International workshop on the safety assessment of nuclear installations for combinations of external hazards

In response to the technical and scientific needs emerged recently in this area, the Working Group of External Events (WGEV) and the Working Group on Risk Assessment (WGRISK) initiated a joint task entitled Combinations of External Hazards – Hazard and Impact Assessment and Probabilistic Safety Analysis (PSA) for Nuclear Installations. This task addresses practices in member countries in considering combinations of external hazards in the design, operation, and safety assessment of nuclear installations. The first phase of the activity was a survey sent to the members of WGEV and WGRISK in order to develop an informed understanding of the regulatory requirements and the technical approaches regarding the treatment of combined external hazards, characterising integrated hazard impacts and performing PSA for combined external hazards.

The second phase of the task will be a workshop where subject matter experts will discuss the nature of combined hazards, hazards impact assessment, and PSA for combined hazards to gain more detailed insights and to draw further conclusions on the topic.

The workshop is expected to help identify and characterise important hazard combinations, analyse the state-of-the-art in assessing the integrated impacts of hazard combinations, as well as in developing PSA for hazard combinations. The workshop discussions will also support the identification of further research and development needs and potential for improvements in the safety assessment of nuclear installations for combined external hazards including PSA in particular.


The focus of the workshop is on exchanging information on the various workshop topics addressing commonalities, key differences and challenges in the safety assessment of nuclear power plants for external hazards. The workshop will provide a forum for discussions and for sharing ideas between nuclear safety professionals including specialists in external hazards and PSA.

The workshop will include plenary and technical sessions in addition to a facilitated wrap-up session. Active participation of the workshop attendees in the discussions as well as formulating conclusions and recommendations is highly appreciated. Information obtained as a result of the workshop will provide a better understanding and improved interpretations of subjects, topics and issues related to safety assessment of nuclear power plants for external hazards.

A joint WGEV-WGRISK report (workshop proceedings with summarised results and some conclusions and recommendations for follow-up activities) will be prepared on the basis of the information presented and discussed during the workshop.

Suggested workshop topics

Presentations addressing all issues and topics related to safety assessment of nuclear power plants for external hazards are requested.

The following topics are planned to be addressed at the workshop:

  • Regulatory environment related to assessing combinations of external hazards (including regulatory requirements and guidance);
  • Supporting data and uncertainties as well as operational experience regarding combinations of external hazards;
  • Selection and assessment of combined external hazards (including the use of deterministic as well as probabilistic approaches);
  • Assessment of integrated hazard impact, as well as the associated plant response and fragilities (including input to PSA);
  • Risk assessment (PSA) for combined external hazards (including modelling of accident sequences, risk quantification and interpretation of results);
  • Overall experience from safety assessment for combined external hazards (including lessons learned as well as recommendations on good practices and new initiatives in this area).

Draft agenda will be available at the end of June 2023.

Dates and deadlines

Deadline for abstracts submission

26 May 2023


Submission Form

Notification of accepted presentations

16 June 2023


Deadline for attendance registration

14 July 2023

Registration Form

Deadline for presentation submission

28 August 2023



The workshop is open to participants from the OECD and NEA member countries.

Registration form


Location and accommodation

The workshop will be hosted by the Institut de Radioprotection et de Sûreté Nucléaire (IRSN) in Fontenay-aux-Roses, France. Fontenay-aux-Roses can be easily reached from Paris by metro and bus.

Venue Address:

IRSN Auditorium

31 avenue de la Division Leclerc

92260, Fontenay-aux-Roses



Security and badges

On arrival, you must register at the IRSN Reception desk and give your passport or identity card to obtain a visitor's badge. The badge should be returned at the same place and you will get back your passport or your identity card. You can keep the badge for the 3 days or obtain a badge each day at the same place. For registration, you must fill in the information required by 14th July 2023 using the registration form. Please arrive well in advance of the start of your meeting to allow sufficient time for the registration formalities. For security reasons, you are requested to wear your visitor's badge at all times.



By plane

Paris Orly Airport:
at 18 km

Paris Roissy Charles de Gaulle Airport:
at 40 km

By car

From Paris/Porte de Châtillon:
take D906 direction CLAMART/VERSAILLES. After 4 km, you arrive at Place de la Divison Leclerc.

From Versailles:
take highway A86, Exit CLAMART PARIS PORTE DE CHÂTILLON. Take D906, after 3 km, you arrive at Place de la Division Leclerc.

By train

RER B (Charles de Gaulle/Robinson):


Then Bus 394: stop DIVISION LECLERC.

RER C (Versailles Chantier/Massy Palaiseau):


Then Bus 394: stop DIVISION LECLERC.

By metro

Line 4:


Then Tramway T6, Stop DIVISION LECLERC.

Line 13:


Then Tramway T6, stop DIVISION LECLERC



Participants have to make their own hotel reservations.