1. European Commission, DG Environment Air & Industrial Emissions Unit
Seveso Directive on the control of major-accident hazards involving dangerous substances Assessment under Article 4 of Directive 2012/18/EU
European Commission, DG Environment
Air & Industrial Emissions Unit

2. Scope of work
Develop a framework assessment methodology to support the assessment of major accident potential of a substance (July 2013–Nov 2014)
For Member States and the Commission
Identify details of information to be provided
Identify questions to be answered
Provide tools which can be used in each of the steps of the assessment (substance identification, initial screening, preparation of notification file, submission, assessment and conclusion) 2

3. Methodology
A. Research on existing modelling/guidance 1. Elements to be considered in initial screening 2. Identification and analysis of suitable consequence assessment models 3. Identification of specific models or guidance on environmental consequences B. Development of accident assessment methodology and associated guidelines 4. Development of accident scenarios 5. Guidance on considering additional elements

4. Methodology 6. Guidance on the notion of ‘major accident’
7. Guidance on interpreting results of consequence assessment modelling
C. Finalisation
8. Workshop second semester 2014 – presentation and discussion of results with stakeholders
9. Draft the framework assessment methodology

5. Task 1 – Elements in initial screening
Clear description of the characteristics listed in Article 4(1)(a),(b) and (c)
Clear description of the important properties of dangerous substances that can play a role in a major accident, in line with Article 4(3) list of required information
Examples of cases where a major hazard potential clearly exists

6. Task 2 – Analyis of consequence models
Review of main tools available for consequence calculations - evaluation of their strengths, weaknesses and suitability for derogation process
A large number of software tools has been developed (especially for Computational Fluid Dynamics) – focus on list of main tools/models
INERIS guidance (called Ω) on modelling accident consequences – expert consultation – literature review – experimental results

7. Task 3 – Environmental consequences
Objective - Identification of specific models or guidance allowing assessment of the environmental consequences of accidents
Few established methods (especially quantitative)
Approach - description of each tool/method–data and outputs - Evaluation of robustness and sensitivity of information - Assessment of potential use in context of Article 4

8. Task 4 – Accident scenarios
Objective - Design a process for defining relevant worst case scenarios in the context of assessment under Article 4
Risk assessments based on worst case scenarios are widely used (e.g. in land-use planning) =› review national practices - literature - past accidents
Expected result = methodology for defining worst case scenarios suitable for an assessment in the framework of Article 4

9. Task 5 – additional elements
The containment/generic packing should be taken into account for the purpose of assessing the major accident potential of a substance based on its physical form
sensitive parameter of the risk assessment method defined under Task 4
Assessment process may not be easy – since it should be valid in a large number of cases

10. Task 5 – Additional elements
Approach - Highlight cases where the worst case approach would not be fully relevant – especially when specific packaging is used
Expected results
Guidance on specific cases that need further development
Guidelines on integration of the element of packaging/containment into the definition of the worst case scenarios

11. Task 6 – Notion of 'major accident'
Objective: Provide guidance on the notion of “major accident” in sense of Article 3 Sev III
Approach - Compare MS understanding and interpretation (e.g. National LUP policies and cut off values) – literature research on thresholds (e.g. Environmental Harm Index)
Outputs - Summary of existing cut-off values in LUP - Summary of values in literature - Overall guidance on how to assess

12. Task 7 – Interpreting the models
Objective - explain how to interpret assessment results and draw conclusions
Approach/outputs
review and summary of previous tasks outputs
Identification of potential knowledge gaps for decision-making
short literature review on existing decision matrices in the field of risk assessments
Proposal of framework for decision making, taking into account the uncertainties identified

13. Task 8 - Workshop
Presentation of results to obtain feedback on draft methodology and integrate it in final methodology
One day in Brussels – second semester 2014 – EN
Background documents sent out on beforehand
20 to 50 participants, including Seveso Expert Group/other national Seveso experts/experts from academia and industry representatives – possibility for written comments after meeting

14. Task 9 – Draft framework assessment method
Objective - allow MS and EC to carry out a logical and easy-to-implement assessment of a request for derogation
Approach
Development of a decision tree
Drawing together guidance developed in Tasks 2,3,5,6,7
Taking into account feedback from workshop
Important caveat – guidance would not suffice - expert judgement will always be required

15. Issues to be addressed
Survey to collect info on consequence models (incl. environmental), cut-off values used in LUP, definition of 'major accident', impact of packaging
Question for discussion with MS
Should it be allowed to demonstrate that a major accident cannot take place below a certain threshold? This could result in a proposal to list a certain substance in Part 2 with higher thresholds than those that would normally apply to its category?