B Hazebrouck
email: benoit.hazebrouck@ineris.fr

M Ledrans
email: m.ledrans@invs.sante.fr

Stakeholder Participation In Site Assessment And Management: A Real

Keywords: contaminated soil, pollutant transfer, epidemiology, stakeholders participation, health risk assessment, perception 1

Stakeholders 1 participation is increasingly considered as a plain part of thé assessment and thé management of a contaminated site. It is also acknowledged to be a difficult and sometimes risky challenge. Beside virtual experiments on "test groups", there is very little feedback on real cases of extensive stakeholders 1 participation on contaminated sites in Europe. No guideline or support document exist in Europe to help to organize Stakeholders' participation. We présent hère thé real case of a Southern area of thé town of Vincennes near Paris: following a high number of cancers among children in a school in thé vicinity of a former industrial site and a hospitai incinerator, thé Health Ministry set up an independent Scientific Committee in charge of designing thé epidemiological and risk assessment studies, of reviewing theirs results and of issuing recommendations. The Prefect directed a Participation Committee gathering ail stakeholders in thé aim of sharing ail information available on thé site, of discussing thé results of thé studies and thé conclusions of thé Scientific Committee and collecting opinions and expectations of each stakeholder in order to prépare décisions. Numerous studies were conducted. The Scientific Committee reviewed more than 30 protocols and reports. This expérience is discussed hère with regard to major questions on stakeholders 1 participation in site assessment and management, such as thé communication between experts and non-experts and between experts of différent fields (health scientists vs. environmental engineers), thé impact of thé média, thé psychological impacts, thé "crisis vs. non-crisis" aspects of participation. The discussion intégrâtes other expérience gathered on stakeholders 1 involvement It leads to thé identification of some ingrédients for an efficient stakeholders 1 participation, event if thé specificity of each case, and thé importance of spontaneity, reactivity, is recognized.

Introduction

Stakeholders 1 participation is increasingly considered as a plain part of thé assessment and thé management of a contaminated site. It is also acknowledged to be a difficult and sometimes risky challenge. Beside virtual experiments on "test groups" [START_REF] Petts | Involving lay audiences in environmental risk assessments[END_REF], there is very little feedback on real cases of extensive stakeholders' participation on contaminated sites in Europe. No guideline or support document exist in Europe to help organize Stakeholders 1 participation.

We présent hère thé real case of a Southern area of thé town of Vincennes near Paris: following a high number of cancers among children in a school in thé vicinity of a former industrial site and a hospitai incinerator, thé Health Ministry set up an independent Scientific Committee in charge of designing thé epidemiological and risk assessment studies, of reviewing theirs results and of issuing recommendations conceming management actions. The Prefect directed a Participation Committee gathering ail stakeholders in thé aim of sharing ail information available on thé site, of discussing thé results of thé studies and thé conclusions of thé Scientific Committee and collecting opinions and expectations of each stakeholder in order to prépare décisions. The whole case was conducted in a constant urgency, which is no exception. This expérience is discussed hère with regard to major questions on stakeholders1 participation in site assessment and management, such as thé communication between experts and non-experts and between experts of différent fields (health scientists vs. environmental engineers), thé impact of thé média, thé psychological impacts, thé "crisis vs. non-crisis" aspects of participation. The discussion intégrâtes other expérience gathered on stakeholders' involvement. It leads to thé identification of some ingrédients for an efficient stakeholders 1 participation.

Présentation of thé real case of Vincennes

History and stakeholders

In 1999 and 2001, three cases of cancers among children were reported in thé infant school named Franklin Roosevelt in thé South of Vincennes. The school had been built between [1987][1988][1989][1990], on a former industrial site (film materials from 1905 until 1987) and immediately downwind of thé incinerator of thé Bégin military hospital . In 2000-2001, limited environmental investigations and epidemiological assessment concerning thé school were conducted. They were reviewed by an ad hoc "national expert committee". They concluded: "thé information gathered on thé environmental quality and thé observed cases of cancer does not allow to suspect a link between thé fréquentation of thé infant school and thé occurrence of thé cancers". Therefore no further investigations were recommended (InVS, 2001). But thé social préoccupation remained high, ail thé more since a new case of cancer got declared, concerning a child who had not visited thé school Franklin Roosevelt but had lived near thé former industrial site. Ail thé cases of cancer were geographically situated on thé periphery of thé former industrial site. Strong demands for complementary epidemiological and environmental investigations were expressed by a local collective.

From June until August 2001, thé State Institute INERIS performed some complementary environmental investigations of surface and sub-surface soils and of thé indoor air in thé Franklin Roosevelt school and in three other schools in thé neighborhood, detecting no sign of contamination from thé underground.

From mid 2001 until end of 2003, a Participation Committee, directed by thé Prefect and later thé Sub-Prefect, gathered représentatives and experts from thé industrial firm which operated on thé site, from thé army health service, from local collectives, from local authorities (town, "département",...), and from thé local and national administration (Health, Environment, Education). The Participation Committee discussed thé issues, and thé Prefect took thé décisions 1 and transmitted them to thé industrial firm. As a former operator of a Classified Installation, thé industrial firm took in charge thé environmental studies on and around its former site2 . The Participation Committee was technically supported by an independent Scientific Committee set up by thé Health Ministry. The Scientific Committee gathered experts from mainly public organisms. No spécifie budget was made available for its works, except for thé epidemiological studies. It was divided in two subgroups, respectively for epidemiological and environmental studies. The Scientific Committee was presided by an expert of thé State Institute InVS, thé environmental subgroup was coordinated by an expert of thé INERIS. Those two experts are thé authors of thé présent article.

Epidemiological studies

The Scientific Committee designed two epidemiological studies, concerning two populations: • thé children who had visited thé school Franklin Roosevelt; • thé children living in thé surrounding town area. Thèse were conducted by Inserm (National Institute for Médical Research) and InVS. In 2004, thé provisory results of thé epidemiological studies (INSERM, 2004) did not confirm, statistically, an excess of cancer in thé two populations considered: thé local aggregation of infant cancers may hâve occurred purely by chance. The epidemiological studies were planned to go on for a longer period of time.

Environmental studies

For thé environmental studies, thé Scientific Committee issued proposais for thé scopes of works and further recommendations, received ail protocols and reports (more than 30) and issued its opinion3 (more than 20) and further recommendations. This work was done after concerting with thé différent stakeholders, especially thé local collective, thé industrial firm, and thé local health and environment authorities.

The environmental studies proposed by thé Scientific Committee (2001) Following thé demands of thé Scientific Committee, an environmental consultant firm was appointed by thé industrial firm to review thé work of thé other contracting party in charge of thé studies around thé former industrial site (hereafter "environmental contractant"). Its review finally did not correspond to thé needs of thé Scientific Committee (CS, 2003a).

In 2003, thé results of thé environmental studies (CS, 2003a) showed a concentrated but apparently punctual pollution of thé groundwater (10 m deep) and sometimes of thé soil and thé soil air, inclusive by vinyl chloride and trichloroethen, two volatile and cancerogenous substances. Nevertheless, no excess of exposure in thé town area linked to thé former industrial site was found. This indication was not définitive, given thé fact that thé investigation of thé exposure média was punctual in time and space, and given some metrological questions concerning thé soil air measures. Outside thé areas potentially concerned by thé underground pollution, such an indication seemed sufficient. Within those areas, a more exhaustive control and monitoring of possible transfer pathways had to be implemented, in order to confirm that no transfer susceptible of causing a significant excess exposure would occur. The control and monitoring program for thé former industrial site was decided by thé Sub-Prefect at thé beginning of 2004, after concerting with thé stakeholders {e.g. CS, 2003b). The participation structure deflated progressively back to thé current usual system: thé technical service of thé Prefect in charge of thé industrial sites would control thé studies and prépare thé prescriptions; it would receive thé comments of thé local collective, to which thé reports of thé control and monitoring were still addressed. The control and monitoring campaigns realized so far hâve not shown significant transfer towards thé receptors.

Besides, thé environmental exploratory studies conducted in 2002 in thé investigated town area and in a nearby référence area showed a significant pollution of thé superficial soil in some places with lead and (to a lesser extent) zinc, baryum, copper. Those results can not be related to thé former industrial site. Thé local health administration handled thé question according to existing procédures for lead contamination.

The impact assessment study for thé Bégin hospital, conducted in 2003, got rejected by thé Scientific Committee due to its insufficient quality in regard to thé state of thé art (CS, 2003 c).

Discussion of the stakeholders' involvement

Each party its part

In thé usual studies of contaminated sites in France, thé industrial firm can choose alone its environmental contractant in charge of thé studies. But a third expert must be chosen in mutual agreement between thé industrial firm and thé local authorities. The environmental contractant and its reviewer were appointed by thé industrial firm without concerting with thé stakeholders or thé Scientific Committee. This may hâve resulted from thé moral and judiciary urgency to start (and then complète) thé studies. During thé whole process, thé local collective expressed some suspicion that thé environmental contractant and its reviewer would not be impartial, even if thé environmental contractant e investigation proposais and studies got reviewed by thé Scientific Committee.

The Scientific Committee thoroughly maintained its visibility as "independent": a balanced relationship with thé main two opposite parties, thé local collective and thé industrial firm, was cultivated: as much as relevant, a meeting with one side was followed by a meeting with thé other side. The world of thé experts in contaminated sites is small. Experts over différent parties were former colleagues. Significantly, thé French casual form of "you", usual between two such acquaintances, was not used in thé meetings. For thé expertise of thé environmental studies, thé appointment and thé financing of one expert of thé Scientific Committee by thé industrial firm were excluded, even if thé décision were taken in thé Participation Committee. Only a public hand would hâve been considered as possible (even if thé money could corne from thé industrial firm).

An expert of thé local collective was first incorporated in thé Scientific Committee. He resigned after one year.

