A Bayesian network-based approach for the assessment and management of ageing in major hazard establishments

Currently, there is an increasing attention towards ageing of industrial equipment, as the phenomenon has been recognised as a cause of severe accidents, recorded in the last years in many process establishments. Recent studies described ageing through a number of key-factors affecting the phenomenon by accelerating or slowing it down. The Italian Competent Authority for the prevention of chemical accidents (Seveso III Directive) adopted a short-cut method, accounting for the assessment of these factors, to evaluate the adequateness of ageing management during inspections at Seveso sites. In this paper, a Bayesian Network was developed, by using the data gathered during the first application of the short-cut method, with the aim to verify the robustness of the approach for ageing assessment and the validity of the a priori assumptions used in assessing the key-factors. The structure of the Bayesian network was established by using experts’ knowledge, whereas the Counting Learning algorithm was adopted to execute the parameter learning by means of the software Netica. The results showed that this network could effectively explore the complex logical and uncertain relationships amongst factors affecting equipment ageing. Results of the present study were exploited to improve the short-cut method.     

Statistical interpolation model for the description of ground pollution due to the TCDD produced in the 1976 chemical accident at seveso in the heavily contaminated zone “A”;

The influence of NTA on chromium genetic activity was studied in the D7 strain of Saccharomyces cerevisiae. At low dose (subgenotoxic) of sodium chromate (CrVI) (5mM), NTA increased the point mutation while at higher dose (25 mM) of chromate in the presence of NTA a decrease of point reverse mutation was observed. Probably NTA affected either the uptake of Cr(VI) favouring the intracellular reduction to Cr(III), or the recombinational repair of DNA breaks induced by chromate oxiding activity.

An increase of point (reverse) mutation was obtained in the experiments with NTA and chromium chloride, suggesting the hypothesis that NTA might interact with Cr(III) forming NTA‐Cr(III) complexes able to permeate cellular membranes and bind to DNA. In addition NTA genetic inactivity was confirmed.     

Trend analysis of machinery safety for globalization: From the Japanese point of view

In Japan, the work of translation to JIS faced many obstacles. Support groups in Western countries have submitted comments on technical problems. The movement to standard harmonization in safety has rapidly developed in international standardization. The movement for global standardization is developing throughout all the economic areas of the EU. The aim of the Machine Directive that comes into effect in stages is to provide an international formula for a type of qualification in machine safety. EN292 is a nucleus for related standards, which are like a group of planets in a universe. It is a European standard as well as a guideline for implementation, showing practical safety requirements for machines. Horizontal standards, such as EN954 and IEC61508, apply in actual practice.     

Influence of new generic frequencies on the QRA calculations for land use planning purposes in Walloon region (Belgium)

In Europe, the article 12 of the “Seveso” Directive focuses on land use planning (LUP) around major hazard plants and imposes to keep a sufficient distance between a major hazard plant and populated areas. In Belgium, the LUP is treated at the regional level. The regional authority defines the policy and manages the LUP according to the quantified risk. The quantified external risk, around each Seveso company in the Walloon Region, is assessed by a unique technical expert, the Faculté Polytechnique de Mons, by means of a full probabilistic approach (QRA). This QRA methodology uses accident generic frequencies published by the Flemish Region (Aminal, 2004). In 2009-2010, the quantification of the external risk of the 90 walloon Seveso plants will be completed, based on this set of generic frequencies. However, the Flemish Region recently published a new set of generic frequencies (LNE, 2009), which, in some cases, are quite different of the previous ones for some equipment. This paper discusses the influence of the new frequency data on the quantified risk. An overview of the changes induced by the new set of data will be presented, as well as their impact on the already defined "consultation zones" in which decisions are made concerning the compatibility of the land use and the intensity of risk.     

Fractal and multifractal approach to environmental pollution

A few case studies will be presented involving both radioactive and chemical pollution at small, medium, and large space-time scales. Reported are recent advances in the field of environmental pollution involving the use of fractals and multifractals. The mathematical tools proposed here may offer new perspectives for investigating many of the problems of nonlinear variability which commonly arise when dealing with pollutants, such as the presence of outliers and the sparseness of the sampling networks. They may also lead to a simplification of the models adopted for studying natural phenomena, thanks to a scaling approach. Finally, they may provide parameters whose values are directly related to the nonlinear dynamics involved in the pollutant distribution in the environment which, in turn, may be relevant for computer simulation and epidemiological or risk assessment purposes.     

