequences.

Usually, damage costs are estimated once the potential consequences have been already materialized. Nonetheless, in order to generate mechanisms for prevention, mitigation and control over these negative impacts, the implementation of a pre-emptive quantification of potential leakages allows the estimation of useful indicators as incomes for decision making analysis. For this purpose, qualitative, semi quantitative and quantitative methodologies have been developed to support risk analysis.

Within this context the present work pretends to propose an a priori quantitative methodology that allows carrying out the economical conversion of impacts originated by major accidents through the integration of two methods. The first method is defined to estimate the impact level over a specific system while the second establishes the transformation of impacts into monetary terms. The suggested methodology is applied later to a particular case of study.

A quantitative vulnerability analysis has been defined for the estimation of impact level. The model used is a classical approach that implements probit analysis which gives the level of impact. The fact that the result corresponds to a quantitative estimation, makes easier its conversion into monetary terms. Even so, as a limitation of the method, it must be considered that each type of major accident, and subsequently their specific cases, has a unique equation that represents the system of study. Accordingly, the application of this method for a particular situation requires the definition of the appropriate expression that relates the probit variable with the dose associated to the specific event.

Once the level of impact is estimated for a system of interest, the second method is applied in order to express these impacts in monetary terms. In this case, the methodology of CEPAL is used. It defines the types of effects produced by an accident: Direct, indirect and macroeconomic. Since the main interest of this work is not the estimation of impacts effects of an accident at socioeconomic level, only the direct and indirect effects over the system are considered. For direct costs, this method defines a set of parameters for each type of system affected (infrastructure, humans, services). These must be considered for the breakdown of costs including sometimes the appraisal over a period according to the item evaluated. In the case of indirect costs, the execution of two analyses is necessary. As a first step, a projection of each item is done to estimate certain economic parameters dependant of the system type. Then a comparison of the values that will be reached in the supposed accidental scenario, with respect to the ones that would be reached if the accident did not happen is developed. With these values, finally the net incomes for each case are estimated.

An explosion in an energy supply facility is considered as a case study. The correspondent vulnerability analysis with probit method is done in order to estimate the damages caused over the structure. As a result, costs of reparation / reconstruction for damaged infrastructure taking into account the appraisal over the period of time that reparation / reconstruction of the facility takes, costs of equipments and costs of raw materials are determined. Also, operation and capital costs are estimated taking into account the time required for reparation / reconstruction of facility. Capital costs include equipment acquisition, operation, labor force and materials. Finally the net incomes for the accidental and no accidental scenarios are estimated in order to obtain the approximate net indirect costs.

The appropriate use of methodologies, as the one proposed in the present work, defines non conventional paths for generation of indicators that support decision making analysis. Due to the different considerations and approaches used within the methodology, the indicators that could be generated contain valuable information different from the one given by indicators that do not consider an economic perspective of effects. The information provided by these indicators offers new perspectives and more accurate points of view for project evaluation.