This général attention to avoid any confusion of rôles implies that thé différent points of view are maintained, and that a consensus should not be expected: in Vincennes, thé control and monitoring program which ended thé environmental studies got very much discussed from September 2003 until February or March 2004, when thé prescriptions of thé local authorities were issued. No consensus was reached on one général conceptual point (was thé net of monitoring points from thé environmental studies sufficient or should it be extended?) and on many détails (positioning of some points). But given thé preceding discussion, this fact, and thé corollary that thé prescription would not be fully satisfactory for oneself, was somehow accepted by thé participants. [START_REF] Hubert | Personal communication about thé participation committee[END_REF] drew a similar conclusion after thé expérience of thé Working Group "Nord-Cotentin" on thé impacts of thé nuclear site of La Hague in France. More essential than thé consensus is thé feeling that thé différent points of view are honestly taken into account. Which should not at ail be confused with an empty communication or a "social treatment" of thé crisis, and manipulation: taking into account thé views of thé différent stakeholders had very concrète conséquences on each part of thé studies eventually performed.

AN thé proposais and recommendations of thé Scientific Committee got accepted by thé Participation Committee -or sometimes integrated in anticipation by thé industrial firm in it proposais-, and then implemented. The Scientific Committee acquired thus a major rôle in thé préparation of thé décisions. But it voluntarily strictly limited its rôle to thé technical aspects, as opposed to management: for instance, it refused to answer thé question whether thé school Franklin Roosevelt should be closed or not, which was a management question, but produced thé technical part of an answer (CS, 2003a). This technical part eventually proved not determining in thé final décision (see § 4.3.4).

Experts and experts

A particularity of thé Scientific Committee was to gather experts of very différent fields. Within thé subgroup for environmental studies, a shift could be observed. It led to passionate technical debating at thé beginning of thé works of thé Scientific Committee. As usually on technical questions (not to confuse with décision making: see § 4.1), an expert consensus could be reached.

The original debate is still visible in thé two approaches ("exposure measurement" vs. "source-toreceptor") which could eventually be combined in thé final recommendations of thé Scientific Committee. On that occasion, some experts on each side leamed something about thé relativity of their own supposedly established approach and on multicultural work among experts.

Experts and non experts: establishing and maintaining thé relationship

An especially highly confident relationship was established between thé future INERIS expert in thé Scientific Committee and thé local collective at thé favor of thé complementary environmental investigations of June 2001 in thé school Franklin Roosevelt. The INERIS expert made thé documentary study and thé soil and soil air sampling himself. A thirty-minutes présentation-discussion of thé study, thé sampling program and thé sampling tools, with explanation of thé difficulties and limits of thé method, and with some tool-handling by thé persons, was organized on-site prior to thé investigation between thé INERIS expert and thé local collective. The local collective watched thé sampling, and some discussion took place again between thé samplings. This first contact determined thé whole further relationship between thé INERIS expert and thé local collective. The same type of relationship could be established by other members of thé Scientific Committee, and with other stakeholders. The ingrédients to an efficient stakeholders 1 involvement as appear in thé first contact described above are further illustrated and discussed hère under. Thèse ingrédients amount to thé respect to thé other party: thé other party must be considered as a legitimate partner with legitimate préoccupations and thé capacity to understand thé case. A key should be to imagine oneself at thé place of thé other.

Personal engagement

The dialog with thé other stakeholders is not delegated, and a strong personal availability is achieved to allow an almost permanent direct contact: a discussion between thé local collective or thé industrial firm for instance and thé président or thé two coordinators of thé Scientific Committee was always possible on a very short term. In thé whole, thé experts of thé Scientific Committee spent together several hundred working days on thé case, much on their personal time. Holidays were interrupted for one meeting, weekends were spent on thé case. The similar financial and personal engagement of thé industrial firm and its environmental contractant got acknowledgment by ail parties thé local collective included, and this certainly help smoothen their relationship in thé curse of time. For example, thé communication director and thé environmental manager of thé industrial firm, thé Prefect, participated themselves to thé meetings.

Honestv on thé limits of thé work

The scientific Committee in its documents and more directly its members in thé personal did not fear to expose thé limits and uncertainties in their proposais, for example concerning thé classification of some cancers in thé epidemiological study, thé ability to model vapor transfer (natural dégradation included) in thé soil air and through thé concrète floor (SC, 2003a), or thé proportionality of some measurements proposed (Hazebrouck et al., 2003). On thé contrary, thé main reproach of thé local collective towards thé environmental contractant, which in its view confirmed its original suspicion and prevented a full collaboration between thé two, besides some local punctual asymmetries in thé détail of some data présentation, concerned thé non disclosure of thé remaining unknown and thé resulting doubts4 . The expert must be able to say: "I do not know". Defining thé limits of thé knowledge, and thus of thé rôle of technique and experts vs. management, should precisely be thé main rôle of thé expert: outside those limits, thé experts are not more legitimate than non experts to make décisions (Testait, 2000). The way this honesty is translated should nevertheless carefully be chosen taking account of thé audience, so as not to end up with more anxiety (see § 4.3.4).

Breaking thé distance between non experts and thé field of expertise: demvstifying thé expertise

It should first be reminded that site investigation and risk assessment, and thé associated uncertainties, are no far-fetched concepts: they are primarily based on common sensé, and can be encountered in everyday's life. Therefore a demystified communication should allow a good général compréhension between experts and non experts.

As a first step, thé access to thé case should be made as concrète as possible, through attendance at investigations, site visits, graphs, pictures,.... For example, an extensive work of mapping and map superposition by thé environmental contractant in thé historical study and in thé proposais for thé investigations, certainly allowed much of thé understanding of thé approach and of thé site itself. Such an approach is recognized to break thé distance between thé field of thé expertise and thé non experts. As a second step, thé INERIS expert, in long discussions with his correspondent of thé local collective, and in a lesser extent in thé Participation Committee meetings, always displayed as extensively as relevant supposedly complicated thèmes such as: • limits, uncertainties, lack of validation, of thé metrological and modeling tools used in thé study in particular and in contaminated site assessment in général, • then thé impossibility to get rid of ail uncertainties, and finally thé subséquent concept of proportionality which is so difficult to accept at first in its concrète applications. The compréhension by thé non-experts seemed good. More detailed technical discussion of thé concepts of thé Johnson and Ettinger model for vapor transfer from soil air into indoor air, or of thé use of active carbon for thé measure of a multiple pollution in soil air, did not seem out of reach at ail for thé person of thé local collective. After three years, having consulted several sources of technical information on thé models, that person had become an expert on vapor measurement and transfer. A Key ingrédient for a good understanding seemed to be time and good will: on thé contrary, one actor, apparently not so motivated by thé technical accuracy of thé décisions, would not understand a more simple issue: thé différence between thé absence of détection of vapor transfer on a few points, and a comprehensive control of vapor transfer through a net of sampling points selected based on thé site history, thé current (partial) knowledge on thé pollution sources, and thé configuration of thé buildings. [START_REF] Bonano | Application of risk assessment and décision analysis to thé évaluation, ranking and sélection of environmental remediation alternatives[END_REF], in an experiment of virtual stakeholders' involvement with a test group, came to thé same conclusion, identifying time and motivation as major ingrédients for an efficient stakeholders 1 involvement. The case of Vincennes brings a confirmation on a real case.

Proactive, non-stressful communication

In thé way they formulate their results and conclusion, or in their silence itself, given thé expectation of thé population and their status, experts and managers of thé expertise hâve a dramatic influence on thé anxiety of thé population.

In Vincennes, thé formai structure of thé Participation Committee did not allow a proactive information especially towards thé média: contacts to thé média were limited to a few persons and occasions, thé messages were previously extensively reviewed. Each public communication to thé général population also got through an extensive review by différent stakeholders and/or thé Scientific Committee. Yet supplementary information was available for thé public, in an indirect way5 , through thé local collective and its direct contacts with thé Participation and Scientific Committees. The school Franklin Roosevelt got closed, based not on thé conclusions of thé site investigations, but on thé need to protect thé children and their families from thé média: TV caméras and journalists were at thé school's door, worst-case rumors were circulating.... The level of psychological stress upon thé children, and its anxiogenous impact, became obvious through thé following story: a child fell on its nose in thé school yard, bled a little, and immediately asked: "Am I going to die?". This story largely contributed convincing thé Participation Committee of thé need to close thé school. Other real-case expérience (Colas, 2004;[START_REF] Hazebrouck | Communiquer auprès du public sur les risques pour la santé dans le contexte des sites industriels pollués[END_REF] shows that proactive information towards thé média and thé population can strongly help to avoid an excessive psychological impact: thé absence of information lets rumors and even phantasms spread out. Making thé information available (if necessary taking time to explain thé situation to a joumalist) will fill this void.

Concerning thé formulation of thé results, discussions with thé epidemiologists on first drafts from thé environmental subgroup of thé Scientific Committee showed that thé same results can be formulated in a stressful way (and will often be so in a first version) or a non stressful way. Review by a non expert person remains a good way to heave this risk. The population should not be left by thé experts with a problem without solutions: at least outlines of a realistic solution, and preferably also a timetable, should be produced. Thus, as thé lead contamination of some superficial soils was discovered, a response was immediately implemented by thé local health administration. In Vincennes, thé population was well educated, which may hâve make thé communication, and specially thé open communication towards thé local collective, easier. A non stressfull communication on thé uncertainties could be much more difficult in less educated populations.

Other aspects of thé context must also be taken into account: thé first public meeting in Vincennes turned violent and had to be interrupted and thé room had to be evacuated. Another one a little later, organized by thé local collective, could go to thé end. For thé meeting, was thé population not ready suspicious that thé authorities would bury thé affair, were thé solutions presented at that time not précise and concrète enough? Was thé médiation of thé local collective necessary? A général explanation would be that thé dialog came a little too late: ail phantasms and rumors had been breading for too long. Other real-case expérience (Colas, 2004;[START_REF] Hazebrouck | Communiquer auprès du public sur les risques pour la santé dans le contexte des sites industriels pollués[END_REF] shows that an anticipated dialog makes things much easier.