Ageing management and monitoring of critical equipment at Seveso sites: An ontological approach

A safe “ageing” of Seveso establishments is a challenge for both operators and regulators. To this scope, Seveso III Directive required to integrate the equipment integrity issue into the safety management system for the major accident prevention; at the same time, the Italian Authority adopted a short-cut method for a quick ageing evaluation, which awards the application of the best techniques to control integrity and prevent deterioration-related failures. In this paper, the use of the ontology has been proposed to support decision-making about the implementation of technical solutions to control equipment ageing and comply the requirements of the Seveso legislation. To contrast deterioration mechanisms, the rapid development of data intensive smart sensors should be exploited and, in this frame, the automated on-line direct monitoring of equipment conditions, based on innovative low-cost sensors, is a novelty and promising solution. The developed ontology-based system points towards the adoption, when possible, of on-line monitoring. This solution provides much more data than traditional measurements and it is essential for the operators to understand how to merge concurrent information and data and to adequately control equipment deterioration. The ontology-based approach appears a viable solution even for this purpose. To demonstrate its potentiality, a real use-case has been used, where the model has been tested in finding the best technical solutions to improve the ageing management of an atmospheric distillation unit of a refinery in order to comply with safety requirements. A further use-case is given to show how the model can be used to react, after real-time damage signals, to restore safety conditions by means of an adequate decision-making.     

Risk assessment in support to land-use planning in Europe: Towards more consistent decisions?

Recognising the importance of establishing appropriate separation distances between hazardous installations and vulnerable residential areas for mitigating the effects of industrial accidents, the European legislation for the control of major accident hazards - the so-called Seveso II Directive - calls for procedures ensuring that technical advice is taken systematically into account for land-use planning (LUP) purposes. Due to historical, administrative, cultural and other reasons, these European Union’s Member States which have consolidated procedures for addressing this issue, have employed different approaches, methods and criteria, with a potential for great divergence in the resulting land-use planning decisions. In order to address this situation and to increase consistency and ‘defendability’ of land-use planning decisions in the EU, a European Working Group has been established and is operating under the coordination of the European Commission’s Joint Research Centre (JRC). This Group, consisting of experts from the EU Member States, the industry and the academia, is trying to understand the different approaches and their implications to LUP decision-making, to develop guidelines in support to these decisions and to examine data sources and tools for consistent application of risk assessment in support to LUP. This paper presents the activities of the Group, reviews the situation with respect to LUP in Europe and discusses whether a direction towards more consistent LUP decisions is being followed in Europe.     

Dioxins in the Venice lagoon

Venice is famous around the world for its uniqueness and architectural splendours, arts and the history of the “Serenissima Repubblica”, as it was known in the past, but few are aware that Venice economy is strongly dependent on the industrial activities based mainly on the adjacent Porto Marghera area. For many years, the lagoon that physically separates the city from the dry land has avoided association between the concern connected with the pollution derived from these industrial activities and the public perception of Venice. Since 1995, dioxins have appeared as a lagoon contaminant, and their presence, at such a level requiring immediate “in depth” studies and interventions, has been fully realized for decades.     

Reducing unknown risk: The safety engineers’ new horizon

A significant gap exists between accident scenarios as foreseen by company safety management systems and actual scenarios observed in major accidents.The mere fact that this gap exists is pointing at flawed risk assessments, is leaving hazards unmitigated, threatening worker safety, putting the environment at risk and endangering company continuity. This scoping review gathers perspectives reported in scientific literature about how to address these problems.Safety managers and regulators, attempting to reduce and eventually close this gap, not only encounter the pitfalls of poor safety studies, but also the acceptance of ‘unknown risk’ as a phenomenon, companies being numbed by inadequate process safety indicators, unsettled debates between paradigms on improving process safety, and inflexible recording systems in a dynamic industrial environment.The immediacy of the stagnating long term downward major accident rate trend in the Netherlands underlines the need to address these pitfalls. A method to identify and systematically reduce unknown risks is proposed. The main conclusion is that safety management can never be ready with hazard identification and risk assessment.     

Evolution of the chemical-environmental risk of territorial compatibility under the framework of the Seveso Directive: A case study of the autonomous community of Andalusia (southern Spain)

In this work, the evolution of the chemical-environmental risk oriented to the spatial planning in the autonomous community of Andalusia was carried out over the 2002–2012 decade. Indicators for determining the variables representing the risk, such as hazard, vulnerability and proximity, were then defined based on a consequence-based approach analysis risk methodology. A suitable mathematical combination based on spatial analysis methods supported by ArcGIS platform was also applied, which resulted in a quantitative and qualitative risk value and provided the territorial compatibility in the study area for each year. Finally, once the indicators that determine the risk level for 2002 and 2012 were obtained, they were combined in order to find out the risk tendency of the region for the whole decade.