Conclusion

Thé présentation of thé real case of Vincennes and its discussion in thé light of other expériences underline that an efficient stakeholders' participation is possible, provided there is personal engagement (including time) and good will on ail sides. The following positive ingrédients were identified: problems "open" and to anticipate thé wish for dialog. The participation process may help remind experts that décisions are not based on technical criteria only, and do not hâve to: given thé many limits in site assessment, thé technique does not answer to ail questions, and an adéquate décision process intégrâtes thé opinions and wishes of stakeholders such as thé population.

A large and formai Participation Committee with a Scientific Committee like in Vincennes would certainly not be recommended for ail types of stakeholders 1 participation. In Vincennes, it responded to a state of crisis, to thé gravity of thé effect (observed lethal cancers on children) and to thé ignorance of a clear source. In its final évaluation, thé Scientific Committee itself recommended to limit thé use of Scientific Committees to situations that can not be solved by thé existing ways. For other situations, such an organization would generally prove counter-productive, due to lack of directness, spontaneity and reactivity. A direct organization of stakeholders 1 participation by thé entity in charge of thé site, under thé control of local authorities and/or a third-expert (selected in a mutual agreement), should be in most cases sufficient and more efficient.

Even if directness and spontaneity are wished, organizational and operational tools for thé stakeholders 1 participation would be useful. Such tools are not available in Europe 6 , as well as thé knowledge on risk perception for contaminated sites necessary for thé development of such tools. The French Institutes on risks INERIS (industrial risk) and IRSN (nuclear risk) are currently working on thé development of support documents and guidelines for stakeholders 1 participation in thé management of health impacts of contaminated sites. This R&D project is financed by thé ADEME (Agence de l'Environnement et de la Maîtrise de l'Energie). A steering committee gathers thé points of view of thé local sanitary administration (including thé InVS), of thé Ministry of thé Environment, of industrial firms and of environmental consultants.

Références

  /www.atsdr.cdc.gov/traininq/public-health-assessment-overview/html/

	ATSDR. A Citizen's	Guide to Risk Assessments and Public Health Assessments.
	http://www.atsdr.cdc.gov/publications/CitizensGuidetoRiskAssessments.html
	ATSDR.	The	Public	health	assessment	process	and	thé	Community.
	http:/

or recommendations to thé army health service, which is not under thé authority of thé Prefect.

The Industrial Firm had achieved a site remediation in 1986-1989, but this did not suppress its responsibility on a residual pollution. In 2001-2003, it actually accepted to take in charge more than legally required, e.g. thé measurement of exposure levels at places and for analyticalparameters not related to its former activities on thé site.

which implied a deep work of critical analysis of thé received documents. Given thé lack of means (time and financing), thé opinions did not hâve thé status of exhaustive third expertises.

In fact, many uncertainties were discussed and taken into account in thé study. But thé Scientific Committee often had to signal other major uncertainties and limits of thé study which would induce a need for further investigations. Given thé generally poor discussion and intégration of thé uncertainties in site assessments in France, this should not suggest any dishonesty from thé environmental contractant: its environmental study was much over thé average on that point.

with thé possible bias. In 2003, a second local collective appeared, with views opposite to those of thé first local collective.

More support is available in thé USA: ATSDR, USEPA.2002.


Carine Chivas

Jean-Pierre Bertrand

Christian Malvaux

Guy Marlair

Karine Tack

SMOKE TOXICITY FROM COMBUSTION PRODUCTS BASED ON POLYMERS CONTAINING FLAME RETARDANT ADDITIVES

The aim of thé study supported by thé French Ministry of Ecology and Sustainable Development was to evaluate thé technical advantages or drawbacks procured by introducing a flame retardant in a polymer. The incorporation of flame retardants (FRs) présents thé advantage of reducing thé fire hazard due to flame spread, but might increase thé toxicity of fire émissions. In fact, thé efficiency of flame retardants is real when thé benefits from improvement of thé fire résistance properties overbalances thé undesired formation of noxious / toxic fumes. The originality of thé study is to analyse thé présence of toxic fumes as resulting from thermal dégradation/combustion reactions of FR polymer Systems.

In this paper, we propose to describe preliminary results on thé smoke toxicity from binary association of one polymer (polyvinyl chloride) and one typical flame retardant (antimony oxide or aluminum oxide) during combustion. In particular, we report on thé interactions between gases (synergistic, additive or antagonist effects), because smoke is confirmed to be thé major threat in accidentai fires.

The paper is finally a contribution to thé analysis of cost/benefit issues of adding FRs in polymer Systems considering potential rôle of related toxic products versus gain in terms of overall fire behaviour.

INTRODUCTION

Polyvinyl chloride (PVC) is an important polymer used in building (pipes, cables, Windows...). According to thé literature, thermal dégradation of PVC begins near 170-200°C. The principal advantage of rigid PVC is thé good self résistance to flaming combustion) or thé difficulty to burn. However, polymer filled with inorganic additives as antimony oxide (Sb 2 O 3 ) or aluminium trihydroxide (ATH), lead to better properties for technological applications. Moreover, additives in technical PVC products (such as plasticizers, antioxidants dyestuffs...) may in total weight more in mass that thé PVC polymer content itself.

Antimony oxide (Sb 2 O 3 ) is widely used as flame retardant additives in combination with halogen compounds. The association of Sb 2 O 3 with halogenated Systems leads to synergistic effects on flame retardancy. Synergistic effects act principally in gaseous phase, antimony oxide reacts with halogens to give SbX 3 (X : halogen).

Aluminium trihydroxide (ATH or A1(OH) 3 ) is well known to act as a barrier to heat and mass transfer between thé polymer and thé flame due to formation of a protective ceramic material at thé surface layer. The use of flame retardant Systems présents thé advantage to reduce thé fire hazard due to thé prorogation, but might increased thé toxicity of fire émissions. Therefore, it is necessary to identify thé bénéficiai and adverse true actions of thé flame retardant, in terms of, kinetic of inflammation and flame spread on thé one hand, and smoke toxicity on thé other hand.

REVIEW ON PVC AND FLAME RETARDANTS DEGRADATION STEPS AND SMOKE POLLUTANTS EMITTED DURING COMBUSTION

Thermal dégradation of PVC

The combustion reactions of PVC under différent fire conditions were studied (among others) by Purser and al. [1]. They showed that thé variety of smoke effluents generated during fire dépend on thé nature of combusting materials and on thé burning conditions. This review summarised thé main décomposition products from PVC under différent fire conditions (Fig. 1.). PVC pyrolyses to form HC1 and volatile compounds, which burn and evolve considérable of smoke.

Cl

Thermal dégradation of flame retardants

For many applications, thé use of flame retardant such as antimony oxide or aluminium trioxide are required. According to thé literature [START_REF] Brossas | Retardateurs de flammes[END_REF], thé antimony trioxide (Sb 2 O3) reacts with HC1 emitted from burning PVC to form antimony oxychloride which then décomposes to form antimony trichloride (Fig. 2.).

Fig. 2 : Reactions between antimony trioxide and HC1 issue from PVC

The ATH flame retardant mechanism (Fig. 3.) is based on thé release of water with cools thé flame zone and dilutes active species. Moreover, thé formation of A1 2 O 3 which contributes to thé formation of a ceramic char. The formulations of FR PVCs designated by thé letters "A" to "E" in table 1 were supplied by LVM member of Tessenderlo Group. The différent test products were manufactured using a blender « Papenmeier » and a hot press moulding (working at 204°C). The residual content of aluminium and antimony is null within PVC alone. Thèse results are correlated with thé theory. Moreover content of AÏ and Sb within thé other formulations were checked.

Theoretical composition of différent formulations

EXPERIMENTAL APPARATUS Tewarson Calorimeter

Experiments were carried out with thé Fire Propagation Apparatus implanted at INERIS Fire Laboratory (Fig. 2). The apparatus originally called "50kW lab-scale flammability apparatus" in thé USA and Tewarson Apparatus in Europe, is a polyvalent fire calorimeter that was recently described in two standards ASTM E 2058 and NFPA 287 under thé final désignation Fire Propagation Apparatus (FPA) [3/4]. Another mass flow meter allow thé introduction of CO 2 , N 2 or O 2 into thé incoming air for non-ambient combustion conditions. The air may be enriched or depleted in oxygen. The composition of oxidising stream is measured by an oxygen analyser, thé sample probe is located below thé spécimen holder in thé combustion chamber. The upper part of thé calorimeter is thé exhaust System with thé instrumentation section. Standard characterisation of thé composition of fire gases and smoke relies on thé routine use of thé on-line gas during devices. The heat release rate is measured from both oxygen consumption and carbon dioxide génération calorimetries. The variables measured during a fire test were thé mass of thé spécimen, thé concentration of O 2 , CO 2 , CO, total unburned hydrocarbons (THC), NO, thé smoke obstruction at four monochromatic wavelengths, and thé température.

Récent papers illustrate early expérience achieved by INERIS with thé described apparatus in collaboration with thé Faculté Polytechnique de Mons [5/6]. In collaboration with FM-Global, round robin tests examining thé behaviour of non fire retarded plastics, close to pure polymers (including rigid PVC) were also recently présented) [START_REF] Marlair | Effects of thé generic nature of polymers on their fire behavior, Fire safety science[END_REF], as well as contributions to thé analysis of thé rôle played by O 2 depletion and air vitiation on global émissions in fires [START_REF] Marlair | Use of ASTM E 2058 fire propagation apparatus for thé évaluation of underventilated fires[END_REF].

In thé framework of thé présent study, combustion tests were performed in normal air samples exposed to 50 kW/m 2 to quantify yield of smoke. The sample mass of products submitted to thé fire test typically reached some 50 g.

Analytical experiments

Elementary analyses on PVC samples Total chlorine : Analyses were performed by volumetric dosage by précipitation (silvermetry) after combustion of thé samples in a calorimetric bomb reactor under oxygen atmosphère (P = 30 bars). Référence standard used is ASTM D-808 obs. DIN51577 [START_REF]sulfur and halogens/chlorine in petroleum products (bomb method)[END_REF].

Antimony and Aluminium : Solubilisation of samples were obtained by use of sulfuric acid (H 2 SO 4 )on hot plates, then in an oven at 55O°C. Ashes obtained were dissolved in hot chlorhydric acid. Analyses were performed by ICP/OES (Inductively Coupled Plasma/Optical Emission Spectrometry). Référence standard used is NF EN ISO 11 885 [START_REF]Qualité de l'eau -Qualité de l'eau -Dosage de 33 éléments par spectroscopie d'émission atomique avec plasma couplé par induction[END_REF].

Analyses of residues issued front combustion

Total chlorine : A carbonate fusion pretreatment was necessary to remove organic interférences. After that, analyses were performed by volumetric dosage by précipitation (silvermetry).

Antimonv and Aluminium : Solubilisation of samples were obtained by use of in H2SO4 on hot plates, then in an oven at 550°C. Ashes obtained were dissolved in hot chlorhydric acid. Analyses were performed by ICP/OES (Inductively Coupled Plasma/Optical Emission Spectrometry).

Analyses ofCl, Sb and Al front gaseous émissions during combustion

Cl, Sb or AÏ containing such émissions were trapped through sampling Unes containing suitable solutions in bubblers.

Chlorine :

Analyses were directly performed by volumetric dosage by précipitation (silvermetry).

Antimony and Aluminium :

Analyses were directly performed by ICP/OES (Inductively Coupled Plasma/Optical Emission Spectrometry).

RESULTS AND DISCUSSION

In order to understand thé contribution of each component of thé FR polymer complex on global smoke toxicity induced by fire a two steps study has been performed. The first part of thé study concerns thé fire behaviour of poly vinyl chloride alone, thé second part deals with thé combined components (e.g. polymer matrix + fire retardant) présent in thé FR plastic.

Results regarding smoke toxicity of several formulations based on PVC are presented in thé foliowing sections.

Preliminary observations during combustion tests

First observable phenomenon once external heat at 50 kW/m 2 is applied to PVC samples is surface bubbling due to gas release from thé irradiated sample. This gas émission is assumed to be linked with HC1 release by chemical bond breakage. After a while, piloted ignition of gases liberated in thé course of thé process occurs. Shortly after ignition, abundant black smoke . Char and carbonaceous residues are formed during combustion (Fig. 3). PVC + 0.2% Sb 2 O 3 The morphology of thé char dépends on thé additive incorporated in thé formulation. In fire conditions, a ceramized char builds on thé surface of thé formulation containing aluminium trioxide.

Kinetics of combustion and thermal aspects

The Table 3 The addition of flame retardant (Sb2O3 or ATH) in PVC doesn't lead to significant changes in terms of mass loss rate during combustion. The évolution of thé burning rate during thé combustion is presented on thé Fig. 4.This observation is likely to be related to thé fact that overall thermal dégradation/combustion of thé treated FR complex keeps dominated by thé rôle played by HC1 libération in our test conditions. The différent formulations presented similar burning rate once steady combustion is achieved. Table 3 gives average burning rates calculated on two différent periods of time Àti and At 2 . Différences are observed mainly at thé beginning during preheating/ignition phase. It could be related with thé différent char structure formed during combustion of thé sample. As it is shown on Fig. 3., samples containing ATH lead to a ceramized structure. Moreover, it is well-known that thé ATH can decrease thé surface température and thus delay thé pyrolysis of thé polymer due to both endothermic décomposition of ATH and heat consumed by water release from thé hydroxide.

Table 4 : Elemental composition of residues issued from combustion of PVC formulations

The influence of thé flame retardant additives introduced in thé matrix PVC was evaluated by analysis of residues. The analysis of thé residues clearly shows, thé mechanisms of action of thé two FR Systems. In addition, thé data are consistent with thé results obtained concerning thé gas pollutants emitted during combustion. Indeed, thé recovery of 100% of thé initial aluminium from thé test sample in thé residue allows us to assume that this élément doesn't lead to any significant Al-contaming gaseous émission in fire conditions. That shows also that thé ATH acts in thé condensed phase. On thé opposite, antimony, acts in thé gaseous phase according to réaction mechanisms displayed in figure 2. This work based on thé use of Tewarson calorimeter has aimed to get a first évaluation of main effluents from PVC and PVC containing a flame retardant system (see Table 5).

Smoke composition : Toxicity of effluents issue from thé PVC chloride and flarae retardant additive combination during combustion

The objective of this paragraph is to identify thé advantages brought by thé incorporation of a FR additive (namely Sb 2 O 3 or A1(OH)3) in PVC matrix in term of réduction of thé " toxicity potential " of thé gas effluents emitted in thé event of fire. Given thé results obtained so far, thé fire retarded effect brought by thé additive is not obvious and seems masked by thé inhérent behavior of thé PVC alone which is itself already "fire résistant" due to thé présence of thé chlorine élément.

However, we can notice a plausible benefit effect of ATH in thé formulations D and E with a réduction of thé total of hydrocarbon (HCt). The use of ATH remaining in condensed phase seems to reduce thé yield of HCt emitted wish somewhat contributed to reduce thé overall toxic potential of PVC. Naturally, pollution and toxicity issues of PVC, with of without thé addition of thé studied FRs keep dominated by HCI émissions. It would thus be useful to explore further whether thé observation regarding thé apparent réduction of HCts is real by performing extra tests with same FRs and other type of technical PVCs and see whether this benefit is extrapolable to other type of polymers. Besides, combining same FRs with other polymer matrices would allow to see if other benefits in terms of réductions of pollutants or toxic yieids could be identified.

CONCLUSION AND FURTHER DEVELOPMENT

Tests comparing thé overall behaviour of non FR and FR PVC based polymers hâve been performed making use of thé Fire Propagation Apparatus (also called thé Tewarson Apparatus).

The main goal was to initiate a study aiming at identifying and quantifying thé benefit issue of adding FRs in polymers (e.g. gain in terms of fire résistance as compared to potential adverse effect due to potentially increased toxic or pollutant émissions). At thé light of data obtained with binary Systems using Al(OH)s or SbiCb as thé studied flame retardant additive in addition to rigid PVC, preliminary results can be summarized as follows : PVC fire retarded or not, are keeps dominated in case of a fire by thé mechanism of libération of HC1 due to thermal décomposition.

In relation with this observation, mass loss rates historiés are quite similar whatever are thé formulations studied, except during preheating/ignition phase (at list in our experiment).

In thé case of ATH addition, thé main apparent benefit lies in some réduction of total hydrocarbons released in thé fire gases (to be confirmed with other experiments) ; in addition, thé élément AÏ remains 100% in thé solid residues. Tests performed with PVC treated with Sb2Û3 revealed that part of thé Sb is emitted in some form in thé fire gases, raising some potential concerns as regard carcinogenic issues.

To go more in depth in thé analysis, it is intended to explore thé following points : a) Behaviour of other binary complexes based on PVC (e.g. plasticized PVCs) in addition with thé already studied FRs. b) Influence of thé external heat flux applied to discriminate behaviours between FR and non FR PVC based polymers. c) Benefits of ATH when used as an additive in other polymer matrices (EVA). This is thé workplan we intend to implement in 2006.

Fig. 1 :

 1 • Chlorinated aromatics and aliphatics, 1Soot CO, CO 2 , H 2 O, HC1 Aromatic and aliphatic hydrocarbons, Chlorinated aromatics and aliphatics, Oxygenated aromatics and aliphatics, Chloro/oxygenated aromatics and aliphatics, Soot Combustion products from PVC under différent fire conditions [1]

Fig. 3 :

 3 Thermal décomposition of Aluminium trihydroxide TEST MATERIALS

Fig. 2 :

 2 Fig. 2 : Tewarson Calorimeter a) View of thé Tewarson Calorimeter at INERIS, b) Standard characterisation of thé composition of fire gases and smoke using thé Tewarson Calorimeter

Fig. 3 :

 3 Fig. 3 : Photos collected during Tewarson Calorimeter experiments of PVC, PVC + 0.2% Sb 2 O 3 , PVC + 3% Sb 2 O 3 , PVC + 0.2% ATH and PVC + 3% ATH at différent phase of combustion

Fig. 4 .

 4 Burning rate versus time at 50 kW/m 2 for (A) PVC, (B) PVC + 0.2% Sb 2

according to LVM Sample (Percentage by weight) PVC CaCO 3 OP (One Pack) Sb 2 O 3 A1(OH) 3

	A	B	C	D	E
	86	86.3	84.3	86.3	86.3
	11	10.8	10.5	10.8	10.8
	3	2.7	2.7	2.7	2.7
	-	0.2	2.5	-	-
	-	-	-	0.2	2.

5 Table 1 : PVC based formulations used as test samples Elemental composition as analysed by INERIS Sample A B C D E Mass % of overall sample weight Theoretical elemental composition Cl%

				As measured from INERIS samples
					analyses
		Sb%	Al%	Cl%	Sb%	Al%
	48.81	-	-	45.65 ±0.17	-	-
	48.73	0.07	-	44.18 ±3.10	0.10	-
	47.58	1.05	-	45.68 ± 0.33	0.10 1	-
	48.73	-	0.06	44.70 ±0.18	-	0.07
	47.58	-	0.90	44.21 ± 1.21	-	0.80

Table 2 : Theoretical chemical composition of selected formulations

 2

  summarised thé main characteristics of combustion : combustion time, burning rate and heat of combustion.

					Effective Heat of
	Sample	Combustion time (s)	Average burning rate (g/m2/s)	combustion * (kj/kg ) CDG oc
			At j = 0 to 70 s	At 2 = 70 to 350 s	method	method
	A	500	19.2	6.5	8 380	7 610
	B	450	18.6	6.4	7 150	7 180
	C	630	15.3	6.9	7 630	7 120
	D	510	18.2	6.3	9 620	9 080
	E	540	16.1	5.8	8 520	8 600

Table 3 : Kinetics of combustion from PVC formulations

 3

* The effective heat of combustion is measured form both methods, Oxygen Consumption Calorimetry (OC) and Carbon Dioxide Génération Calorimetry (CDG) [111

Table 5

 5 summanses thé results from chemical analysis performed by INERIS conceming thé émissions of toxic combustion products issue from PVC formulations with and without additives.

	Pollutants	A	Yieids of gaseous toxic émission loss (mg/g) B C D	E
	CO 2	673	563	581	775	689
	CO	62	68	101	68	56
	(NO,NO 2 )	15	8	10	10	7
	méthane	3	3	6	2	1
	HCt	81	79	151	53	45
	HCI	502	504	498	452	499
	soot	99	98	77	82	81
	Sb< »	-	0.5	17.6	-	-
	A1(OH) 3	-	-	-	-	-
	counted in Sb 2 O 3

Table 5 : Yieids of gaseous toxic émission in % by wt. involving from PVC Pollutants

 5

			Theoretical yieids of HCI émission (mg/g)
		A	B	C	D	E
	HCI (theoretical)	565	550	581	561	576
	HCI (expérimental)	502	504	498	452	499
	Conversion effîciency (%).	89	92	86	81	87

Table 6 : Theoretical yieids of HCI émission [12]

 6

Table 6

 6 compares measured yieids of HCI in our experiments to maximum theoretical yieids according to Cl content in PVC test samples. As clearly stated in thé literature[START_REF] Terrill | Toxic gases from fires[END_REF], we found expérimental values very close to maximum potential yieids.

Acknowledgements

The authors acknowledge thé French Ministry of Ecology and Sustainable development of for supporting this work.


B. Debray INERIS O Salvi

CONVERGENCE IN RISK ASSESSMENT FOR SEVESO SITES FROM ASSURANCE RESULTS TO ARAMIS METHOD

INTRODUCTION

In thé SEVESO il Directive, thé objectives in terms of risk management are very clear, but thé remaining question is: How to reach them ? For example, there is no harmonisée! définition of thé scénarios that hâve to be considered for risk assessment Typically, thé chosen scénarios (BLEVE, total loss of containment, fire in thé largest tank, explosion of thé largest mass of explosive, etc.) can be différent according to thé spécifie risk analysts and according to thé deterministic or risk-based approach of thé country applying thé Directive.

In this présentation, I will share with you thé main results of thé ASSURANCE project, in which 7 European organisations performed a benchmark exercise for thé risk analysis of a spécifie plant. ASSURANCE pointed out thé need for further development that were achieved in thé ARAMIS project. For this latter project, I will présent thé main results and thé perspectives and how thé ARAMIS results constitute a major step forward in thé convergence of practices in risk assessment.

ASSURANCE PROJECT

Project description

ASSURANCE means ASSessment of Uncertainties in Risk Analysis of Chemical Establishments. This project was a benchmark exercise on risk analysis of chemical installations to understand discrepancies between experts. The project consisted in thé comparison of thé sélection of scénarios, thé comparison of thé estimation of thé conséquences and finally thé comparison of thé estimation of thé probabilités. The project lasted 3 years from 1998 to 2001. The 9 partners from 7 différent countries, représentatives of thé risk assessment approaches implemented in Europe.

Main results

The partners used various risk analysis techniques and arrived at quite différent conclusions with respect to thé sélection of thé scénarios, thé estimation of their probabilities and thé estimation of their conséquences.

For example, in terms of probabilities, for a classical event which is thé "Rupture of 4 inch. pipe on a distribution Une", thé most optimistic partner estimated a probability of occurrence at 3.4 . 10" 8 per year, and thé most pessimiste partner at 2.3 . 10" 4 per year. Concerning thé conséquences of thé scénario, for a rupture in a pressurized tank, thé distance to reach thé end point 6200 ppm in a normal atmospheric condition, was estimated by thé most optimistic partner at 0,4 km and by thé most pessimistic partner at 2 km. The last comparison concerned thé iso-curves for 10-5 / year that a person dies in thé vicinity of thé plant because of an accident. There is a différence of about 800 m between thé most optimistic and thé most pessimistic partners.

Main

Main results : Conséquences

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Main results

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Lessons learnt from ASSURANCE

The ASSURANCE project has shown that there are discrepancies between thé experts in thé définition of scénarios considered for risk assessment. Some assumptions are différent and thèse hâve a strong impact on conséquence calculations.

There are also discrepancies in thé estimation of thé probabilities of some events because there is a lack of reliable and contextual data (on failure rates, reliability...) Moreover, thé project pointed out that risk curves mapping is not meaningful for local authorities and thé public (consequence-based approach countries).

ARAMIS PROJECT

Project description

The ARAMIS project built further on thé conclusions of thé ASSURANCE project and proposed a structured approach that reduces thé discrepancies in risk assessment.

The main objective is to build a methodology that will improve thé effectiveness of thé safety reports required by thé Seveso 2 directive. This method combines thé benefits from risk-and consequence-based approaches. It will help operator to better demonstrate that hazards are identified and risks are controlled.

Finally, it will provide appropriate information to base risk-related décisions like thé deliverance of permit, lands use planning and emergency planning.

The project, which lasted from 2002 to 2004, consisted in thé élaboration of a methodology givîng consistent ruies for thé identification of scénarios that take into account mitigation devices and safety management, and being recognised by a large number of risk experts from Compétent Authorities and from Industry, gathered in a Review Team. In ARAMIS, thé risk level of an establishment is characterised with an integrated approach where 3 independent parameters are quantified:

Project Overview

• thé Frequency of thé scénarios • their Severity • and thé vulnerability of thé environment

From thé risk analysis, Major Accident Scénarios are identified and then Référence Accident Scénarios that take into account thé préventive measures implemented by thé operator. The severity Sref and thé frequency Fref of thèse référence scénarios are estimated.

The sélection of thé Référence Accident Scénarios is made possible thanks to thé évaluation of thé efficiency of thé safety management System: both thé formai aspect and thé safety culture within thé plant.

The environment vulnerability estimation describes thé sensitivity of thé potential targets located in thé vicinity of thé SEVESO II establishments The outputs of thé ARAMIS method are mainly represented on maps.

Main results

ARAMIS method is well structured and contents 6 major steps that are described more extensively in thé main chapters of a user guide.

-Identification of major accident hazards (MIMAH) -Identification of thé safety barriers and assessment of their performances -Evaluation of safety management efficiency to barrier relîability -Identification of Référence Accident Scénarios (MIRAS) -Assessment and mapping of thé risk severity of référence scénarios -Evaluation and mapping of thé vulnerability of thé plant surroundings I will présent some key part of thé method to give an overview of its content.

The scénario identification

One of thé crucial step is thé scénario identification. It is based on thé bow-tie approach where fault trees and event trees are connected through thé critical events. The identification of thé scénarios consists in thé identification of typical and generic events: direct causes (DDC and DC), necessary and sufficient conditions (NSC), thé critical events (CE), thé secondary and tertiary critical events (SCE and TCE), thé dangerous phenomena (DP).

This représentation enables then to identify thé safety functions and thé safety barriers.

rapi {ut Scénario identification (2/2) Characteristics of safety barriers

F pnr L-, ---*• ;-i'-X • • --

Frequency of

Frequency of -^ aSSS* of initiating event Critical Event dangerous phenomenon

The influence of safety barriers is determined in assessing their performances (level of confidence, efficiency and time response in accordance with thé scénario).

The référence accident scénario identification

Then, a risk réduction goal, defined in terms of aggregated level of confidence, is assigned to each scénario in order to reach an acceptable level of risk during risk analysis. This phase use thé principles described in thé standard IEC 61508 on thé évaluation of thé functional safety of safety instrumented Systems.

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Risk reduction and ref. scenario selection

Risk

Conséquence classes

At this stage, thé scénarios taking into account thé safety barriers are ranked in a matrix. Those scénarios that are in thé yellow zone are considered as Référence Accident Scénarios while thé scénarios in thé red zone hâve to be further worked out to reduce their conséquences or their fréquence by implementing appropriate risk reducing measures.

The barrier management performance

The barrier management performance combines a generic and a spécifie approach. The method allows thé use of databases with generic levels of confidence. But 2 tools hâve been developed to assess thé specificity of thé studied plant:

-an audit protocol to assess thé barrier-related management activities -and a questionnaire to assess safety culture/climate onsite

The barrier management performance reflects thé level of control of thé activities relating to safety barrier life cycle.

Example

It is proposed to consider an example from thé paper industry taken from thé test cases of ARAMIS. The critical event is a runaway réaction that can be caused by thé introduction of an excess of methanol in thé réaction, because of thé failure of a BPCS pump. This runaway réaction will lead to an overpressure with an explosion and thé release of chlorine dioxide, which is toxic.

In this example, we can estimate thé probability of thé dangerous phenomena if we know thé frequency of thé initiating event and thé level of confidence of thé safety barriers.

Example (paper industry)

BPCS failure The severîty calculation and mapping

The severity SCEÎ(CI) is estimated in every point in thé surrounding of thé plant for each dangerous phenomena associated to ail critical events. Then, thé multiplication of thé frequency by thé severity of each critical event is summed up to calculate thé severity S(d) at a given distance.

m saa en s 1 4^ - ' • • • ' • • • ] i' i , MmMMMim
Risk severity mapping i^m ' j 1

Thé vulnerability

The estimation of thé vulnerability of thé environment consists in an inventory and a quantification of thé possible targets by using a Geographical Information System. Three types of targets are considered:

-environmental targets -human targets -material targets

Risk vulnerability mappAff 1

i Human

£<• T• --.? i * 1; Material Environmental I GlobaTi
The importance and sensitivity of thé targets was achieved by implementing a multicriteria decision-aiding method where thé ranking factors were elicited through questionnaires distributed to a large number of experts.

CONCLUSIONS AND PERSPECTIVES

The ARAM IS method has answered some of thé difficulties related to risk assessment pointed out by thé ASSURANCE project.

Three project main conclusions can be drawn up. ARAMIS method is based on thé safety barrier approach. This constitutes an alternative to thé probabilistic/consequence based approaches which is well understandable by thé industry as well as by thé compétent authorities. It is didactic and pédagogie.

The safety barrier approach is also compatible with Layer Of Protection Analysis (LOPA) method and thé IEC 61508 standard, which is largely implemented in thé industry. This approach leads to constructive discussions on thé level of performance of safety barriers within thé plant and with thé authorities.

ARAMIS îs a method that takes into account thé specificity of thé plant, ifs safety management System performance and its safety culture, when other methods consider only generic data.

Beside thé development of an integrated risk assessment method, ARAMIS project has achieved a tremendous exchange of practices between practitioners from more than 15 EU Member States if we consider thé consortium and thé review panel. This has led to a certain convergence among countries (partners and reviewers) in thé way of implementing risk assessment in thé framework of thé Seveso 2 directive.

The project has brought éléments to fulfil thé need to establish a method that is capable to assess thé risk level of an installation by integrating thé préventive measures implemented by thé operators. Such a method is a prerequisite in order to reach thé goals of thé SEVESO II Directive, that are to improve thé prévention linked in particular with thé safety management. The application of this method results in a more consistent risk évaluation and safety management strategy in ail European Countries

This reflection has continued in thé European Working Group on Land Use Planning (EWGLUP) which aims at exchanging expérience in risk assessment and land use planning in ail Member States.

  report : Rîs0-R-1344(EN) May 20Û2

Acknowledgement

The work présentée! in this paper has been elaborated in thé frame of thé EU project ARAMIS "Accidentai Risk Assessment Methodology for Industries", co-ordinated by INERIS (F) and inciuding EC-JRC-IPSC-MAHB (I), Faculté Polytechnique de Mons (B), Universitat Politècnica de Catalunya (E), ARMINES (F), Ris0 National Laboratory (D), Universita di Roma (I), Central Mining lnstitute (PL), Delft University of Technology (NL), European Process Safety Centre (UK), École des Mines de Paris (F), École des Mines de Saint Etienne (F), École des Mines d'Alès (F), Technîcal University of Ostrava (CZ) and Jozef Stefan lnstitute (Si). The project is co-funded under thé Energy, Environment and Sustainable Development Programme in thé 5th Framework Programme for Science Research and Technological Development of thé European Commission.


Patrick Bonnet
email: patrick.bonnet@ineris.fr

Jean-Marc Lacome

Experimental Study of Accidental Industrial LPG Releases: Rain out investigation

The objective of the atmospheric dispersion research projects of INERIS are to develop models of flashing releases as encountered in realistic industrial environments. Equivalent source term models exist for flashing release in current long range dispersion models. Several factors can, however, invalidate simplified equivalent source models, especially in the very near field where obstacles can be found.

To perform these objectives, INERIS took part in an European project called FLIE [1] (Flashing Liquids in Industrial Environment). In this project, INERIS carried out large-scale experiments with propane and butane releases. The French ministry in charge of Environment also supported INERIS participation which dealt with the modelling of two-phase jets. This paper aims at presenting the large-scale experiments and the main results relative to the rain out observations. The experimental set-up is located in the INERIS test site. It allows performing propane and butane liquid releases at ambient temperature with a regulated pressure from the saturation pressure to 15 bar with an orifice (circular or rectangular shape) of an equivalent diameter from 10 mm to 25 mm. It is possible to realize free jets but also impinging jets by introducing obstacle at a maximum distance of 2 meters from the release point.

To develop models requires experimental validation data. Up to now, little of experiments were carried out on a great scale with such a variety of measurements. The results revealed some new points related in particular to the rain-out which are seldom discussed in the literature and which can be useful to develop models of flashing releases. Another important lesson learnt is that pools formed by LPG release jets do not contain liquid exclusively but also a mixture with ice. This has a great influence on the pool evaporation.

Introduction

1.1

Context Liquefied gases are in widespread use in industry due to their chemical or physical properties. In parallel, numerous industrial processes use fluids that are overheated compared with ambient temperature conditions. Following a loss of containment around an installation, the hazards faced can be instantaneous, as with the explosion of flammable products, or differed as is the case with releases of toxic products.

In order to calculate safety perimeters around industrial installations, one of the objectives of atmospheric dispersion research projects of INERIS is to develop models of flashing releases in realistic industrial environments. Now, equivalent source term models exist for flashing releases. However, several factors can invalidate these simplified equivalent source term models, especially in the context of realistic industrial environments. For instance, liquefied pressurized gases released are rarely pure products, the shape and size of the breach can be strongly different than which had been usually used to develop existing models, in the very near field of the release, obstacles can be found, etc... To perform his objective, INERIS carried out "large-scale" trials of "industrial" (that is not pure) propane and butane releases in order to develop a tool able to evaluate the gas and the liquid fraction (size of droplets forming the aerosol and liquid pool) in the near field of the flashing release. This INERIS paper aims to present the large scale experimental set-up and the main current results.

What happens in the event of an accidental release?

The consequences of an accidental release will depend on the one hand on the initial storage conditions, and also on the environment. This is because the presence of obstacles of sufficient size may affect the jet and change the characteristics of the hazardous cloud.

At the breach level, in the case of an accidental release of pressurized liquefied gas, the product released in the ambient air is suddenly placed under temperature and pressure conditions that are such that a part of the liquid vaporizes violently. This phenomenon is generally called a "flash" or a "thermal fragmentation". The sudden vaporizing of a part of the liquid leads to the fragmentation of the liquid jet into fine droplets whose diameter and speed will be especially dependent on the difference between the initial substance temperature and the substance boiling point. A mechanical fragmentation can also be observed when shear stress due to friction turbulences break the liquid phase despite the surface tension forces [START_REF] Bigot | Flashing liquid Fragmentation : is there a hindered mass ? 3[END_REF].

In the absence of any obstacle, after a length of a few times the diameter from the breach, a twophase jet develops. This jet is made up of droplets in suspension in a mixture of gas and ambient air that is drawn along. The atmospheric dispersion of this two-phase jet is notably dependent on the environment. In cases where no obstacles are present along the path of the jet, the different contributions to the formation of a flammable or toxic cloud are as follow [START_REF] Stéphane | COUILLET Dispersion de gaz liquéfiés dans un environnement industriel Préventique sécurité[END_REF]:

• the quantity of product likely to be quasi-instantaneously vaporized and the droplet size distribution due to the flash phenomena at the breach level ; • the quantity of product likely to form a pool on the ground (commonly called rain-out) that then evaporates into the atmosphere due to mass and heat transfer phenomena; and lastly, • the quantity of product likely to be drawn into the air in aerosol form.

In this case, the estimation of the main amounts of vapour released in the air consists in studying the evaporation of the formed droplets and the formation, and then the evaporation, of a liquid pool at ground level. This estimation is important to define a realistic source term that will be used in an atmospheric dispersion model.

In the case of a release in the presence of obstacles, the interaction between the jet and the obstacle may notably change the calculation of the source term. In that case, it is important to determine what becomes of the drops after impact. To do this, it is necessary to know the characteristics of the jet and the droplets prior to impact as well as those of the obstacle.

The experimental set-up

The experimental set-up, developed in order to understand these phenomena, is located in the INERIS site. The figure 1 shows the release field and the control room in the background. The figure 2 is a diagram of the experimental set-up. The experimental set-up allows us to perform propane and butane liquid releases (the release point is presented in figure 3) at ambient temperature with a regulated pressure from the saturation pressure to 15 bar with an orifice of an equivalent diameter from 10 mm to 25 mm. It is possible to carry out free jets but also impinging jet by introducing obstacle at a maximum distance of 2 meters from the release point.

Figure 3 : Photograph of the release point

The table 1 presents the values chosen for each of the main parameters that play a role on the jet and rain out characteristics. In this table, one will notice that the temperature of the fluid, even if it plays a fundamental role, was not a fixed parameter. Indeed, to heat a tank containing 1 ton of LPG in full safety is very constraining.

Commentary

We did not use "pure" gases, we preferred use typical gases usually found in industrial sites. We decided to fix the gas pressure taking into account his saturation pressure (at ambient temperature) because we wanted to compare two different gases in their usual use in industry, that is ambient temperature and saturation pressure for storage use or ambient temperature and saturation pressure plus some bars due to filling operations or hydraulic pressure for example. Free jet is an horizontal jet at 1.5 m from the ground For impinging jets, we used steel plates 3 mm thickness During releases, several parameters are recorded:

• Ambient conditions: direction and speed of the wind, temperature, humidity and atmospheric pressure. • Release tank: pressure, temperature at several heights in the tank and at the liquid/gas interface, weight of the tank (to calculate the mass flow rate). • Release point: pressure and temperature just before the outside.

• Inside the jet: a Dual Phase Doppler Anemometer allows to measure speed and size of droplets at several locations in the jet. • Rain out: Six bonds equipped with continuous weight measurements are used to study the phenomena of liquid pool formation. • Obstacle: Six surface temperature thermocouples.

Rain out observations

This section deals with main results obtained with rain out measurements for free and impinging jets of propane and butane.

Free jets

Concerning free jets, only butane gave us measurable rain out. This can be explained by the much lower boiling point of propane (-42°C) than the boiling point of butane (-0.5°C). Moreover, the propane saturation pressure at ambient temperature (8.3 bar at 20°C) is higher than that of butane (2.1 bar with 20°C). Figure 4 and table 2 present the influence of the storage pressure (the storage temperatures are identical) on the distribution of the rain out on the ground.

In the figure 4 and table 2, the % rain out is the ratio between the mass flow recorded in a retention dike and the total mass flow rate of the release.

In this figure, the vertical dotted lines present the position of the gravity centre estimated of the measured rain out for pressures (storage and release pressure are very near) of 2.6 bar, 3.8 bar and 5.6 bar. The gravity centre position, noted x g , is calculated starting from the relation: The rain out distribution for these three pressures shows that the mechanical fragmentation is dominating on the thermal fragmentation. Indeed, in his thesis [START_REF] Touil | Modélisation des jets diphasiques liquide vapeur et du rainout[END_REF], A. Touil showed that in the case of thermal fragmentation, the gravity centre of the rain out is often located close to the orifice. For these tests, we can explain the mechanical fragmentation by the fact that the superheat temperature (difference between the storage temperature and the boiling point of the fluid) of the butane is low (< 20°C).

Concerning the influence of the storage pressure, the higher the pressure is, the more the gravity centre is far away from the orifice. That rises owing to the fact that the storage pressure influences directly the speed of the jet.

Concerning the total quantity of rain out, one notes obviously that the higher the pressure is, the less the rain out is significant. That is related to the fact that by increasing the pressure, the speed of the jet increases and thus mechanical fragmentation generate finer drops which can then evaporate more easily.

It is significant to note that the total rain out can exceed 12% of the initial released mass flow. Indeed, the liquid recovered in the six retention dikes corresponds inevitably to an underestimation: we can't capture all the liquid part touching down on the ground. In addition, it should not be forgotten that the quantity of rain out depends on the altitude of the breach compared to the ground. For these tests, this parameter was fixed at 1,5 m. This means that if tests had been carried out at lower altitudes, the measured quantities doubtless would have been larger.

Impinging jets

For impinging jets, propane rain out can be observed. Total rain out is more significant for butane than for propane. As indicated in the case of the free jets, that is explained by the differences in boiling point and saturation pressure of the two gases.

Figure 5 represents, for butane and propane, the rain out part measured according to the distance between the obstacle and the outlet. The main tendency is that the longer the distance between the obstacle and the orifice is, more the rain out is small. That can be explained by the fact that the more the impact takes place late, the more the droplets forming the aerosol have time to evaporate before impact. It should be noted that it is possible to connect the measured rain out with the liquid fraction theoretically calculated for the same free jet at a distance equal to that of the obstacle. Qualitatively, it is interesting to note that after releases, the liquid present in the retention dikes is sufficiently cold (below the boiling point) so that the mass transfer seems to govern the pool evaporation [START_REF]Committee for the prevention of Disasters (TNO) Methods for the calculation of physical effects, CPR 14E "Yellow Book[END_REF]. The observation of rain out records as a function of time during release tests shows that less than one minute is required to observe liquid accumulation in retention dikes. This might correspond to the time required to cool down the obstacle and retention dike enough to be able to "capture" a fraction of the liquid part of the jet. This duration of one minute is of course a function of many parameters (nature of the gas, release and ambient conditions, distance from the obstacle, nature of obstacle and retention dike, etc..) but for a first approach, it is an order of magnitude that we observed in many cases in these tests carried out with LPG and also in the case of Ammonia [START_REF] Bouet | AMMONIAC -Essais de dispersion atmosphérique à grande échelle INERIS[END_REF] tests carried out 6 years before.

Thus, a simple method to characterize the source term resulting from an impinging two-phase jet, can be to considerer that, during the first minute of release, all the droplets are vaporized in contact with the obstacles and that, beyond the first minute, part of the droplets will be captured by the obstacles becoming enough cold to contribute to the pool formation of which it will be necessary to evaluate the evaporation rate.

The figure 6 shows an example of a rain out record as a function of time that comes from an impacting jet of propane. The experimental conditions are :

• storage pressure : 9.6 bars,

• orifice diameter : 10 mm,

• distance of the obstacle distance : 0.86 m,

• ambient conditions : temperature : 22.5 °C, relative humidity humidity dew point : 16.2°C.

65%, temperature

Water of the atmosphere makes part of the rainout due to the phenomenon of jet-entrainment that mixes the released propane with moist air. The measured mass in the retention dike results from an equilibrium between rain out of this mixture and his evaporation. When all the phenomena are in a steady-state in terms of temperature, a slope can be observed on the curve. The component evaporation is certainly very weak: during the jet, the "air" above the pool could be saturated with LPG vapours. In a first approximation the evaporation component can be neglected so the slope corresponds to the accumulation on the ground of a part of droplets and a part of condensed water coming from ambient humidity. Moreover, after releases we observed the almost systematic formation of "ice" in the retention dikes like on the obstacle. The nature of this "ice" was not analyzed but it is very probable that it is not entirely made up of water. Indeed, the observation of this solid reveals that while it's melting, cavities appears on the solid surface as if a gas (is it LPG or a LPG hydrate?) was desorbing after being captured by initial solidification. Thus, it appears that the determination of the pool evaporation rate will have to take into account the possible presence of a solid part whose nature and behaviour is not well defined.

Release duration

Conclusion

In order to develop models of flashing releases as encountered in realistic industrial environments, INERIS carried out large-scale experiments with propane and butane. In the first part, this article presented the large scale experiments. The second part was dedicated to the main results concerning the rain out formation.

We presented the influence of type of product, storage pressure, type of jet and distance of impact over the rain out formation. Moreover, we highlighted difficulties to interpret rain out measurements and to evaluate pool evaporation rate due to the presence of the water in the atmosphere.

Following these tests, it seems significant to continue the investigations to understand the influence of the air moisture on the formation of the rain out. Moreover, pool evaporation model taking into account a solid part in the pool will have to be developed.

Figure 1 :

 1 Figure 1 : Photograph of the test field

Figure 2 :

 2 Figure 2 : Diagram of the experimental set-up

  the orifice of the centre of the retention dike i The mass measured in the retention dike i o Rain out as a function of storage pressure (butane) Position of each retention dike (in m)

Figure 4 :

 4 Figure 4 : Rain out as a function of storage pressure (butane)

Figure 5 :

 5 Figure 5: Rain out as a function of the obstacle distance

Figure 6 :

 6 Figure 6 : Example of a rain out record as a function of time

Table 1 . Values of parameters set for the experimental trials Parameter

 1

		Value
	Product	Propane Butane
		Saturation Pressure + 0 bar
	Storage	Saturation Pressure + 1 bar
	pressure	Saturation Pressure + 3 bar
		Saturation Pressure + 6 bar
	Type of jet	Free jet Impinging jet
	Distance of impact	0.8 1.6 2.6
	Exit orifice shape and size	Circular (diameter of 10, 15, 20 and 25 mm) Rectangular (9*9, 6*18 and 3.2*25 mm 2 )

Table 2 . Rain out distribution as a function of pressure storage

 2

	Storage pressure (bar) / Position of the rain out gravity centre (m)	Position of the center of retention dike (en m) 2.6 3.9 5.1 6.4 7.5 8.3	Total
			% rain out in each retention dike		Rain Out
	2.6bar/<4.7m	1.6%	3.5%	5.2%	1.6%	0.0%	0.0%	11.8%
	3.8 bar/6.7 m	0.0%	0.0%	1.4%	3.7%	2.7%	0.5%	8.2%
	5.6bar/>7.0m	0.0%	0.0%	0.9%	1.1%	0.9%	1.5%	4.3%


Olivier Salvf

Bruno Debray
email: bruno.debrav@ineris.fr.

ARA MI S: An integrated risk assessment methodology for SEVESO Plants

Keywords: Risk analysis, Risk assessment, SEVESO, land use planning, risk reduction, safety barriers, safety culture, safety management, vulnerability, risk severity

This paper intends to give a very general description of the ARAMIS Methodology and to show how it answers the needs of various stakeholders concerned by the safety of industrial plants.

ARAMIS is divided into six major steps, which will be described shortly in this paper. The potential end users of ARAMIS are mainly the industry, the competent authorities and the local authorities. If all of them have an interest in the same risk management process, their needs are slightly different. Their expectations are detailed and the way ARAMIS brings an answer is explained in this paper.

Introduction

ARAMIS overall objective was to build up a new Accidental Risk Assessment

Methodology for Industries that combines the strengths of both deterministic and riskbased approaches. It was also to provide a way to reduce or at least explain the discrepancies of the results produced by different risk assessment approaches that wer observed, for example in the ASSURANCE project [START_REF] Hourtolou | ASSURANCE -Assessment of the Uncertainties in Risk ANalysis of Chemical Establishments[END_REF]. Co-funded under the 5th EC Framework Programme, ARAMIS was a three-year project that started in January 2002. Four years later, the basic methodology is achieved and aims at becoming a supportive tool to speed up the harmonised implementation of SEVESO II Directive in Europe. This paper summarises the major features of the methodology and shows how the needs of ARAMIS potential users are addressed.

Needs of potential ARAMIS users

The potential end users of ARAMIS are numerous but the most concerned are the industry, the competent authorities and the local authorities. If all of them have an interest in the same risk management process, their needs are slightly different. Plant operators need a method to identify, assess and reduce the risk. This method has to be accepted by the competent authorities. This method also has to bring useful information about the ways to reduce the risk and to manage it daily. The competent authorities need to be able to assess the safety level of the plant, particularly through the safety report. They need to know why scenarios have been kept for modelling of consequences. Both need to assess the influence of the management on the safety level. The plant operator has to improve its management to reduce the risk and the competent authority to assess a true risk level which takes into account this major influencing factor. About 80% of the major accidents have causes related with human and organisational factors, which is a sufficient reason to take these aspects specifically into account. The local authorities are interested in land use planning issues. They need a clear view about the risks or hazards the population actually faces. They also want to get information that can be used in decision processes, which now often involve the population. Basically, their capacity is about reducing vulnerability either by limiting the number of targets exposed to the risk or by introducing barriers between the source and these targets. They also need to trust the plant operator and competent authorities when they propose risk or consequence-based contours from scenarios. The aim of ARAMIS is to answer all these needs. It is also to make the convergence between the deterministic and the probabilistic approaches and to resolve some difficulties inherent to each of them [START_REF] Kirchsteiger | On the use of probabilistic and deterministic methods in risk analysis[END_REF]. As far as the deterministic approach is concerned, the limit deals with the difficulty to justify the choices of the reference scenarios used for land-use planning decisions. For the probabilistic approach, the difficulty resides both in producing the probability data and in interpreting the results to take appropriate decisions. ARAMIS does not completely solve these difficulties but furnishes the tools and the structure to improve decision-making. It also provides a framework for the definition of further research programs as discussed in the last paragraph.

Main features of the ARAMIS methodology

ARAMIS is divided into six major steps.

1. Identification of the major accident hazards (MIMAH) 2. Definition and evaluation of safety systems 3. Assessment of the management efficiency 4. Definition of the reference accident scenarios (MIRAS) 5. Risk severity mapping from the set of Reference Accident Scenarios 6. Vulnerability mapping of the plant surroundings A last step involves the crossing of this information for decision making

Identification of the major accident hazards (MIMAH)

MIMAH [START_REF] Ch | Aramis Project: Effect of safety systems on the definition of reference accident scenarios in SEVESO establishments[END_REF] is the method for the identification of major accident hazards. It is based mainly on the use of bow-tie diagrams composed of a fault tree and an event tree. These turned out to be a very powerful tools to communicate on risks, in particular towards non-technicians (managers, politicians, etc.). The major input of ARAMIS was to define a precise bow tie structure and to define precisely and exhaustively the list of equipment, potential critical events and their consequences. The critical events were defined to be either losses of containment for fluids or losses of physical integrity for solids. The complete list contains twelve critical events including breach, collapse, explosion, etc. From a description of the plant including the chemical substances used, produced or stored, it is possible from MIMAH to list all the critical events susceptible to occur in the plant. For each of these critical events, MIMAH allows to identify all their consequences in terms of secondary events and dangerous phenomena. Then, MIMAH provides the user with a set of generic fault trees, which are based on the most frequently observed causes. From these generic fault trees, the user will build specific fault trees that take into account the specificity of the studied plant: types of process used, presence of equipment, etc. The specific fault trees are obtained mainly by the suppression of causes and consequences which are not relevant to the context without any consideration on probability at this stage. It is important to notice that both the fault and event trees are considered without safety barriers, which will be defined in the next step of the method. This has the advantage to make an explicit distinction between hazard and risk. This first step allows the identification of hazards. The next one aims at identifying the risks which result from the hazard scenarios and the failure of safety barriers.

An alternative to classical probabilistic approaches

Classical risk analysis methods propose to assess the probability of major accident and to decide from this evaluation whether the risk is acceptable or not. But, during the ARAMIS project, this calculation of the probability was shown not to be an easy task. An inventory of the probabilistic data sources was carried out and showed that many of the available data are not adequate for the tools developed in the first steps of the methodology. Only very generic frequency ranges could be obtained for causes of the critical events, which hindered the possibility to rely solely on the probability of events. However, one main objective of ARAMIS was to valorise through contextual frequency data the efforts made by the operators both in prevention and mitigation. An alternative method was developed, which focuses on generic values for safety systems and clear guidelines to lower the final frequency of identified scenarios. First, it aims at helping the user with the definition of the safety requirements applying to the plant. Then, the method helps the user to define the safety barriers [START_REF] Debray | Defining safety functions and safety barriers from fault and event trees analysis of major industrial hazards[END_REF] by promoting the concept of safety function and by providing different possible strategies of barrier implementation for a given safety function.

Defining the safety requirements

As it can be understood from the previous paragraph, the definition of the safety requirements is a keystone of the ARAMIS methodology. The proposed method is inspired by the IEC 61508 standard [START_REF]Functional safety of electrical, electronic and programmable electronic safety-related systems, parts[END_REF]. The idea is to guide the user in the identification of the risk reduction goals that should be associated with different scenarios. This approach has a triple interest. It helps the user improving the management of risks by defining clear targets. It helps the competent authorities checking the risk reduction measures. It provides an evaluation of the residual risks. The way it was built also reduces the stress put on the quality of probability values.

Once this work carried out in risk analysis, the resulting dangerous phenomena can be ranked according to their classes of probability and consequences in a Risk Matrix where acceptable risk levels are defined.

Assessing the influence of safety management and safety culture

The safety management has a strong influence on the capacity to control the risk. Here again, the interest of ARAMIS is to provide tools to assess the safety management system (SMS) and the safety culture and to take them into account to help the operators identify the opportunities for improvement. The approach in ARAMIS [START_REF] Duijm | ARAMIS project: Effect of safety management's structural and cultural factors on barrier performance[END_REF] consists in devising a process-oriented audit protocol focusing on the activities relating to the life cycle of the safety barriers including design, installation, use, maintenance and improvement activities. For each, ten important structural elements are evaluated as requirements for the SMS. The outcomes of the audit are then combined with the results of a safety climate questionnaire collected from employees in order to get a contextual level of confidence, in particular regarding behavioural barriers. The questionnaire is made up of eight cultural factors that characterise a company's safety culture.

•

learning and willingness to report • felt responsibility • safety prioritisation, rules and • trust and fairness compliance • leadership involvement and • work team atmosphere and commitment support • risk and human performance • motivation, influence and limitation perception involvement From the previous step, each type of barrier was given a generic level of confidence indexed on its probability of failure on demand. These indicative values require then to be adjusted from the local context where they are implemented and maintained. For instance for a behavioural barrier, the generic confidence in the barrier is adjusted depending on whether the operator knows the stakes of his actions, or his decisions require complex diagnosis, conflict with production. The aim of the project was also to aggregate the results from the auditing and questionnaires into a final score for adjusting -possibly lowering-the generic values into contextual ones. This link and the whole scoring process was obviously an ambitious goal and still needs to be worked out. The case studies already helped getting some benchmark between different types of management and enabled eventually to propose a set of "minimum requirements" for both the culture and management system in order to anchor a first scoring scale. This remains however an important area of research.

Risk severity assessment and mapping

Each reference accident scenario (RAS) is defined by an initiating event that leads to a critical event, which can potentially lead to different dangerous phenomena. For each phenomenon, a severity index S Dp has been defined [START_REF] Planas | ARAMIS project: application of the severity index[END_REF] in a single scale ranging from 0 to 100 according to its intensity which varies with the distance from the plant. For each RAS the risk severity is defined for one scenario as the combination of the probability of the phenomena with their specific severity S D PJ. Risk severity can be represented for each scenario in a geographical way, as a function SRA s (d) of the distance from the source term. A final mapping of risk severity considering all RAS is then obtained by multiplying the frequency of each RAS with its specific risk severity index. Risk severity mapping as it is defined provides an innovative way to aggregate the information for a decision-maker to elaborate relative priorities for land-use or emergency planning purposes. However, the range of values obtained with such an approach still requires to be interpreted and the decision making process to be adapted to this new approach.

Assessing the vulnerability

The last innovative attempt from ARAMIS is to address the vulnerability of the environment independently of the hazardous site [START_REF] Tixier | Vulnerability of the environment in the proximity of an industrial site[END_REF]. This has the fundamental interest of allowing the local authorities to take useful decisions to reduce the global risk level by reducing the vulnerability whereas the plant operator only can act on the potential hazard or risk of the installation. The vulnerability is calculated on the basis of a multicriteria decision-aiding approach. With the development of new ways of governance involving local population in riskinformed decisions, the main interest of this approach is to base the vulnerability study on stakeholder risk perception through expert judgement elicitation. On a given spot of the environment, the vulnerability is thus characterised by the number of potential targets and their relative vulnerability to different phenomena. The global vulnerability is a linear combination of each target vulnerability to each type of effect for the various types of impacts.

Conclusion

The ARAMIS methodology was briefly described in this paper. It aims at offering an alternative way to the traditional risk-based and consequence-based methodologies for risk analysis by providing a series of integrated tools. These were designed to answer the specific needs of potential ARAMIS users who are industry, competent authorities and the local authorities. They were also elaborated to solve some of the difficulties raised by the lack of reliable data, namely concerning the accident frequencies. By promoting the barrier approach, ARAMIS helps the users defining the safety requirements, which apply to a plant, and therefore helps the competent authorities verifying the explicit control of risk by the operator. This approach also enables an easy and explicit identification of the reference accident scenarios, making the communication between the stakeholders easier or at least more straightforward and structured. The same applies to the approaches of the severity and the vulnerability, which are exploited through a clearly understandable spatial representation.

Acknowledgements

The work presented in this paper has been elaborated in the frame of the EU project ARAMIS "Accidental Risk Assessment Methodology for Industries", co-ordinated by

INERIS (F) and including EC-JRC-IPSC-MAHB (I), Faculté

Polytechnique de Mons (B), Universitat Politècnica de Catalunya (E), ARMINES (F), Ris0 National Laboratory (D), Universita di Roma (I), Central Mining Institute (PL), Delft University of Technology (NL), European Process Safety Centre (UK), École des Mines de Paris (F), École des Mines de Saint Etienne (F), École des Mines d'Alès (F), Technical University of Ostrava (CZ) and Jozef Stefan Institute (Si). The project is co-funded under the Energy, Environment and Sustainable Development Programme in the 5 th Framework Programme for Science Research and Technological Development of the European Commission.